Frequency Doubling Silicon Nitride Laser Diodes for Deep UV Production

[kecked]

Anybody know of a good crystal to SHG deep UV using the 445nm laser diodes? I'm figuring with 5 watt in I should be able to get a 100mw of UV around 220-250nm. What I want to do is setup a few of these on a quartz tube and allow the light to self refract down the length of the water filled tube as a long life UV sterilizer for my Reef Aquarium. I'm thinking three of them at 120 degrees down the tube should do the job. I can align it using a dye in the water. Hey add mirrors and might make a nice dye laser too!

Ok tell me why I am soo not going to make this work. Seems too simple. PS the main wavelength in the gas sterilizer tubes is 245nm so yea this if it works is right there.

Come on mixedgas ruin my day...................

[planters]

The low pressure Hg lamps are pretty effective and inexpensive, not to mention the marine industry has the systems integrated and so it's plug and play. I'm not sure what the efficiency of the 253nm line generation is, but I think it is remarkably high like better than 30%. This is what pumps the florescent lamp phosphors.


In any case, you probably want BBO coated for both wavelengths. This is the best crystal for the UV range. The hurdle will be achieving the intensity at the extra-cavity focus with a multimode diode and the relatively broad bandwidth around the 445 diode's output, will decrease the efficiency as well. Nonlinear conversion is very dependent on intensity. The cost for these crystals will be relatively high if they are provided coated. I have ordered from this company before, good pricing, good quality, but long delivery times.

http://www.foctek.net/products/bbo_n...r_crystals.htm

I'm the last to advise practicality over experimental fun, so it might be interesting to see if this is possible. You should first determine what the recommended operational intensity will be and then test the actual diode with a very long FL lens. You can extrapolate this measurement to a shorter lens to increase the intensity. The limit here is that it is a high power of the intensity times the non-linear interaction length which shortens as the focal depth of the beam becomes shorter.

I believe there are UV sterilizing LED's out there and this might be an alternative to frequency doubling.

[VDX]

... are high power 405nm-LED's of any use here?

I have some with 9Watts optical output and was thinking to use them for pumping ruby rods.

Another methode for sterilizing water could be ultrasonic (or better hypersonic) ...

Viktor

[planters]

405 will be too long. You need DNA and RNA denaturing. Even 365 is too long and that is why it is safe for entertainment "black lights".

Another methode for sterilizing water could be ultrasonic (or better hypersonic) ...

I don't know if this would work. Ultrasonic cleaners are used in the medical field, but they are always followed by an autoclave or ethylene oxide as one example, for sterilization.

[kecked]

254nm is the usual wavelength. This or lower works fine. I'm more interested in the SHG part of it than the end result. I found a fluoride doped zinc oxide material that looks promising as a thin film. Shows promise using 1064nm as the pump and the band gap looks appropriate to pump in the 400nm range. I will try 532 first which should yield 266nm as a starting point. I then have to use an electric field to move the band gap to work at 445nm if I can. Will also have to heat the crystal. I need to find a high pass material for a window to stop the visible leakage. I just want to see if UV can be obtained in a SHG rather than tripling or quadrupling. I also want if possible to avoid feedback arrangements. Basically looking for a KTP like material to get from diode to UV.

The other material I have interest in is linear superposition materials that go non linear when controlled by an external field or heat. Thus making them tunable. What will ne interesting is if I find a material that transitions softly with a non mans zone. Wish me luck I'm going for a grant.

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ultrasonics is interesting but I think it would propagate to the main tank and irritate the inhabitants.

[planters]

254nm is the usual wavelength. This or lower works fine. I'm more interested in the SHG part of it than the end result.

Fine.

Can you go into more detail about this material? Where did you get it. What is the relationship of the band gap and the non-linear doubling process? A band gap makes me think you would be operating this as an optically pumped emitter.

You're not talking about something like this are you?

http://www.covesion.com/products/mag...ppln-crystals/

I then have to use an electric field to move the band gap to work at 445nm if I can

I'm sorry, but you have got me here. Can you explain this process or link some papers?

The other material I have interest in is linear superposition materials that go non linear when controlled by an external field or heat.

What is this!?

[mixedgas]

I'm not in the mood on this beautiful Saturday to ruin your day. Can that wait till tomorrow? If you put the doubler in a ring cavity of three or four mirrors you'll get uv. I can loan you a crystal to try.

STEVE

[mixedgas]

I have crystals for 532 + 532 = 266

Steve

[mixedgas]

I also have a used 185 nm 15 watt Germacidal UV lamp that runs off a fluorescent ballast. You can have one as we replace them every 16,000 HOURS. Did I mention it's designed to be submerged on one end in 100 psi water? That would save us the disposal costs for the special alloy fill and it probably has 8000 more hours left on it. 185 + 256 nm and it breaks down organics too. It can't go into the normal lamp disposal grinder due to the amalgam. Do leave a few beneficial , symbiotic organisms in the tank.....

For flowing drinking water to be guarented sterile in one pass, it's 40 mJ
Per cm^2 at 256 nm.

[planters]

I have crystals for 532 + 532 = 266

OK, but the idea of a 445nm diode was the premise and I fear this would not work.