Quantum cascade lasers based on guided modes at a metal-semiconductor interface

Summary form only given. Planar waveguides for long-wavelength quantum cascade (QC) lasers require thick cladding layers. This prolongs and complicates the growth and processing procedures of these lasers. In this paper we demonstrate that optical waveguiding for a laser in this wavelength range can also be achieved using electromagnetic surface waves at a metal-semiconductor interface directly above the active region of the laser. No cladding layer is needed. The interface-guided modes are transverse-magnetic modes existing at the interface between a metal and a semiconductor, which have dielectric constants opposite in sign. Therefore, the metal layer, which is usually deposited on the top surface of a semiconductor laser for the purpose of an electric contact, can be also exploited to provide the waveguide interface.