will a diode cooled with  liquid nitrogen wor

VillageIdiot said:

why would it change wavelengths?

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Spyderz20x6 said:

That would be cool if they had mini TEC's, that you could fit inside a small project box.

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Spyderz20x6 said:

That would be cool if they had mini TEC's, that you could fit inside a small project box.

Click to expand...

The wavelength shift for 808 nm diodes is generally around 2.5 nm (+/- 0.2 or 0.3 nm) per 10 °C, with the wavelength shift to the red with increasing temperature.

(From: Lynn Strickland (stricks760@earthlink.net).)

It really depends on the laser (i.e., manufacturer) and temperature range you are talking about. A good rule of thumb is 0.3 nm per °C over the operating temperature range of the device (About 30 GHz per °C). That's the average slope of the curve though - it includes mode hops. If you're operating at a mode hop, you can get a lot more change than 30 GHz with a 1 °C temperature change. If you are between mode hops, it can be much less.

Mode hops can be a moving target too. Optical feedback can cause them (even minute amounts). Or, you can operate at a specific temperature where there are no mode hops today, but next week it might mode hop at that temperature.

Note that you can only go so far if you want to use temperature to reduce the wavelength. Even if you got the electronics to work under frigid conditions, there is a minimum laser wavelength you can get from a particular diode laser chip. I'm not a physicist, but it has to do with the bandgap of the materials used. What you would get, as you cooled the thing, is lower and lower threshold current, lower operating current, and longer lifetime.

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