86% internal differential efficiency from 8 to 9 μm-emitting, step-taper active-region quantum cascade lasers

Jeremy D. Kirch, Chun Chieh Chang, Colin Boyle, Luke J. Mawst, Don Lindberg, Tom Earles, Dan Botez*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

8.4 μm-emitting quantum cascade lasers (QCLs) have been designed to have, right from threshold, both carrier-leakage suppression and miniband-like carrier extraction. The slope-efficiency characteristic temperature T1, the signature of carrier-leakage suppression, is found to be 665 K. Resonant-tunneling carrier extraction from both the lower laser level (ll) and the level below it, coupled with highly effective ll-depopulation provide a very short ll lifetime (∼0.12 ps). As a result the laser-transition differential efficiency reaches 89%, and the internal differential efficiency ηid, derived from a variable mirror-loss study, is found to be 86%, in good agreement with theory. A study of 8.8 μm-emitting QCLs also provides an ηid value of 86%. A corrected equation for the external differential efficiency is derived which leads to a fundamental limit of ∼90% for the ηid values of mid-infrared QCLs. In turn, the fundamental wallplug-efficiency limits become ∼34% higher than previously predicted.

Original languageEnglish
Pages (from-to)24483-24494
Number of pages12
JournalOptics Express
Volume24
Issue number21
DOIs
Publication statusPublished - 2016 Oct 17
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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