Large-aperture Fabry-Perot filters based on silicon/silicon carbonitride distributed Bragg reflectors for the near-infrared
This contribution presents silicon carbonitride as a new low refractive index material for integration together with silicon in suspended distributed Bragg reflector membranes. We show how its benign mechanical stress properties can be used to fabricate inherently flat mirror membranes of up to 5 mm diameter. Due to the large refractive index contrast to silicon such mirror membranes exhibit high reflectance over a wide spectral range. Using these mirrors, we demonstrate a proof of concept for a large aperture Fabry-Perot filter with narrow bandwidth that could help miniaturize hyperspectral imaging sensors.
Optical transmission performance of a surface-micromachined Fabry–Pérot interferometer for thermal infrared
We developed a surface-micromachined tunable Fabry–Pérot interferometer for the thermal infrared spectral range of wavelengths 7–12 µm. In this paper, we present the device performance in terms of the optical transmission and the tunability. The device represents the first layout that proved successful in terms of the manufacturing process yield (about 80%). The optical transmission over the wavelengths from 3 to 20 µm is presented with the emphasis on analysing the first-order transmission peak. The transmission band width and the peak height are compared using the existing theory for this type of an interferometer. The deviation from an ideal performance is resolved and partly explained through the known structural unidealities.
Electrically Tunable Surface Micromachined Fabry-Perot interferometer for Visible Light
Abstract We present a new kind of electrostatically tunable surface micromachined Fabry-Perot interferometer (FPI) structure and a process flow which was successfully used to fabricate devices for visible wavelength range. The novel fabrication process is based on using polymeric sacrificial layer. Fabricated devices have five-layer dielectric mirrors made of atomic layer deposited Al 2 O 3 and TiO 2 thin films. An AC voltage control together with integrated series capacitance enable tuning range of the FPI etalon in excess of 60%. The FWHM (Full Width at Half Maximum) of the 4 th order transmission is 5.4 nm with maximum transmission being about 67% at λ = 500 nm.