Multi-Spectral Quantum Cascade Lasers on Silicon With Integrated Multiplexers

Multi-spectral midwave-infrared (mid-IR) lasers are demonstrated by directly bonding quantum cascade epitaxial gain layers to silicon-on-insulator (SOI) waveguides with arrayed waveguide grating (AWG) multiplexers. Arrays of distributed feedback (DFB) and distributed Bragg-reflection (DBR) quantum cascade lasers (QCLs) emitting at ∼4.7 µm wavelength are coupled to AWGs on the same chip. Low-loss spectral beam combining allows for brightness scaling by coupling the light generated by multiple input QCLs into the fundamental mode of a single output waveguide. Promising results are demonstrated and further improvements are in progress. This device can lead to compact and sensitive chemical detection systems using absorption spectroscopy across a broad spectral range in the mid-IR as well as a high-brightness multi-spectral source for power scaling.