Interesting studies on green and yellow and the future

[Blackwolf]

I was checking some of the expensive databases that my tuition helps pay for and I found a few interesting articles about green and yellow lasers. One was about using a 398.8nm diode to pump some Dy3 floro-aluminate glass to get 575nm at 17% efficiency. that would be pretty sweet. I also read about MQW laser diodes that operate in the 500-510nm range. lastly I read about using SHG on 1074nm and 1112nm using a YAG-->LBO setup to get 537nm 546nm and 556nm and they said that they are getting up to 51% efficiency. These are exciting times indeed. I hope that in the next 5 years the price of 473 starts to decline and more wavelengths pop up in the 490-510 and 530-630 ranges.

 

[pschlosser]

These are exciting times indeed. I hope that in the next 5 years the price of 473 starts to decline and more wavelengths pop up in the 490-510 and 530-630 ranges.

They ARE exciting times. But I think until there is widespread use of these other wavelengths, the supply and demand principle we all know and love will continue influencing our costs in the surplus and hobbyist community.

For example, the wonderful 2000mW 445nm diodes we enjoy (and are becoming bored with) are available to us at such low cost because of abundant supply. The industry was strongly motivated to find a low-cost solution, and as such, it trickles back to us.

As long as Yellow (and orange and other fun wavelengths) continue to have limited application, I predict we'll continue finding them at premium costs.

The RGB (red, green and blue) color model we find so prevalent in digital imagery these past few decades is presently met, more or less, by the laser diode industry. I expect to see improvements in the green wavelengths because we still seem lacking in high-power direct diode solutions.

 

[crazyspaz]

I was checking some of the expensive databases that my tuition helps pay for and I found a few interesting articles about green and yellow lasers. One was about using a 398.8nm diode to pump some Dy3 floro-aluminate glass to get 575nm at 17% efficiency. that would be pretty sweet. I also read about MQW laser diodes that operate in the 500-510nm range. lastly I read about using SHG on 1074nm and 1112nm using a YAG-->LBO setup to get 537nm 546nm and 556nm and they said that they are getting up to 51% efficiency. These are exciting times indeed. I hope that in the next 5 years the price of 473 starts to decline and more wavelengths pop up in the 490-510 and 530-630 ranges.

THAT excites me. However, like pschlosser said, these wavelengths and diodes will continue to be very expensive, unless there is a demand for them commercially-which most likely will never happen. Yellow/orange/cyan are not primary colors (as the above picture shows), so really, projectors wont ever use them (although I'm sure some company will, similar to when Sharp put yellow pixels in their TV's- it makes zero difference, but to people who didn't know that, it seemed really "cool and new and more high def."

...I hope that in the next 5 years the price of 473 starts to decline and more wavelengths pop up in the 490-510 and 530-630 ranges.

I'm sure 473 will continue to drop in price. I have said this several other times in posts. I think it will follow the 532 trend line, in that it starts off as new and expensive, but some day we will be buying 473 overspec ebay pens.



Also, it is too bad that Soraa didn't continue research on yellow diodes, apparently they either successfully produced some, or got very close. But, there isn't any commercial need for direct yellow diodes, so I imagine that's why they halted research. I emailed their laser branch asking about whatever happened with the yellow diodes, but I got no response (this was a while ago).
Now, wheres our tunable diodes! :crackup:

Exciting times indeed! Not only lasers, but in general. Every day I read about new discoveries, like new stem cell research, a cure for HIV, spray on skin, so on and so forth. The only thing that makes me sad is that I live in the generation that more than likely wont develop advanced space travel- I'm talking manned travel out of this solar system, out of this galaxy- and in a matter of days/weeks, instead of the years that it takes currently.

But who knows, I won't know the future until I get there

 

[ZRaffleticket]

There are a few problems with the theories here... Just a few

It's all a question of practicality. What NEED is there for a 546nm laser? What NEED is there for a 495nm laser?

Also, the 51% efficiency thing... you'd be lucky to see a tenth of that transferred to a handheld. Efficiency of DPSS lasers IMMENSELY depend on the temperature of the crystals. Keeping a stabilized temperature in a handheld unit is one heck of a task. Also, efficiency improves drastically on slight variations in pump diode wavelength. Also controlled via temp.

What you're reading are laboratory experiments that have been conducted for two decades, with very, very few actually going into the hands of the public.

For the orange spectrum, that is slightly more promising. RGBY laser lighting still has a chance, specifically for more "natural" looking light. Though that's the only real practical application unless superpowered hobby telescopes suddenly pop up out of nowhere.

Yellow diodes have been invented, but run at temps like -30C or something absurd like that.

__

As per 473nm...

I do believe it is going to drop in price. A little bit.

Going back to practicality, what on god's green earth do we need a 473nm pen for? They'd be unstable as hell, featuring more mode hops and shorter duty cycles.

What the heck do we need 473nm for at all? Its been effectively replaced with 445nm. The practical use of 473's have dropped dramatically. If anything, I expect 457nm to drop to something "affordable" in upcoming years. It's approximately the wavelength needed for projectors, and it has nicer beam specs.

 

[ultimatekaiser]

There are a few problems with the theories here... Just a few

It's all a question of practicality. What NEED is there for a 546nm laser? What NEED is there for a 495nm laser?

Also, the 51% efficiency thing... you'd be lucky to see a tenth of that transferred to a handheld. Efficiency of DPSS lasers IMMENSELY depend on the temperature of the crystals. Keeping a stabilized temperature in a handheld unit is one heck of a task. Also, efficiency improves drastically on slight variations in pump diode wavelength. Also controlled via temp.

What you're reading are laboratory experiments that have been conducted for two decades, with very, very few actually going into the hands of the public.

For the orange spectrum, that is slightly more promising. RGBY laser lighting still has a chance, specifically for more "natural" looking light. Though that's the only real practical application unless superpowered hobby telescopes suddenly pop up out of nowhere.

Yellow diodes have been invented, but run at temps like -30C or something absurd like that.

__

As per 473nm...

I do believe it is going to drop in price. A little bit.

Going back to practicality, what on god's green earth do we need a 473nm pen for? They'd be unstable as hell, featuring more mode hops and shorter duty cycles.

What the heck do we need 473nm for at all? Its been effectively replaced with 445nm. The practical use of 473's have dropped dramatically. If anything, I expect 457nm to drop to something "affordable" in upcoming years. It's approximately the wavelength needed for projectors, and it has nicer beam specs.

my thoughts exactly +1 got to it before I did.

473 will continue to drop a bit, but not too far I'd imagine. cost of materials prevents this, as well as the fact that 473 as mentioned above is hard to stabilize, particularly in a small closed off handheld. the vanadate isn't particularly hard to deal with...its the LBO. This particular crystal generating the blue light gets really hot very fast as very little of the light is transmitted through it, which in turn messes up your output stability. Yellows are even more susceptible to this issue as its eating even more at two different lasing lines to join them into visible light.

But hey...new non linear optics and processes are being found as we speak. so ultimately, who can say exactly what the future holds?

 

[crazyspaz]

my thoughts exactly +1 got to it before I did.

473 will continue to drop a bit, but not too far I'd imagine. cost of materials prevents this, as well as the fact that 473 as mentioned above is hard to stabilize, particularly in a small closed off handheld. the vanadate isn't particularly hard to deal with...its the LBO. This particular crystal generating the blue light gets really hot very fast as very little of the light is transmitted through it, which in turn messes up your output stability. Yellows are even more susceptible to this issue as its eating even more at two different lasing lines to join them into visible light.

But hey...new non linear optics and processes are being found as we speak. so ultimately, who can say exactly what the future holds?

very true. And thanks for the info on the LBO (cant BiBO also be used?) being the crystal that overheates- I thought it was the vanadate. Also, have you any idea how crystals (i.e. Nd:YVO4, Nd:YAG) are coated for different wavelengths? Can't find an answer to that question anywhere...

 

[ZRaffleticket]

BiBO, LBO and KTP can all be used.

Typically, our hobby uses KTP. BiBO is pretty much outdated. LBO is much more finicky but will give a very tight beam.

It is that crystal and the pump diode that need to be kept under temperature modulation. Nd:YAG and Nd:YVO4 really don't care too much about temperature from what I've read.

Also, 473nm uses Nd:YAG, not Nd:YVO4.

--

Coatings... how they are... no. Apparently a lot of Nd: crystals are coated for a lot of wavelengths but the SHG crystals are coated to only allow certain lines to pass into the process. Not 100% on that.

 

[hwang21]

I mean you can probably go ask Nichia for a 495nm laser diode right now if you wanted, and they'd probably be able to supply you with one. It's just a matter of cost... and that is completely dependent upon practicality and usefulness. Our high powered 445nm's got into the mass production market in China, so now they're abundant and therefore not expensive. I don't think there's any particularly devastating reason why we need yellow and cyan laser colors in the world, so those prices are likely to stay on the high side. Of course, as technology advances, sooner or later we will probably find a reason or two. Not to mention, as the technology ages, the prices do slowly drop

 

[ultimatekaiser]

very true. And thanks for the info on the LBO (cant BiBO also be used?) being the crystal that overheates- I thought it was the vanadate. Also, have you any idea how crystals (i.e. Nd:YVO4, Nd:YAG) are coated for different wavelengths? Can't find an answer to that question anywhere...

well really both of them get hot but the vanadate doesn't care as much, and yes it can use a BBO as well, in fact thats one of the most commonly used in smaller lasers I believe and in larger ones a KNBO3 tends to be used. in fact a KTP works for this extracavity, but the output is very low and hard to obtain.

As for the doping of the optical surfaces, i'm not sure what is used to index them. they're usually doped to request when they are produced, but the exact process/materials I'm not sure.

 

[crazyspaz]

BiBO, LBO and KTP can all be used.

Typically, our hobby uses KTP. BiBO is pretty much outdated. LBO is much more finicky but will give a very tight beam.

It is that crystal and the pump diode that need to be kept under temperature modulation. Nd:YAG and Nd:YVO4 really don't care too much about temperature from what I've read.

Also, 473nm uses Nd:YAG, not Nd:YVO4.

--

Coatings... how they are... no. Apparently a lot of Nd: crystals are coated for a lot of wavelengths but the SHG crystals are coated to only allow certain lines to pass into the process. Not 100% on that.

KTP doesnt like to double below 500nm though. Also, just found an interesting page from a company called Beijing Gospel OptoTech Co.

Crystals and optical components being coated are usually called substrates. Optical coatings used to vary the reflectance, transmittance, absorbance, or polarizer properties on substrates, are an essential part of modern laser designs. Coatings are manufactured in high vacuum by the process of deposition, in thin layers which thickness are typically equal to one-quarter to one-half the wavelength of the light used in the application, or about 10 to 20 millionths of an inch. A high-performance coating is not just one coating but several thin layers deposited on top of each other, any one of the layers might exhibit modest performance. Alternating between layers of high index of refraction, and low index of refraction, a reflective stack of layers can achieve very high reflectivity (99.9%) and an antireflective stack can achieve very low reflectivity (0.1%). Optical interference coatings respond differently to s and p polarized light, so it is essential to specify s, p, or random (the average performance of the s and p) polarization when the angle of incidence exceeds 20 degrees.

Just google the company name, and go to their "coating services" page. very informative read.


EDIT: YEESH, googled the machines that the above mentioned company uses, these things are wicked crazy. link. I sent a price eenquiry email, because im curious...Lets guess, shall we? My guess is around $75k.

 

[ultimatekaiser]

That's about what I thought. but I didn't know for sure...good find.

 

[ZRaffleticket]

Crap I'm so used to dealing with 532, 589 and 650nm DPSS talk. Forgot that little detail of KTP...

It's still unlikely LBO is used in handhelds due to phase matching that needs to take place. Maybe BBO is still used. Gah, I need to brush up.

 

[crazyspaz]

Yes, company didn't respond. I bet those coating machines cost an absolute fortune...

 

[NightExplorer96]

Life would be boring if we only got what we needed. We want 495nm/473nm because It's cool.

Simple as that.

Those wavelength's are pretty nice indeed

 

[Roam]

As per 473nm...

I do believe it is going to drop in price. A little bit.

Going back to practicality, what on god's green earth do we need a 473nm pen for? They'd be unstable as hell, featuring more mode hops and shorter duty cycles.

What the heck do we need 473nm for at all? Its been effectively replaced with 445nm. The practical use of 473's have dropped dramatically. If anything, I expect 457nm to drop to something "affordable" in upcoming years. It's approximately the wavelength needed for projectors, and it has nicer beam specs.

Nichia has only recently started manufacturing 473 nm diodes (as well as 488, and emerald and light green). Giving it a few years they will hopefully get cheaper just like the 450's did.

Actually looking at their datasheets their specs are not that different (temperature, electrical, divergence, etc).

I don't think any laser oscillating in one region of spectrum can ever replace one in another region. As for applications... 488 nm diode might perhaps replace Ar and Kr lasers in some of their medical applications, for instance. 473 will be used whenever you want aquamarine instead of royal blue/indigo. They are clearly different colors.

 

[ZRaffleticket]

I didn't say 488's were out of the question. They have a good chance of getting cheap.

But 473nm, what practical use does aquamarine/sky blue hold in anything? The 445's are better for color mixing, and as far as I know there's no medical use for 473nm.

And it wasn't too recent, those diodes have existed for quite some time. (though it might've been osram making them)