@@superdau Lots of different non-linear crystals can produce green, KTP happens to be a very efficient one. I have a lot of photo's of this unit taken apart, google this term to find the thread: "TwoTrees T20 1064 nm Engraver - 2 W average, 15 KW peak power." It's at the photonlexicon forum
Hey there！ We just wanted to give you a huge high five for your awesome video explaining how our TwoTrees 1064nm Infrared Laser works! Your explanations were super clear and easy to follow, and we loved how you used fancy equipment like the Gentec pyroelectric sensor and Thorlabs fast photodiode. 🤓👍 And let's not forget about that Second Harmonic Generation (SHG) explanation - you rocked it! We were all impressed with how you showed us how a Potassium Titanyl Phosphate (KTP) nonlinear crystal can turn boring old 1064nm infrared light into cool 532nm green light.🎉🔥 We also appreciate any feedback or suggestions you have about our product. We're always looking to improve our stuff, so don't hesitate to contact our friendly TwoTrees team with any questions or ideas you may have. Thanks again for your awesome review and for sharing your knowledge with our audience. We can't wait to keep in touch and provide you with the best service possible. 🙏🏼😎🚀
Received a TwoTrees 1064 nm laser, the box includes everything you need to hook it up to an engraver controller including a 12 VDC power supply, but the included documents don't tell me anything about hooking it up for non-engraver use to pump a KTP crystal. I just need to know the PWM voltage level and permitted duty cycle and if continuous CW (Q-Switched output of course) is permitted just using an on-off DC voltage (not pulsed, just used to turn it on and off) into the PWM line and if so, what voltage? +5 VDC? I promise not to shoot myself in the eye :) Have OD 12+ 1064 nm goggles. It's the green I also need to watch out for. Anyone have info which could help me? The Two Trees web site doesn't give any information regarding the PWM I can find as they aren't selling these for someone to do what I want.
@@laserhobbyist9751 Directly connected to a DC power supply to act as a ttl circuit signal is possible, the allowable voltage is 5v, but so start the laser head is only able to maintain the state of the strongest light, more wear and tear of the laser head, can be, but do not recommend trying.
@@LesLaboratory Yes true. Such a item under $500 is incredible. Got me thinking perhaps a means of evaporating very high melting point materials for thin film vacuum deposition. Be it a very limited amount of material. But if only a 100 nm thickness or so x 10 mm square is required. A few nano grams depending on the material evaporated should not take long. I need to do some math to check this out.
Some clinical ophthalmology lasers provide both a Q-switched Nd:YAG laser and a frequency doubled output to provide two different laser wavelengths for ophthalmic treatments (capsulotomy or trablecoplasty). At least one commercial product advertises 0.3-10 mJ per pulse (4 ns) for 1064 nm output and 0.3-2.6 mJ per pulse (3 ns) for 532 nm doubled output. They always have red aiming beams.
Thanks! I have not, but is would be interesting to see if there is anything there. I suspect though that I am right at the limit of what can be resolved with my current equipment, though I am told there are ways and means!
Fascinating stuff, well done. Always a treat. Got my little optical bench and M6 cap screws, just waiting for the laser mounts. Wife is giving me the stinkeye as the cost creep up.
The green beam emitting from the crystal in the stand was straight out of sci-fi. I generally understand the physics of it, but clearly have a lot to learn about non-linear crystals. Awesome. 👍
This channel is severely under rated. You deserve way more subs than you currently have. I have officially subbed to your channel at 22.2 k subs, this channel will have atleast 500k in the following years
@@LesLaboratory of course you do my friend! I would expect nothing less lol. Even your most simple videos teach me something awesome and new. Thanks for the reply, can’t wait for more!
Agreed! He's answered several questions I've had in a few of his videos I've viewed none of the other laser specialists have touched upon in theirs. It's why I subscribed.
All interesting stuff and watched quite a few of your videos. Very nicely presented and a joy to watch . Back in the 2000’s I used to install large CO2 industrial laser cutting machines ie triumph , bystronic and the American PRC lasers from 1.5kw up to 8kw . Back on the day there was an 8kw at Sussex university which was for heat treatment and a few other things off memory. The purple discharge from the resonators always used to be awesome . Massive turbines for vacuum pumps etc etc . These were all non fibre and used mirror blocks on the gantries. To think back then there were no YT channels around!!! And I even paid 24k for a 3d printer back in 2006 !!!! . How prices have come down and technology has moved on . Channels like yours are so vital to the education of people and to expand their knowledge and interests in life . Got a sub from myself 👍 Oh yeh green laser and smoke 😃🇬🇧
Thanks! That sounds like a very cool job! I saw a huge CO2 Laser for sale on eBay lately, unfortunately nowhere to put the thing! The stuff we have access to these days, for the price, is simply astonishing, and from what I am seeing, is only going to get better. Soon high power Fiber Lasers will start turning up at "teardown" prices! Cheers!
Very Sweet laser indeed. The simplicity of passive Q-switching is just so elegant. Only thing I never like about these packages is that you can not really do much to them to change the output beam characteristics. SHG is very fun to play with and IMHO one of the most beautiful processes and still quite easy to achieve. With sufficient peak power practically any non linear crystal starts converting your fundamental. Take it from there to OPA and you have yourself a tunable broadband light source that you can seed with pretty much anything. Your Supercontinuoum for example.
Yeah, passive Q-switching is nice, but as you say, there is no control over the output energy and you can see at 6:56, the pulse to pulse stability is pretty poor as well. I have a crusty broken LBO that I managed to coax some green photons out of. Now an OPA/OPO, that would be something. It would be interesting to see how achievable this is on a tight budget. I am hoping to do a THG setup (LBO on order), to see if I can either drive a Fiber directly, or pump the dye Laser with it.
@@LesLaboratory Yeah, shot noise is not something that these lasers are built for. Once you're done with the experiments you have planned and you're brave enough it would be worth checking out if the laser cavity is extractable, or if everything is cemented together. If you set up the cavity on a bench and the absorber is separate, you may be able to exchange it to tweak the time constant of the cavity or replace it for an active Q-switch. For non-linear stuff you obviously want peak power, and for Nd:YAG the sweet spot for energy extraction efficiency and output pulse energy is somewhere around 3kHz. The pulse duration is probably going to grow as well, but that would still give you quite a significant increase in peak power. OPO/OPA is going to become efficient around 1GW/cm², difficult to achieve at ~10kW peak power, but doable at ~100. I achieve about 50% conversion using 400kW peak power, 2ns pulses to pump BBO. You could also just pump Ti:Sapphire directly with the green output to drive a broadband cavity from 700-900nm. Less exciting though :)
Nice! 18kw Pulses, that will be very useful. I am looking forward to seeming more videos. I have some interesting projects coming up as well. Also, if you can warm the SHG crystal to it's optimum temperature you will get more power out!
Totally! At these powers, I figure I can get away without a heater, at least for now. Next stop the third harmonic... Cool, I look forward to seeing more of your stuff!
@@DAVOinIN Hmm, interesting to know. I had figured they all where to a degree, The Laserscopes are about the only somewhat experience I have had with pulsed DPSS Lasers.
@@Zenodilodon There's a ton of variability and it's all pretty interesting. There's Critical Phase Matching, Quasi Phase Matching, and more. For example, LBO can use thermal phase matching, but something like Lithium Niobate doesn't necessarily require it. It also completely depends on the crystal boule cut angle, fundamental/signal/idler frequencies, etc...
Great work, Les! I'll look forward to the dye laser step. There are $50k scientific Q-switched, frequency-doubled Nd:YAG lasers out there, and we had a couple of them in my former university lab. At 200mJ/pulse the beam focus would break down the air and produce a bright repetitive white-light flash, which my students and I used as a non-coherent light source for high-speed digital imaging. Your little engraving laser will not cause the air to flash, but might provide enough low-spatial-coherence light for the same purpose by pumping a dye cell if the efficiency is high enough. There's a lot of interest in bright, high-speed noncoherent light sources but, again, the price of admission is typically $50k. It would be great to do this at small scale and 2 orders of magnitude cheaper!
Thanks! The doubled or tripled light should easily pump a Dye Laser, though the Dye will need circulating though beuse of the high repetition rate (or I could be smart about how I drive the PWM signal into the Laser... I have a flash-lamp pumped Q-Swich YAG project that will break down air, but I never thought of using that light for imaging. Interesting! Recently I built a Supercontinuum Laser, generating light across the visible spectrum that could also be used for high speed imaging: ruclips.net/video/w1wSHizmbYg/видео.html
its honestly pretty amazing i had done something similar with a 808nm laser using a Nd:YVO4 and a KTP crystal to make a standard 532nm dpss laser, which is also common to see in chinese Dpss lasers.
If you wanna do a short little experiment: (Di-) Potassium Hydrogen Phosphate is common fertilizer and it's very easy to grow clear crystals with it and it's cheap way to make some non-linear crystals yourself. Just in case you need a quick and easy video idea.
Great video, loved the q switching explanation and graphic. Is the thickness of the non linear crystal important, maybe for efficiency or power levels? You never did say what the laser changes, “everything” is a wild claim. Maybe the addition of a non linear crystal lens to change from visible to invisible but that’s already well known and done.
Thanks! For thickness is depends on the application I guess. I just bought an off the shelf crystal, but ordinarily you would go through a design process with the manufacturer. Somewhere near the beginning I remarked that it changes everything for micromaching and nonlinear optics experiments at the price point. These are cheap, almost dirt cheap. I had actually priced up components to build one of these before I saw them advertised, and you would be looking at over $1000 in parts and a considerable investment in time.
If you projected non-coherent 1064nm monochromatic light through the KTP crystal, would it still convert to green? Or does the input light have to be coherent? This is the best demonstration of that frequency doubling effect I have ever seen. Excellent video!
The KTP needs coherent light because it needs to be phase matching. The ND:YAG you can practically pump with anything that has enough optical power. There used to be incandescent lamp pumped YAG Lasers.
@@LesLaboratory Those things use ridiculous amounts of power and aren't very efficient. I used to work with one, the power supply was 3-phase several kW and the laser head required a high flow of chilled water, but output was less than your one there (~1W avg power, active Q-switch). You could hear the water start to boil around the lamp if the current was turned up too high!
Wow... a fantastic demo and explanation. I think, your job is far far better than what I learned from NL optics at school. Keep going, wanna get more. By the way, could you upload a demo on SFG using two beams + crystal, like BBO/LBO? I CANNOT help but wait for
Thanks, I am glad you liked it! Yes, SFG is something I am working towards, but it is down to availability of parts. I am waiting for a suitable BBO to show up on ebay, though it might be possible with KDP.
I'm highly impressed, that Q-switched lasers have become so affordable. They can probably open opportunities to create cheap UV laser sources for multiphoton (actually two -photon) photo induced chemical reactions. The only question is where to get cheap fourth-harmonic generators ( BBO for example).
Thanks! The expense stacks up though! As well as BBO (or LBO) you need one or more polarization rotators as well to correctly match the incoming 1064nm and 532nm beams.
@@LesLaboratory This is true, additional optical componentes are needed as well as thermal stabilization, especially for 4-th harmonic crystals (several degrees Celsius). Temperature fluctuations can result in dramatic decrease of output power. Total costs can be much more than bare laser module, but still components are getting more affordable, still an optimistic trend)
Thanks for the explanation. A client recently bought a laser engraver (20W, 450nm) and we particularly decided for the model because of the option to install an IR head. PS: still no Patreon?
I owe most of my career to SHG green lasers as a service engineer with all the systems based on a Z fold cavity with the Q switch and the SHG crystal or crystals in some cases actually in the cavity instead of external to the cavity. Usually KTP for lower power systems and LBO for higher power with the latest incarnation using 2 LBO crystals within the cavity and capable of generating 300W Average power with maximum peak power of 1.33 MW in service mode but limited for customer use to 180W Average power and 800 KW peak power. All used for medical applications, aligning one of these resonators is a whole bunch of fun.
This sounds fantastic, that is some amount of power, that would be amazing for pumping Dyes! I have a little UV Z-Fold Laser that I have been repairing here.
12:47 is the crystal lattice why you get all the speckling in the laser itself but also the spurious emmission that you see in surroundings? The crystal being made up of many smaller prismatic shapes there would be alot of refraction and i imagine a kaleidoscope effect? Playing with lasers over the years i often wondered why the spilled light looks the way it does . Ive probably damaged my eyes looking at it, its mesmerising.
Hi Les, you make it look so easy! I love your episodes. I have an SSLE machine for my crystal glass business in South Africa, it stopped working during Covid and I received no more support from China, they just want to sell me a new machine! The system uses an active Q-Switch system and frequency doubling process; may I ask a few questions? I have been working on it for a year and there are no companies in South Africa that can help. 1). The system suddenly stopped doubling a week ago, could this be because the diode has become too weak! Is there a power threshold for doubling? It is a 50w DILAS fibre coupled system, 400um. The label says 780-1000nm - It is red, I am guessing it is 808nm? I tried a newer similar diode, it had the exact same label specs, but the beam was almost invisible - I am guessing 970nm - so no doubling ocurred. 2) 2 years ago the green laser beam started flickering, then came strong again..this happened several times, then the beam went dull green permanently. It was, though, still doubling from red to green (532nm). I have tried a different RF signal driver ( AA Optoelectronics in France) as I thought the Q-Switch wasn't switching and boosting the laser. No change, though I am testing with an Oscilloscope tomorrow. I have tried another 50w diode( also quite old), initially it doubled from red to green, suddenly it just stays red. I removed the Q-Switch it made no difference.. Would you possibly have any suggestions please? Things are getting a little tight now. Many thanks Richard Nield info@3dcrystalstudio.co.za Durban
This is a fascinating experiment. For low-power lasers, KTP crystals are the best choice for double frequency crystals. For medium-high power lasers, BBO crystal and LBO crystals from CRYSMIT should be better choices.
Robert L. Forward did something similar in his story "Roche World" when he had to change the "color" of a laser being used to drive a solar sail from IR to green (due to budget reasons).
Thorlabs is probably the best place in Europe. You would be looking at just under 200 Euros, which sounds like a lot, but eyesight is not replaceable at any cost.
amazing demonstration! I have one question tho, why does this conversion also work in green laserpointers? There you don't have those high peak powers, so do they have some additional optic in them? I am asking this, since "the thought emporium" tried the same thing as you, but he used an IR diode to pump his crystal, not a pulsed laser and he didn't manage to get it to work. Also what optical bench do you use and were did you get it? I saw similar ones on the Thorlabs website but they were very expensive.
In green laser pointers, they mount the KTP crystal within the cavity, where a huge amount of power is circulating. Imagine you had a small IR laser that produced 1mW from a 0.1% transmitting output coupler, for 0.1% or 1mW to escape, there would be on the order of ~1000X more light circulating in the cavity, and this is enough to generate SHG. Another consideration is power density. What I demonstrated is on a macro scale (the beam diameter is on the order of 2mm across) inside laser pointers the beam diameter is much smaller (microns) resulting in huge power densities even at low power. I got my bench from Thorlabs, and yes they are pretty pricey, but I got fed up with having to cut and drill metal to set up experiments. These are pretty convenient and well worth it. I did consider getting a metal shop to make me one, but it would have cost almost as much.
@@LesLaboratory Interesting, I thought that it had something to do with the power-density but I would have never thought that it could become so high in a small pointer. Also, have you ever measured the power of the green laser in your setup?
@@firefox1136 I have not measured the green yet, though it should be possible to get 60%conversion efficiency at least. I need to get a nother mount so I can tilt on the Y-axis and really tune this thing. I ordered an LBO crystal as well so I can attempt Third Harmonic Generation so see if I can get some UV photons out of this!
Great video! Can you comment on how you powered the module? I imagine that the laser head connections are set up for connecting to the laser engraver and thus not standardized. Did you use the laser engraver itself to power the laser or a home-built power system? If the latter, can you please elaborate? Thx.
Razor sharp beams excellent, I love this video😉👍. What collimation lens did you use? Where can I buy it, can you give me a link? I am planning to build this laser.
I think it's kinda funny that when laser diode is erroneously translated into English it becomes Laser Tree or two trees. Then these Chinese laser companies officially name themselves using these bad translations. Also I didn't know passive q-switching could achieve such high peak output. That's amazing.
Wow! Don't think that I've seen this demonstrated before. So, you are pumping the crystal with the IR laser? Does the crystal heat up? that would be my question. Thanks for the demo.
Thanks! Yes, 1064nm IR light enters the crystal and 532nm Light emerges. As far as I know, no significant heating takes place in the crystal. Any IR not converted into green, just passes through. Temperature control is often used as the lattice shape is related to the temperature. This means if you allow the temperature of the crystal to drift too much, the lattice is no longer matched to the wavelength, and efficiency drops off.
spectacular to see such a large crystal and they are at a reasonable price now? amazing to see the green beam just emerging out of it like that it is a nice optical illusion , i tried making a lamp pumped ndyag-doubled laser long time ago my dream was to see if i can get that beast working using 4x500w halogen lamps in a circular array wired in parallel so i only built the pump part of it and tried to get it to work with a dimmer switch but it was acting strange it would work at first then the light got bright as if the dimmer was not even there im not to savvy when it comes to more complicated circuit and electrical design, i have a glass tube that would presumably hold the ndyag inside the circular array cavity then i wanted to get the mirrors with mounts and eventually a doubling crystal and maybe have the whole thing water cooled using distilled water but it never went any further than building the pump which i still have and enjoy looking at once in a while , i did not get the rest of the parts though perhaps i was too timid with the costs and not sure of the success although i heard sam did manage to build one and get it to slightly work although it was weak beam coming out every now and then
On Aliexpress they can be had for about $20 USD for a 6x6x5 crystal, almost giving 'em away! :-) Interesting, do it! I saw a halogen lamp pumped YAG on eBay some time ago, and wished I had bid on it. I have a huge YAG rod, and the lamps and cavity reflector just waiting for some optics. The rod and lamps are about a foot long!
@@LesLaboratory well i should have made it more clear i am not using halogen lamps but rather tungsten filament halogen lamps like the kind you get at a store for a ceiling lighting lamp, the ones i have are 500w each and i don't think they don't make them anymore , most now are 300w but i basically wired them parallel in a circular array (well 4 of them anyways) and i calculated they would draw about 17 amps from my wall which may be nearing or exceeding the rated fuse outlet if mine are 15 or 20 amps so depending where i plug it perhaps but anyways im surprised the thing worked without melting apart with all the heat it put out in short time since im only using solder for the wiring and the wire is much smaller than the required 12 gauge its more like aaa battery wire lol in order to be malleable and compact enough to cram into the small package design but it works, would like to show you on cam if possible so you can maybe advise or tip me if this is even possible for a laser or give me better design idea, yeah i've seen the one you are talking about on ebay its like a big cylinder size of a small trash can i think they still have them maybe at throb labs
Thanks, this is very nice. I was wondering as them infrared lasers have become this cheap and whilst pulses are used to blast away tattoos I can see the industry switching more and more to laser welding. Robots can replace the cumbersome spot welding and say weld sides to car bodies with a continues seam. Slower but since robot do it 24h a day the end product is sealed and the end product has a much higher quality and its strength is far more predictable with a minimum of materials used.
@@LesLaboratory Sadly I am in Australia. Have over 50 lasers in stock mainly from repairs but we no longer receive strong ones even though we pay for them.
The collimator is built from the housing from a laser diode module , but I replaced the plastic lens with a glass collimating lens. At some point, I am going to turn a piece on the lathe, since it is a faff to align as it stands.
I think I need to get a large aluminium plate for my 40w FAP800 which is now working a treat with marco reps laser driver. I have a 2" long YAG rod which by the colour of it and the coatings on the ends seems to be a diode pumped rod and has a pencilled arrow on it showing the beam direction. Can I just pump the rod with the fibre laser and expect 1064nm output or do I also need a Q-Switch? Love the videos by the way, every single one of them are really informative and interesting. Keep up the great work Les!!
Thanks! You may well be able to pump the rod with it, though at that length, it is probably designed for side pumping. You only require a Q-Switch, if you require high peak powers, without it, you would have CW operation.
The power density required for visible SHG is ludicrously high, on the order of kilowatts per square cm. So with a pulsed laser with high peak power this is easy. For CW Lasers, such power densities are available within the cavity itself. Intracavity powers, even in a small laser of a few miliwatts output can be tens of watts (kW's per square cm).
thanks for it@@LesLaboratory , i see, my SLD's max power is 20 mW. i actually study single photo emission from quantum dots using our home-built TIRF microscope where 10mW/cm2 illumination is more than enough. so you suggest for my work BBO crystal would help? and instead of buying can i scavenge from any laser pointer like you did? many thanks again
It would have been interesting to see some numbers and waveforms from the pyrometer and photodiode to see how the KTP crystal changes the beam in the time domain and how (probably very) inefficient it is.
It would and I will. I am working on another video at the moment on KDP, but once that is done I will likely do a comparison video. Extracavity doubling can be very efficient if the peak powers are high and the setup is right (polarization, crystal angle and so on).
Can you do an Experiment with The Nonlinear crystal attached to peltier With bidirectional Hbridge controlled Pwm input to control heating and cooling of crystal and see the Temperature vs Wavelength characteristics of NL Crystal !!
Can you do Photonics Entanglement experiment ? Is it possible to use green laser crystal from opposite Directions to do the opposite of Input phone mean splitting into two ? Or both crystal and Diode Wavelength are Very spesific ??
I tried to reproduce the experiment on generating the second hormonics on a 1064 nm laser in a TO18 case with a power of 20 mW and a KTP crystal, but I did not get the green light. So I don’t know, either this pumping power is not enough, or Ali Express sent a different wavelength. There is a 3000 mW diode on Ali, I think I’ll try it. Or I can disassemble a regular green laser module and extract the part that generates 1064 nm, and use it with my own KTP crystal.
Not yet, I am looking at two avenues for short pulse lasers: Ti:Sapphire (If I can get the crystals cheaply enough) Fiber might be a possibility, again if I can get cheap doped fiber and a cheap fusion splicer. Neither approaches will be trivial though, and should keep me busy! :-D
Hello Les. I have a fiber laser engraver (50w). And I've purchased KH2PO4 to replicate your experiments. Do you believe that my laser can pump the non linear crystal?
Does the beam hurt when you touch it? I suspect not, as the energy per pulse is so small and the finger is probably going to be fairly transparent at 1064nm, causing the volume over which the energy is deposited to be fairly large. And what is that red light I see on the penny when it is away from the focal point? Obviously the bright white/pink light at the focal point is ablation incandescence, but that deep red light.... it doesn't look like camera-misinterpreted IR to me. It looks very suspiciously like UV excited ruby fluorescence. Is it possible then that we are seeing something like two photon absorption induced fluorescence of the trivalent chromium ions in the saturable absorber optic?? Can you hit your spectrometer with that light and do another video 😁?
It gets pretty warm. I only ran it at around 20% duty cycle for that portion of the video, so maybe half a watt. The red light is there because the head has a built in aiming laser, which is pretty useful, but there is no way to turn it off. Given its design purpose, it is remarkably coaxial with the IR beam over about 30cm or so.
I've heard that some IR lightsources can been "seen" would this be in the same 2ir=1green; but the nervous system merely gets a read on green photons without any ever being manifested?
This is a different effect. If you fire a pulsed IR laser at the retina, a cell can absorb two long wavelength photons in rapid succession, and register one of twice the frequency. I'm not sure of the mechanism involved, but it sound like two-photon absorption. What you are seeing in this video is the physical doubling of the frequency of light itself.
Amazing video! I watched many videos where use a KTP with a nd/yag pulsed laser. I have a q-switched 30W fiber laser from a laser marking machine. 1064nm with 30 khz to 50khz pulse frequency. Will it work with a kTP crystal ?
Without a doubt. At that average power, you will have to do some thermal management of the KTP though, and get safety glass that will block 532nm as well as 1064nm.
I have a 532nm laser but when I increase the power(A) in the driver the laser output power is reduced. Do you know which part of my device is damaged? My device is Spectra-Talon-532-40.Hope you can help, thanks
i am trying to understand what is average pw and peak pw, from what i know average is basically the amount of pw the lasing medium is emitting while running in normal cw mode and peak is when more pw is allowed to collect in the lasing medium either due to two things one being a q switch that is blocking the resonance from happening and allowing more atoms to get into the exited state from the pumping source before the switch is open and the remaining exited states are being stimulated by the rest of the incoming photons from the pump and released in a powerful pulse train and the other would be a similar q switch only one that is acting like a closed mirror that allows a closed loop resonator to form multi mega passes return trips of the photons back and forth to boost the pw then the mirror opens to release a powerful pulse train but i am wondering if your 15kw can be further increased if using this mirror type q switch instead or if its the same results? ok so if this peak pw only happens in 1 nanosecond but is being repeated that fast would this not mean the beam is basically cw and that much pw is being emitted every other nanosecond?? so its like a cw 15kw pw beam no?
You are on the right lines, but this particular crystal won't do it. The Light exiting the KTP consists of 532nm and residual 1064nm. It is possible to mix these with a BBO crystal to get UV light at 355nm. If you want blue, you would use mirrors in the YAG laser coated for 946nm, that you could then double to 473nm, with either LBO or BBO
Is there a way cheaper? I've seen a Nd:Ce:Yag + Cr4:Yag Rod 5x85+5mm with 1064nm coatings for around $250. Is it possible to get this to work with (many) LED or blue laser (2-8W) ?
Interesting, though when you figure in the cost of optics and machining a cavity ou migth find it gets expensive fast. Do you have a link? Pumping with LED's might be possible, but it would be insanely inefficient...
This one is pretty large at 6x6x5mm, however so long as the beam can effectively be coupled in, even small ones should work fine. I got green photons out of a broken LBO crystal at one point.
I have not measured that yet. I reckon maybe upto 60% conversion might be possible. I m hoping to do Third Harmonic generation with it (Just ordered an LBO crystal), so I will have to preform some serious measurements.
Kinda, it depends what you expect so see. It is possible for example to double the output of a He-Ne Laser, but the effect is exceedingly small, you would need a photomultiplier tube to detect the light, which would be at single photon levels. You can intracavity double to get the required power energy density, as is done in Green Laser pointers, but you would need proper optics, and a stable setup to achieve it. There is some info on Sam's Laser faq on rolling your own DPSS Laser.
Yes there are, they go down into the 180nm range I believe. My 355nm uses the same optical arrangement with a third harmonic crystal after the second harmonic one.
Yes but you need to remember the process is nonlinear and more and more inefficient the deeper you go. You can only get to the vacuum ultraviolet with this method, x-rays are absorbed by crystals and the conversion efficiencies even in the UVC are utterly, abysmally, miniscule.
I think it's certainly misleading to call it a 15KW laser. I certainly don't think it would even cut through 10mm of plywood. My crappy K40 would probably be better value if all people want is IR laser output.
The green beam just coming out of a transparent crystal looks unreal. As if it were a portal.
@@laserhobbyist9751
KTP as said in the video.
@@superdau Lots of different non-linear crystals can produce green, KTP happens to be a very efficient one. I have a lot of photo's of this unit taken apart, google this term to find the thread: "TwoTrees T20 1064 nm Engraver - 2 W average, 15 KW peak power." It's at the photonlexicon forum
Anyone want to see what is inside this laser? The PhotonLexicon forum Lounge section has a post showing photographs.
Hey there！
We just wanted to give you a huge high five for your awesome video explaining how our TwoTrees 1064nm Infrared Laser works! Your explanations were super clear and easy to follow, and we loved how you used fancy equipment like the Gentec pyroelectric sensor and Thorlabs fast photodiode. 🤓👍
And let's not forget about that Second Harmonic Generation (SHG) explanation - you rocked it! We were all impressed with how you showed us how a Potassium Titanyl Phosphate (KTP) nonlinear crystal can turn boring old 1064nm infrared light into cool 532nm green light.🎉🔥
We also appreciate any feedback or suggestions you have about our product. We're always looking to improve our stuff, so don't hesitate to contact our friendly TwoTrees team with any questions or ideas you may have.
Thanks again for your awesome review and for sharing your knowledge with our audience. We can't wait to keep in touch and provide you with the best service possible. 🙏🏼😎🚀
Received a TwoTrees 1064 nm laser, the box includes everything you need to hook it up to an engraver controller including a 12 VDC power supply, but the included documents don't tell me anything about hooking it up for non-engraver use to pump a KTP crystal.
I just need to know the PWM voltage level and permitted duty cycle and if continuous CW (Q-Switched output of course) is permitted just using an on-off DC voltage (not pulsed, just used to turn it on and off) into the PWM line and if so, what voltage? +5 VDC?
I promise not to shoot myself in the eye :) Have OD 12+ 1064 nm goggles. It's the green I also need to watch out for. Anyone have info which could help me? The Two Trees web site doesn't give any information regarding the PWM I can find as they aren't selling these for someone to do what I want.
@@laserhobbyist9751 Directly connected to a DC power supply to act as a ttl circuit signal is possible, the allowable voltage is 5v, but so start the laser head is only able to maintain the state of the strongest light, more wear and tear of the laser head, can be, but do not recommend trying.
Awesome to see 'second harmonic generation' like this, it is truly a sight to behold...cheers !
Thanks, It really is quite amazing!
Why isnt this channel better known? this is awesome content.
Thanks! To be fair it is a fairly new channel, but it is growing. Perhaps it will start copping up on social media as it grows...
You always have the best toys!
...but on a budget! :-)
@@LesLaboratory Yes true. Such a item under $500 is incredible. Got me thinking perhaps a means of evaporating very high melting point
materials for thin film vacuum deposition. Be it a very limited amount of material. But if only a 100 nm thickness or so x 10 mm square
is required. A few nano grams depending on the material evaporated should not take long. I need to do some math to check this out.
Some clinical ophthalmology lasers provide both a Q-switched Nd:YAG laser and a frequency doubled output to provide two different laser wavelengths for ophthalmic treatments (capsulotomy or trablecoplasty). At least one commercial product advertises 0.3-10 mJ per pulse (4 ns) for 1064 nm output and 0.3-2.6 mJ per pulse (3 ns) for 532 nm doubled output. They always have red aiming beams.
Pretty cool! Did you by any chance measure the pulse width of the SHG light?
Thanks! I have not, but is would be interesting to see if there is anything there. I suspect though that I am right at the limit of what can be resolved with my current equipment, though I am told there are ways and means!
The pulse duration will be just a bit shorter after SHG
Fascinating stuff, well done. Always a treat. Got my little optical bench and M6 cap screws, just waiting for the laser mounts. Wife is giving me the stinkeye as the cost creep up.
Thanks! Yeah, they do that ;-)
The green beam emitting from the crystal in the stand was straight out of sci-fi. I generally understand the physics of it, but clearly have a lot to learn about non-linear crystals. Awesome. 👍
It gets stranger still once you delve into it, but it sure is cool!
@@laserhobbyist9751 News to me, I have unrestricted posts and don't normally remove anything... Maybe it's youtube, can you obfuscate any links?
This channel is severely under rated. You deserve way more subs than you currently have. I have officially subbed to your channel at 22.2 k subs, this channel will have atleast 500k in the following years
Thanks for the positive comment! And thanks for the sub! I have many more cool projects in the works!
@@LesLaboratory of course you do my friend! I would expect nothing less lol. Even your most simple videos teach me something awesome and new. Thanks for the reply, can’t wait for more!
Agreed! He's answered several questions I've had in a few of his videos I've viewed none of the other laser specialists have touched upon in theirs. It's why I subscribed.
All interesting stuff and watched quite a few of your videos. Very nicely presented and a joy to watch . Back in the 2000’s I used to install large CO2 industrial laser cutting machines ie triumph , bystronic and the American PRC lasers from 1.5kw up to 8kw . Back on the day there was an 8kw at Sussex university which was for heat treatment and a few other things off memory. The purple discharge from the resonators always used to be awesome . Massive turbines for vacuum pumps etc etc . These were all non fibre and used mirror blocks on the gantries. To think back then there were no YT channels around!!! And I even paid 24k for a 3d printer back in 2006 !!!! . How prices have come down and technology has moved on .
Channels like yours are so vital to the education of people and to expand their knowledge and interests in life .
Got a sub from myself 👍
Oh yeh green laser and smoke 😃🇬🇧
Thanks!
That sounds like a very cool job! I saw a huge CO2 Laser for sale on eBay lately, unfortunately nowhere to put the thing!
The stuff we have access to these days, for the price, is simply astonishing, and from what I am seeing, is only going to get better. Soon high power Fiber Lasers will start turning up at "teardown" prices!
Cheers!
Wow that is so cool. Thanks Les, top work as always.
Thanks!
If your ultrafast measuring diode is compatible with 532nm you should scope the green light at time domain as well and compare with infrared.
Interesting, someone else mentioned this as well. I winder if there is anything to see...
Very Sweet laser indeed. The simplicity of passive Q-switching is just so elegant. Only thing I never like about these packages is that you can not really do much to them to change the output beam characteristics.
SHG is very fun to play with and IMHO one of the most beautiful processes and still quite easy to achieve. With sufficient peak power practically any non linear crystal starts converting your fundamental.
Take it from there to OPA and you have yourself a tunable broadband light source that you can seed with pretty much anything. Your Supercontinuoum for example.
Yeah, passive Q-switching is nice, but as you say, there is no control over the output energy and you can see at 6:56, the pulse to pulse stability is pretty poor as well.
I have a crusty broken LBO that I managed to coax some green photons out of.
Now an OPA/OPO, that would be something. It would be interesting to see how achievable this is on a tight budget.
I am hoping to do a THG setup (LBO on order), to see if I can either drive a Fiber directly, or pump the dye Laser with it.
@@LesLaboratory Yeah, shot noise is not something that these lasers are built for.
Once you're done with the experiments you have planned and you're brave enough it would be worth checking out if the laser cavity is extractable, or if everything is cemented together. If you set up the cavity on a bench and the absorber is separate, you may be able to exchange it to tweak the time constant of the cavity or replace it for an active Q-switch.
For non-linear stuff you obviously want peak power, and for Nd:YAG the sweet spot for energy extraction efficiency and output pulse energy is somewhere around 3kHz. The pulse duration is probably going to grow as well, but that would still give you quite a significant increase in peak power.
OPO/OPA is going to become efficient around 1GW/cm², difficult to achieve at ~10kW peak power, but doable at ~100. I achieve about 50% conversion using 400kW peak power, 2ns pulses to pump BBO.
You could also just pump Ti:Sapphire directly with the green output to drive a broadband cavity from 700-900nm. Less exciting though :)
Thank you! Clear and meaningful content.
Fantastic work as usual Les!
Thanks!
Nice! 18kw Pulses, that will be very useful. I am looking forward to seeming more videos. I have some interesting projects coming up as well. Also, if you can warm the SHG crystal to it's optimum temperature you will get more power out!
Totally! At these powers, I figure I can get away without a heater, at least for now. Next stop the third harmonic... Cool, I look forward to seeing more of your stuff!
Many of these SHG crystals aren't designed for thermal phase matching
@@DAVOinIN Hmm, interesting to know. I had figured they all where to a degree, The Laserscopes are about the only somewhat experience I have had with pulsed DPSS Lasers.
@@Zenodilodon There's a ton of variability and it's all pretty interesting. There's Critical Phase Matching, Quasi Phase Matching, and more.
For example, LBO can use thermal phase matching, but something like Lithium Niobate doesn't necessarily require it.
It also completely depends on the crystal boule cut angle, fundamental/signal/idler frequencies, etc...
Awesome work Les!
Thanks!
Great work, Les! I'll look forward to the dye laser step. There are $50k scientific Q-switched, frequency-doubled Nd:YAG lasers out there, and we had a couple of them in my former university lab. At 200mJ/pulse the beam focus would break down the air and produce a bright repetitive white-light flash, which my students and I used as a non-coherent light source for high-speed digital imaging. Your little engraving laser will not cause the air to flash, but might provide enough low-spatial-coherence light for the same purpose by pumping a dye cell if the efficiency is high enough. There's a lot of interest in bright, high-speed noncoherent light sources but, again, the price of admission is typically $50k. It would be great to do this at small scale and 2 orders of magnitude cheaper!
Thanks!
The doubled or tripled light should easily pump a Dye Laser, though the Dye will need circulating though beuse of the high repetition rate (or I could be smart about how I drive the PWM signal into the Laser...
I have a flash-lamp pumped Q-Swich YAG project that will break down air, but I never thought of using that light for imaging. Interesting!
Recently I built a Supercontinuum Laser, generating light across the visible spectrum that could also be used for high speed imaging: ruclips.net/video/w1wSHizmbYg/видео.html
It will be interesting to measure the power efficiency and the response time of the non linear crystal with your 2 sensors.
A couple of people have mentioned this, I will have a poke at it and see if there is anything to be seen!
its honestly pretty amazing i had done something similar with a 808nm laser using a Nd:YVO4 and a KTP crystal to make a standard 532nm dpss laser, which is also common to see in chinese Dpss lasers.
Nice understandable explanation of Q-switching - thanks!
Glad it was helpful!
If you wanna do a short little experiment: (Di-) Potassium Hydrogen Phosphate is common fertilizer and it's very easy to grow clear crystals with it and it's cheap way to make some non-linear crystals yourself.
Just in case you need a quick and easy video idea.
I have a bag of he stuff on my shelf ;-) I just haven't gotten around to it yet, but it could be pretty cool.
Wow, that's so fascinating! Thanks for sharing!
Thanks, you are welcome!
Great video, loved the q switching explanation and graphic. Is the thickness of the non linear crystal important, maybe for efficiency or power levels? You never did say what the laser changes, “everything” is a wild claim. Maybe the addition of a non linear crystal lens to change from visible to invisible but that’s already well known and done.
He said that this kind of peak power levels was never previously available this cheaply on a normal consumer unit
Thanks! For thickness is depends on the application I guess. I just bought an off the shelf crystal, but ordinarily you would go through a design process with the manufacturer.
Somewhere near the beginning I remarked that it changes everything for micromaching and nonlinear optics experiments at the price point. These are cheap, almost dirt cheap. I had actually priced up components to build one of these before I saw them advertised, and you would be looking at over $1000 in parts and a considerable investment in time.
That Cr: YAG crystal reminds me of a TR cell used in high power radar transmitters.
If you projected non-coherent 1064nm monochromatic light through the KTP crystal, would it still convert to green? Or does the input light have to be coherent? This is the best demonstration of that frequency doubling effect I have ever seen. Excellent video!
The KTP needs coherent light because it needs to be phase matching. The ND:YAG you can practically pump with anything that has enough optical power. There used to be incandescent lamp pumped YAG Lasers.
What @Zenodilodon said :-) I saw one on eBay years ago. It had what looked like a standard tungsten halogen lamp in the cavity. Wish I had bought it!
@@LesLaboratory Those things use ridiculous amounts of power and aren't very efficient. I used to work with one, the power supply was 3-phase several kW and the laser head required a high flow of chilled water, but output was less than your one there (~1W avg power, active Q-switch).
You could hear the water start to boil around the lamp if the current was turned up too high!
Wow... a fantastic demo and explanation. I think, your job is far far better than what I learned from NL optics at school. Keep going, wanna get more. By the way, could you upload a demo on SFG using two beams + crystal, like BBO/LBO? I CANNOT help but wait for
Thanks, I am glad you liked it! Yes, SFG is something I am working towards, but it is down to availability of parts. I am waiting for a suitable BBO to show up on ebay, though it might be possible with KDP.
I'm highly impressed, that Q-switched lasers have become so affordable. They can probably open opportunities to create cheap UV laser sources for multiphoton (actually two -photon) photo induced chemical reactions. The only question is where to get cheap fourth-harmonic generators ( BBO for example).
Thanks! The expense stacks up though! As well as BBO (or LBO) you need one or more polarization rotators as well to correctly match the incoming 1064nm and 532nm beams.
@@LesLaboratory This is true, additional optical componentes are needed as well as thermal stabilization, especially for 4-th harmonic crystals (several degrees Celsius). Temperature fluctuations can result in dramatic decrease of output power. Total costs can be much more than bare laser module, but still components are getting more affordable, still an optimistic trend)
i would love to see you try pumping a cuvette of R6G with that 532nm output.
That and Rhodamine B are on my to-do list. I will have to build a circulator =for the dyes at this repetition rate.
Thanks for the explanation. A client recently bought a laser engraver (20W, 450nm) and we particularly decided for the model because of the option to install an IR head. PS: still no Patreon?
You are welcome! they are pretty neat. I got sidelined with this video, I will go and set one up ;-)
I owe most of my career to SHG green lasers as a service engineer with all the systems based on a Z fold cavity with the Q switch and the SHG crystal or crystals in some cases actually in the cavity instead of external to the cavity. Usually KTP for lower power systems and LBO for higher power with the latest incarnation using 2 LBO crystals within the cavity and capable of generating 300W Average power with maximum peak power of 1.33 MW in service mode but limited for customer use to 180W Average power and 800 KW peak power. All used for medical applications, aligning one of these resonators is a whole bunch of fun.
This sounds fantastic, that is some amount of power, that would be amazing for pumping Dyes! I have a little UV Z-Fold Laser that I have been repairing here.
The Thought Emporium gave you a shout out on his TEA laser video today.
Awesome!
12:47 is the crystal lattice why you get all the speckling in the laser itself but also the spurious emmission that you see in surroundings? The crystal being made up of many smaller prismatic shapes there would be alot of refraction and i imagine a kaleidoscope effect? Playing with lasers over the years i often wondered why the spilled light looks the way it does . Ive probably damaged my eyes looking at it, its mesmerising.
Hi Les, you make it look so easy! I love your episodes. I have an SSLE machine for my crystal glass business in South Africa, it stopped working during Covid and I received no more support from China, they just want to sell me a new machine!
The system uses an active Q-Switch system and frequency doubling process; may I ask a few questions?
I have been working on it for a year and there are no companies in South Africa that can help.
1). The system suddenly stopped doubling a week ago, could this be because the diode has become too weak! Is there a power threshold for doubling? It is a 50w DILAS fibre coupled system, 400um. The label says 780-1000nm - It is red, I am guessing it is 808nm? I tried a newer similar diode, it had the exact same label specs, but the beam was almost invisible - I am guessing 970nm - so no doubling ocurred.
2) 2 years ago the green laser beam started flickering, then came strong again..this happened several times, then the beam went dull green permanently. It was, though, still doubling from red to green (532nm). I have tried a different RF signal driver ( AA Optoelectronics in France) as I thought the Q-Switch wasn't switching and boosting the laser. No change, though I am testing with an Oscilloscope tomorrow. I have tried another 50w diode( also quite old), initially it doubled from red to green, suddenly it just stays red. I removed the Q-Switch it made no difference..
Would you possibly have any suggestions please? Things are getting a little tight now.
Many thanks
Richard Nield
info@3dcrystalstudio.co.za
Durban
This is a fascinating experiment.
For low-power lasers, KTP crystals are the best choice for double frequency crystals. For medium-high power lasers, BBO crystal and LBO crystals from CRYSMIT should be better choices.
Robert L. Forward did something similar in his story "Roche World" when he had to change the "color" of a laser being used to drive a solar sail from IR to green (due to budget reasons).
Can you suggest where to buy secure and certified security glasses, possibly not too much expensive? I live in Europe (Italy)
Thorlabs is probably the best place in Europe. You would be looking at just under 200 Euros, which sounds like a lot, but eyesight is not replaceable at any cost.
amazing demonstration!
I have one question tho, why does this conversion also work in green laserpointers? There you don't have those high peak powers, so do they have some additional optic in them? I am asking this, since "the thought emporium" tried the same thing as you, but he used an IR diode to pump his crystal, not a pulsed laser and he didn't manage to get it to work.
Also what optical bench do you use and were did you get it? I saw similar ones on the Thorlabs website but they were very expensive.
In green laser pointers, they mount the KTP crystal within the cavity, where a huge amount of power is circulating. Imagine you had a small IR laser that produced 1mW from a 0.1% transmitting output coupler, for 0.1% or 1mW to escape, there would be on the order of ~1000X more light circulating in the cavity, and this is enough to generate SHG. Another consideration is power density. What I demonstrated is on a macro scale (the beam diameter is on the order of 2mm across) inside laser pointers the beam diameter is much smaller (microns) resulting in huge power densities even at low power.
I got my bench from Thorlabs, and yes they are pretty pricey, but I got fed up with having to cut and drill metal to set up experiments. These are pretty convenient and well worth it. I did consider getting a metal shop to make me one, but it would have cost almost as much.
@@LesLaboratory Interesting, I thought that it had something to do with the power-density but I would have never thought that it could become so high in a small pointer.
Also, have you ever measured the power of the green laser in your setup?
@@firefox1136 I have not measured the green yet, though it should be possible to get 60%conversion efficiency at least. I need to get a nother mount so I can tilt on the Y-axis and really tune this thing. I ordered an LBO crystal as well so I can attempt Third Harmonic Generation so see if I can get some UV photons out of this!
Great flic. Thank you. Very interestingm
Great video! Can you comment on how you powered the module? I imagine that the laser head connections are set up for connecting to the laser engraver and thus not standardized. Did you use the laser engraver itself to power the laser or a home-built power system? If the latter, can you please elaborate? Thx.
Razor sharp beams excellent, I love this video😉👍. What collimation lens did you use? Where can I buy it, can you give me a link? I am planning to build this laser.
Nice Tektronix scope you got there !!!! 😂
Thanks! I hacked it up to a 784, so now it has a 1ghz bandwidth 😁
I think it's kinda funny that when laser diode is erroneously translated into English it becomes Laser Tree or two trees. Then these Chinese laser companies officially name themselves using these bad translations.
Also I didn't know passive q-switching could achieve such high peak output. That's amazing.
Now that is very cool! I just thought it was a weird name! It's common with flashlamp pumped lasers to get into tens of Megawatts with Q-Switching.
Wow! Don't think that I've seen this demonstrated before. So, you are pumping the crystal with the IR laser? Does the crystal heat up? that would be my question. Thanks for the demo.
Thanks! Yes, 1064nm IR light enters the crystal and 532nm Light emerges. As far as I know, no significant heating takes place in the crystal. Any IR not converted into green, just passes through. Temperature control is often used as the lattice shape is related to the temperature. This means if you allow the temperature of the crystal to drift too much, the lattice is no longer matched to the wavelength, and efficiency drops off.
spectacular to see such a large crystal and they are at a reasonable price now? amazing to see the green beam just emerging out of it like that it is a nice optical illusion , i tried making a lamp pumped ndyag-doubled laser long time ago my dream was to see if i can get that beast working using 4x500w halogen lamps in a circular array wired in parallel so i only built the pump part of it and tried to get it to work with a dimmer switch but it was acting strange it would work at first then the light got bright as if the dimmer was not even there im not to savvy when it comes to more complicated circuit and electrical design, i have a glass tube that would presumably hold the ndyag inside the circular array cavity then i wanted to get the mirrors with mounts and eventually a doubling crystal and maybe have the whole thing water cooled using distilled water but it never went any further than building the pump which i still have and enjoy looking at once in a while , i did not get the rest of the parts though perhaps i was too timid with the costs and not sure of the success although i heard sam did manage to build one and get it to slightly work although it was weak beam coming out every now and then
On Aliexpress they can be had for about $20 USD for a 6x6x5 crystal, almost giving 'em away! :-)
Interesting, do it! I saw a halogen lamp pumped YAG on eBay some time ago, and wished I had bid on it. I have a huge YAG rod, and the lamps and cavity reflector just waiting for some optics. The rod and lamps are about a foot long!
@@LesLaboratory well i should have made it more clear i am not using halogen lamps but rather tungsten filament halogen lamps like the kind you get at a store for a ceiling lighting lamp, the ones i have are 500w each and i don't think they don't make them anymore , most now are 300w but i basically wired them parallel in a circular array (well 4 of them anyways) and i calculated they would draw about 17 amps from my wall which may be nearing or exceeding the rated fuse outlet if mine are 15 or 20 amps so depending where i plug it perhaps but anyways im surprised the thing worked without melting apart with all the heat it put out in short time since im only using solder for the wiring and the wire is much smaller than the required 12 gauge its more like aaa battery wire lol in order to be malleable and compact enough to cram into the small package design but it works, would like to show you on cam if possible so you can maybe advise or tip me if this is even possible for a laser or give me better design idea, yeah i've seen the one you are talking about on ebay its like a big cylinder size of a small trash can i think they still have them maybe at throb labs
Inspiring!
All optic modulation!
Pretty cool right?
Thanks, this is very nice. I was wondering as them infrared lasers have become this cheap and whilst pulses are used to blast away tattoos I can see the industry switching more and more to laser welding. Robots can replace the cumbersome spot welding and say weld sides to car bodies with a continues seam. Slower but since robot do it 24h a day the end product is sealed and the end product has a much higher quality and its strength is far more predictable with a minimum of materials used.
For sure! I expect some really interesting Laser tech will end up on the likes of eBay to tear down and play about with!
@@LesLaboratory Sadly I am in Australia. Have over 50 lasers in stock mainly from repairs but we no longer receive strong ones even though we pay for them.
I love this laser, thanks for posting the link, where and how did you make the excellent collimator?
The collimator is built from the housing from a laser diode module , but I replaced the plastic lens with a glass collimating lens. At some point, I am going to turn a piece on the lathe, since it is a faff to align as it stands.
@@LesLaboratory It looks great, where did you get the collimating lens?
Идеально.
Laserrs are so cool. :)
They are the coolest!
So my question is can you use a similar crystal to change a co2 laser beam into a ir laser
You can try to tripple the output with another type of crystal, makes nice blue light.
If I triple, I will get 355nm (UV) I have already ordered what 'might' be a suitable crystal for this...
I think I need to get a large aluminium plate for my 40w FAP800 which is now working a treat with marco reps laser driver. I have a 2" long YAG rod which by the colour of it and the coatings on the ends seems to be a diode pumped rod and has a pencilled arrow on it showing the beam direction. Can I just pump the rod with the fibre laser and expect 1064nm output or do I also need a Q-Switch? Love the videos by the way, every single one of them are really informative and interesting. Keep up the great work Les!!
Thanks! You may well be able to pump the rod with it, though at that length, it is probably designed for side pumping. You only require a Q-Switch, if you require high peak powers, without it, you would have CW operation.
Beautiful..!!!
Thanks!
so cool
Thanks! :-)
wonderful!! i jus want to know how much is the power loss after SHG? and can only pulsed laser cause SHG?
The power density required for visible SHG is ludicrously high, on the order of kilowatts per square cm. So with a pulsed laser with high peak power this is easy. For CW Lasers, such power densities are available within the cavity itself. Intracavity powers, even in a small laser of a few miliwatts output can be tens of watts (kW's per square cm).
thanks @@LesLaboratory . ah i thought of converting my 785nm SLD to UV :p ..
@@nvspraneeth9468 you could do that with BBO, but it would be single photon level.
thanks for it@@LesLaboratory , i see, my SLD's max power is 20 mW. i actually study single photo emission from quantum dots using our home-built TIRF microscope where 10mW/cm2 illumination is more than enough. so you suggest for my work BBO crystal would help? and instead of buying can i scavenge from any laser pointer like you did? many thanks again
It would have been interesting to see some numbers and waveforms from the pyrometer and photodiode to see how the KTP crystal changes the beam in the time domain and how (probably very) inefficient it is.
It would and I will. I am working on another video at the moment on KDP, but once that is done I will likely do a comparison video. Extracavity doubling can be very efficient if the peak powers are high and the setup is right (polarization, crystal angle and so on).
Can you do an Experiment with The Nonlinear crystal attached to peltier
With bidirectional Hbridge controlled Pwm input to control heating and cooling of crystal and see the Temperature vs Wavelength characteristics of NL Crystal !!
Could be a cool experiment! At the high peak powers, I'm not sure I would get anything out of it other than green, but I have some BBO on the way...
@@LesLaboratory i guess it should shift the wavelength of Parametric Conversation.
Can you do Photonics Entanglement experiment ? Is it possible to use green laser crystal from opposite Directions to do the opposite of Input phone mean splitting into two ? Or both crystal and Diode Wavelength are Very spesific ??
It is possible to do entanglement I believe with BBO crystals. See this vide here for a run-down: ruclips.net/video/tn1sEaw1K2k/видео.html
I tried to reproduce the experiment on generating the second hormonics on a 1064 nm laser in a TO18 case with a power of 20 mW and a KTP crystal, but I did not get the green light. So I don’t know, either this pumping power is not enough, or Ali Express sent a different wavelength. There is a 3000 mW diode on Ali, I think I’ll try it. Or I can disassemble a regular green laser module and extract the part that generates 1064 nm, and use it with my own KTP crystal.
So, have you dabbled in designing and fabbing pico/femtosecond fiber laser?
Not yet, I am looking at two avenues for short pulse lasers:
Ti:Sapphire (If I can get the crystals cheaply enough)
Fiber might be a possibility, again if I can get cheap doped fiber and a cheap fusion splicer.
Neither approaches will be trivial though, and should keep me busy! :-D
Hello Les. I have a fiber laser engraver (50w). And I've purchased KH2PO4 to replicate your experiments. Do you believe that my laser can pump the non linear crystal?
Does the beam hurt when you touch it? I suspect not, as the energy per pulse is so small and the finger is probably going to be fairly transparent at 1064nm, causing the volume over which the energy is deposited to be fairly large. And what is that red light I see on the penny when it is away from the focal point? Obviously the bright white/pink light at the focal point is ablation incandescence, but that deep red light.... it doesn't look like camera-misinterpreted IR to me. It looks very suspiciously like UV excited ruby fluorescence. Is it possible then that we are seeing something like two photon absorption induced fluorescence of the trivalent chromium ions in the saturable absorber optic?? Can you hit your spectrometer with that light and do another video 😁?
It gets pretty warm. I only ran it at around 20% duty cycle for that portion of the video, so maybe half a watt.
The red light is there because the head has a built in aiming laser, which is pretty useful, but there is no way to turn it off. Given its design purpose, it is remarkably coaxial with the IR beam over about 30cm or so.
@@LesLaboratory ah, well, so much for my clever 'theory' 😆
I've heard that some IR lightsources can been "seen" would this be in the same 2ir=1green; but the nervous system merely gets a read on green photons without any ever being manifested?
Or is than an other effect?
This is a different effect. If you fire a pulsed IR laser at the retina, a cell can absorb two long wavelength photons in rapid succession, and register one of twice the frequency. I'm not sure of the mechanism involved, but it sound like two-photon absorption.
What you are seeing in this video is the physical doubling of the frequency of light itself.
That's a pretty price chunk of KTP you have there on the Bench...
Real cheap on Aliexpress!
Amazing video! I watched many videos where use a KTP with a nd/yag pulsed laser. I have a q-switched 30W fiber laser from a laser marking machine. 1064nm with 30 khz to 50khz pulse frequency. Will it work with a kTP crystal ?
Without a doubt. At that average power, you will have to do some thermal management of the KTP though, and get safety glass that will block 532nm as well as 1064nm.
Hey may I take a piece of this video to make an informative video regarding second harmonic generation? I would give credits, of course :).
Sure, so long as credit is given, it seems like fair use.
I have a 532nm laser but when I increase the power(A) in the driver the laser output power is reduced. Do you know which part of my device is damaged? My device is Spectra-Talon-532-40.Hope you can help, thanks
Can you give me more info on this machine?
What would the first harmonic be in this case?
There is no first harmonic, only the fundamental at 1064nm. There are higher harmonics that can be achieved though at 355nm and 266nm.
i am trying to understand what is average pw and peak pw, from what i know average is basically the amount of pw the lasing medium is emitting while running in normal cw mode and peak is when more pw is allowed to collect in the lasing medium either due to two things one being a q switch that is blocking the resonance from happening and allowing more atoms to get into the exited state from the pumping source before the switch is open and the remaining exited states are being stimulated by the rest of the incoming photons from the pump and released in a powerful pulse train and the other would be a similar q switch only one that is acting like a closed mirror that allows a closed loop resonator to form multi mega passes return trips of the photons back and forth to boost the pw then the mirror opens to release a powerful pulse train but i am wondering if your 15kw can be further increased if using this mirror type q switch instead or if its the same results?
ok so if this peak pw only happens in 1 nanosecond but is being repeated that fast would this not mean the beam is basically cw and that much pw is being emitted every other nanosecond?? so its like a cw 15kw pw beam no?
thx for the love lee but what about my question?
what happens if you use two of these crystals? Does it turn blue?
You are on the right lines, but this particular crystal won't do it.
The Light exiting the KTP consists of 532nm and residual 1064nm. It is possible to mix these with a BBO crystal to get UV light at 355nm.
If you want blue, you would use mirrors in the YAG laser coated for 946nm, that you could then double to 473nm, with either LBO or BBO
Is there a way cheaper?
I've seen a Nd:Ce:Yag + Cr4:Yag Rod 5x85+5mm with 1064nm coatings for around $250.
Is it possible to get this to work with (many) LED or blue laser (2-8W) ?
Interesting, though when you figure in the cost of optics and machining a cavity ou migth find it gets expensive fast. Do you have a link? Pumping with LED's might be possible, but it would be insanely inefficient...
Where you buying that 532nm crystal???
Aliexpress. If you search for KTP, they show up quite inexpensively.
@@LesLaboratory thx
How critical the KTP crystal dimensions are?
This one is pretty large at 6x6x5mm, however so long as the beam can effectively be coupled in, even small ones should work fine. I got green photons out of a broken LBO crystal at one point.
@@LesLaboratory Thanks! So it is what I expected. This seems to be quite fun area for experimentation.
@@user255 for sure! I'm looking into seeing how practical other nonlinear effects are as well. The projects are stacking up!
Just wondering, what is the peak power like after conversion ?
I have not measured that yet. I reckon maybe upto 60% conversion might be possible. I m hoping to do Third Harmonic generation with it (Just ordered an LBO crystal), so I will have to preform some serious measurements.
@@LesLaboratory thanks, I'd be interested to see the results.
I'm sorry, I'd need to excited to a MUCH higher energy state to be able to have a good particle-wave duality argument.
😂🤣😂🤣
Could a low powered laser be used for non linear experiments Les?
Kinda, it depends what you expect so see. It is possible for example to double the output of a He-Ne Laser, but the effect is exceedingly small, you would need a photomultiplier tube to detect the light, which would be at single photon levels. You can intracavity double to get the required power energy density, as is done in Green Laser pointers, but you would need proper optics, and a stable setup to achieve it. There is some info on Sam's Laser faq on rolling your own DPSS Laser.
Thank you sir. @@LesLaboratory
Sam's Laser sir?@@LesLaboratory
@@hoofheartedicemelted296 www.repairfaq.org/sam/lasersam.htm
Are there crystals that could go further? Green to UV? UV to X-rays, etc?
Yes there are, they go down into the 180nm range I believe. My 355nm uses the same optical arrangement with a third harmonic crystal after the second harmonic one.
Yes but you need to remember the process is nonlinear and more and more inefficient the deeper you go. You can only get to the vacuum ultraviolet with this method, x-rays are absorbed by crystals and the conversion efficiencies even in the UVC are utterly, abysmally, miniscule.
If you wanted x-rays, far cheaper I imagine to build an x-ray Laser. Nonlinear crystals with that short a wavelength aint gonna be cheap!
@@Zenodilodon Can this be used for low cost deep ultraviolet lithography light source?
How transparent crystal can shine on its own from nothing? Magic....
It is pretty magical!
its not from nothing, its just invisible to the naked eye lol
huh the diode is 2w output but your laser output is 2.7w??
The claimed output is 2W, the measure output is 2.7W, over-spec, so bonus!
I think it's certainly misleading to call it a 15KW laser. I certainly don't think it would even cut through 10mm of plywood. My crappy K40 would probably be better value if all people want is IR laser output.
Most obnoxious title on RUclips, along with "You won't believe..."
You are right, it is an experiment to see what the algorithm does with it and/or how clickable it is.