Design of high-efficiency scanning grating mirror for near-infrared micro-spectrometer

In the last few years, with the rapid development of micro-opto-electro-mechanical-systems(MOEMS), near-infrared(NIR) spectrometers are moving towards low cost, high performance and miniaturization. As a key component of NIR micro-spectrometers, the scanning grating mirror has an imponderable advantage on diffraction efficiency compared to other grating mirrors, which makes it feasible to develop high optical detecting sensitivity systems with one single photodiode. In order to improve the detecting performance of NIR spectrometers, a single silicon MOEMS scanning grating mirror has been designed, which integrates a high diffraction efficiency blazed grating on the top and an electromagnetic actuator on the bottom. Based on a tilted (111) silicon substrate, the scanning grating mirror structure can be easily fabricated by micromachining technology. Meanwhile, a simulation has also been carried out by optical software and finite element analysis(FEA), and the results show that the dynamic diffraction efficiency is more than 54% and the peak value reaches 90% in the spectrum range of 800-1800 nm, meanwhile the maximum torsion angle of MOMES scanning grating mirror is 4.55 at the frequency of 484.38 Hz.