Non-dispersive infrared (NDIR) absorption spectroscopy is a widespread approach to gas sensing due to its selectivity and conceptual simplicity. One of the main challenges towards the development of fully integrated NDIR sensors is the design and fabrication of microstructures, typically waveguides, that can combine high sensitivity with the ease of integrability of other sensor elements (sources, filters, detectors). Here, we investigate theoretically and experimentally a class of coupled strip-array (CSA) waveguides realized on a SiO₂/Si₃N₄ platform with mass semiconductor fabrication processes. We demonstrate that this class of waveguides shows comparable sensitivity for a wide range of presented geometries, making it a very promising platform for satisfying multiple sensor and fabrication requirements without loss of performance.

We demonstrate an experimental assessment of a high-Q, high-angle piezoelectric (2 µm PZT) MEMS scanning micromirror featuring distributed backside reinforcement, suitable for applications demanding energy-efficient and high-quality image projection. Frequency response measurements at 10 different vacuum levels ranging from atmospheric pressure to 10⁻⁶ mbar allow for the quantitative separation of damping mechanisms (air and structural). Stroboscopic digital holographic microscopy was used to assess the static and dynamic deformation of the mirror surface. The experimental results are in good agreement with simulations and models.