Quantum Cascade Lasers with Very Low Loss Chalcogenide Lateral Waveguides

Quantum cascade lasers have been fabricated with chalcogenide lateral waveguide claddings. Several-micrometer thick Ge sub (0.25) Se sub (0.75) glass has been deposited by pulsed laser ablation onto the side walls of narrow, deep etched laser ridges. Due to the intrinsically low mid-infrared attenuation of the chalcogenide material, the waveguide loss of the lasers is significantly reduced, by up to ~ 50%, depending on the ridge width, when compared to conventional ridge waveguides. This resulted in an improved overall laser performance, such as a strong reduction of the threshold current density, an increase in slope efficiency, and an improved temperature performance.