Role of edge inclination in optical microdisk resonator for label-free sensing

TL;DR

This study investigates how the edge inclination of silicon nitride microdisk resonators affects their performance in label-free optical sensing, finding that disk thickness is more critical than edge inclination for sensor optimization.

Contribution

The paper provides a numerical analysis showing that microdisk thickness significantly impacts sensor figure of merit, while edge inclination has a lesser effect, guiding design improvements.

Findings

Microdisk thickness critically influences sensor performance.

Edge inclination has a minor effect on the figure of merit.

Figures of merit up to 1600/RIU are achievable.

Abstract

In this paper we report on the measurement and modelling of enhanced optical refractometric sensors based on whispering-gallery-modes. The devices under test are optical microresonators made of silicon nitride on silicon oxide. In our approach, these microresonators are vertically coupled to a buried waveguide with the aim of creating integrated and cost-effective devices. The optimization analysis is a delicate balance of resonance quality factor and evanescent field overlap with the sorrounding environment to analyze. By numerical simulations we show that the microdisk thickness is critical to yield high figure of merit for the sensor, while edge inclination is less important. We also show that figures of merit as high as 1600/RIU are feasible.