Thermally Stable Refractometer Using Capillary-Based Structural Long-Period Gratings

Abstract

We propose a thermally stable refractometer based on capillary with arc-discharge-induced structural long-period gratings (SLPGs) between two single-mode fibers. Transmission spectral performances of the SLPGs were investigated theoretically and experimentally. The refractive index (RI) sensing characteristics of SLPGs with period of 1 mm and period number of 4 were further studied, showing a maximum RI sensitivity of 8409.2 nm/RIU in the RI region of 1.435-1.443. In addition, the proposed SLPGs presents thermally stable to temperature variations. Therefore, the proposed capillary-based refractometer can be potential in the application of environmental monitoring.