What is the farthest red shift you've seen in a 405nm diode?

[Gryphon]

I have a BDR-209 that is at 410nm but I've heard some people have gotten theirs up into the 415-418nm range. Has anyone spectro-ed one of the Sharp GH04W10A2GC diodes when its pushing out 2W? I might pick one up just to see.

On a similar note I had some cheap 405s from ebay that sat in the 410-412nm range at just 100mW, I tried pushing them farther and managed to get one of them to 414nm when it popped. Its very surprising to see that even the simple mass produced 405nm pointers have quiet a long wavelength.

My spectro is nothing fancy, just a ThunderOptics USB spectro but even still with its two point calibration at 473nm DPSS and 594nm DPSS it can accurately pick out my green and red HeNes rounded to the nearest whole number. So for a comparative tool I think its worth while.

 

[paul1598419]

I have measured many diode's wavelengths, but haven't spent much time with the 405 nm ones. I use an Ocean Optics USB2000 which is calibrated using more than 6 lines. Is there a specific reason you are interested in the shift of these diodes? Another way you can shift them is to use a diffraction grating and use it as a feedback loop which will shift the wavelength as much as 6 nm for some diodes.

 

[Gryphon]

Is there a specific reason you are interested in the shift of these diodes?

It seems to be general convention that when we push diodes well beyond their rating we see a red shift of a couple nm, but these 405nm diodes that are very abundant are either very poorly calibrated for their target wavelength or they just shift more. I'm just curious to see if anyone has experienced any "405nm" that tends to drastically miss the mark.

Another way you can shift them is to use a diffraction grating and use it as a feedback loop which will shift the wavelength as much as 6 nm for some diodes.

Now that's something I haven't heard of before; I'll have to look into that.

 

[CurtisOliver]

InGaN/GaN typically doesn’t thermal shift very much. However I have found that both 405’s I own actually sit at 408nm.

 

[atomd]

It seems to be general convention that when we push diodes well beyond their rating we see a red shift of a couple nm, but these 405nm diodes that are very abundant are either very poorly calibrated for their target wavelength or they just shift more. I'm just curious to see if anyone has experienced any "405nm" that tends to drastically miss the mark.



Now that's something I haven't heard of before; I'll have to look into that.

look into external cavity or tunable laser diodes.

Basically you put diffraction grating in littrow configuration to reflect light back into grating.

 

[Gryphon]

Basically you put diffraction grating in littrow configuration to reflect light back into grating.

Thank you for that, I read some articles and watched a video on that and its fascinating, I had no idea something like that was possible

 

[atomd]

First picture is diffraction grating in littrow configuration in my dye laser setup. Because it's blazed diffraction grating enough light gets reflected back to resonator support lasing even at the edges of gain of dye.
To get sharper tuning and narrower line sometimes light is sent twice through grating by using mirror almost in parallel to grating as on second picture. The trick is to get correct relative angle of grating and mirror for both 0th order from diode and first order from mirror to overlap.
In general if you ever want to try it you need to get yourself blazed reflection grating for roughly your wavelength range.

 

[Gryphon]

I purchased one of the Sharp GH04W10A2GC diodes and the shift is quite amazing. 406nm at 150mA and 417nm at 1.5A, that is a pretty good swing.