# Piezoelectric Thin-Film Actuator for Dynamic Tuning of Micro-Optical Cavities

## TL;DR

This paper introduces a piezoelectric thin-film actuator that improves the performance of micro-optical cavities in MOEMS devices.

## Contribution

A novel piezoelectric thin-film actuator using the d33 mode for dynamic tuning of micro-optical cavities is proposed.

## Key findings

- The actuator achieves sub-100 nm displacement with nanometer-level resolution.
- It operates at a first-order natural frequency of approximately 5.8 kHz.
- The device successfully modulates optical path length in a Fabry–Pérot microcavity system.

## Abstract

In micro-opto-electro-mechanical systems (MOEMS), the micro-optical cavity plays a pivotal role. As performance requirements for MOEMS devices continue to rise, these cavities must achieve higher performance levels while simultaneously reducing their physical footprint. However, existing high-precision micro-optical cavities face challenges such as high process sensitivity and conflicting trade-offs between dynamic range and precision. To address these issues, piezoelectric thin-film actuators present a viable solution due to their high precision, stroke flexibility, electromagnetic interference resistance, and structural scalability. This study proposes a piezoelectric thin-film actuator based on the d33 mode. The device adopts an island-circular structure that integrates a lead zirconate titanate (PZT) piezoelectric film with metal electrodes. By employing particle swarm optimization (PSO) to enhance displacement output and anti-gravity capabilities, the actuator achieves displacement outputs below 100 nm within a compact form factor while maintaining nanometer-level resolution. Simulation and experimental results confirm a first-order natural frequency of approximately 5.8 kHz, along with a reasonable linear displacement response across a 4–6 V drive voltage range. Furthermore, the device demonstrates functionality within a Fabry–Pérot (F-P) microcavity system, enabling active optical path length modulation through precise cavity tuning. This research provides an effective approach to enhancing the dynamic performance and process compatibility of micro-optical cavity devices, advancing the development of next-generation MOEMS systems.