We propose and experimentally demonstrate an optofluidic refractive index sensor based on surface plasmon resonance with a figure of merit (FOM) reaching 20 in fluids at oblique incidence. The device consisting of a dielectric nano-grating sandwiched between double-layer gold stripes. A finite difference time domain (FDTD) method is employed to understand the optical properties and determine appropriate device parameters. The double-layered metal nano-grating (DLMNG) is fabricated by combining two beam interference lithography and electron beam evaporation deposition. A refractive index sensitivity of more than 560 nm/RIU is obtained using an optimized structure. The simple optical configuration of the DLMNG with high refractive index sensitivity make it possible for optofluidic sensors to be a promising candidate as a functional optical component in label-free biomedical sensing and integrated microfluidic chips.

Date Published: 18 December 2019
PDF: 6 pages
Proc. SPIE 11336, AOPC 2019: Nanophotonics, 113360O (18 December 2019); doi: 10.1117/12.2547768

Published in SPIE Proceedings Vol. 11336:
AOPC 2019: Nanophotonics
Zhiping Zhou; Xiao-Cong Yuan; Daoxin Dai, Editor(s)