Sensing performance of temperature insensitive microring resonators with double

An temperature insensitive microring resonator with double-layer U-shaped waveguide for sensing applications is proposed and investigated theoretically. The unique structure of microring resonator with double-layer U-shaped waveguide not only limits the light field in the ring, but also releases the evanescent field from the waveguide through the coupling of the upper and lower layers, thus enhancing the interaction between light and matter and improving the sensing ability. Then, through correctly selecting the cross-sectional dimensions of the waveguide, the bending radius, the spacing between the upper and lower waveguides and the shape of overlapping area, it is designed to have very low temperature dependence in aqueous solution, so as to obtain sensing accuracy and stability. The simulation results show that the sensitivity is 496 nm/RIU +/- 5 pm/K. Within the temperature change range of 3.2 K, it can be considered that the measurement result is irrelevant to the change in ambient temperature. Compared with the other ring resonators, this resonator does not need extra temperature compensation equipment, active temperature controller, polymer cladding, or even extra processing of the measured data to eliminate the effect of temperature. Thanks to its excellent performance in temperature insensitive and sensing performance, the device is suitable for refractive index measurement in a complex environment. It might have broad application prospects in portable real-time monitoring equipment, for example, analyzing health status from the change of sweat composition, or detecting the content of microorganisms and other harmful substances in drinking water.

Automated summary

A temperature insensitive microring resonator with double-layer U-shaped waveguide is proposed for sensing applications. The unique structure of the resonator enhances the interaction between light and matter, and the correct selection of parameters allows for low temperature dependence in aqueous solution. The device shows a sensitivity of 496 nm/RIU +/- 5 pm/K and has potential applications in refractive index measurement and real-time monitoring.