Low-loss low thermo-optic coefficient Ta2O5 on crystal quartz planar optical waveguides
Abstract
Optical resonator-based frequency stabilization plays a critical role in ultra-low linewidth laser emission and precision sensing, atom clocks, and quantum applications. However, there has been limited success in translating traditional bench-top stabilization cavities to compact on-chip integrated waveguide structures that are compatible with photonic integration. The challenge lies in realizing waveguides that not only deliver low optical loss but also exhibit a low thermo-optic coefficient and frequency noise stability. Given the problematic sources of frequency noise within dielectrics, such as thermorefractive noise, resonators with small thermo-optic response are desirable for on-chip reference cavities. We report the first demonstration of a Ta2O5 (tantala) waveguide core fabricated on a crystal quartz substrate lower cladding with TEOS-PECVD SiO2 upper cladding. This waveguide offers significant advantages over other waveguides in terms of its low thermo-optic coefficient and reduced thermorefractive-related frequency noise. We describe the waveguide structure and key design parameters as well as fabrication considerations for processing tantala on quartz waveguides. We report a waveguide thermo-optic coefficient of −1.14 × 10−6 RIU/K, a value that is over 6 times smaller in magnitude than that of SiO2-substrate tantala waveguides, with a propagation loss of 1.19 dB/cm at 1550 nm and <1.33 dB/cm across the 1525 nm–1610 nm wavelength range. Within a 1.6 mm radius ring resonator, we demonstrate a 2.54 × 105 intrinsic Q factor. With the potential for very low loss and the ability to control the thermal response, this waveguide platform takes a key step toward creating thermally stable integrated resonators for on-chip laser frequency stabilization and other applications.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 01, 2020
- Source ID
- 10.1063/5.0024743
Entities
People
- Andrei Isichenko
- Chad Fertig
- Chad Hoyt
- Daniel Blumenthal
- Jiawei Wang
- Mu Hong Lin
- Nitesh Chauhan
- Peter T Rakich
- Qiancheng Zhao
- Ryan O Behunin
Organizations
- ARPA-E
- Defense Advanced Research Projects Agency
- Honeywell International, Inc.
- Northern Arizona University
- University of California
- Yale University