Single-mode ultra-short quantum-cascade microlasers with deeply etched Bragg-mirrors

Quantum-cascade (QC) microlasers with monolithically integrated semiconductor-air Bragg-mirrors based on GaAs were fabricated and investigated. In this paper we report the device properties of QC microlasers with strongly reduced cavity lengths and improved temperature properties. Based on a three-quantum well (3QW) active region design, the cavity length could be reduced from 180 /spl mu/m to about 100 /spl mu/m and based on a bound-to-continuum (BTC) active region design down to 50 /spl mu/m. The devices were fabricated with an improved single etch step fabrication process, where the contact area is insulated with MgO to minimize leakage current. The ridge waveguide geometry and the Bragg-mirrors are defined separately by optical and electron-beam lithography, respectively.