Homogeneous photonic integration of mid-infrared quantum cascade lasers with low-loss passive waveguides on an InP platform

Abstract

Mid-infrared (mid-IR, λ≈3–12 μm) photonic integrated circuits on low-loss passive waveguide platforms are of significant interest for a wide range of mid-IR applications. Quantum cascade lasers (QCLs) are currently the only room-temperature electrically pumped semiconductor light sources that can operate in a continuous-wave at room temperature over the entire mid-IR spectral range. Given very high thermal dissipation in QCL active regions, achieving long-term reliability and continuous-wave operation of heterogeneously integrated devices on silicon platforms is challenging. Here we experimentally demonstrate homogeneous integration of mid-IR QCLs with low-loss In0.53Ga0.47As passive waveguides epitaxially grown on InP substrates. The homogeneous integration approach uses materials, growth, and processing steps nearly identical to those used for conventional high-performance mid-IR QCLs, which offers superior reliability and performance of photonic integrated circuits. Over 0.57 W of peak-pulsed optical power was coupled to the passive waveguide from a homogeneously integrated λ≈4.6 μm QCL, which represents an order of magnitude improvement in optical power compared to the best results obtained with heterogeneously integrated QCLs.