Plasmonic slanted slit gratings for efficient through-substrate light-plasmon coupling and sensing

Fatemeh Fouladi Mahani; Luis Angel Mayoral Astorga; Hyung Woo Choi; Arash Mokhtari; Pierre Berini

doi:10.1038/s41598-024-52564-9

Plasmonic slanted slit gratings for efficient through-substrate light-plasmon coupling and sensing

Sci Rep. 2024 Jan 24;14(1):2084. doi: 10.1038/s41598-024-52564-9.

Authors

Fatemeh Fouladi Mahani¹, Luis Angel Mayoral Astorga², Hyung Woo Choi², Arash Mokhtari³, Pierre Berini^{2

4}

Affiliations

¹ Optical and RF Communication Systems (ORCS) Lab, Electrical Engineering Department, Shahid Bahonar University of Kerman, Kerman, 7616913439, Iran.
² School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
³ Optical and RF Communication Systems (ORCS) Lab, Electrical Engineering Department, Shahid Bahonar University of Kerman, Kerman, 7616913439, Iran. amokhtari@uk.ac.ir.
⁴ School of Electrical Engineering and Computer Science, Department of Physics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.

PMID: 38267488
DOI: 10.1038/s41598-024-52564-9

Abstract

We present an experimental study of plasmonic slanted slit gratings (PSSGs) designed to achieve directional coupling between an incident light beam and surface plasmon polaritons (SPPs) propagating along the surface of the structure. We also investigate mirrored PSSG pairs interconnected by a plasmonic slab waveguide. The structures are fabricated using direct milling by a gallium focused ion beam (FIB). In a mirrored pair arrangement, the first PSSG couples a perpendicularly-incident light beam to SPPs propagating in one direction along the waveguide, while the second PSSG decouples SPPs to perpendicularly-emerging light. This configuration shows promise for sensing applications due to the high sensitivity of the excited SPPs to changes in the refractive index of the bounding medium, and the separation of the optics from the fluidics by the substrate. The design also exhibits robustness to fabrication tolerances. The optical characteristics and sensing potential are investigated theoretically and experimentally, highlighting its potential for a wide range of applications.