Racetrack Ring Resonator-Based on Hybrid Plasmonic Waveguide for Refractive Index Sensing

Abstract

In this study, a comprehensive numerical analysis is conducted on a hybrid plasmonic waveguide (HPWG)-based racetrack ring resonator (RTRR) structure, tailored specifically for refractive index sensing applications. The sensor design optimization yields remarkable results, achieving a sensitivity of 275.7 nm/RIU. Subsequently, the boundaries of sensor performance are pushed even further by integrating a subwavelength grating (SWG) structure into the racetrack configuration, thereby augmenting the light–matter interaction. Of particular note is the pivotal role played by the length of the SWG segment in enhancing device sensitivity. It is observed that a significant sensitivity enhancement can be obtained, with values escalating from 377.1 nm/RIU to 477.7 nm/RIU as the SWG segment length increases from 5 µm to 10 µm, respectively. This investigation underscores the immense potential of HPWG in tandem with SWG for notably enhancing the sensitivity of photonic sensors. These findings not only advance the understanding of these structures but also pave the way for the development of highly efficient sensing devices with unprecedented performance capabilities.

Optimized hybrid plasmonic waveguide-based ring resonator for advanced refractive index sensing

“…Notably, the HPWG structure with an s of 50 nm exhibited a significantly higher extinction ratio (ER) compared to configurations with s > 50 nm. ER can be calculated as [20]:…”

“…Determining the Q-factor entails measuring the resonance linewidth, defined as the width of the resonance dip at half its maximum intensity (FWHM). Typically, this factor is computed as [20]:…”

“…These sensors leverage the principle of confining light within a ring-shaped structure, where alterations in the refractive index of the surrounding medium induce shifts in either the resonant wavelength or intensity [19]. This heightened sensitivity enables the detection of minute variations in refractive index, rendering RRbased sensors indispensable across a wide spectrum of applications including biomedical sensing, environmental monitoring, and chemical analysis [20]. Moreover, their compact design facilitates seamless integration into portable and miniaturized devices, facilitating real-time and on-site measurements.…”