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• Chinese Optics Letters
• Vol. 19, Issue 10, 102202 (2021)
Chao Liu1、*, Jingwei Lü1, Wei Liu1, Famei Wang1, and Paul K. Chu2
Author Affiliations
• 1School of Physics and Electronic Engineering, Northeast Petroleum University, Daqing 163318, China
• 2Department of Physics, Department of Materials Science & Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
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Abstract

Optical fibers have been widely applied to telecommunication, imaging, lasers, and sensing. Among the different types of fibers, photonic crystal fibers (PCFs), also called microstructured optical fibers, characterized by air holes arranged along the length of fibers have experienced tremendous advance due to their unique advantages. They are regarded as a desirable platform to excite surface plasmon resonance (SPR) because of easy realization of phase matching conditions between the fundamental core mode and the plasmonic mode, which plays a critical role in miniaturization and integration of SPR sensors. In this mini-review, the current status of PCF sensors based on SPR is summarized. The theory of SPR is discussed, and simulation methods for PCF-SPR sensors are described. The important parameters including the refractive index detection range, resonance wavelength, and spectral sensitivity responsible for the sensing properties of PCF-SPR sensors are reviewed. The fabrication and the comparison of performances are also illustrated, and, finally, the challenges and future perspectives are outlined.

1. Introduction

Surface plasmon resonance (SPR) is a critical physical–optical phenomenon involving excitation of electron density oscillations at metal-dielectric interfaces under the irradiation of $p$-polarized light waves[14]. As a versatile sensing technique, SPR has the outstanding advantage of extremely high sensitivity to variations of the refractive index (RI) of analytes, thereby greatly applied to biomedicine, biology, and chemistry monitoring[58]. The first, to the best of our knowledge, documented observation of surface plasmons was reported in 1902 when Wood observed narrow dark bands in the diffraction spectrum of metallic gratings illuminated with polychromatic light[9]. SPR excited by total internal reflection was observed by Otto[10] as well as Kretschmann and Raether[11], and the great potential of SPR sensing technology pertaining to detection of chemical and biological substances has spurred growing interest[1216]. The conventional operating platform to excite SPR is based on the total internal reflection prism of the Kretschmann and Otto configuration. However, the Kretschmann–Raether prism configuration suffers from drawbacks such as bulky mechanical equipment, large size, and non-remote measurements, and thus new sensing platforms with miniaturization and remote sensing capabilities are highly desirable[17,18].

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Chao Liu, Jingwei Lü, Wei Liu, Famei Wang, Paul K. Chu. Overview of refractive index sensors comprising photonic crystal fibers based on the surface plasmon resonance effect [Invited][J]. Chinese Optics Letters, 2021, 19(10): 102202