Photo is representative of beam configuration only. Coloration is incorrect.

Parameter                Condition  Symbol    Minimum   Typical  Maximum  Unit
---------------------------------------------------------------------------------
Dominant Wavelength      If=20mA    _D        390       400      401      nm
Forward Voltage          If=20mA    Vf        3.6       3.8      4.0      volts
Reverse Current          Vr=5v      Ir                           10       uA
Luminous Intensity       If=20mA    lv        200       350               mcd
Viewing Angle            If=20mA    2_1/2               30                degrees
Radiant Flux                        P,mW      10.0      12.0              mW
---------------------------------------------------------------------------------

Maximum Ratings (Ta=25°C)
DC Forward Current: 30mA
Peak Forward Current (10% duty cycle @ 1KHz): 100mA
Junction Temperature: 125°C
Reverse Voltage: 5V
Operating Temp. Range: -20°C to +80°C
Storage Temp. Range:   -20°C to +100°C
Electrostatic Discharge Threshold: 400V
Electrostatic Discharge Class (MIL-STD 883E): Class 1

(Uses same dice as) Uniroyal # UVA-L50ACA (http://www.ledreps.com/intro.htm), price unknown
(05-18-02) An anonymous visitor to The LED Museum recently wrote me and said he had come across some "418nm" violet LEDs, so I asked him to send me a couple. Sure enough, when I zipped open the little silver bag and popped them into the test set, an intense blue-violet light flooded the area around the hookup. That light was coming from an LED made with a new Uniroyal Optoelectronics LED die, and it appears to be very close to 420nm. The other two samples appear to be one of Uniroyal's several 416nm variations.


This 420nm LED appears to be functionally identical to the UVA-L50ACA shown on the website, and should be emitting approximately 6mW of optical energy. When the LED is viewed directly, it appears to have a piercing deep electric blue color, while the beam itself as projected onto a target appears to have a distinct pure violet color to it, not unlike the surface color of a lighted fluorescent blacklight bulb. This can change depending on the ambient lighting conditions though, and you may see more of a bluish tint on the target instead of violet. The 416nm LED looks very similar to the 420nm version, with only a very slightly less bluish color to the eye.



The LED's spectrum contains a strong band from the deep blue to mid violet, with a much less intense broadband emission as a byproduct, which extends from red to deep violet. Emission seems to stop almost completely below 400nm.



Wilycon # WUV503-C395-C, Wilycon Corp. (http://www.led-center.com), $0.65 each for more than 50,000 pcs
(11-30-01) The quest is over. The spectrum is now relatively complete - at least for the more "important" (or the most flashy) colors.
This is a 395nm deep violet LED, which makes the unknown sample that came in the flashlight below a 405nm model. With wavelengths this short, you pretty much have to line them up side by side to tell the difference until you get used to seeing things at this end of the spectrum. In this regard, even I'm a bit new at this. :-O

This LED uses the new Cree Megabright series UV dice, and should be outputting 10-12mW of radiant power when run at 20mA.


Left: Beam on a target.
Right: Beam shined onto a high-end computer monitor.
There's enough UV component that my camera is just starting to show the purple color like it does with the Nichia at 370nm.

For the more technically-minded, here are the basic specs for this part:

Absolute Maximum Ratings
Continuous DC Forward Current (If): 30mA maximum
Pulse Forward Current (Ifp): 100mA maximum
Reverse Voltage (Vr): 5 volts

Typical operating conditions:
DC Forward Voltage (Vf) at 20mA: 3.7 volts typical, 4.0 volts max
DC Reverse Current (Ir): 10 microamps maximum
Radiant Flux (P): 10mW minimum, 12mW typical
Wavelength: 390nm minimum, 395nm typical, 400nm max
Spectral line half width: 20nm typical
Rise time: 30 nanoseconds typical

Just want to see one going in a computer case? Too bad it's only for the picture.
I'll have to wait till I get a bunch of these as I can't use the only test unit for frivolous purposes. :)

When viewed side by side, the 395nm version has a more "purple" look to it than the 405nm version. It also causes a brighter fluorescent glow in things like dead TV tubes and copying machine paper than the 405nm one.

Wondering if someone pissed the bed in your hotel room and the maid didn't change the sheets before you got there? A near-UV source like this *might* help you find it on the sheets or on the mattress. But you might have a bit more luck using the Nichia UV, because old urine glows a bit brighter at shorter wavelengths. Same with cat pee in the rug.

One thing you'll notice is that violet LEDs look "funny" when viewed from a distance. They will appear all furry and out of focus, while objects or other lights around them look just fine. This is normal. The farther away you get from the LED, the fuzzier and bigger (and deeper violet) it seems to get. They will also appears to glow a deeper violet if you put them behind dark glass or dark plastic, like you might find on the fronts of computers or expensive stereos.

* This price applies only when you tell Ken Ma that you saw this page.
They cost $2.95 apiece in small quantities.

Wilycon is also selling UV/Violet LED Keychain Flashlights with this LED in it for $8 each plus $5 shipping. The light is very small, and runs on a pair of CR1616 lithium coin cells (included). It comes in a transparent body with a keyring attachment. You can e-mail Ken about those too.

CAUTION! Although these LEDs are just on the edge of being UV and could still be considered "visible emitters" (they're actually quite visible), the human eye really wasn't made to see wavelengths of light much shorter than around 420nm (blue-violet), so please don't hold one of these up to your eye and turn it on. Brief viewing of the emitted light from a foot or so away is generally alright as long as you don't just stare at the thing for minutes at a time.

I cannot be held responsible if you tape one of these things to your eye and let it cook there; then later discover you don't see out of that eye quite as well as you used to.



Wilycon # WUV503-C400-C-C, Wilycon Corp. (http://www.led-center.com), $0.52 each for more than 50,000 pcs
(11-30-01) Here's another kind of violet LED. It comes in the same case and uses the same leadframe style as the other Wilycon parts, but this one uses an as of yet unknown die. The die is an artificial sapphire type and has two bond wires, not like the Cree which uses silicon carbide and has only one bond wire. There are some other technical differences too, which I'll get to shortly. I'm still looking for my "spectroscope", so I haven't done any of that kind of testing or comparisons yet.

The color of the visible light is very similar to the 405nm Cree model, but closer examination reveals it is in fact closer to 407 or 408nm, near the lower end of its wavelength range. To the eye, it appears slightly more bluish than the 405nm LED, and substantially more bluish than the 395nm model.


Test installation in my "Toilet Bowl" PC case... just for these pictures thank you. :)
That's why the drive bay is all hacked up, so I can pull the LED back out afterwards.

Besides the obvious use for violet LEDs - the manufacture of a new breed of white, these make VERY COOL indicator lights in computers, stereos, and what have you. Be the first on your block to put a violet LED in your computer case, video game console, or boombox. I'll be adding these to my wheelchair as soon as I can buy more samples.

Now, some of the technical differences. Besides the die being artificial sapphire (and thus having a double wirebond attachment), this LED has some electrical and optical differences.

Absolute Maximum Ratings
Continuous DC Forward Current (If): 30mA maximum
Pulse Forward Current (Ifp): 100mA maximum
Reverse Voltage (Vr): 5 volts

Typical operating conditions:
DC Forward Voltage (Vf) at 20mA: 3.2 volts typical, 4.0 volts max
DC Reverse Current (Ir): 4 microamps typical, 10 microamps maximum
Radiant Flux (P): 1.2mW minimum, 1.6mW maximum
Wavelength: 390nm minimum, 400nm typical, 410nm max
Spectral line half width: 20nm typical
Rise time: 30 nanoseconds typical

Despite the lower output power, this LED doesn't look all that much dimmer than the two Cree models. I'll have to run more extensive testing to find out why.

(Update) I believe this LED uses a Uniroyal near-UV chip. Having come across a picture of the chip's surface geometry while doing a web search , this LED seems to match the Uniroyal UV chip's parameters quite well.


Red, orange, yellow, green, blue, violet. These make up the world's first LED-based "gay pride light". They are connected to a pseudo-random flasher board, so the green & orange ones were off in this shot.



Cree Corp. # C405-MB290-E400, found in a LED keychain flashlight. $15 each (LED plus flashlight) on e-bay.
(11-20-01) Next up to bat: this more or less nameless "Hi Lux Emergency Light" that happens to be using one of Cree's new Megabright violet LEDs. The LED in this flashlight clocks in at around 405nm and produces a royal purple beam on anything you shine it on.
The flashlight itself is a knock-off of the popular Photon II, and isn't that different from the real thing except for the plastic it's made from (real Photon lights use a glass-reinforced resin material). But the interesting part about it is the LED inside.


Beam hitting a plain white (non-fluorescent) target from 2 feet.

Ok, so why doesn't it look purple in this picture?!?
The reason it looks blue and not purple is the way the camera works. Digital cameras don't see a full spectrum of color, but only see the world through three distinct bands: red, green, and blue. This is usually accomplished by using colored filters. Since the closest thing to violet is blue, most of the light goes through the blue filter, and gives you a blue picture. If you viewed this scene with your own eyes, the circle of light on the target would look a very deep, pure violet color. So cameras aren't going to work very well on this page; though I will shoot some pictures with a disposable film camera and see what happens with those pictures.

There are at least two different types of violet keychain flashlights using LEDs like this currently on the market; and both have started showing up on ebay within the last week. The LED I'm using here is from one such light; I am also expecting three different types of violet / near-UV LEDs within the next few weeks, so don't change that channel!!
I can recognise this as a Cree product because of the peculiar metallization pattern on the bottom of the die and because of the unusual non-cubical chip geometry.

Additional data is available about these LEDs but which I've been asked not to post until after the 1st of the year. So please don't bombard me with e-mails telling me I've missed something important about these LEDs... thanks :)
Hint: A limited amount of this type of data can be found hidden within the bowels of my UV LEDs page. It's somewhere in the text for the Nichia UV LED.

Until this type of information becomes available for this LED, you can find out for yourself by trying one. And this is where you might be able to find one:

Look up "UV LED" or "violet LED" on e-bay, and you might find some of these for sale.
(Remember the camera, and the blue? It really is violet when you see it for yourself.)



Origin unknown, source unknown. $5-8 each on e-bay.
(07-15-01) Found this sucker on ebay a few weeks back. The picture looked convincing, so I bid & won.
But nope, this isn't a true violet LED either, although it tries.



This LED has Nichia-like internal leadframes, but there is just enough of a difference that somebody like me can know they aren't Nichia. They may be Toyoda-Gosei, Sharp, or any of a number of other manufacturer's part. Does not look at all like ISP's pink LED.
The functional mechanism appears to be a blue GaN chip covered with a light pink phosphor. When off, this phosphor has a color like a very pale cotton candy pink.

Spectrally, these appear to have a strong band in the blue peaking around 475-480nm (a bit more aqua than usual) and a strong phosphor band in the red from around 620-660nm. Red and blue, depending on the mixture, tend to create a synthetic purple shade. A weaker broadband emission gives a whitish tinge to the output, so the overall color appears as a pale, bluish lavender color.

Measures 587mcd @20mA.


Alpha Cellular, unknown manufacture; possibly ISP Korea, "Ultra Purple LED", ~$25-$30 for order of 6 pcs.
(04-15-01) This is being marketed as a purple LED, and is in fact, being called "ULTRA PURPLE".
So when I switched to tuna & baloney sandwitches for the last several weeks and spent the grocery money on these, I was expecting to get my first look at Toyoda Gosei's new super violet. Unfortunately, this was not to be the case.

These LEDs come in 0603 SMD packages (they're barely larger than grains of sand!) and consist of a standard GaN blue LED emitting at around 470nm, a clear epoxy case, and a red dyed layer at the top of the lens. This red dye is the key: it absorbs very strongly in the green and emits some red light of its own; so when combined with the blue LED chip, a hot pink color is generated. Yes, I said pink. Ok, purplish pink.


I have been working with my laughably crude equipment lately, and have managed to coax some decent spectra out of it. So let's compare a regular phosphor white LED with this phosphor "purple" model.



Spectrum of a standard Nichia SMD white (phosphor downconvert) LED.
As always, it is deficient in violet and blue-green, and peaks strongly at mid-blue.



Spectrum of this "Ultra Purple" phosphor downconvert LED.
Notice the lack of blue-green through green and the more intense output from blue through mid-red.
Also notice there is no VIOLET in this spectrum. Pretty odd, for a PURPLE LED! :(

I haven't gotten these under a microscope yet, but I think these just might be ISP Korea or maybe even Sanyo "Flip Chip" LEDs. I need to get in there and examine the die under 100x magnification before I can even try to determine this though.
The red dye in these fluoresces strongly under green laser radiation or blue LED light applied externally.

These LEDs should work very well in a Nokia cellular phone to change the display color to a purplish pink color. That alone would give you the most unique cell phone on the block.
No, it might not be TRUE violet, but it's the best thing available until the real thing comes out.

There are several "do it yourself" guides to installing these in your Nokia phone; one is at http://www.nokiainfo.f2s.com/do_it_yourself_guide.html and another at http://www.all4cell.com.

Find these on ebay by typing in "purple LED" in the Search box.

UPDATE 10-26-01:
I was shocked to discover that not only is this not a true violet LED, but the "red dye" is actually just RED FINGERNAIL POLISH! Once it comes off (and it flakes off rather easily), you're stuck with an ordinary, if not small sized blue LED.
I now know what it looks like to see $36 whirling down a commode. :(



Nitres, part #unknown, $uknown
(As of mid-2001, no test samples of a true violet LED have become available)

These are currently being made by several out-of-country manufacturers, and I have not yet seen a violet LED "live" with thine own eyes (See top of page for update on this)

As of early 2001, violet LEDs exist in the laboratory, but they aren't available to the public or to OEMs yet because the manufacturers have run into a problem with short device lifetimes and high failure rates. Until they can achieve useful lifetimes of 2000 hours or greater, it is unlikely that violet LEDs will show up at your local Radio Shack anytime soon.


From 1998, this unretouched photograph is the only evidence I have of one in a "finished" state of manufacture - a possible indication they may soon be introduced into the public. It is shown being fired next to an InGaN blue and an InGaN green model.
There's still that failure thing to work on, so don't hold your breath waiting for them.
(See top of page for great news - as of 01-2002, they are available in several "flavors")




[[BEGIN SERMON MODE]]
You should at least somewhat protect your eyeballs when using any one of these LEDs. The human eye really wasn't designed to be exposed to EM radiation at wavelengths much below 420nm (a violet-blue color). And try not to stare directly into these LEDs for more than brief periods.

DISCLAIMER: I shall not be held responsible for any damage or loss of eyesight arising from your use or misuse of the information on this page. Thank you for listening.
[[END SERMON MODE]]

---

WHITE 5500-6500K InGaN+phosphor 
ULTRAVIOLET 370-390nm GaN 
BLUE 430nm GaN+SiC
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TURQUOISE 495-505nm InGaN
GREEN 525nm InGaN 
YELLOW-GREEN 555-575mn GaAsP & related
YELLOW 585-595nm
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INFRARED 700-1300nm
True RGB Full Color LED
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