We present a relative sensitivity of in-fiber inter-cross demodulation of a Mach- Zehnder interferometer (MZI) based on an etched Multi-core fiber (eMCF). The sensor can measure the external refractive index (RI) and temperature with a large fringe visibility of 15dB. It is tuned using a simple technique of slow chemical etching. When the outer cores of MCF will be exposed to the surrounding, a large difference of relative effective RI is observed, which enhances the sensitivity of the sensor. The sensor's wavelength and intensity responses have displayed that it can function with three different inter-cross-demodulation phenomena. A superior RI sensitivity of 178.20 dB/RIU in the range of 1.334 to 1.370, and temperature sensitivity of 66.73 pm/°C in the range of 30 to 80 °C are obtained, with an adequate linear response. Besides, it can readily resolve the issues of cross-sensitivity. Moreover, it has many advantages including easy fabrication, compact size, multiplex, repeatable, stable and can easily differentiate RI and temperature, which lack others.

Ship detection and tracking is an important task in video surveillance in inland waterways. However, ships in inland navigation are faced with accidents such as collisions. For collision avoidance, we should strengthen the monitoring of navigation and the robustness of the entire system. Hence, this paper presents ship detection and tracking of ships using the improved You Only Look Once version 3 (YOLOv3) detection algorithm and Deep Simple Online and Real-time Tracking (Deep SORT) tracking algorithm. Three improvements are made to the YOLOv3 target detection algorithm. Firstly, the Kmeans clustering algorithm is used to optimize the initial value of the anchor frame to make it more suitable for ship application scenarios. Secondly, the output classifier is modified to a single Softmax classifier to suit our ship dataset which has three ship categories and mutual exclusion. Finally, Soft Non-Maximum Suppression (Soft-NMS) is introduced to solve the deficiencies of the Non-Maximum Suppression (NMS) algorithm when screening candidate frames. Results showed the mean Average Precision (mAP) and Frame Per Second (FPS) of the improved algorithm are increased by about 5% and 2, respectively, compared with the existing YOLOv3 detecting Algorithm. Then the improved YOLOv3 is applied in Deep Sort and the performance result of Deep Sort showed that, it has greater performance in complex scenes, and is robust to interference such as occlusion and camera movement, compared to state of art algorithms such as KCF, MIL, MOSSE, TLD, and Median Flow. With this improvement, it will help in the safety of inland navigation and protection from collisions and accidents.

This work reports a simple optical fiber Surface Plasmon Resonance (SPR) sensor with ultra-high sensitivity for simultaneous measurement of the dual-parameter. The sensor is based on a D-shaped fiber with a nanolayer coating of Silver (Ag) and Hematite (α−Fe ₂ O ₃ ). The Ag/α− Fe ₂ O ₃ layer is deposited on the longitudinal surface of residual cladding, and a Fiber Bragg Grating (FBG) is inscribed on the single-mode fiber (SMF) for temperature compensation. The α− Fe ₂ O ₃ layer protects the Ag layer from oxidation and effectively enhances the surface plasmon wave while interacting with free electrons. Finite Element Method (FEM) modeling is employed to investigate the refractive index (RI) and temperature response of the SPR sensor. The SPR sensor exhibits an ultra-high RI sensitivity of 8,518 nm/RIU (refractive index unit) in the RI range of 1.33 to 1.40, and a temperature sensitivity of -52 pm/°C in the temperature range of 20°C to 60°C. The SPR performance suggests that it is a potential candidate for various applications of dual-parameter sensing.

We propose and demonstrate Mach-Zehnder interferometer (MZI), which is the refractive index (RI) insensitive and temperature highly sensitive based on etched multi-core fiber (MCF) structure. The MCF and Fiber Bragg Grating (FBG) are used as hybrid sensing elements. The fabrication of the interferometer is provided a new taper-like structure by etching the MCF to further expose the side cores to the surroundings. The interferometer has produced a sensitivity of 103.2pm/°C within the ambient temperature up-to 70°C. Moreover, the superior temperature sensitivity is 89.19pm/°C, 66.64pm/°C, 56.42pm/°C in the range of 24°C to 130°C, and RI-insensitive in the range of 1.34 to 1.38, for different waists of etched seven-core fiber interferometers (E7CFIs) ~ 84.70μm, 93.10μm, 108.67μm, respectively. Compared with the conventional FBGs, the sensitivity of the interferometer is significantly improved by 8 times. E7CFI's novel and advantageous features can easily be distinguished other devices. Besides, the proposed sensing architecture is compact, easy to fabricate, highly sensitive, easy to reproduce, and makes it an inexpensive fiber optic device.

A hybrid interferometer for simultaneous measurement of strain and temperature is proposed and investigated experimentally. This hybrid design is composed of Fabry-Perot interferometer (FPI) and Michelson Interferometer (MI) cascaded with each other. It is developed by fusion splicing a single mode fiber (SMF), a multimode fiber (MMF), a dual side hole fiber (DSHF), a hollow core fiber (HCF) and a tapered-SMF. The tapered SMF was inserted into the HCF to form a reflection mirror for the FPI. The maximum temperature and strain sensitivity of the hybrid interferometer achieved through experiments is 11.6 pm/°C and 6.8 pm/με, respectively. The different sensitivities of FPI and MI to temperature and strain enable us to achieve simultaneous measurement. The proposed hybrid interferometer sensor has many attractive features such as, novel design, low cost, easy fabrication, compact size, and good sensitivity. Therefore, the proposed hybrid sensor could be widely deployed in plenty of applications, for instance, structural health monitoring, civil engineering, food manufacturing, chemical and medical fields.