Characterization of the influence of the fiber diameter and sensing region length upon lossy mode resonance (LMR) fiber sensors

Abstract

This paper explores high sensitivity fiber optic sensors based on lossy mode resonance (LMR). The sensitivity enhancement is achieved by simultaneously optimizing the diameter of the fiber core and the length of sensing region. The influence of these factors on the sensor sensitivity was analyzed by simulation using the transfer matrix method (TMM) and verified by experiments. The simulation results show that the sensor has high sensitivity and a narrow full width at half maxima when the sensing area is 10 mm. The sensitivity was as high as 3261 nm/refractive index units (RIU) when the core diameter is 200 μm. The experimental results have the same trend as the simulations, with a maximum value of 3100 nm/RIU. The resolution of the sensor may be as high as 1.29 × 10−8 RIU using a spectrometer with a resolution of 0.04 pm. The sensor was also shown to be relatively precise and stable. Since no systematic study concerning the influence of combining the sensing area length and fiber diameter on the sensor performance index yet has been published, this paper provides a reference for future characterization of high-sensitivity and high-precision optical fiber LMR sensors.