520nm Diode laser... Info?

[Rafa]

I read somewhere some time ago that some people are researching and that they made a 520nm diode laser, but I don't know anything more.

Any info? Thanks!

 

[pullbangdead]

There are several groups/companies out there. Sumitomo, Kaai/Soraa, Osram, Nichia are all companies that have published laser diodes in that wavelength regime. Also, a university, UCSB, has published up to 513nm I think?

Nichia has samples available of 515nm diodes, Sumitomo has published all the way up to 531nm, I know Kaai/Soraa has talked about results in the 520s, Osram is at least up to 515 and maybe a little higher published results (I don't remember their exact number). That's just off the top of my head.

 

[Rafa]

Thanks. That colour should look like blueish green right? It must be awesome...

I guess getting samples from there is almost imposible.

 

[Kulhu]

We should do a big group buy thingy.

 

[pullbangdead]

Thanks. That colour should look like blueish green right? It must be awesome...

I guess getting samples from there is almost imposible.

It's green. It's not the same green as 532nm, but it's green.

And getting samples isn't impossible at all. They're like Doritos, they make more every day, it just takes money.

 

[Rafa]

Do you know how powerful they are? And how much samples cost? (I guess this is not like requesting some TI IC's, I suppose you have to pay for them, lol)

And what applications do they have?

 

[pullbangdead]

The green is for display purposes. With a green diode, RGB full-color displays can be made with all-laser light sources.

I've read the stuff they're sampling now is maybe like 50mW of green? And it might've actually been 510nm that they're sampling now, which is still green as well. But with paying a lot of money for it, you won't want to push the power with paying a lot of money for it.

And as far as cost, it's hundreds or thousands of dollars per sample, you'd just have to ask.

 

[Gappa]

It really is strange that specific wavelength is so hard to achieve. We have red which is mid 600s and blue mid 400s.

 

[BShanahan14rulz]

It really is strange that specific wavelength is so hard to achieve. We have red which is mid 600s and blue mid 400s.

I think that's exactly why it's so hard to achieve. PBD will be able to say exactly what is going on, but I'm thinking it's because it's hard to push GaN that low to get that high of a wavelength, and hard to push GaAs that high to get that low of a wavelength.

If PBD had a class, I'd take it (If I passed all the prerequisites )

 

[Meatball]

Yep! We have mainly two different materials used in LDs. One of them is good at lasing in the IR, and can be pushed down into the red. And the other is good at the violets and blues, but can be pushed into the greens. There aren't a large number of diodes available that lase between 515-625nm.

I think I have heard of a 612nm setup that requires heavy cooling but that's not very ideal.

 

[pullbangdead]

It's a real-world problem, often referred to as the "green gap". Attached is a decent illustration showing how materials just aren't/haven't been available that can emit green light with high efficiency and long lifetime. This chart is for LEDs and is a bit older now, but the same ideas still hold true and carry straight over to laser diodes (even if the current situation is looking better than what's on this graph). Millions of dollars have been spent in research trying to "close the green gap".

The right side of the chart, ie the red material side, hasn't really moved much in a long time. The left side however, the nitride material side, has been on its way up and is still moving, trying to "close the green gap". On the left side, pure GaN emits at like 365nm, and the more indium you add the higher the wavelength you get. But you have to make structures out of the material and the material quality has to be good for light emission, but the more indium you add, the harder it is to maintain good material quality. Instead of a nice InGaN alloy/mixture that's uniform and homogeneous, the material can sometimes want to become more like a mixture of InN and GaN, or the indium likes to cluster together, or you get other defects, like misfit dislocations. It's really hard to make materials that emit green light from direct injection of electricity, and then it's even harder to incorporate those materials into semiconductor structures, especially laser diodes, because the structures are much more complicated than LEDs and the tolerances much more strict as far as material quality and other things like that.