Advances in laser cooling of semiconductors

Abstract

Laser cooling in semiconductor structures due to anti-Stokes luminescence is reviewed. Theoretical background considering luminescence trapping and red-shifting, the effect of free carrier and back-ground absorption, Pauli bandblocking, and the temperature-dependence of various recombination mechanisms are discussed. Recent experimental results demonstrating record external quantum efficiencies (EQE) in GaAs/GaInP heterostructures are described, and conditions favorable for the first observation of laser cooling in semiconductors are discussed. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/10/2015 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 6115 611518-2 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/10/2015 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 6115 611518-3 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/10/2015 Terms of Use: http://spiedl.org/terms

Laser cooling of solids

“…At pump photon energies much more than k B T below hν f , η abs is too small to make η c > 0 and laser cooling is unattainable. The above analysis defines the approximate condition needed for laser cooling [6,17]. :…”

“…Researchers have examined other condensed matter systems beyond RE-doped materials, with an emphasis on semiconductors [17,[43][44][45][46]. Semiconductor coolers provide more efficient pump light absorption, the potential of much lower temperatures, and the opportunity for direct integration into electronic and photonic devices.…”

“…A novel method based on the frustrated total internal reflection across a vacuum "nano-gap" is being developed at the University of New Mexico [17,83,84]. In this scheme, the luminescence photons tunnel through the gap into the absorber region.…”

Exploring Coulomb interaction in piezoelectric materials for assisting the laser cooling of solids

“…This trend also led to growth of semiconductors which can have potential use for laser cooling applications [7]. As for the case of enhancing the extraction efficiency, some novel techniques have been proposed such as attaching a dome lens to the semiconductor[7], using surface plasmon polaritons[8], Mie scattering [5],evanescent coupling through a nano-gap [3], and surface roughening [9].Another technique of laser cooling, known as optomechanical backaction, can be implemented when the optical and mechanical modes of a cavity are coupled effectively [10]. In this case, cooling -or amplification of the mechanical mode depends on laser detuning.…”

Thermal links for the implementation of an optical refrigerator

“…[8][9][10][11][12] Laser cooling has been reported for a variety of other materials including those doped with Yb 3+ ͓fluorochloride glass ͑CNBZn͒, 13 Another new research area of great interest is the cooling of GaAs optoelectronics using semiconductor materials that can theoretically reach temperatures as low 10 K; however, several problems including extraction of the fluorescent radiation have prevented any net cooling from being realized. [24][25][26][27][28] All practical laser refrigerators inevitably involve the attachment of heat loads. In this paper, we present thermal link designs for the attachment of heat loads that minimize the loss of cooling power due to poor thermal conductivity and due to absorption by the load of thermal radiation and fluorescence photons.…”