Actuator/Reflector Decoupling for Reduced Excitation of Secondary Mechanical Resonance Modes in MEMS-Tunable VCSELs

This report describes a suspension design for a tunable vertical cavity surface-emitting laser (VCSEL) electrostatic MEMS mirror that separates the reflector from the electrostatic actuator to reduce the influence of secondary mechanical resonance modes. Compared to a monolithic actuating membrane design, a hundredfold reduction in the mechanical displacement of the mirror in the secondary resonance mode relative to the fundamental mode has been achieved. This enhancement of the main mode over higher-order modes is expected to improve interferometric stability when higher-frequency feedback may otherwise cause undesired fluctuation, especially during low frequency operation.