Low-loss low thermo-optic coefficient Ta 2 O 5 on crystal quartz planar optical waveguides
[1];
- Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering
- Northern Arizona Univ., Flagstaff, AZ (United States). Dept. of Applied Physics and Material Sciences; Northern Arizona Univ., Flagstaff, AZ (United States). Center for Materials Interfaces in Research and Applications (¡MIRA!)
- Yale Univ., New Haven, CT (United States). Dept. of Applied Physics
- Honeywell Aerospace, Plymouth, MN (United States)
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.
- Research Organization:
- Univ. of California, Santa Barbara, CA (United States)
- Sponsoring Organization:
- USDOE Advanced Research Projects Agency - Energy (ARPA-E); US Air Force Office of Scientific Research (AFOSR)
- Grant/Contract Number:
- AR0001042; FA9453-19-C-0030
- OSTI ID:
- 1848352
- Alternate ID(s):
- OSTI ID: 1706197
- Journal Information:
- APL Photonics, Vol. 5, Issue 11; ISSN 2378-0967
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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