Document Detail


Laser cooling of a semiconductor by 40 kelvin.
MedLine Citation:
PMID:  23344360     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Optical irradiation accompanied by spontaneous anti-Stokes emission can lead to cooling of matter, in a phenomenon known as laser cooling, or optical refrigeration, which was proposed by Pringsheim in 1929. In gaseous matter, an extremely low temperature can be obtained in diluted atomic gases by Doppler cooling, and laser cooling of ultradense gas has been demonstrated by collisional redistribution of radiation. In solid-state materials, laser cooling is achieved by the annihilation of phonons, which are quanta of lattice vibrations, during anti-Stokes luminescence. Since the first experimental demonstration in glasses doped with rare-earth metals, considerable progress has been made, particularly in ytterbium-doped glasses or crystals: recently a record was set of cooling to about 110 kelvin from the ambient temperature, surpassing the thermoelectric Peltier cooler. It would be interesting to realize laser cooling in semiconductors, in which excitonic resonances dominate, rather than in systems doped with rare-earth metals, where atomic resonances dominate. However, so far no net cooling in semiconductors has been achieved despite much experimental and theoretical work, mainly on group-III-V gallium arsenide quantum wells. Here we report a net cooling by about 40 kelvin in a semiconductor using group-II-VI cadmium sulphide nanoribbons, or nanobelts, starting from 290 kelvin. We use a pump laser with a wavelength of 514 nanometres, and obtain an estimated cooling efficiency of about 1.3 per cent and an estimated cooling power of 180 microwatts. At 100 kelvin, 532-nm pumping leads to a net cooling of about 15 kelvin with a cooling efficiency of about 2.0 per cent. We attribute the net laser cooling in cadmium sulphide nanobelts to strong coupling between excitons and longitudinal optical phonons (LOPs), which allows the resonant annihilation of multiple LOPs in luminescence up-conversion processes, high external quantum efficiency and negligible background absorption. Our findings suggest that, alternatively, group-II-VI semiconductors with strong exciton-LOP coupling could be harnessed to achieve laser cooling and open the way to optical refrigeration based on semiconductors.
Authors:
Jun Zhang; Dehui Li; Renjie Chen; Qihua Xiong
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Nature     Volume:  493     ISSN:  1476-4687     ISO Abbreviation:  Nature     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-01-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  England    
Other Details:
Languages:  eng     Pagination:  504-8     Citation Subset:  IM    
Affiliation:
Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Energy release in the solar corona from spatially resolved magnetic braids.
Next Document:  Interface-engineered templates for molecular spin memory devices.