Thin-film mid-infrared semiconductor waveguide technology

In this contribution we describe recent progresses on ultra-sensitive chemical sensing in the mid-infrared (MIR; 3-20 μm) spectral range combining microfabricated thin-film GaAs/AlGaAs and HgCdTe waveguides with quantum cascade lasers (QCL). Epitaxial grown methods including molecular beam epitaxy (MBE) and metal-organic vapor-phase epitaxy (MOVPE) were applied facilitating the growth of 6 μm thin on-chip waveguide layers, which may be further structured using e.g., reactive ion etching (RIE) and/or focused ion beam milling (FIB) for establishing a variety of substrate-integrated waveguide geometries. Such waveguides readily combine with single-wavelength-emitting or broadly tunable quantum cascade lasers (tQCL) providing access to the entire MIR window for advanced chem/bio sensing applications.