Micro-machined Fabry-Pérot interferometer for thermal infrared

We designed and demonstrated a surface micro-machined tunable Fabry-Pérot interferometer for the thermal infrared wavelengths 7.6 μm <; λ <; 10.3 μm. The device is based on two poly-Si/air distributed Bragg reflectors, separated by an electrostatically adjustable gap. Our work introduces the first micro-machined single-wafer solution for this wavelength range with the resolution adequate for the spectroscopic applications in pharmaceutics and biotechnology. The optical performance under the electrostatic tuning is presented and analyzed. Analytical model and numerical computation, including electromechanical FEM simulation, are exploited for evaluating the spectral behavior of the measured transmission peak width, height, and location.