High-quality factor Ta₂O₅-on-insulator resonators with ultimate thermal stability

Area of Science:

• Photonics
• Quantum Technology
• Materials Science

Background:

• Photonic integrated circuits demand low-loss, thermally stable components.
• Nanophotonic materials often face challenges with propagation loss and thermal drift, hindering precise frequency stabilization.
• Existing monolithic chips offer interferometric stability but not for all critical nanophotonic systems.

Purpose of the Study:

• To develop micro-ring resonators with high quality factors and minimal temperature-dependent wavelength shifts.
• To enable athermal operation in nanophotonic devices at cryogenic temperatures.
• To pave the way for ultra-stable, cost-effective resonators for advanced optical technologies.

Main Methods:

• Fabrication of tantalum pentoxide (Ta₂O₅) on insulator micro-ring resonators.
• Characterization of resonator quality factors (Q-factors).
• Measurement of wavelength shift as a function of temperature in the 70 K to 90 K range.

Main Results:

• Achieved quality factors exceeding 1.8 million (1.8 Mio).
• Demonstrated vanishing temperature-dependent wavelength shift between 70 K and 90 K.
• Ta₂O₅-on-SiO₂ devices exhibit athermal behavior in this temperature range.

Conclusions:

• Tantalum pentoxide micro-ring resonators offer unprecedented stability for photonic applications.
• Athermal operation at liquid nitrogen temperatures is now feasible.
• These devices are suitable for wavelength division multiplexing, on-chip frequency stabilization, and optical frequency comb generation.