CMOS-fabricated ultraviolet light modulators using low-loss alumina piezo-optomechanical photonic circuits

TL;DR

This paper presents a CMOS-fabricated UV light modulator using alumina waveguides and aluminum nitride actuators, enabling fast, low-power, reconfigurable optical filtering at wavelengths as low as 320 nm.

Contribution

It introduces a novel alumina-based photonic integrated circuit platform with piezo-optomechanical tuning, overcoming limitations of thermal tuning in UV photonics.

Findings

Achieved UV wavelength operation down to 320 nm.

Demonstrated a 6 ns switching time for optical filters.

Tuning rate of -120 MHz/V with power consumption below 20 nW.

Abstract

Ultra-violet (UV) and near-UV wavelengths are necessary for many important optical transitions for quantum technologies and various sensing mechanisms for biological and chemical detection. However, all well-known photonic platforms have excessively high losses in the UV, which has prevented photonic integrated circuits (PICs) being used to address these and other important application spaces. Photonic waveguides using low-loss alumina cores have emerged as a promising solution because of almunia's large optical bandgap and the high quality of films enabled by atomic layer deposition. However, to the best of our knowledge, active alumina PICs have only been realized using thermo-optic tuning, which precludes switching speeds shorter than one microsecond, high circuit densities, and cryogenically compatible operation. Here, we introduce a CMOS-fabricated, piezo-optomechanical PIC platform using alumina waveguides with low optical losses at UV wavelengths and aluminum nitride piezoelectric strain actuators, which solves the issues associated with thermal tuning. We demonstrate a high-performance, reconfigurable optical filter operating at wavelengths as low as 320 nm. The filter has a 6 nanosecond switching time, a loaded linewidth of 3.3 GHz, tuning rate of -120 MHz/V, and a hold power less than 20 nW.