Abstract
A metal-clad planar polymer waveguide refractive index sensor based on epoxy (EPO) polymer materials by using light intensity interrogation at 850 nm is designed. The polymethyl methacrylate (PMMA) material is deployed as the low refractive index (RI) buffer layer in order to better couple the optical guided mode and the surface plasmon polaritons (SPP) mode for working in water environment. The effects of the gold film thickness, PMMA buffer layer thickness, waveguide layer thickness, waveguide width, and gold length on the sensor sensing characteristics have been comprehensively studied. Simulation results demonstrate that the normalized transmission increases quasi-linearly with the increment of RI of the analyte from 1.33 to 1.46. The sensitivity is 491.5 dB/RIU, corresponding to a high RI resolution of 2.6×10−9 RIU. The designed SPP-based optical waveguide sensor is low-cost, wide-range, and high-precision, and has a broad application prospect in biochemical sensing with merits of miniaturization, flexibility, and multiplexing.
Highlights
Refractive index (RI) is a critical parameter of liquid closely related to density, concentration, and temperature
Due to the wavevector mismatch with optical waves, Surface plasmon polariton (SPP) waves are traditionally excited by using the Kretschmann or Otto prism based on attenuated total reflection, which has disadvantages of large volume, complex system, and high cost [8,9,10]
We present a waveguide-type surface plasmon resonance (SPR) sensor based on epoxy (EPO) polymer materials by using light intensity interrogation at 850 nm
Summary
Refractive index (RI) is a critical parameter of liquid closely related to density, concentration, and temperature. The integrated optical waveguide technology is exploited to fabricate SPR sensor chips with advantages of low cost, small size, and easy integration [11,12,13]. The sensitivity was 4 180 nm/RIU, and the detection limit was up to 3.7×10–7 RIU Most of these works are done with wavelength interrogation and heavily rely on precise spectrometers and broadband optical sources, which are expensive, large-volume, and complex. This is difficult for low-cost, small-size, and portable monolithic integration. We present a waveguide-type SPR sensor based on epoxy (EPO) polymer materials by using light intensity interrogation at 850 nm. The RI resolution is as high as 2.6×10–9 RIU in the analyte RI range from 1.33 to 1.46, higher than those of the most SPR-based works that are on the 10–6 orders of magnitude [10,11,12,13,14,15,16]
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