Thermorefractive stable tantalum pentoxide microring resonator for dual-polarization four-wave mixing spectral translation

Integrated tantalum pentoxide (Ta₂O₅) photonics has emerged as a promising platform for nonlinear optical applications due to its high Kerr nonlinearity, low propagation loss, CMOS compatibility, and exceptionally low thermo-optic coefficient. In this work, we demonstrate, for the first time, dual-polarization four-wave mixing (FWM) spectral translation in a Ta₂O₅ microring resonator. The device features a trapezoidal waveguide geometry optimized to support both TE₀₀ and TM₀₀ fundamental modes with intersecting dispersion curves at 1548 nm. The fabricated resonator exhibits high loaded quality factors of 1.78 × 10⁵ (TE₀₀) and 1.46 × 10⁵ (TM₀₀), and low propagation losses of 1.85 dB/cm and 1.96 dB/cm, respectively. The device also shows excellent thermorefractive stability, with temperature-dependent wavelength shifts (TDWS) as low as 7.19 pm/K (TE₀₀) and 7.49 pm/K (TM₀₀). The difference of the TDWS enables accurate resonance alignment via chip temperature tuning. Under on-chip pump powers of 14.13 dBm (TE₀₀) and 13.87 dBm (TM₀₀), FWM conversion efficiencies of -36.15 dB and -35.29 dB are achieved at the same pump wavelength. These results underscore the potential of Ta₂O₅ for doubling spectral capacity, including polarization-multiplexed optical communication and dual-comb generation for spectroscopy.