CMOS-compatible, piezo-optomechanically tunable photonics for visible wavelengths and cryogenic temperatures

TL;DR

This paper presents a CMOS-compatible platform for visible-wavelength, cryogenic-temperature, piezo-optomechanical photonic modulation using aluminum nitride actuators, enabling scalable, high-Q, fast, and low-power integrated photonics.

Contribution

The authors develop a scalable, CMOS-fabricated platform for piezo-optomechanical modulation in visible wavelengths that functions effectively at cryogenic temperatures, demonstrating high-Q resonators and low-power operation.

Findings

Achieved >1.5 million Q-factor in silicon nitride ring resonator at 780 nm.

Demonstrated sub-4 ns switching time and 0.5 pJ/bit energy in modulators.

Operated devices at 7 K with sub-picowatt electrical power dissipation.

Abstract

We demonstrate a platform for phase and amplitude modulation in silicon nitride photonic integrated circuits via piezo-optomechanical coupling using tightly mechanically coupled aluminum nitride actuators. The platform, fabricated in a CMOS foundry, enables scalable active photonic integrated circuits for visible wavelengths, and the piezoelectric actuation functions without performance degradation down to cryogenic temperatures. As an example of the potential of the platform, we demonstrate a compact (~40 {\mu}m diameter) silicon nitride ring resonator modulator operating at 780 nm with intrinsic quality factors in excess of 1.5 million, >10 dB change in extinction ratio with 2 V applied, a switching time less than 4 ns, and a switching energy of 0.5 pJ/bit. We characterize the exemplary device at room temperature and 7 K. At 7 K, the device obtains a resistance of approximately 20 Teraohms, allowing it to operate with sub-picowatt electrical power dissipation. We further demonstrate a Mach-Zehnder modulator constructed in the same platform with piezoelectrically tunable phase shifting arms, with 750 ns switching time constant and 20 nW steady-state power dissipation at room temperature.