Comparative analysis of fabrication techniques for sensing windows on silicon nitride waveguide platforms
Year: 2026
Type: article
Abstract: Localized sensing windows enable functionalization of silicon-nitride (Si 3 N 4 ) photonic sensors but introduce a cladding discontinuity that can dominate loss at visible/near-IR wavelengths. We benchmark two window modules—lift-off and post-etch—on 250-nm-high Si 3 N 4 waveguides ( w = 450–750 nm) at 850 nm in transverse-electric (TE) polarization using wafer-level, three-length cutback spirals with equalized bend inventory and bend-loss spiral families ( R = 10–35 μ m). Atomic force microscopy (AFM) roughness spectra parameterize a semi-analytical scattering model, and curvature radiation is captured by a mode-overlap model. Lift-off windows yield systematically lower propagation and bend excess loss, with the gap increasing for narrow widths and tight bends; etched windows trade higher loss for robustness and back-end compatibility.
Source: Optics Continuum
Language: English
Topic: Photonic and Optical Devices
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,372
OpenAlex ID: W7140129327