Blue wavelength shift

[steve-o]

Hiya All,
I was just over on the "other forum" (yes I'm giving them credit because they say we never acknowledge their hard work ;] ..and the big news is an Osram 450nm 1.4W blue diode P/N PLTB450. Being discussed was running them hot, seeing if a wavelength change can be invoked. We know that running a 637nm red diode hot will probably push it toward 640, right? How about this one; 450 nm pushed toward 453-454. Not a huge color difference but maybe just enough to get it out of the "violet-ish" look like the 445s. Does anyone know if the blue diodes temperature/wavelength shift like the red ones do? I may pick one up at DTRs store (they're cheap like the 445s) and putz around with it. Anybody done this yet?

[Meatball]

I have only seen that the standard deviation on units out of projectors is about the same for reds. +-10nm.

Something from memory tells me that the color shift vs. temp shift slope for GaN diodes is very small..

looking at a typical datasheet, it seems this is the case. http://www.nichia.co.jp/specificatio.../NDB4116-E.pdf

+ or - 1.5nm from -10C to 60C.

This should be the case for all GaN diodes. ~340nm-530nm

EDIT: I do know someone who has the means to being binning diodes by wl, but I do not think they have begun this work.

Their testing showed that high wavelength blues generally perform with much less efficiency.

[steve-o]

Hey thanks for the idea Meat! Found a chart for it. Looks almost 453nm around 60C. Max operating temp is 70C.


http://temlaser.wordpress.com/2012/0...diode-pltb450/

[steve-o]

I just realized that this should have gone in the "445" section ... velly sory ..

[krazer]

You will get a very small wavelength shift, and the reduced life associated with running the diodes at 60-70C (especially when you consider the active region is usually much hotter than the can) is probably not worth the effort.

If you really want the longer wavelengths just run them at higher currents ;-)

[steve-o]

You will get a very small wavelength shift, and the reduced life associated with running the diodes at 60-70C (especially when you consider the active region is usually much hotter than the can) is probably not worth the effort.

If you really want the longer wavelengths just run them at higher currents ;-)

Yeah that's how I was going to keep them hot, running at higher currents. Maybe some sort of regulation circuit monitoring the temperature and adjusting the current accordingly to keep maintained at the set temp. I'm sure that the lifespan will be shortened, that's why I'll have a few extra diodes lying around :]