More like downright misleading.
The effect might look like an intermediate wavelength but it consists of a mixture of the fixed laser wavelengths of monochromatic R,G,B.
Growing a semiconductor laser that supports all three wavelengths is quite a stunt. Here is a version of the press release that hasn't been mangled by journalists (or at least not to the same extent).
-- Regards, Martin Brown
gn
They've obviously got a lot of control over the frequency at which each of the three lasers emits.
"This strategy of decoupling structural shapes and composition represents a major change of strategy and an important breakthrough that finally made i t possible to grow a single piece of structure containing three segments of different semiconductors emitting all needed colors and the white lasers p ossible. Turkdogan said that, "this is not the case, typically, in the mate rial growth where shapes and compositions are achieved simultaneously.""
The article does talk about using very thin films and very narrow structure s to allow a lot of strain in the relevant lattices.
It certainly does seem to be producing three monochromatic beams, but the w avelength of each individual beam does seem to be to some extent negotiable .
irst-white-lasers/
-- Bill Sloman, Sydney
Certainly not big spikes of energy poking up through nothingness!
I suppose that BB radiation at 6000K makes the most sense -- something like sunlight, with the emission and absorption lines removed.
Of course, some critter that sees into the deep ultraviolet and lives under a much hotter star than we do might disagree.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
I think you mean flat in frequency space. Like the Johnson noise we all know and love. It's too bad you see black body (BB) radiation plotted vs wavelength, frequency is a more natural scale. (at least to us physics types.)
OK I maybe sticking my foot in my mouth.... I believe that BB radiation is just the high frequency end of Johnson noise.
And at low frequencies BB follows the Rayleigh-Jeans law,
OK scratch most of that.... I'm getting myself all turned around. Searching the web... here's what Dicke said a "few" years ago.
(I'll have to read it too.)
George h.
Considering for the past 20 years I have used Mixed Gas "Whitelight" Ion la sers with up to 18 lines lasing at the same time. I think they need a new title. I can modulate any eight of the above mentioned lines, using a Polychromati c Acousto-Optic modulator. Whitelight Ion lasers have been around since 197
6 or so... Mine use a 15% Argon, 85% Krypton mixture and some very speciali zed cavity optics to obtain a balanced white.I downloaded the article. It is one chip with three growth regions dropped onto the same substrate. The three regions are each pumped by 366 nm light from a frequency tripled ND:YAG laser, giving red, blue, green, cyan, mage nta, yellow, and white depending on which chips are pumped.
The ASU group is unique in that they figured out how to add the blue...
Dr. Hobbs, check your inbox under Educational USE copyright rules.
Steve
lasers with up to 18 lines lasing at the same time. I think they need a n ew title.
tic Acousto-Optic modulator. Whitelight Ion lasers have been around since 1
976 or so... Mine use a 15% Argon, 85% Krypton mixture and some very specia lized cavity optics to obtain a balanced white.Interesting, I'd expect one (or two) of the spectral lines to "suck up" al l the "gain".
George H.
ed onto the same substrate. The three regions are each pumped by 366 nm lig ht from a frequency tripled ND:YAG laser, giving red, blue, green, cyan, ma genta, yellow, and white depending on which chips are pumped.
all the
Krypton's 647, 568, and 530 nm lines compete with each other, with 647 and
568 sharing an upper state. Changing the gas pressure, gas mix, and magnet ic field has all sorts of wild effects. But if you use optics that kill th e 568 line, things are fairly stable. For indoor shows and displays the yel low-green 568 line is desired, so some users were willing to watch red and yellow trade gain with each other every few minutes.We do see some lines go away, and others are enhanced. But it worked well e nough to be the mainstay of the military laser display and laser light show industry for 20 years.
A fair amount of mixed systems made it into lab use. For the simple fact t hat while the initial cost was high, it was still cheaper then using a pair of laser heads to cover the spectrum.
I have a HENE with non-standard optics showing a mix of 6 visible lines and the better part of a dozen IR and Raman Mixing lines. So yes, it is possi ble, and there is a large portion of Sam's Laser FAQ devoted to multi-line lasers.
Some neater widgets like Co2 lasers lase in spectral bands... :-)
Steve
They said "color" not "wavelength"
-- \_(?)_
If you want to draw that distinction, you'd have to invent a meaning for "in between" for colors. "In between" only has meaning for wavelengths.
I have the benefit of seeing the paper. The lines are not sharp and there is more then one line for some of the doped regions, plus a little band spectra.
So possibly tunable with Littman-Metcalf feedback across a small band, but no where near the bandwidth of a dye laser.
Steve
What sort of bandwidth (range of lasing wavelengths) can you get from a dye laser? I really like diode lasers! You can temperature tune them ~10 nm or so. We sell a 780 nm laser, but can swap diodes and do 650 nm. (What cool stuff can you do with a 650 nm diode laser, you ask.) Well, I was at a "lab guy" physics meeting early this month. I sat next to David Pengra at the bar one night. He does the Lamb shift.
George H.
the RGB colourspace has all the properties of a 3 dimebsional coordinate system. Between is well defined.
Cyan (rgb(0.0,0.5,0.5)) is between green (rgb(0.5,1.0,0.0)) and blue (rgb(0.0,0.0,1.0))
-- \_(?)_
George, you can do Lamb Dip with a HENE plasma tube, its one of the means we use to lock a Hene to single mode, single frequency..
If you want to see dye laser tuning curves, go to Exciton.com
Dye lasers can do both wide and narrow lasing bandwidths over a wide range of tenability, depending on the cavity optics and feedback...
Steve
Hi Steve, That's interesting. I'm most likely telling you something you already know, but the Lamb dip, is different from the Lamb shift. The Lamb shift is a slight (1 GHz) difference in the
2S(1/2) and 2P(1/2) energy levels. The difference can't be explained by "normal" quantum mechanics and thus heralded Quantum electrodynamics.George H.
No, I just learned something.... I'm so used to working with Lamb Dip that I need to read up on the Shift.
Anyways, small sealed mirror, HENE tubes are well behaved, well documented, tools for teaching some interesting wave physics. Especially when slightly heated to change the cavity length.
Steve
Good, I'm glad I said something. For more kicks, I'd use something like the Lamb dip*, to see the Lamb shift. :^)
George H.
(*saturated absorption spectroscopy.. a way to see inside a Doppler broadened spectra, and not in a laser cavity)
End Quote..
Having worked on enough Lamb Dip stabilized Hene lasers, I think my next Lamb will be on a Kabob, or Gyro,,, And I will think of George when I eat it.
Steve
On Sun, 9 Aug 2015 18:57:03 -0700 (PDT), snipped-for-privacy@gmail.com Gave us:
How lambastic of you.
AH, it was just a Baaaaa Humbug moment while working late at the office to fix software problems caused by layoffs, :-)
Steve
On Sun, 9 Aug 2015 19:26:48 -0700 (PDT), snipped-for-privacy@gmail.com Gave us:
Doncha mean "lamboffs"?
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