Waveguide optical losses in InGaAs∕AlAsSb quantum cascade laser

Abstract

The authors present a technique for broadband study of the optical waveguides used for midinfrared quantum cascade lasers. This method allows insight into the waveguide properties and helps in improving the waveguide design. Using this method the waveguide losses in the whole range of waveguide transparency of about 1.8–9μm have been found for a λ∼4.4μm In0.53Ga0.47As∕AlAs0.56Sb0.44∕InP quantum cascade laser. The polarization dependence of waveguide losses in a quantum cascade laser is discussed.