Design and Simulation of a Highly Sensitive Refractive Index Sensor based on Grating-assisted Strip Waveguide Directional Coupler

TL;DR

This paper presents a novel on-chip refractive index sensor using a grating-assisted strip waveguide directional coupler, achieving high sensitivity and low temperature dependence through optimized waveguide design.

Contribution

The paper introduces a new sensor design with a grating-assisted directional coupler that significantly improves sensitivity and reduces temperature effects compared to existing sensors.

Findings

Refractive index sensitivity of ~ 10^4 nm/RIU achieved

Sensor exhibits negligible temperature sensitivity (< 1 nm/°C)

Optimized waveguide parameters enhance sensor performance

Abstract

A highly sensitive refractive index sensor based on grating-assisted strip waveguide directional coupler is proposed. The sensor is designed using two coupled asymmetric strip waveguides with a top-loaded grating structure in one of the waveguides. Maximum light couples from one waveguide to the other at the resonance wavelength, and the change in resonance wavelength with the change in refractive index of the medium in the cover region is a measure of the sensitivity. The proposed sensor would be an on-chip device with a high refractive index sensitivity of ~ 104 nm/RIU, and negligible temperature sensitivity (< 1nm/0C). The sensor configuration offers a low propagation loss, thereby enhancing the sensitivity. Variation of the sensitivity with the waveguide parameters of the proposed sensor have been studied to optimize the design.