Design of Suspended Slot Racetrack Microring Refractive Index Sensor Based on Polymer Nanocomposite

Recently, polymer nanocomposites have attracted great interest due to their remarkable characteristics of high performance and enabling production of low-cost devices. This article explores the reflective index sensing application of the polymer nanocomposite IOC-133, which is a TiOx/polymer nanocomposite with a reflective index between 1.8 and 1.9. Considering the material properties of high reflective index, low absorption loss, and compatibility with nanoimprint lithography, a microring-based reflective index sensor with a suspended slot waveguide structure is proposed. We combined the sensing mechanism of slot waveguides with high reflective index polymer nanocomposites and designed the suspended structure to address the problem of decreasing sensitivity caused by residual layers. The sensing device was adopted as a microring resonator, which is conducive to large-scale integration. The finite-difference time-domain (FDTD) method was employed to analyze the effects of several key parameters. The results showed that the racetrack microring sensor we propose can achieve a high sensitivity of 436 nm/RIU (Refractive Index Units), about six times higher than the microring sensor with a ridge waveguide. The Q factor of the microring reaches 1.42 x 10(4), and the detection limit is 1.38 x 10(-4) RIU. The proposed suspended slot microring sensor has potential value in the field of nanoprinted photonic integrated circuits.

Automated summary

This article explores the application of the polymer nanocomposite IOC-133 in refractive index sensing. A suspended slot waveguide structure is proposed to combine with the high refractive index polymer nanocomposites, addressing the issue of decreasing sensitivity caused by residual layers. The proposed suspended slot microring sensor achieves a high sensitivity of 436 nm/RIU, six times higher than the microring sensor with a ridge waveguide.