High mechanical stability MEMS-based cantilever tunable FP filter for cooled infrared spectral detector

Spectral integrated detection is one of important branch anticipated for the next generation infrared FPA, which includes so-called multi-dimensional detection capabilities with function diversity. Such enhancement of the current state-of-the-art FPA technologies allow real-time tuning of spectral information to be gathered from multiple narrow wavelength bands, getting data-cube to meet the requirements of clear target recognition in complex noisy scenarios. In order to provide a reduced size, weight and power (SWaP) solution, microelectromechanical systems (MEMS) based electrically tunable filter technology has been developed. This adopted approach is capable of delivering on-chip spectral detector by obtaining narrow-band spectral sensitivity utilizing tunable MEMS optical filter directly integrated on FPA chips. Especially for integration with cooled infrared FPA, it is necessary to meet the reliability and stability challenges of large-sized filters matching FPA chip area under low-temperature vacuum environment. In this paper, a multi physics field coupling analysis work was also dug out for understanding the stability performance of electromechanical characteristics. Then we produced MEMS based tunable FP filters, which demonstrated a transmission of 45 % with a well uniformity within the filter area of 3 mm radius, and maximum tuning wavelength range of 0.7 μm (from 5.3 to 4.6 μm) under voltage bias. We integrated the tuning filter with InAs/GaSb Type-II superlattice infrared detector and tested the performance of tunable photo-responsivity at liquid nitrogen temperature. All the work laid the foundation for integration with cooled FPA in our next step work.