407nm?

I was searching around for dirt cheap blue ray diodes and I came across these that seamed rather strange. I thought that blue rays are all 405nm, but these are 407nm... Is it just a typo or are 407nm diodes out there? I doubt it would make any difference to visibility what-so-ever but still.

http://www.laserenthusiast.com/stor...Path=1&zenid=9ed36892f08c507f081d30cf9c6d8a52

Edit: I am guessing theres a reason Laser Enthusiast is blocked?

lamborgini8 said:

I was searching around for dirt cheap blue ray diodes and I came across these that seamed rather strange. I thought that blue rays are all 405nm, but these are 407nm... Is it just a typo or are 407nm diodes out there? I doubt it would make any difference to visibility what-so-ever but still.

http://www.laserenthusiast.com/stor...Path=1&zenid=9ed36892f08c507f081d30cf9c6d8a52

Edit: I am guessing theres a reason Laser Enthusiast is blocked?

Click to expand...

All diode wavelengths are +-.  Depending on which violet diode it is it could be +-10nm or +- 5nm.  405nm is the "normative average."  I have seen a couple of diodes that were at 415nm.  They are visually MUCH brighter.  I have also seen diodes that I'm sure were closer to 395nm.  I didn't have them tested, but they sure "looked" less bright than normal (even though the LPM read the expected mW).  I have no idea why the seller would be reporting 407nm.

The Laser Enthusiast block is an old story.  We live with it.

Peace,
dave

Dave got it, as usual.  It's pretty much impossible to get an exact wavelength out of these diodes as they are made.  With more complicated designs, you can get *some* wavelength tuning, and of course you can tune the bandgap some.  There are so many variables that are so hard to control, you can get close and you can get an average around a certain number, but it's pretty much impossible to get it exact with how these diodes are made and used.

For instance, one of the main contributors to wavelength is the bandgap, which for violet lasers is controlled by indium incorporation into indium gallium nitride quantum wells. You literally have to control the number of indium atoms in the sea of gallium and nitrogen atoms. The number of atoms in the quantum wells will change the bandgap, and as you can imagine, it's REALLY hard to get an exact number of atoms into certain places. Each quantum well will only be a few nanometers thick, literally just a few dozen atoms thick. So a few more or a few less indium atoms will change the bandgap.

And then, even with the right bandgap, other things can shift the output. For instance, if the manufacturer uses a DBR mirror to increase the reflectivity of the mirrors, the construction of the DBR can change what wavelength lases and what doesn't within a few nm (it can shift the mode of a certain mode has a much better reflectivity than another mode).

i suppose seller reported it like 407 because of one reason.. he will sell it much better than 405nm.. he know why he did it like this...

..........  :

http://cgi.ebay.com/HIGH-POWER-PURPLE-BLUE-VIOLET-LASER-DIODE-MODULE-100mW_W0QQitemZ250346464104QQ

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