Polycrystalline silicon based photonic crystal Fabry-Perot etalon

We demonstrated the design, fabrication and characterization of a polycrystalline silicon based photonic crystal Fabry-Perot etalon that is aimed to work in the mid-infrared wavelengths. The highly reflective mirrors required in a Fabry-Perot etalon are realized by free-standing polycrystalline silicon based photonic crystal membranes with etched circular air holes. A peak reflection of 96.5% is observed at 3.60μm with very low absorption loss. When two of the photonic crystal mirrors are configured to be in parallel to form a Fabry-Perot etalon, a filtered transmission centered at 3.51μm is observed. The quality factor measured was around 520 which is significantly higher than existing works. This paves the possibility of using such devices for high-resolution applications such as gas sensing and hyperspectral imaging.