Hybrid MEMS Actuator With 3 Degrees-of- Freedom for Efficient Planar Optical Switching

This work demonstrates a hybrid MEMS actuator platform that combines electrostatic and piezoelectric actuators to displace a suspended MEMS platform along 3 degrees-of-freedom (DOF). The prototype MEMS actuator tested produces maximum displacements of $8.8 \mu \text{m}$ along the positive X-axis, and $8.5 \mu \text{m}$ along the negative X-axis, with digital control. Analog control produces maximum displacements of $5.9 \mu \text{m}$ along the positive X-axis, and $5.8 \mu \text{m}$ along the negative X-axis. It can also provide $2.2 \mu \text{m}$ of in-plane displacement along the negative Y-axis with analog control. The electrostatic actuator used for displacement along the negative Y-axis also compensates for any out-of-plane misalignment between the suspended MEMS platform and fixed silicon due to the significant residual stress caused by deposited piezoelectric material layers. In addition, up to 550 nm of misalignment compensation using the electrostatic actuator before electrostatic pull-in is demonstrated. The piezoelectric actuator provides fine alignment capability with a maximum out-of-plane displacement of 200 nm and 100 nm with analog control along the positive and negative Z-axis, respectively. This hybrid MEMS actuator can be integrated with channel waveguides for efficient planar optical switching applications. [2023-0121]