First principles jitter characterization of two-axis MEMS mirrors

Abstract

Recently developed MEMS micromirror technology provides an opportunity to replace macroscale actuators for laser beamsteering in lidar and free-space optical communication systems. Precision modeling of mirror pointing and its dynamics are critical to the design of MEMS beamsteerers. Beam jitter ultimately limits MEMS mirror pointing, with consequences for bit error rate and overall optical system performance. Sources of jitter are platform vibration, control voltage noise, and Brownian motion noise. This work relates the random jitter of the mirror facet to its originating sources via a multidimensional first-order Taylor expansion of a first-principles-derived analytic expression for the actuating torque. The input torque, consisting of deterministic and stochastic components, is related to the 2-D jitter through a pair of coupled damped harmonic oscillator differential equations. The linearized 2-D jitter model for the mirror is simulated using Matlab, while the full nonlinear torque model was simulated using Simulink. The work describes an experimental setup and methodology that is used to make precise micromirror measurements. Experimental measurements are in agreement with the jitter model, i.e., the linearized model is able to predict mirror facet jitter based on the measured power spectral densities for the sources of jitter.