Design and simulation of micro spectrometer based on torsional MEMS grating

Micro-opto-electro-mechanical systems (MOEMS) has prominent advantages over conventional optical devices, such as smaller, lighter, more stable, lower cost and power consumption. It has been widely applied in the last few years. This paper presents a micro spectrometer based on torsional MEMS grating with micromachining process. As a diffractive component in the micro spectrometer, the torsional MEMS grating is actuated by electrostatic force to scan the spectrum. In contrast to common linear detector arrays with stationary diffraction grating and non-fixed grating rotated by stepper motor to scan spectrum used in most micro spectrometer, MEMS-based spectrometer is dynamically controllable, and has no mechanical moving parts with small size. ZEMAX is used for design, optimization, and simulation analysis of the micro spectrometer with multi-configurations in the cross Czerny-Turner optical system. The results indicate that torsional MEMS grating operates at a torsion angle of ±3 degree, the spectrometer can scan spectral range of 800- 1600nm in NIR (near infrared) , spectral resolution is around 10 nm, and the whole spectrometer has a volume of 80mm×55mm×30mm. The study provides an initial theoretical foundation for the further development and design.