Quantum Cascade Lasers Feature Summary

Type:
From Physics Research
Title:
Quantum Cascade Lasers
Description:
The image above shows a quantum cascade laser captured by a camera that images infrared light. The laser light is the small dot in the middle of the round window. The laser itself--behind the window--is kept at a temperature of -193° C, just above the temperature of liquid nitrogen.

Quantum cascade lasers work like this:
- In a thin slice of a semiconductor, an electron can occupy discrete energy levels.
- When an electron moves from a higher level to a lower level, a photon is emitted.
- If many thin slices of semiconductor are stacked together, the electron can cascade from one to another, emitting a photon of the same frequency in each slice. These photons form the laser beam.
- To learn more, see Quantum Cascade Lasers.
Image:
image credit: Fatima Toor; <a href="http://www.princeton.edu/~artofsci/2009/" target="_blank">image source</a>; <a href="http://www.physicstogo.org/images/features/quantum laser -large.jpg" target="_blank">larger image</a>
image credit: Fatima Toor; image source; larger image
Image URL:
http://www.compadre.org/Informal/images/features/quantum laser -large.jpg
Featured:
November 1, 2010 - December 1, 2010