Micro-electromechanical systems-based microspectrometers covering wavelengths from 1500nm to 5000nm

摘要

There is an increasing need for infrared spectroscopic instrumentation that is low-cost and extremely robust for applications in agriculture, environmental monitoring, food science and medicine. This paper describes a MEMS-based tunable Fabry-Perot filter that can be directly integrated on a detector. The fabrication process is detector independent, and has been demonstrated on Si as well as one of the most unforgiving detector material systems, HgCdTe. Results are presented that show that the technology is applicable for coverage of a wide spectral range, with examples of tuning from ～1600nm to ～2300nm and ～3800nm to ～4800nm using voltages < 20V with line widths < 100nm and tuning speeds of 50kHz. Modeling shows that the device should be stable to shocks up to 250G. Line widths and tuning speeds can be significantly improved using different actuator designs and removal of squeezed-film damping effects. The process uses a maximum process temperature of 125℃, and is therefore compatible with a wide range of detector materials including Si, Ge, InGaAs, InSb, as well as more specialized detector materials such as InAs quantum dots and InAs/GaSb superlattices. Work is currently underway to demonstrate application of microspectrometers fabricated using this technology in real-time testing of soils for agricultural applications.