A Self-Phase Modulation Effect Temperature Sensor Based on Tapered Single-Mode Optical Fiber

Drawing on the effect of self-phase modulation (SPM), a novel fiber-based temperature sensor is presented in this work by using a polydimethylsiloxane (PDMS)-coated single-mode fiber (SMF) with a tapered structure. The tapering not only increases the nonlinearity for generating SPM at a low power threshold but also reduces the longitudinal distance of the fiber core in contact with the external environment, thereby increasing the temperature-sensing sensitivity. The PDMS coating layer is used to protect the fiber-sensing probe, effectively enhancing the tenacity of the sensor and solving the cross-sensitivity problem. By analyzing the change of 3-dB bandwidth of the SPM output spectra with the temperature variation from 35 °C to 75 °C, the temperature sensitivity of 1.634 nm/°C with a resolution of 0.012 °C is achieved at 320 mW and 1050 nm. The effect of average pump power on sensor performance is discussed theoretically and experimentally. It is discovered that the sensitivity rises in proportion to the average pump power. Such a superior temperature sensing property has key prominence for developing novel SPM-based temperature sensors. The exploratory combination of the SPM effect and tapered SMF tremendously coated with PDMS enhances the stability, tenacity, sensitivity, and resolution of the temperature detection technology, which can lead to a ground-breaking and innovative nonlinearity-based sensor for various extreme environmental applications.