Wavelength beam combining of quantum cascade laser arrays for remote sensing

Abstract

Wavelength beam combining was used to co-propagate beams from 28 elements in a linear array of distributedfeedback quantum cascade lasers (DFB-QCLs). The overlap of the beams in the far-field is improved using wavelength beam combining; the beam-quality product of the array, defined as the product of near-field spot size and far-field divergence for the entire array, was improved by a factor of 21. We measured the absorption spectrum of isopropanol at a distance of 6 m from the laser arrays, demonstrating the efficacy of wavelength beam combined DFB-QCL arrays for remote sensing.