Reduction of Facet Reflectivity of Quantum Cascade Lasers with Subwavelength Gratings

— We demonstrate the reduction of the facet reflectivity of Quantum Cascade Lasers (QCLs) by using sub-wavelength gratings. The gratings were fabricated on ë = 4.9 ìm and 9.8 ìm QCLs using focused ion beam milling. Reflectivities as low as 1- 3% for the 4.9 ìm QCL and as low as 4-8% for the 9.8 ìm QCL are reported.