Regular Article

An optical fiber surface plasmon resonance biosensor for wide range detection

¹ School of Electrical Engineering, Yanshan University, Qinhuangdao 066004, PR China
² College of Liren, Yanshan University, Qinhuangdao 066004, PR China

^* e-mail: tongkai@ysu.edu.cn

Received: 16 July 2017
Received in final form: 19 September 2017
Accepted: 21 September 2017
Published online: 13 October 2017

Abstract

An optical fiber surface plasmon resonance biosensor is presented that allows to numerically demonstrate, using transfer matrix method and the finite difference time domain method, the detection range is very wide. Two different structures of graphene photonic crystal multilayer (i.e. sensor I and sensor II) are constructed in the cladding region of single-mode fiber. Graphene is used as the plasma layer instead of the traditional metal. According to the analysis, the properties of graphene can be changed by adjusting the chemical potential µ_c. In the spectral region of 1.667|µ_c| < ћω < 2|µ_c|, the imaginary part of conductivity σ″ becomes negative. Thus the weakly bounded low-less TE-SPR is supported by graphene. The results of the numerical simulation show that the relationship between refractive index and resonant wavelength is linear. The sensor I can detect the refractive index range of 1.33–1.4, and the sensitivity is 1942 nm/RIU. The sensor II can detect the refractive index range of 1.41–1.67, and the sensitivity is up to 2315.4 nm/RIU. Therefore, the detection of wide refractive index range of 1.33–1.67 or simultaneous detection of different biological medium concentration is realized by the sensor.