Mode Sensitivity Analysis of Subwavelength Grating Slot Waveguides

Abstract

In this paper, we investigate the mode sensitivity (S mode) of subwavelength grating slot (SWGS) waveguides. S mode is an important parameter in various waveguide-based photonic circuits such as sensors, modulators, and thermally-controlled devices. It is a measure of the sensitivity of the waveguide effective index towards the refractive index perturbations in the cladding medium. The SWGS waveguide exhibits high mode sensitivity, as it combines sensitivity enhancement features of both slot and subwavelength grating waveguides. Finite-difference time-domain simulations are performed for the analysis, design, and optimization of the hybrid structure. The SWGS waveguide is incorporated into a Mach-Zehnder interferometer and fabricated on a silicon-on-insulator platform for the experimental estimation of S mode. The measured S mode value of 79% is consistent with the theoretical prediction of 83%.

Cost-Effective Mach-Zehnder Interferometer Liquid Refractive Index Sensor Based on Conventional Polymer Strip Waveguide

“…arm, Δφ is an constant, thus our proposed MZI sensor can enhance the sensitivity by optimizing the reference arm length while maintain a fixed DR. This is different from most sensitivity enhancement schemes in which the Δφ is increased by enhancing the light-analyte interaction length or degree of the MZI sensor [11][12][13][14]. We followed the designed parameters to fabricate the proposed device.…”

“…Over the past decades, optical waveguide liquid refractive index (RI) sensors have received more and more attention as an increasingly important tool in biochemical analysis applications by virtue of their unique advantage enabling high-sensitive, real-time, and label-free detection [1]. To date, various optical waveguide liquid RI sensors employing various configurations, including ring resonator [2][3][4], grating-assisted directional coupler [5], grating [6], Young interferometer [7], multimode interferometer [8], and Mach-Zehnder interferometer (MZI) [9][10][11][12][13][14][15][16][17][18], have been proposed. Among them, the MZI-based sensors have distinctive advantages of structural simplicity and diversity, design flexibility, and the potential of ultra-high sensitivity, making them an important and promising type.…”

“…As the MZI-based sensors also utilize evanescent field probing scheme, to enhance light-analyte interactions and hence to achieve large waveguide sensitivity, strong penetration of the evanescent field into the analyte is required. To this end, some novel waveguides, including plasmonic waveguide [10], slot waveguide [11], hybrid plasmonic waveguide [12,13], subwavelength grating slot waveguide [14], and the waveguide with metal under-cladding [15], have been proposed and evaluated during the past years. And they actually help the improvement of the waveguide sensitivity.…”

Silicon‐Based Integrated Label‐Free Optofluidic Biosensors: Latest Advances and Roadmap

“…In 2018, Luan et al proposed and demonstrated a “multi‐box” microring biosensor as a fusion of SWG and slot structures (see Figure 7k) with one of the characterized record highest sensitivities to bulk refractive index change of ≈580 nm per RIU and surface sensitivity of ≈1900 pm nm −1 in a standard bio‐sandwich assay. [ 178,179 ] Very recently, the concept of “multi‐box” waveguide has been further investigated with the incorporation of Bragg grating [ 180 ] and MZI‐based [ 181 ] sensing structures.…”

Polarization-Insensitive Hybrid Plasmonic Waveguide Design for Evanescent Field Absorption Gas Sensor

“…S mode is an essential parameter which should be taken into consideration while designing sensing devices [31]. S mode is evaluated for the geometric parameters of the WG and is calculated by using the following expression:…”