Scanning-electron-microscope image showing the CdS nanobelt draped diagonally across a silicon-dioxide substrate. The nanobelt is seen bridging a tiny square hole, where the cooling takes place. (Courtesy: Qihua Xiong)

Laser pulses cool semiconductor

Jan 25, 2013

Physicists in Singapore are the first to create a refrigerator that cools a piece of semiconductor using light, using their technique to cool a room-temperature sample of cadmium sulphide by some 40 K. Although a similar technique has previously been used to chill glasses doped with rare-earth elements, this latest work could lead to practical optical refrigeration devices for use in satellites, or even “self-cooling” lasers.

First developed in the 1980s, laser cooling has opened up the new and incredibly fruitful study of ultracold atomic gases. The technique involves firing counter-propagating laser beams at an atomic gas, with the atoms absorbing and emitting photons in such a way that the net effect is to reduce the average motion of the atoms, and thus lower the temperature of the gas.

Read more: Laser pulses cool semiconductor – physicsworld.com.

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