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What happens to these other wavelengths above threshold? I noticed that after I LED ed a 638 nm diode, the output, although low, spanned a range from deep green to deep red (probably beyond visibility). This happened before I had a spectrometer and only a handheld monochrome. The lack of yellow and orange diodes maybe due to the lack of sufficient gain in these bands or a lack of a market?
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They are still present. But because the brightness of the dominate wavelength of the diode is so bright when you turn the diode up its nearly impossible to see. These other wavelengths do not increase in power passed more then 1mW if even that. It really is just a faint glow.
So running the diode pre threshold allows you to see it easier because you don't have to deal with the added brightness of the main wavelength output since even if you have some very good dicros or filter optics to block the main wavelength you still get some leakage of it through and if its anything above 1mW of leakage which more then likely it will be its still enough to hide these other wavelengths pretty good. At least enough to make it hard to see the other wavelengths. In other words its easier to see without having the main beam lazing.
Pretty interesting that you seen Green in the 638nm diodes. I have not looked at 638nm diodes yet. It all seem that alot of these diodes are made very similar to one another.
Your guess is as good as mine on Yellow and orange diodes. But iam leaning towards the lack of market being the reason. Iam sure there is some gain issue too but i bet if one of these large diode manufacture got an order for a orange or yellow diode they would do it if they have not already and are just waiting to get interest. Its hard to say though.
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This thread was just point out to me, my apologies for the threadjacking.
Angelos, how many lines have you observed in one diode? Are the cyan lines common in these 462nm diodes?
You know as well as I do that cyan is a spectrum that I dream of obtaining outside of my argon.
Do these show significant deficiencies from running at or below threshold, similar to running above?
Only an electron wiggler like you would resonate at 30cm.
Senior Member
It is funny I just saw that. I was powering a LEDed M140 yesterday and saw a distinct green spot in the output with blue all around it. Was really surprised to see that.
Senior Member
I long time ago I saw half green and blue output in a dead PL450B. I took this video a long time ago before I understood the finesse of videography, so pardon the rambling.
As mentioned, I had an 803T do similar things. It LEDed and I had to bang it out of a module. I tested it for shagrins and it still output. With yellow, white, violet, and deep purple output. I don't think there was red, I don't remember red ... It only output a couple mW max.
Only an electron wiggler like you would resonate at 30cm.
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Ive never been able to get an exact number due to the violet (410-440) Lines being so close to one another that its hard to get on the spectrometer to show up differently. Id say its 5 or more.Originally Posted by SoulFeast
These extra WL lines that show up are nothing more then a glow. So although you see it and its interesting in the output you will never be able to get a beam out of it more then half a mW "If that" More of Just a glow. Unless there is someway that can make these Hidden Lines stronger in the output by the use of external optics but i have no idea and that thought of "External optics" is Just a wild guess. I have not done much reading and searching on this subject Yet, But maybe one of the more advance guys on here might know of a way to pull out one of these WL and have it put out Greater powers by the use of Optics or gratings or etc... I'd have to read about it more its just hard to find info on this stuff.
Its pretty interesting.
Senior Member
You could technically amplify them quite well.Ive never been able to get an exact number due to the violet (410-440) Lines being so close to one another that its hard to get on the spectrometer to show up differently. Id say its 5 or more.
These extra WL lines that show up are nothing more then a glow. So although you see it and its interesting in the output you will never be able to get a beam out of it more then half a mW "If that" More of Just a glow. Unless there is someway that can make these Hidden Lines stronger in the output by the use of external optics but i have no idea and that thought of "External optics" is Just a wild guess. I have not done much reading and searching on this subject Yet, But maybe one of the more advance guys on here might know of a way to pull out one of these WL and have it put out Greater powers by the use of Optics or gratings or etc... I'd have to read about it more its just hard to find info on this stuff.
First, by pulsing the diode, and amplify the wavelengths using a handful of waveplates, some mirrors, a faraday rotator, and a pockels cell.
Very expensive, but it's possible using "external optics" :P
I wasn't expecting to get beamshots, but I was hoping that they'd at least be visible. I am familiar with playing with 500uW of light. Much of my multiline HeNes have <500uW lines, even <250uW. I am very used to playing with fractions of milliwatts.
That being said, still not sold on the idea. I think it could be fun.
PS - Angelos, you have a very overdue email
Only an electron wiggler like you would resonate at 30cm.
Senior Member
UPDATE:
My NDB7675 LEDed a couple nights ago.
It now does orange (~600nm eyeballing it, look lower than my 604's) and a lemon-lime (~570nm looks more yellow than my ArKr)
Though since it's a multimode diode, these other outputs are not in spots, but the regular rectangle that we get from these multimode blues and reds (and recent green).
What is very neat, however, is that when unfocused (not lensless) I can see speckles of red and green. If I unfocus even further, I can see entire bars on each side of the main blue bar, of green, and then red. Exactly like you would see them in a grating. Blue -> green -> red.
Very neat.
Gathered a few pictures, but the blue overloads every camera I've tried. You can barely see the green bars, no red. Though I do have pictures of the orange and green when the blue, and green or orange is removed.
Only an electron wiggler like you would resonate at 30cm.
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Any idea why it LEDed?
Senior Member
No idea, but I saw something very cool today
I found my 500ln/in grating, and discovered something.
These LEDed diodes are really like white LEDs. I guess that's where the name comes from.
Through the grating, I saw a large rectangle (the standard rectangle on these diodes) but across the whole spectrum, a rainbow from deep violet to green, and yellow. I also saw another significant blue spot, bluer than whatever line this diode is. I mean that scientifically speaking, as in blue shifted, not closer to "blue".
I only wish the thing was single mode. If it were a clean single mode without the massive rectangle/wing, it would be a pretty cool diode. Dual line, with a supercontinuum-type output.
Only an electron wiggler like you would resonate at 30cm.
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