Quantum-Cascade Polychromatic Lasers

eznihm writes: "This article describes a new laser, developed by Lucent and others, that emits a band of light and operates at room temperature. "The result: a beam of high intensity at every wavelength from 6 to 8 micrometers, in the so-called midinfrared range.""

Comments

Not quite right...

[Myriad]

An ordinary laser emits only a single color because it's built with a light-emitting substance that naturally generates one wavelength of light when energized.

Technically speaking this isn't quite true - it depends on what your lasing medium consists of. While each colour line emitted will be monochromatic, a single laser is capable of producing multiple lines.

In the case of a Krypton or Helium Neon ion gas laser you will get a single line out (usually, but not necessarily, red for either of these).

However, if I look at an Argon laser with apropriate optics you get primarily Blue and Green (514nm "Green" and 488nm "Blue") lines (with combinations in between). If I put a prism to the output of my little American Laser 60x I can see 7 individual lines - 5 are of such lower power as to be virtually useless, but the primary Green and Blue are strong.

Then if you look at a Copper Vapor laser which works by evaporating copper you get two lines: an emerald green and *gold* (this type of laser was made famous during the Pink Floyd Division Bell tour).

Newer solid state are very much single line. If you ever see a very harsh green beam you are probably looking at a Nd:YAG laser. The new solid state stuff is really looking promising... much more reliable with a much longer lifespan. Now, if they could just get the Blue solid states more powerful reliable we would be laughing. A low to mid powered white-light lasershow that could fit in a briefcase! On the down side though, typically much lower power output than their ion cousins (and the YAG green is, in my opinion, really nasty).

Could almost make me miss lugging 909's around... :)

Re:Isn't this a contradiction?

[caffeinated_bunsen]

Typically, you're correct. Traditional lasers emit almost all their energy at a single wavelength, with very small deviations of energy (determined by the time it takes an atom to emit a photon, thanks to the good ol' uncertainty principle, dE*dt>h/(2pi)). What Lucent did here is to create a whole mess of lasers in one package, which all emit slightly different wavelengths. The wavelength uncertainties overlap enough that you get a fairly smooth distribution of energy, rather than a single, well-defined peak at one wavelength.