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

Area of Science:

• Photonics and Materials Science
• Optoelectronics and Integrated Photonics

Background:

• Silicon nitride photonic integrated circuits (PICs) are crucial for various optical applications.
• Developing active PICs with efficient modulation capabilities, especially for visible wavelengths, remains a challenge.
• Piezoelectric actuation offers a promising route for active control in PICs.

Purpose of the Study:

• To demonstrate a novel platform for phase and amplitude modulation in silicon nitride PICs.
• To leverage piezo-optomechanical coupling with aluminum nitride actuators for enhanced device performance.
• To enable scalable active PICs for visible wavelengths, functional from room temperature down to cryogenic conditions.

Main Methods:

• Fabrication of a CMOS-compatible platform integrating silicon nitride waveguides and aluminum nitride piezoelectric actuators.
• Utilizing piezo-optomechanical coupling to achieve modulation of light.
• Demonstrating a silicon nitride ring resonator modulator and a Mach-Zehnder modulator on the developed platform.

Main Results:

• A compact silicon nitride ring resonator modulator (∼40 µm diameter) operating at 780 nm demonstrated high quality factors (>1.5 million).
• Achieved >10 dB extinction ratio change with 2 V applied, <4 ns switching time, and 0.5 pJ/bit switching energy.
• Demonstrated robust performance down to cryogenic temperatures (7 K) with ultra-low power dissipation (< picowatt) and a Mach-Zehnder modulator with 20 nW steady-state power consumption.

Conclusions:

• The demonstrated platform enables scalable, active silicon nitride PICs for visible wavelengths.
• Piezoelectric actuation provides efficient modulation without performance degradation at cryogenic temperatures.
• The technology holds significant potential for low-power, high-performance optical modulation in diverse applications.