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Cooling Semiconductor by Laser Light © Based on Material by Niels Bohr Institute, DK
esearchers at the Niels Bohr Institute discovered a new method for laser cooling semiconductor
membranes. The new cooling method works quite paradoxically by heating the material. Using lasers, researchers cooled membrane fluctuations to minus 269° C (-452° F).
“In experiments, we have succeeded in achieving a new and efficient cooling of a solid material by using lasers. We have produced a semiconductor membra- ne with a thickness of 160nm and an unprecedented surface area of 1 by 1mm. In the experiments, we let the membrane interact with the laser light in such a way that its mechanical movements affected the light that hit it. We carefully examined the physics and discovered that a certain oscillation mode of the membrane cooled from room temperature down to minus 269° C, which was a result of the complex and fascinating interplay between the movement of the membrane, the properties of the semiconductor and the optical resonances,” explains Koji Usami, associ- ate professor at Quantop at the Niels Bohr Institute.
“We managed to produce a nanomembrane that is only 160 nanometers thick and with an area of more than 1 square millimetre. The size is enormous, which no one thought it was possible to produce,” explains Assistant Professor Søren Stobbe, who also works at the Niels Bohr Institute.
12-01 :: January 2012
Koji Usami shows the holder with the semiconductor nanomembrane. The holder measures about one by cm, while the nanomembrane itself has a surface area of 1 by 1mm and a thickness of 160nm. © Ola J. Joensen
K. Usami, A. Naesby, T. Bagci, B. Melholt Nielsen, J. Liu, S. Stobbe, P. Lodahl & E. S. Polzik: Optical cavity cooling of mechanical modes of a semiconductor nanomembrane, In: nature physics AOP, January 22, 2012, DOI:10.1038/ nphys2196: