LPF Donation via Stripe | LPF Donation - Other Methods
Links below open in new window
ArcticMyst Security by Avery
yellow diodes
- Thread starter NickB95
- Start date
Regarding green, yellow, etc...
Isn't the (naïve, at least) technical limit for InGaN around 600nm?
If memory serves, the yellow halo found in 405nm InGaN diodes is due to issues with the local indium concentration being too high. According to Igor's testing, the Nichia diodes have a more pronounced halo, while their datasheets give a bit of a short wavelength tail on their spectrum; in essence, this would seem to indicate they use a different process (or simply a different quality process) to dope their diodes. That would match well with an article (a story or interview, I think) that commented something to the effect that they had a single amber diode on display (one presumes cryogenic cooling and/or gratings are used?).
I'm no laser physicist, though. I just collect hearsay that conforms to my prejudices.
Isn't the (naïve, at least) technical limit for InGaN around 600nm?
If memory serves, the yellow halo found in 405nm InGaN diodes is due to issues with the local indium concentration being too high. According to Igor's testing, the Nichia diodes have a more pronounced halo, while their datasheets give a bit of a short wavelength tail on their spectrum; in essence, this would seem to indicate they use a different process (or simply a different quality process) to dope their diodes. That would match well with an article (a story or interview, I think) that commented something to the effect that they had a single amber diode on display (one presumes cryogenic cooling and/or gratings are used?).
I'm no laser physicist, though. I just collect hearsay that conforms to my prejudices.
- Joined
- Apr 29, 2007
- Messages
- 1,076
- Points
- 0
There are many materials used in production of laser diodes. Currently the best bet for green has been Aluminum Indium Gallium Phosphate die.
- Joined
- Aug 25, 2007
- Messages
- 2,007
- Points
- 63
For LEDs, sure, yellowish or amberish is completely possible, and has been done.
But for lasers, you run into a HUGE set of problems. Green isn't quite there yet, and I doubt there will ever be a big commercial need for yellow, so I doubt the investment will ever be made to make yellow happen. As far as technological problems, for one thing, when you're putting that much indium into the InGaN, it becomes a big problem just to keep it in one homogeneous phase, especially once you start growing the p-type GaN on top of it. To get good p-GaN, (at least with MOCVD, which is what is generally used) you have to raise the temperature back up higher, and the InGaN has trouble witht he higher temperatures. It sometimes would rather phase segregate than stay in one uniform phase.
And of extreme importance to lasers and less importance to LEDs, as you increase the the amount of indium in the active region, you also change the index of refraction of the material. Since the index of refraction is what creates the cavity and the guiding of the light, changing the index of refraction can have MAJOR effects on how the cavity behaves.
The more indium you put in, the more you have to change the other materials as well. You have to push the other materials in the diode stack further without them cracking or phase segregating or what have you, you have to make all kinds of changes. The entire structure of the laser diode has to change, and as of yet, no one has made it work.
-----------------------------------------
AlInGaP for green? I haven't seen that at all, maybe you could point to a reference? Everything I've seen is focused on the nitrides, InGaN, for making green laser diodes.
But for lasers, you run into a HUGE set of problems. Green isn't quite there yet, and I doubt there will ever be a big commercial need for yellow, so I doubt the investment will ever be made to make yellow happen. As far as technological problems, for one thing, when you're putting that much indium into the InGaN, it becomes a big problem just to keep it in one homogeneous phase, especially once you start growing the p-type GaN on top of it. To get good p-GaN, (at least with MOCVD, which is what is generally used) you have to raise the temperature back up higher, and the InGaN has trouble witht he higher temperatures. It sometimes would rather phase segregate than stay in one uniform phase.
And of extreme importance to lasers and less importance to LEDs, as you increase the the amount of indium in the active region, you also change the index of refraction of the material. Since the index of refraction is what creates the cavity and the guiding of the light, changing the index of refraction can have MAJOR effects on how the cavity behaves.
The more indium you put in, the more you have to change the other materials as well. You have to push the other materials in the diode stack further without them cracking or phase segregating or what have you, you have to make all kinds of changes. The entire structure of the laser diode has to change, and as of yet, no one has made it work.
-----------------------------------------
AlInGaP for green? I haven't seen that at all, maybe you could point to a reference? Everything I've seen is focused on the nitrides, InGaN, for making green laser diodes.
- Joined
- Jul 27, 2007
- Messages
- 3,642
- Points
- 63
Justin said:
DO NOT post this link. These URLs are distributed to specific customers for specific reasons, to enable easy online payment using credit cards. These URLs exist to make things easier for our customers but if you are going to EXPLOIT it we will have to stop using them altogether. I personally check every order that comes through our website and we will not be shipping anything that is purchased at a false price. Processing and refunding a credit card transaction costs us money and if this becomes a problem we will begin withholding the transaction fees from anyone who places an order using this dishonest exploitation of our online billing system.[/quote]
I really don't think it's fair to yell at a member here just because your website isn't coded the way it should be. As was covered in a previous thread the items and prices should be SKUs stored on the website server itself, not generated by the page and transmitted via URLs and javascript. If you needed to "modify" a price for a specific customer which seems fishy to me to begin with, you could always create coupon codes which wouldn't really be any more difficult than getting a customized link for them to click.
Back on topic - it seems right now your best chance for yellow is to get a nicely discounted yellow CNI like the Rigel, or you could get a yellow HeNe laser off ebay (not very portable though)
- Joined
- Dec 24, 2007
- Messages
- 1,000
- Points
- 63
MarioMaster said:
DO NOT post this link. These URLs are distributed to specific customers for specific reasons, to enable easy online payment using credit cards. These URLs exist to make things easier for our customers but if you are going to EXPLOIT it we will have to stop using them altogether. I personally check every order that comes through our website and we will not be shipping anything that is purchased at a false price. Processing and refunding a credit card transaction costs us money and if this becomes a problem we will begin withholding the transaction fees from anyone who places an order using this dishonest exploitation of our online billing system.[/quote]
I really don't think it's fair to yell at a member here just because your website isn't coded the way it should be. As was covered in a previous thread the items and prices should be SKUs stored on the website server itself, not generated by the page and transmitted via URLs and javascript. If you needed to "modify" a price for a specific customer which seems fishy to me to begin with, you could always create coupon codes which wouldn't really be any more difficult than getting a customized link for them to click.
Back on topic - it seems right now your best chance for yellow is to get a nicely discounted yellow CNI like the Rigel, or you could get a yellow HeNe laser off ebay (not very portable though)[/quote]
By being one of the first (if not THE first) member here to legitimately use that link, I can testify that Justin has a good reason for it's existance. By telling what exactly he and I talked about for me to get that offered to me I would consider myself to be doing something as dirty as jamilm9's posting the link. Justin has a perfectly legit reason for offering that link, it's there on his website for anyone with a bit of imagination to figure out. I know of several people other than myself who have figured it out and used it. I'll agree that there's better ways to offer the discount through the site, but he can run his business however he sees fit.
