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



Applied Physics Letters Vol. 97, Issue 26


Copyright (2011) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Tillmann Kubis, Saumitra Raj Mehrotra, and Gerhard Klimeck. Design concepts of terahertz quantum cascade lasers: Proposal for terahertz laser efficiency improvements. Appl. Phys. Lett. 97, 261106 (2011) and may be found at: The following article has been submitted to/accepted by Applied Physics Letters. Copyright (2010) Tillmann Kubis, Saumitra Raj Mehrotra, and Gerhard Klimeck. This article is distributed under a Creative Commons Attribution 4.0 Unported License.


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.


Electrical and Electronics