High-performance surface plasmon resonance refractometer based on a no-core fiber coated with a silver film

Abstract

Owing to their high sensitivity, surface plasmon resonance (SPR)-based sensors depict broad application prospects in biochemical detection, environmental monitoring, and food safety. In this paper, an optical fiber-based SPR sensor is proposed and demonstrated for the refractive index (RI) detection of liquid samples. This sensor is composed of a multimode fiber (MMF), a no-core fiber (NCF), and another MMF that is connected in sequence. The length of the NCF is 2 cm. A thin silver film is deposited on the NCF surface to stimulate the SPR effect. Experimental results indicated that the shift amount of resonance dip wavelength is as high as 303.6 nm as RI increases from 1.333 to 1.4107. A sensitivity of 2507.58 nm/RIU with a fitting linearity <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> of 0.9931 is obtained in the lower RI region of 1.333–1.3723, while the sensitivity and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> reaches 5228.21 nm/RIU and 0.97395, respectively, in the higher RI region of 1.3723–1.4107. Compared with previously reported RI sensors, the proposed fiber optic SPR sensor exhibits the advantages of simple structure, small volume, low cost, high sensitivity, and wide detection range.