Long-Period Fiber Grating Sensor Based on a Conductive Polymer Functional Layer

A temperature sensor was fabricated with a functional conductive poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) coating on a long-period fiber grating (LPFG). The LPFG was fabricated by laser-assisted wet-chemical etching for controlling the grating depth of the LPFG after the treated surface of an optical fiber was inscribed by laser light. The functional conductive polymer acts as a temperature sustained sensing layer and enhances the grating depth of the LPFG sensor as a strain buffer at various temperatures. The sensor was subjected to three cycles of temperature measurement to investigate the sensor’s wavelength shift and energy loss when exposed to temperatures between 30 and 100 °C. Results showed that the sensor’s average wavelength sensitivity and its linearity were 0.052 nm/°C and 99%, respectively; average transmission sensitivity and linearity were 0.048 (dB/°C) and 95%, respectively.