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 Upcoming Talks        Past Talks        Calendar View

Departmental Colloquium


Terahertz Quantum Cascade Lasers

Dayan Ban
Institute for Microstructural Sciences, National Research Council of Canada

Time
 
Thu. January 27, 2005     3:30 PM     Stirling C

Abstract
 


The Terahertz gap, lying roughly between 300 GHz (0.3 THz) and 30 THz in the electromagnetic spectrum, exists because the frequencies generated by semiconductor-based transistors and lasers don’t overlap. Generation of coherent terahertz radiation has traditionally involved either extending electronic techniques to higher frequencies, or extending photonic sources to longer wavelengths. In both cases, the efficiency drops rapidly as the frequency approaches to the terahertz region.

It was recently reported that the operation of the quantum cascade lasers based on GaAs/AlGaAs could be extended from the mid-infrared range to the terahertz. In this talk, I will first talk about the basic principles of operation of the quantum cascade lasers. A few key issues related to the THz generation will be addressed. The design, fabrication and electrical and optical characterizations of our terahertz quantum cascade lasers will be presented. Experimental results on the impacts of the doping in the active region will be reported. A simple model is proposed to explain the experimental observation.

The speaker is a candidate for the ATOP-funded Assistant Professorship in Engineering Physics. Refreshments will be available in the Departmental coffee room following the talk.

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