title: A silicon photonic biosensor using phase-shifted Bragg gratings in slot waveguide.
abstract: We present a novel silicon photonic biosensor using phase-shifted Bragg gratings in a slot waveguide. The optical field is concentrated inside the slot region, leading to efficient light-matter interaction. The Bragg gratings are formed with sidewall corrugations on the outside of the waveguide, and a phase shift is introduced to create a sharp resonant peak within the stop band. We experimentally demonstrate a high sensitivity of 340 nm/RIU measured in salt solutions and a high quality factor of 1.5 × 10⁴, enabling a low intrinsic limit of detection of 3 × 10⁻⁴ RIU. Furthermore, the silicon device was fabricated by a CMOS foundry, facilitating high-volume and low-cost production. Finally, we demonstrate the device's ability to interrogate specific biomolecular interactions, resulting in the first of its kind label-free biosensor.
authors.affiliation: Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. xuw@ece.ubc.ca.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.forename: Jonas
authors.initials: J
authors.lastname: Flueckiger
authors.forename: Shon
authors.initials: S
authors.lastname: Schmidt
authors.forename: Samantha
authors.initials: S
authors.lastname: Grist
authors.forename: Sahba T
authors.initials: ST
authors.lastname: Fard
authors.forename: James
authors.initials: J
authors.lastname: Kirk
authors.forename: Matt
authors.initials: M
authors.lastname: Doerfler
authors.forename: Karen C
authors.initials: KC
authors.lastname: Cheung
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Ratner
authors.forename: Lukas
authors.initials: L
authors.lastname: Chrostowski
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D004129:Dimethylpolysiloxanes; D046210:Microfluidic Analytical Techniques; D055620:Optical Phenomena; D017785:Photons; D012825:Silicon
chemical_list: D004129:Dimethylpolysiloxanes; C013830:baysilon; D012825:Silicon
keywords: Bragg grating; biosensor; limit of detection; microfluidics; silicon photonics; slot waveguide