This study presents a photonic integrated optical sensor based on a dual-polarization microring resonator with angular gratings on a silicon-on-insulator (SOI) waveguide, enabling simultaneous and precise refractive index (RI) and temperature measurements. Due to the distinct energy distributions for transverse electric ($\mathit{TE}$) and transverse magnetic ($\mathit{TM}$) modes in SOI waveguides, these modes show distinct sensitivity responses to the variation in ambient RI and temperature. Simultaneous measurements of both temperature and RI are enabled by exciting both these transverse modes in the microring resonator structure. Furthermore, incorporating angular gratings into the microring resonator’s inner sidewall extends the temperature measurement range by mitigating free spectral range limitations. This work presents a novel approach to dual-polarization microring resonators with angular gratings, offering an enhanced temperature measurement range and detection limit in optical sensing applications requiring an extended temperature range. The proposed structure is able to yield a simulated temperature measurement range of approximately 35 nm with a detection limit as low as $2.99\times {10}^{-5}$. The achieved temperature sensitivity is 334 pm/°C and RI sensitivity is 13.33 nm/RIU for the ${\mathit{TE}}_0$ mode, while the ${\mathit{TM}}_0$ mode exhibits a temperature sensitivity of 260 pm/°C and an RI sensitivity of 76.66 nm/RIU.

Advancements in fabrication technology have enabled the development of various waveguide structures for integrated optical sensors, including subwavelength-based designs. This study introduces a subwavelength-based design for optical sensing applications. To extend the sensing range, side-mode suppression techniques based on angular grating subwavelength microring resonators have been implemented. These angular gratings employ silicon pillars of distinct widths, facilitating effective index modulation along the optical path of microring resonator. For refractive index (RI) based sensing, ambient temperature variations significantly impact the RI. To address this challenge, we propose a dual-polarization angular grating subwavelength microring resonator (DP AG-SWGMRR) capable of simultaneously measuring RI and temperature. A comprehensive analysis of the effects of key structural parameters on the center wavelength, side-mode suppression ratio and quality factor is presented. Simulation results for bulk sensing applications indicate that the proposed device achieves a high sensitivity of 1222 nm/RIU for the TM₀ mode and 850 nm/RIU for the TE₀ mode. Furthermore, under ambient temperature variations, the sensor provides sensitivities of 208 pm/°C for the TM₀ mode and 286 pm/°C for the TE₀ mode. The side-mode suppression capability achieves a free spectral range of approximately 47.8 nm for the TE₀ mode. The proposed structure demonstrates excellent performance, accuracy, compact size, and compatibility with other subwavelength grating waveguide-based devices, underscoring its significant potential for applications in compact biomedical sensing.