Incoherent polarization beam combination for mid-infrared semiconductor lasers

摘要

The mid-infrared band of 3~5 μm wavelength is a very important atmospheric window. The mid-infrared lasers arewidely applied in laser countermeasure, laser illumination and trace gas detection. At present, the mid-infrared lasersources mainly include solid-state optical parametric oscillation lasers, fiber lasers, mid-infrared supercontinuumspectrum laser and mid-infrared semiconductor lasers, i.e. quantum cascade lasers. In these lasers, quantum cascadelaser is the only one that can realize the conversion from electricity to light. In this paper, the method of incoherentbeam combination of mid-infrared semiconductor lasers is studied. Two lasers are combined in a common apertureby using a single polarizer based on the polarization characteristics of the output laser of quantum cascade laser.Results show that the incoherent power superposition of mid-infrared quantum cascade lasers can be achieved bypolarization beam combining, and the beam combining efficiency is not less than 90%. The farfield divergence angleis about 5 mrad, which is consistent with the farfield divergence angle of the two sub-beams.