FR4-based electromagnetic scanning micro-grating integrated with an angle sensor for a low-cost NIR micro-spectrometer.

Aiming to implement a low-cost single-photodetector-based NIR micro-spectrometer, we present a novel flame retardant 4 (FR4)-driven micro-grating for spectral dispersion and spatial scanning. It consists of a silicon blazed grating directly bonded onto the FR4 actuator platform and an integrated differential electromagnetic angle sensor. Owing to the better shock and vibration reliability, larger aperture, shorter fabrication cycle, and much lower cost, it may be a potential alternative to conventional silicon microelectromechanical systems scanning micro-gratings. The micro-spectrometer prototype based on this device shows a spectral range of 800-1800 nm, a spectral accuracy of ±1.3  nm, and a 10 nm spectral resolution.