A biocompatible and robust fiber surface plasmon resonance (SPR) temperature sensor was fabricated based on an alcohol-filled hollow-core fiber. The fabrication process of this designed sensor included Ag film coating, liquid injection and fusion splicing, which was low-cost and efficient. Due to the high refractive index sensitivity of SPR effect and the high thermal optical coefficient of alcohol, the designed sensor performed well in temperature sensing, whose linear sensitivity reached as high as 1.16 nm/°C in the range of 35.5 °C ~ 70.1 °C. Being small in size, low in fabrication cost and highly sensitive in performance, this sensor is suitable for temperature detection during biological and chemical reactions, and has the potential to realizing multi-parameter or distributed temperature measurement.

Fiber-optic biosensors based on localized surface plasmon resonance (LSPR) have the advantages of great biocompatibility, label-free, strong stability, and real-time monitoring of various analytes. LSPR fiber-optic biosensors have attracted extensive research attention in the fields of environmental science, clinical medicine, disease diagnosis, and food safety. The latest development of LSPR fiber-optic biosensors in recent years has focused on the detection of clinical disease markers and the detection of various toxic substances in the environment and the progress of new sensitization mechanisms in LSPR fiber-optic sensors. Therefore, this paper reviews the LSPR fiber-optic sensors from the aspects of working principle, structure, and application fields in biosensors. According to the structure, the sensor can be divided into three categories: traditional ordinary optical fiber, special shape optical fiber, and specialty optical fiber. The advantages and disadvantages of existing and future LSPR fiber-optic biosensors are discussed in detail. Additionally, the prospect of future development of fiber-optic biosensors based on LSPR is addressed.

A temperature compensated magnetic field sensor using magnetic fluid (MF) filled exposed core fiber (ECF) has been proposed to detect magnetic field strength and temperature (MFT) simultaneously in this article. The designed sensor was formed by splicing an ECF between two sections of single-mode fibers (SMFs), in which the ECF’s exposed side was filled with MF. ECF is a multimode fiber that supports multiple modes of light transmitting and produces mode interference in the core. Different order modes of light excited in the ECF have individual sensitivities to MFT. Therefore, interference spectra of two different pair modes can be monitored to measure MFT simultaneously. The results show that the sensor responds well to MFT. The maximum MFT sensitivities are −0.18 nm/mT and −0.16 nm/lpzrptcircC. The limit of detections (LOD) of MFT is 1.7 mT and 1.9 lpzrptcircC. The sensor is particularly suitable for simultaneous detection of MFT in narrow spaces, such as industrial flaw detection, aerospace, and medical applications.

A highly sensitive humidity sensor with low temperature sensitivity is proposed and demonstrated using a polyvinyl alcohol coating tapered fiber. The taper fiber is highly sensitive to the environmental medium due to its microscale diameter. Thus, a humidity sensor can be prepared by plating a polyvinyl alcohol moisture sensitive film in a tapered region. The experimental results show that the sensor has a high humidity sensitivity of 0.1194 nm/%RH but with a relatively low temperature sensitivity of 0.029 nm/°C. Thus, the sensor can eliminate temperature interference and achieve accurate measurement of environmental humidity. At the same time, the sensor has excellent reversibility, stability and advantages common to optical fiber sensors, such as small size, antielectromagnetic interference and remote measurement.

A practical sensor based on surface plasmon resonance in a ring-shaped core photonic crystal fiber was proposed. A thin Au film was coated on the designed PCF, which caused the occurrence of SPR on the PCF surface and greatly simplified the measurement process. The sensor’s performance has been investigated by the finite element method. The results show that the maximum wavelength sensitivity can reach 6900nm/RIU and the maximum amplitude sensitivity can reach 132RIU⁻¹ in the analyte refractive index range from 1.33 to 1.41. The designed sensor has many advantages, such as high sensitivity, simple operation, anti-interference, remote transmission, and self-calibration, etc. Moreover, it can work in the near infrared region, which makes it highly applicable in the biomedical domain.

A benzobisthiadiazole-based Pdot was successfully developed as a broadband SA for Q-switched fiber lasers at 1, 1.5, and 2 μm.