Design Concepts of Terahertz Quantum Cascade lasers: Proposal for Terahertz Laser Efficiency Improvements

Tillmann Kubis, NCN, Purdue University
Saumitra Raj Mehrotra, NCN, Purdue University
Gerhard Klimeck, NCN, Purdue University

Date of this Version

12-28-2010

Citation

Applied Physics Letters Vol. 97, Issue 26

Abstract

Conceptual disadvantages of typical resonant phonon terahertz quantum cascade lasers 􏰎THz-QCLs􏰍 are analyzed. Alternative designs and their combination within a concrete device proposal are discussed to improve the QCL performance. The improvements are 􏰎1􏰍 indirect pumping of the upper laser level, 􏰎2􏰍 diagonal optical transitions, 􏰎3􏰍 complete electron thermalization, and 􏰎4􏰍 materials with low effective electron masses. The nonequilibrium Green’s function method is applied to predict stationary electron transport and optical gain. The proposed THz-QCL shows a higher optical gain, a lower threshold current, and a higher operation temperature. Alloy disorder scattering can worsen the QCL performance.

Discipline(s)

Electrical and Electronics

 

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