Coupled Strip-Array Waveguides for Integrated Mid-IR Gas Sensing

Abstract

Non-dispersive infrared (NDIR) absorption spectroscopy is a widespread approach to gas sensing due to its selectivity and conceptual simplicity. One of the main challenges towards the development of fully integrated NDIR sensors is the design and fabrication of microstructures, typically waveguides, that can combine high sensitivity with the ease of integrability of other sensor elements (sources, filters, detectors). Here, we investigate theoretically and experimentally a class of coupled strip-array (CSA) waveguides realized on a SiO2/Si3N4 platform with mass semiconductor fabrication processes. We demonstrate that this class of waveguides shows comparable sensitivity for a wide range of presented geometries, making it a very promising platform for satisfying multiple sensor and fabrication requirements without loss of performance.

Plasmonic platform for integrated mid-IR sensing applications

“…Different schemes for fully integrated photonic sensors have been discussed in the past, mostly based on dielectric waveguides, where the evanescent field of a waveguide mode interacts with the analyte of interest [2]. Besides Si-on-isolator waveguides [3] [4], which are more simple to fabricate, but often feature low sensitivities, also free-standing waveguides [5] [6] and slot waveguides [7] have been discussed, in order to increasing the effective interaction with the gas.…”