Why are green diodes so expencive?

I don't understand the reason to build one with thos prices.:yabbem:

They are hard and expensive to manufacture plus something else which I can't remember

from my understanding it is 2 reasons...

1- not much need for green diode in the maket place
2- the parts to make it are much more expensive and sensitive.

i could be wrong but...

michael.

Gofilord said:

I don't understand the reason to build one with thos prices.:yabbem:

Click to expand...

Actually the "green laser diodes" are more of a blue green than a true green like DPSS.
They are ~510nm compared to 523nm. There have been some more recent breakthroughs but true green efficiency is "very poor" due to the complexity of the diode.

There isn't a market for these diodes as they are lossy, poor output for input energy and OVERLY complex to make. There is also a shortage of rare earths needed to make the substrate at the moment to boot.

-- 1% efficiency for a green LD vs 6% or there abouts for a DPSS ( green) laser. Make your pick.

InGaN is hard to grow in the orientation needed to make these green diodes. s'gotta be all clean too, yo! And like, dope that sht to perfection and still end up with crappy yields, dawg.

Inefficient, as previously mentioned

Nothing that has a specific need for those wavelengths that couldn't get by with the cheaper 532nm

"Actually the "green laser diodes" are more of a blue green than a true green like DPSS.
They are ~510nm compared to 523nm. There have been some more recent breakthroughs but true green efficiency is "very poor" due to the complexity of the diode."

I bet you that this is way more than what was being asked. This member is very new and still unwise to many things here. There have been many postings that have answers easily accessible. If he was actually asking about the diode version versus the DPSS versions I would be surprised.
But I won't say that it is all bad because I just learned something new by reading this thread ! I love learning about the chemistry and manufacturing side of things.

ShortyInCanada said:

"Actually the "green laser diodes" are more of a blue green than a true green like DPSS.
They are ~510nm compared to 523nm. There have been some more recent breakthroughs but true green efficiency is "very poor" due to the complexity of the diode."

I bet you that this is way more than what was being asked. This member is very new and still unwise to many things here. There have been many postings that have answers easily accessible. If he was actually asking about the diode version versus the DPSS versions I would be surprised.
But I won't say that it is all bad because I just learned something new by reading this thread ! I love learning about the chemistry and manufacturing side of things.

Click to expand...

if you are interested in learning more.... look up members pullbangdead and frothychimp. check out some of their posts. 2 very knowledgable and friendly member.. too bad they don't come around much anymore.

michael.

Wow 6% for DPSS that's bad I had no idea it was that low...

The other reason these are so expensive is they are new, when
people find new and better ways of making them the price will
go down, just like all other electronic devices.

Seoul_lasers said:

There isn't a market for these diodes as they are lossy, poor output for input energy and OVERLY complex to make. There is also a shortage of rare earths needed to make the substrate at the moment to boot.

-- 1% efficiency for a green LD vs 6% or there abouts for a DPSS ( green) laser. Make your pick.

Click to expand...

I don't think your comment about the lack of a market is accurate. There is a big market for green laser diodes in the media projection field. Picos and small integrated projectors are all waiting on these diodes. Lasers have an advantage over LEDs in that the focusing mechanisms required (or rather not required) for laser projection allow size optimizations.

I suppose it's fair to say "Ok, but the projector industry is not itself a huge market, like, say optical drivers are". To which I would comment that I've never seen our normal 445s used outside of projectors, and yet there's clearly a viable market for 445s.

Also, where did you get your 1% efficiency for a green LD figure? I can't point to any literature to back this up, but you've got to be wrong. No?

These "upcoming" green diodes are generally rumored to be around 50mW. At 1% efficiency, you would be pumping 5W of power into them. Assuming a Vf of even 5V, that's a full 1A of current going in for 50mW of output. That just seems very questionable to me.

Yea I believe they run on just 200mA, I don't recall the voltage tho. Also they will have a ton of uses for sure.

Seoul_lasers said:

Actually the "green laser diodes" are more of a blue green than a true green like DPSS.
They are ~510nm compared to 523nm. There have been some more recent breakthroughs but true green efficiency is "very poor" due to the complexity of the diode.

There isn't a market for these diodes as they are lossy, poor output for input energy and OVERLY complex to make. There is also a shortage of rare earths needed to make the substrate at the moment to boot.

-- 1% efficiency for a green LD vs 6% or there abouts for a DPSS ( green) laser. Make your pick.

Click to expand...

Several things. First, they're not just blue-green. Published results go all the way up to 532nm, and several companies have published in the 520nm region, which is very green.

Also, the substrates are not made of rare-earths. In fact, in your average laser diode, there's not a single rare-earth element in the entire diode (unless it's an impurity, which is undesirable).

rhd said:

I don't think your comment about the lack of a market is accurate. There is a big market for green laser diodes in the media projection field. Picos and small integrated projectors are all waiting on these diodes. Lasers have an advantage over LEDs in that the focusing mechanisms required (or rather not required) for laser projection allow size optimizations.

I suppose it's fair to say "Ok, but the projector industry is not itself a huge market, like, say optical drivers are". To which I would comment that I've never seen our normal 445s used outside of projectors, and yet there's clearly a viable market for 445s.

Also, where did you get your 1% efficiency for a green LD figure? I can't point to any literature to back this up, but you've got to be wrong. No?

These "upcoming" green diodes are generally rumored to be around 50mW. At 1% efficiency, you would be pumping 5W of power into them. Assuming a Vf of even 5V, that's a full 1A of current going in for 50mW of output. That just seems very questionable to me.

Click to expand...

FireMyLaser said:

Yea I believe they run on just 200mA, I don't recall the voltage tho. Also they will have a ton of uses for sure.

Click to expand...

Green diodes are pretty low efficiency so far. Nichia and OSRAM reported something like 524nm, 50mW, and 2.3% wall-plug efficiency. Soraa's published green result is something like 521nm, 60mW, and 1.9% wall-plug efficiency. The voltage is a big part of this, the voltages can be quite high when they're quoted in papers. And even when voltages aren't quoted, it's a pretty safe assumption that it's bad, (if it was good, they'd quote it in the paper). The currents as higher as well

These diodes are still very new, and will continue improving. Vs. DPSS, you're comparing a very old/mature technology vs. state-of-the-art fresh out of the lab. They're hard to make. But remember, they still have major advantages besides efficiency. Size (diodes are MUCH smaller), stability (DPSS isn't stable at all), modulation, cost, etc.

As a technology, green diodes are still in their infancy. They'll only get better.

I'm still skeptical of this 1 or 2% efficiency figure.

Look at it from the other angle, this implies 99% inefficiency.

Or simplified even further, this implies that there will be 99x more energy to dissipate as heat, than will go out the front of the diode. So, for 50mW of output, you'll produce 4.95 W of heat. That's more heat to deal with in a 3.8mm green laser diode doing 50mW of output, than we have to deal with in a 445 running at 1,000 mW of output.

If that were the case, then there would be NO WAY these green diodes could be utilized in a pico projector. The heat issues alone would make it a non-starter. The battery life issues would put a second nail in that coffin. How long do you think you can drive a diode that takes more energy input than the 445s we build with, on a battery that has less than half the capacity of a single 18650 ? (basing this on the battery in a Microvision pico)

That's why they're still in labs and not on store shelves.

Soraa's paper has CW LIV curves for a 520nm green laser diode. The diode was actively temperature controlled. From the figure, at 30C, 50mW comes at ~350mA and ~8.2V. That's ~2.87W in, for ~1.7% wall-plug.

The 510nm stuff is better, and both will continue improving.

pullbangdead said:

That's why they're still in labs and not on store shelves.

Click to expand...

Perhaps... But I would still be willing to bet that the Nichia greens we're seeing (errr, hearing about) bouncing around the real world now, are already hitting at least 5% efficiency (something reasonably close to the wall plug of DPSS).

It doesn't make sense to me that Nichia would have these green diodes out there, even as engineering samples, with 1 or 2% efficiency figures.

EDIT: Found some citations:

"It offers an output power of 50 mW at a current of 200 mA, a voltage of 5 V and a case temperature of 25 ° C."
http://scienceray.com/technology/the-green-laser-diode-becomes-a-reality/

"The optical output of the green diode laser is 50mW when driven at 200mA and 5V (case temperature: 25°C)"
http://techon.nikkeibp.co.jp/english/NEWS_EN/20100708/184088/

From those articles (which are a year old at this stage), it looks like we're talking about 50 mW / (200mA * 5V) = 5% wall plug efficiency.

Holy hell at that. Over 8 volts just to power a freakin dioide? A 2 Watt IR laser would use less power over all.

That last 10nm from 510 to 520 is a big jump. You start running into some serious materials science issues in that range, some issues that are still being worked on very actively.

It'll get there. Blue diodes were the same way when they were new, and now they're great.