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Mid-Infrared Spectroscopy Platform Based on GaAs/AlGaAs Thin-Film Waveguides and Quantum Cascade Lasers
- Sieger, Markus, Haas, Julian, Jetter, Michael, Michler, Peter, Godejohann, Matthias, Mizaikoff, Boris
- Analytical chemistry 2016 v.88 no.5 pp. 2558-2562
- Fourier transform infrared spectroscopy, absorption, crystals, infrared radiation, lasers, spectrometers, transducers (equipment), wavelengths
- The performance and versatility of GaAs/AlGaAs thin-film waveguide technology in combination with quantum cascade lasers for mid-infrared spectroscopy in comparison to conventional FTIR spectroscopy is presented. Infrared radiation is provided by a quantum cascade laser (QCL) spectrometer comprising four tunable QCLs providing a wavelength range of 5–11 μm (1925−885 cm–¹) within a single collimated beam. Epitaxially grown GaAs slab waveguides serve as optical transducer for tailored evanescent field absorption analysis. A modular waveguide mounting accessory specifically designed for on-chip thin-film GaAs waveguides is presented serving as a flexible analytical platform in lieu of conventional attenuated total reflection (ATR) crystals uniquely facilitating macroscopic handling and alignment of such microscopic waveguide structures in real-world application scenarios.