On-Chip Chemical Sensing Using Double-slot Silicon Waveguide

TL;DR

This paper introduces a double-slot silicon waveguide-based Mach-Zehnder interferometer for highly sensitive on-chip chemical sensing, achieving record sensitivity and low detection limits for refractive index measurements.

Contribution

The paper presents a novel double-slot waveguide design with superior sensitivity and detection limits, along with experimental validation of ultra-low loss coupling and sensing capabilities.

Findings

Achieved a sensitivity of 700 nm/RIU

Demonstrated a limit of detection of 7.142e^-6 RIU

Established the highest sensitivity for on-chip guided wave sensing

Abstract

In this paper, we present refractive index measurement using a double-slot silicon waveguide-based Mach Zehnder interferometer. We present a double-slot waveguide that offers the best sensitivity and limit of detection compared to wire and single-slot waveguides. We demonstrate ultra-low loss coupling between a single-mode waveguide and a double-slot waveguide and experimental proof for double-slot excitation. The double-slot waveguide is used to demonstrate a highly sensitive concentration sensor. An unbalanced Mach-Zehnder is used as the sensor device to demonstrate concentrations of Potassium Chloride in deionized water. A sensitivity of 700 nm/RIU and a limit of detection (LOD) of 7.142e^-6 RIU are achieved experimentally. To the best of our knowledge, the demonstrated sensitivity is the highest for an on-chip guided waveguide sensing scheme.