Spectroscopic study of transparency current in mid-infrared quantum cascade lasers

Opt Express. 2012 Aug 13;20(17):18925-30. doi: 10.1364/OE.20.018925.

Abstract

We report measurements which give direct insight into the origins of the transparency current for λ ~5 µm In0.6Ga0.4As/In0.42Al0.58As quantum cascade lasers in the temperature range of 80-280 K. The transparency current values have been found from broadband transmission measurements through the laser waveguides under sub-threshold operating conditions. Two active region designs were compared. The active region of the first laser is based on double-LO-phonon relaxation approach, while the second device has only one lower level, without specially designed resonant LO-phonon assisted depopulation. It is shown that transparency current contributes more than 70% to the magnitude of threshold current at high temperatures for both designs.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Computer-Aided Design
  • Equipment Design
  • Equipment Failure Analysis
  • Infrared Rays
  • Lasers*
  • Quantum Theory
  • Spectrophotometry, Infrared / instrumentation*
  • Surface Plasmon Resonance / instrumentation*