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FrozenGate by Avery

Is there a yellow laser direct diode ?

TheMaxii2007

TheMaxii2007

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hi... 589 nm yellow laser DPSS already exists.... but is there a yellow laser direct diode...? Will he come ?
 





That article is 20 years old. Has anyone heard any developments since then? Only 565 nm lasers I've ever seen were DPSS. To put into perspective Nakamura published his work on 405 nm diode lasers just three years before that paper.
 
The market is already satisfied with fiber lasers and dpss so there is no reason for a low power yellow diode. The 20 year old diode needed cooling and was not cw from what I remember. This is just a very inefficient part of the spectrum for semiconductors to laze it seems. If you must have yellow you will spend 5k on opsl or 100.00 on 8-10mw. Opsl nets you true 577nm yellow the other a green with 571nm about the best pumped out right now. There was575 for a few but no more. So yes it can be done and gotten but there are limits depending on power and cash
 
Sadly from an information storage perspective, lots more money goes into development of diodes with significantly shorter wavelengths than 405nm (to enable finer pitch etching features to write media).

From a data transmission over fiber perspective, they like encoding data in modulation of IR wavelengths which also permit cheaper fiber and lower attenuation over distance.

For visual display projectors, its been lowest cost to use blue light engines lasers, green, and red light engines, and then overlap red and green, and our eyes get spoofed a bit to see a yellowy seeming colored spot in the Rayleigh scattering diffused light reflection our eyes detect. This means you can have a relatively small and cheap and wide range of power level visually yellow spot looking laser module, but it's only a pseudo yellow illusion. The cool thing is, you can adjust your green red balances to set the illusions visual resulting spot colors wavelength from red to red orange to orange, to yellow, to lemony yellow, to green. Obviously if you need the actual orange or yellow wavelength rather than it's useless for you, but you can have a yellow laser illusion to human eyes in wide power ranges for cheap.
 
For yellow diodes to be developed there needs to be a major demand for them where other technologies won't suit the application.
There are not many uses for yellow semiconductor lasers as of current.
So I gave it some thought for a bit.
The only major commercial market that I can foresee having a niche need for semiconductor yellows is the television industry.
They are always looking for the next way to up their colour gamut to compete against rival companies. Everyone here knows that RGB is the principal behind every display. However technology and computing has developed massively over the years. Displays are not static but instead every frame is now computed. Upscaled, local dimming, HDR etc. Why not have a feature a 'yellow boost' function to give a wider colour gamut in the longer part of the visible spectrum? A true natural yellow and orange isn't currently possible using existing models, but featuring a yellow semiconductor would widen the colour range. Obviously DPSS or gas lasers are not ideal for this application.

1642538173145.png

My prediction is at some point a company like Sharp who makes their own laser diodes will probably utilise their inventory to create a almost complete colour gamut like this: Featuring: 450, 488, 505, 520, 575 & 650nm.

1642538888356.png
 
Sadly not too likely. There was once a television with a 4 channel HD display. In theory, it should have been able to show much more vivid oranges, yellows, and greens. However, it could not work, because all colour information fed to the display was in RGB, so the added technology was useless.

Any future projector would suffer from the same problem. You'd need to feed it data that actually contains extra colour information for a fourth channel in order for the image to be affected in any positive way, or else the extra hardware just makes the resolution a little worse, as there is a functionally dead 25% of each pixel taking up valuable real estate on the screen and 25% more weight in the colour engine that is essentially unused.

Green is more highly visible. As pointed out, UV and IR are much more useful for hardware. So, there will never be a yellow diode laser in the mass market.

Even if someone stumbled upon a yellow laser diode tomorrow, which won't happen, they'd be another item accessible only to academics for federal-grant-levels of money ($$$,$$$.$$). It's okay to be optimistic, but from any sort of realistic standpoint, this will never happen.
 
I'm looking forward to quantum laser diodes which should make it easier to produce much better quality beam, better coherence length, laser diodes across the visible spectrum.
 
bostjan said:
Sadly not too likely. There was once a television with a 4 channel HD display. In theory, it should have been able to show much more vivid oranges, yellows, and greens. However, it could not work, because all colour information fed to the display was in RGB, so the added technology was useless.

Any future projector would suffer from the same problem. You'd need to feed it data that actually contains extra colour information for a fourth channel in order for the image to be affected in any positive way, or else the extra hardware just makes the resolution a little worse, as there is a functionally dead 25% of each pixel taking up valuable real estate on the screen and 25% more weight in the colour engine that is essentially unused.

Green is more highly visible. As pointed out, UV and IR are much more useful for hardware. So, there will never be a yellow diode laser in the mass market.

Even if someone stumbled upon a yellow laser diode tomorrow, which won't happen, they'd be another item accessible only to academics for federal-grant-levels of money ($$$,$$$.$$). It's okay to be optimistic, but from any sort of realistic standpoint, this will never happen.
Click to expand...
We live in the age of AI and fast computing. You wouldn't necessarily need a 4th channel. TV's are able to compute each frame nowadays, you could just use an AI algorithm to decide when and where to apply a colour boost based on that frames data input. Therefore you can still have RGB data without too much compromise. Not too hard to program either. You just set thresholds based on conditions that correspond to RGB value of yellows, oranges and reds.
 
I also think computing a 4th channel out of 3 existing one is certainly possible. Not for accurate color reproduction but rather for enhanced "pop". Most TV do stuff with the color to make the picture pop, making it less accurate in the process but providing a "better" look.

If this technology gets added, I would think that one would add a color around the cyan part of the spectrum. As BT2020 is already quite good for yellow colors. Red (around 635nm) is already quite low wavelength and green (525-530nm) a high one. This gives good coverage of the red to orange / yellow space.
Every colorspace below that only uses higher green and lower red wavelengths e.g. DCI -P3 or REC-709.

I think this is done because yellows and orange need to be quite accurate to reproduce skin tones.

On the other hand, all of these colorspaces are quite lacking in the cyan range of colors. So I would expect some company adding something like 488nm.

Sadly no current technology uses lasers for color production in TVs. Its only starting in the projector market with mostly blue diodes that get phosphor converted. Some use green but its still quite rare.
Yellow diodes would give no advantage. They would not be able to keep up with the already mature technology of blue diodes and phosphor. The efficiency is already quite high.
It also would be easy to change the phosphor composition and just add more yellow.
 
Yellow semiconductors exist as leds and have been available for a long time. It’s getting the gain to laze that is the hard part. in fact one of the first oleds was orange. Tv’s don’t need lasers.
 
CurtisOliver said:
We live in the age of AI and fast computing. You wouldn't necessarily need a 4th channel. TV's are able to compute each frame nowadays, you could just use an AI algorithm to decide when and where to apply a colour boost based on that frames data input. Therefore you can still have RGB data without too much compromise. Not too hard to program either. You just set thresholds based on conditions that correspond to RGB value of yellows, oranges and reds.
Click to expand...
That's not really how that works, though.

Yes, you could calculate the yellow channel by weighting an average of the R and G channels, but that won't make it look any better than just showing the R and G channels. If you want some sort of extra colour information, which is the only way you could economically justify the Y channel, you need to record with a camera with a Y channel.

Otherwise, if there is some mathematical formula to weigh the R and G channels to make the colour pop more, we would just do that without needing the extra Y channel.

As I said, this has already been done before and it was a financial flop.

But don't just take my word for it - http://www.eecs.qmul.ac.uk/~tb300/pub/Appendix_Quattron.pdf

"The introducing of a yellow primary would therefore serve little or no function"

Of course, if you really wanted to re-invent the television, using a deeper red and a bluer green with a yellow and a violet, something like RYCV - red, yellow, cyan, violet - would really make the colour depth better for viewing, but in order to do that, you'd have to reinvent the television camera to record information that way. You could go 4 channel television and RGB camera and use an algorithm to convert, but your resultant image would still only contain the three channels worth of data, so it wouldn't look any better than RGB.

It all boils down to the quality of information provided to the display.

For example, streaming 720p video through an algorithm to make it 4k video and then pass that onto a display won't look any sharper than just watching it at 720p, because the information you are seeing is only as good as the 720p source. Unless you are living in the script of a cop show or movie, in which case, all you have to do is shout "enhance!" and then you can see everything infinitely clear regardless of how poorly it was recorded. :)
 
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