Design and Simulation Investigation of Si3N4 Photonics Circuits for Wideband On-Chip Optical Gas Sensing around 2 µm Optical Wavelength

Abstract

We theoretically explore the potential of Si3N4 on SiO2 waveguide platform toward a wideband spectroscopic detection around the optical wavelength of 2 μm. The design of Si3N4 on SiO2 waveguide architectures consisting of a Si3N4 slot waveguide for a wideband on-chip spectroscopic sensing around 2 μm, and a Si3N4 multi-mode interferometer (MMI)-based coupler for light coupling from classical strip waveguide into the identified Si3N4 slot waveguides over a wide spectral range are investigated. We found that a Si3N4 on SiO2 slot waveguide structure can be designed for using as optical interaction part over a spectral range of interest, and the MMI structure can be used to enable broadband optical coupling from a strip to the slot waveguide for wideband multi-gas on-chip spectroscopic sensing. Reasons for the operating spectral range of the system are discussed.

Silicon Waveguide Sensors for Carbon Dioxide Gas Sensing in the Mid-Infrared Region

“…Most of the sensing chips are composed of silicon material as the core layer, and conventional cladding layer materials including silicon dioxide (SiO 2 ), silicon nitride (Si 3 N 4 ), and sapphire (Al 2 O 3 ) [22][23][24]. A high refractive index difference between the core and cladding layer generates a strong evanescent field at the interface of the very small waveguide.…”