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Why and when do laser diodes shift in wavelegth?

MrMcChicken

MrMcChicken

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Hello everyone, there is a question I have and I hope somebody here can help me out.
Does the wavelength of a laser diode depend on the current it is driven or on the temperature it heats up during high currents? If it would depend mostly on a high current it would be pretty neat, because I would really like to have a 470nm laser but DPSS are quite expensive. So I could just pulse it with high power pulses to get the shift in wavelength but don't have to struggle with extreme high power CW output. (well, for me everything higher than 100mW is already high power).

Greetings, MrMcChicken :yh:
 





Higher current translates to a higher wavelength. Higher temperature also translates to a higher wavelength. To what extent depends on the diode. A cold violet on low current for example could be 403nm. The same violet might be upwards of 420nm when warm and with high current. With blues, violets, and greens, the current will have a greater effect on wavelength.
 
That was a really cool video, thanks for sharing. Very informative.
 
Just to add, there are two major mechanisms that influence the wavelength shift in laser diodes:
  • Semiconductor bandgap changes- Energy difference that electrons experience across the semiconductor becomes different.
  • Lasing Medium/Cavity Changes- The geometry of the laser itself can change with temperature and shift wavelength.

Of course the average operating temperature and load current are very closely related.
 
Thanks for sharing this video. This looks pretty amazing. However it doesn't seem to be a very practical method. Sadly most diodes don't shift that much. Has anybody did some tests of different diodes? I have seen some threads where single diodes were tested and got some information on DTRs site.

Greetings, MrMcChicken
 
MrMcChicken said:
Thanks for sharing this video. This looks pretty amazing. However it doesn't seem to be a very practical method. Sadly most diodes don't shift that much. Has anybody did some tests of different diodes? I have seen some threads where single diodes were tested and got some information on DTRs site.

Greetings, MrMcChicken
Click to expand...
Lol, I wasn't proposing it to be a practical method. Just showing you the extremes. :D
Your right most diodes under normal operating conditions will only shift a few nm either way. I contacted Styropyro before on this matter, and the 650/635's tend to shift more and don't thermal damage as easily as the 520's. I don't know about the 445/450/465's etc. But I take it that they will behave similar to the 520's as it seems that InGaN doesn't like thermal tweaking as much AlGaInP.
 
Lol. Out of these lasers, which one would you choose?
You could have a wonderful liquid nitrogen cooled 580nm diode that you would have to handle with gloves.
Or a 589 that you can use normally.
9nm makes a difference you know. :D
 
MrMcChicken said:
Thanks for sharing this video. This looks pretty amazing. However it doesn't seem to be a very practical method. Sadly most diodes don't shift that much. Has anybody did some tests of different diodes? I have seen some threads where single diodes were tested and got some information on DTRs site.

Greetings, MrMcChicken
Click to expand...
Pman, pushed a few "costly":eek: 07 diodes hard just to see and got some good results kinda recently. None seemed to fry out.
I'm not to sure on what thread he posted it?
 
Last edited by a moderator:
CurtisOliver said:
Lol. Out of these lasers, which one would you choose?
You could have a wonderful liquid nitrogen cooled 580nm diode that you would have to handle with gloves.
Or a 589 that you can use normally.
9nm makes a difference you know. :D
Click to expand...

I pesonally love complexity - I would go for DPSS laser, where the process of creation of output radiation is just amazing. :)
 
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