Going green: Nichia laser hits 515 nm

[steve001]

Commercial viability of green diodes beckons with devices that boast lifetimes of hundreds of hours.

Nichia has produced individual 515 nm continuous wave laser diodes, crashing past the 500 nm mark that was previously the longest wavelength reached by electrically-driven InGaN lasers

More http://optics.org/cws/article/research/39355

 

[Grix]

Is 515 nm brighter than 532?

 

[diachi]

Nope .

 

[chipdouglas]

i believe 555nm is the most visible to the average person.

 

[ElektroFreak]

It may not be as bright, but I still want one..

 

[hydrogenman15]

Is 515 nm brighter than 532?

515nm can be brighter under lower light conditions while 555nm can be brighter in well lighted conditions.

Quote:"At room temperature, threshold current and current density for the 515 nm diodes were 53 mA and 4.4 kA/cm2 respectively. The devices hit 5 mW optical output at 88 mA operating current and 5.5 V operating voltage."

This diode has very interesting electrical caracteristicts.
--hydro15

 

[pullbangdead]

But they totally cheated. :evil:

Nah, they didn't cheat, but it is AMAZING how they got this thing to work, and they did not do it in a way that will likely be commercially viable in the future. They also did it in a way which is very different from what everyone else is talking about as the likely way to get green diodes to work. It's kind of complicated to explain what they did vs. what will likely be viable in the future, but I could give it a shot. Basically, them doing it on c-plane was a clever trick, and they used a couple of different things to their advantage, but what they ended up with is not likely to work much beyond a proof-of-concept. But I've been wrong before.

It's certainly an interesting proof-of-concept, but it's most interesting for the shear fact of how well they are able to control their crystal growth, and just how good their epitaxy is. That's the key for any of this, and theirs is the best.

 

[pullbangdead]

515nm can be brighter under lower light conditions while 555nm can be brighter in well lighted conditions.

Quote:"At room temperature, threshold current and current density for the 515 nm diodes were 53 mA and 4.4 kA/cm2 respectively. The devices hit 5 mW optical output at 88 mA operating current and 5.5 V operating voltage."

This diode has very interesting electrical caracteristicts.
--hydro15

Which electrical characteristics are you talking about specifically?

The voltage is high, like it is for any research result because contacts, especially the contact to p-GaN, are VERY hard to optimize. You can't just stick a piece of metal on it and hope it'll work, it's tough. In production, contacts get optimized, and all the other layers get optimized as well to reduce any barriers that might be hiding.

It's a very low optical output because to get it to lase, they probably had to put very high reflectivity mirrors on it to cut mirror loss. And mirror loss is your output, so when you cut mirror lose to get it to lase, you lose output power.

Threshold could also be quite high, just because of how bad your internal losses can be, especially on c-plane. But I don't remember off the top of my head if that threshold current density is particular bad or not too bad.

 

[Flaminpyro]

Green laser diodes

If any one can do this Nichia can after all they invented the blue LED and the White LED :bowdown: to make this story short I'll say we have been buying them by the hundreds of thousands ever since. we have done millions of dollars in business with Nichia and as such know there style so I can almost guarentee it won't be long now boys !!! yipeee and we will have a green LD !!! :drool:

Peace Pyro...:eg:

 

[Benm]

It's certainly a nice prospect to have these one day...

But it's clear it is still in its infancy, threshold at 53 mA, and 88 mA for 5 mW. This means that a lot of power is dissipated in either non-radiating transitions, or is lost in the medium some other way.

Then again, it does work, and in combination with blue diodes under developing and red diodes readily available, small projectors seem an attractive mass market now more then ever before.

Perhaps we'll have as many laser diode colors to choose from as we have led's today