High-performance quantum cascade lasers: physics and applications

Abstract

ABSTRACT Physics and applications of recent quantum cascade laser active region designs are discussed. Specifically, theuse of bound—to—continuum and two—phonon resonance active regions for high temperature, high duty cycle operation is reviewed. Threshold current densities as low as 3kA/cm2 at T = 300K, operation with a peak power of 90mW at 425K, and single mode, high power operation up to temperatures above 330K at A 16gm are demonstrated. QC lasers able to operate at high duty cycles (50%) on a Peltier cooler were used in a demonstration of a 300MHz free space optical link between to buildings separated by 350m.Keywords: Laser, Intersubband, mid-infrared, quantum cascade 1. INTRODUCTION The quantum cascade laser1 (QC) lasers have demonstrated operation in a wide wavelength range between ( 3—24gm) . This technology is now maturing for applications such as chemical 23 or last mile internet distribution through line—of—sight atmospheric an5 Optimization of the device performance, necessary for these applications, requires an accurate modeling ofthe electronic and optical processes. At cryogenic temperatures, good agreement has been obtained betweencomputed and measured threshold current densities and slope efficiencies for a large class of 67