Linewidth broadening factor in semiconductor lasers--An overview

TLDR

The paper provides an overview of the linewidth broadening factor α in semiconductor lasers, which links carrier‑concentration changes to variations in the real and imaginary parts of susceptibility. The authors define α, discuss its dependence on carrier concentration, photon energy, temperature, and device structure, trace its historical development, and review laser properties affected by α along with estimation methods. The review compiles existing measurement results and identifies the most reliable methods for estimating α.

Abstract

The objective of this paper is to present an overview of topics related to one of the fundamental parameters for semiconductor lasers-the linewidth broadening factor α that describes the coupling between carrier-concentration-induced variations of real and imaginary parts of susceptibility. After introducing the definition of α and discussing its dependence on carrier concentration, photon energy, and temperature, we give a short historical summary on how the concept of α evolved over the past two decades. This is followed by a discussion of α dependence on device structure in gain-guided and subdimensional lasers (quantum wells and quantum wires). The bulk of the paper is devoted to a detailed review of laser properties influenced by α and of associated methods of estimating the value of α. Results of measurements reported to date are collected and the most reliable methods are indicated.