Spectral performance of a micromachined infrared spectrum analyzer in silicon

The spectral performance of a grating-based optical microspectrometer fabricated in silicon is presented. Fabrication is based on IC-compatible micromachining with the optoelectronic components distributed over two silicon wafers. One wafer contains an aluminum-based grating and the other an array of polysilicon thermocouples. Device dimensions are typically 5×5×1 mm³, with the optical path defined by an aligned wafer-to-wafer bond. The optical design constraints of this microsystem are discussed. Measurements confirm an infrared (IR) operating range between 2 and 5 μm and spectral resolution R=10.