Piezoelectric MEMS Phase Modulator for Silicon Nitride Platform in the Visible Spectrum

TL;DR

This paper presents a novel, ultra-low-power piezoelectric MEMS phase modulator integrated with silicon nitride waveguides, achieving significant phase shifts with minimal power in the visible spectrum, enabling advanced on-chip photonic applications.

Contribution

The work introduces a compact, efficient PZT-based MEMS phase modulator on a silicon nitride platform with superior scalability and low power consumption compared to existing stress-optic modulators.

Findings

Achieved phase shifts of 1.45π and 2.5π at 10 V for 3 mm and 5 mm modulators.

Scalability metric of 2.25 V·cm at 635 nm, an order-of-magnitude improvement.

Device exhibits ultralow power consumption (~12 nW) and low optical loss (<0.75 dB/cm).

Abstract

Active photonic integrated circuits (PICs) in the visible spectrum are essential for on-chip applications, requiring low-loss waveguides with broad transparency and efficient, low-power phase modulation. Here, we demonstrate a compact, ultra-low-power phase modulator based on a silicon nitride (Si$_3$N$_4$) waveguide integrated with thin-film lead zirconate titanate (PZT) that actuates a bridge-type MEMS. The suspended actuator exploits PZT's strong piezoelectric effect to induce mechanically driven phase shifts, enabling efficient modulation in a Mach--Zehnder interferometer. For 3~mm and 5~mm modulators, phase shifts of $1.45\pi$ and $2.5\pi$ are achieved at 10~V, corresponding to a scalability metric ($V_{\pi}\cdot L$) of 2.25~V$\cdot$cm at 635~nm. This represents an order-of-magnitude improvement in scalability over stress-optic PZT modulators. The devices also exhibit ultralow power consumption ($\sim 12\,\mathrm{nW}$), $\sim 5\,\mathrm{ms}$ rise time, and optical loss $< 0.75\,\mathrm{dB/cm}$. Furthermore, we demonstrate on-chip beam shaping.