Large-aperture electromagnetically actuated MEMS Fabry-Perot filtering chips for visible spectral imaging.

Benefitting from the inherent merits of tiny volume, customizable performance, good system compatibility and high-yield production, micro-electro-mechanical-system-based Fabry-Perot filtering chip (MEMS-FPFC) with a large aperture size gives a feasible way for the realization of miniaturized spectral imagers which can serve in many civilian and military scenarios. Although the aperture size of MEMS-FPFCs in mid-wave and long-wave infrared has reached to the centimeter scale, that of visible wavelength (VIS) MEMS-FPFC is always unsatisfied which is mainly limited by micromachining stress, especially in the thin films. In this work, we propose a large-aperture electromagnetically actuated MEMS-FPFC based on Si3N4 supporting membrane for VIS spectral imaging, which is designed with the assistance of multi-field coupling simulation model. A low-stress wafer-scale bulk micromachining process is developed to guarantee the high-quality and high-yield production for the aimed VIS MEMS-FPFCs. Finally, by the strictly controlling and rationally allocating the film stress of multi-layer film stack, VIS MEMS-FPFCs with 6 mm aperture size are thus developed, which can be tuned bidirectionally and continuously in 612-678 nm waveband with a good linear response of better than 95%. The achieved VIS MEMS-FPFCs can be utilized to construct miniaturized spectral imagers directly, aiming for such applications as intelligent agriculture, environmental protection and industrial inspection.

Large-aperture, widely and linearly tunable, electromagnetically actuated MEMS Fabry-Perot filtering chips for longwave infrared spectral imaging.

Longwave infrared spectral imaging (LWIR-SI) has potential in many important civilian and military fields. However, conventional LWIR-SI systems based on traditional dispersion elements always suffer the problems of high cost, large volume and complicated system structure. Micro-electro-mechanical systems Fabry-Perot filtering chips (MEMS-FPFC) give a feasible way for realizing miniaturized, low cost and customizable LWIR-SI systems. The LWIR MEMS-FPFC ever reported can't meet the demands of the next-generation LWIR-SI systems, due to the limitation of small aperture size and nonlinear actuation. In this work, we propose a large-aperture, widely and linearly tunable electromagnetically actuated MEMS-FPFC for LWIR-SI. A multi-field coupling simulation model is built and the wafer-scale bulk-micromachining process is applied to realize the design and fabrication of the proposed MEMS-FPFC. Finally, with the rational structural design and fabrication process, the filtering chip after packaging has an aperture size of 10 mm, which is the largest aperture size of LWIR MEMS-FPFC ever reported. The fabricated electromagnetically actuated MEMS-FPFC can be tuned continuously across the entire LWIR range of 8.39-12.95 µm under ±100 mA driving current with a pretty good linear response of better than 98%. The developed electromagnetically actuated MEMS-FPFC can be directly used for constructing miniaturized LWIR-SI systems, aiming for such applications as military surveillance, gas sensing, and industry monitoring.