Feasibility of Optically-Pumped Four-Level Infrared Lasers

Abstract

Recently, there has been an interest in integrated opto-electronic devices working in 10μm range¹. Since the energies of intersubband transitions in the conduction band of modulation-doped III-V quantum wells and superlattices are in the above range, they seem to be a promising material for various electro-optical devices: detectors², modulators³ e.t.c. Since the first observation of strong intersubband transition⁴, proposals⁵ were made for far-infrared lasers utilizing this transitions. Energy of intersubband transition can be defined by choice of well and barrier thicknesses, and then can be tuned by applying external voltage. Most of propos-als concentrated on injection pumping of the infrared laser, and as such included complicated geometry and doping profile for insuring good current flow.