UV laser diode <400nm

hikmetsezen · Mar 7, 2016

Hi, I am postdoc researcher at Elettra Synchrotron - Fermi Free Electron Laser facility at Trieste, Italy. For a research project I need to excite TiO2, titanium dioxide, with a 3.1-3.2 eV (400-385 nm) band gap. I start to look laser diode because of our limited budged, however I immediately see that price of laser diodes below 405 nm wavelength dramatically increases. I got offers from Nichia, Toptica, Thorlabs, etc., prices are around 2000-3000 $ per pieces, which is already over our budged. I could not get any offer from Chinese companies, they would like to offer me only diode lasers starting from 5000 $.

Could you suggest me a laser diode less than 400nm wavelength, CW, 10-100mW power and costing a few hundreds.

P.S. After spending a few day in this forum, I got an enough encouragement to build a 405nm laser for personal interest. Thanks all.:wave::thanks:

Isaac Clarke · Mar 7, 2016

unfortunately all the UV wavelength are super expensive and you won't find the UV lasers that cost a few hundreds... there are alternative systems.. however the cost would be on par with the diodes....it's called DPSS laser...check out CNI/Eforcelaser/Ultralaser.....

as for your 405nm question, that wavelength won't be very bright...it's at the edge of the human eye sensitivity.... only 5 nm away from UV.... for the diodes check out DTR laser shop...( very cheap compare to the UV.... 10 times cheaper to be exact)...i hope you have safety goggles...( check out Eagle pair from survival laser)..

Welcome to the forum...

paul1598419 · Mar 7, 2016

Welcome to the forum. Sorry I didn't get here earlier, but the time difference makes it difficult. I'm glad you decided to build a 405nm laser, as it will be much less expensive than the ultraviolet ones. The problem with a DPSS laser is it will cost you as much as the semiconductor ones. They are more stable, however.

diachi · Mar 7, 2016

Actually - you *might* be able to get a 405nm diode down to ~399nm or a little lower.

If you can get someone to put a bunch of them on a spectrometer, then pick the one with the shortest wavelength at room temperature. You can then cool that diode down to bring the wavelength down. I'm looking at the datasheet for what may be a PHR-803T or something similar (100mW rated output) and the wavelength/temperature coefficient is 0.3nm/*C.

So say you can find a diode that's 403nm @ 20*C - you can cool that to 0*C and bring the wavelength down to ~397nm, which is within the range that you specified.

Datasheet: http://docs-asia.electrocomponents.com/webdocs/0eec/0900766b80eece88.pdf

That's the only affordable solution I can think of.

Isaac Clarke · Mar 7, 2016

binning a bunch of diodes sound great.... but diodes tend to be higher in wavelength though....and the cost for buying diodes would add ups....but sound possible..

Cyparagon · Mar 7, 2016

They're usually in the 410-415nm range for high power. The ~30mW pointers will be lower. I have one that is 403nm somewhere.

Rivem · Mar 8, 2016

Would you happen to have access to liquid nitrogen at your facility? Maybe you could get a 405nm diode well into the UV region with cryogenic cooling. Anybody know how well something like this would work?

hikmetsezen · Mar 8, 2016

Thank you for suggestions.

Cooling with peltier and liquid nitrogen is a solution to decrease emission wavelength. I already checked this effect, but the 405nm lasers are usually based on InGaN, and they have relatively low wavelength/temperature coefficient. In the literature it calculated and measured around 0.05nm/K. We can gain 10nm with liquid nitrogen, but we have make sure about decreasing of peak wavelength, stability of output power, and life time. Thanks to diachi SLD-405-120 laser diode from CNIOptics promissing 0.3nm/K. I hope this value is correct, maybe they use different material for this laser diode. I will ask them about the is the minimum operation temperature of this laser diode.
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Update info:
I get quotation and official datasheet for SLD-405-120 and SLD-405-150. The values of wavelength/temperature coefficient are 0.054nm/K for both. The values on the webpage are unfortunately wrong!

Chicxulub · Mar 8, 2016

Just a thought, but if you reach out to some of the bigger companies like CNI, they might throw you a bone because you're doing legitimate science. It's always worth a try to reach out, explain what you're doing and see what happens.

Pman · Mar 11, 2016

Drives me nuts how wavelengths are advertised as a specific frequency when they in fact are not. Just learned that most 650nm are actually 655-670nm. Of course over driving like we generally do tends to shift it anyways. Would be nice to personally be able to measure all of my units and label them properly. I'm sure the price tag is pretty high though.

doubleone44 · Mar 11, 2016

What about a 385nm led? Those are pretty cheap for quite a bit of power and might do the trick if focused well. Maybe a couple focused at the same spot could work? Good luck on your project!

hikmetsezen · Mar 11, 2016

Thank you, doubleone44. The distance between light source and sample in the best condition is 100 cm, and along pathway of light a couple of slits with 2-3 mm aperture are presented. We checked high power UV LEDs, deuterium and mercury lamps with even focusing, but we got ca. 1% transmission. To get an enough flux density definitely we need a well collimated light source. Laser options looks like only solution for us.

doubleone44 · Mar 11, 2016

Hmm I see. You could try roithner laser, they have a 400nm 50mW CW laser diode for 700 EUR: http://www.roithner-laser.com/pricelist.pdf

Isaac Clarke · Mar 11, 2016

may be that could works....

styropyro · Mar 12, 2016

You may want to look into building an external cavity on a 405nm diode to take it to the ~395nm range. It would require some work, but ECDLs are used by a lot of labs to get very narrow linewidth and adjustable wavelength from laser diodes.

You might also be able to get away with 375nm diode lasers. Now I don't know much of the physics of TiO2, but if 375nm light will excite electrons into some short lived energy state, only to drop back down to the level at 385nm~400nm, you'd have an easy way to excite your material. There are some complete 375nm diode laser systems on eBay now. Cube 16mW Laser System from Coherent 375nm | eBay

hikmetsezen · Mar 12, 2016

styropyro, thank you for ebay link. I hope we can get one of these.

UV laser diode <400nm

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