Juan Kang

Multiple optical scattering occurs when light propagates in a non-uniform medium. During the multiple scattering, images were distorted and the spatial information they carried became scrambled. However, the image information is not lost but presents in the form of speckle patterns (SPs). In this study, we built up an optical random scattering system based on an LCD and an RGB laser source. We found that the image classification can be improved by the help of random scattering which is considered as a feedforward neural network to extracts features from image. Along with the ridge classification deployed on computer, we achieved excellent classification accuracy higher than 94%, for a variety of data sets covering medical, agricultural, environmental protection and other fields. In addition, the proposed optical scattering system has the advantages of high speed, low power consumption, and miniaturization, which is suitable for deploying in edge computing applications.

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A brief review of recent progress in researches, productions and applications of distributed fiber Raman sensors at China Jiliang University (CJLU) is presented. In order to improve the measurement distance, the accuracy, the space resolution, the ability of multi-parameter measurements, and the intelligence of distributed fiber sensor systems, a new generation fiber sensor technology based on the optical fiber nonlinear scattering fusion principle is proposed. A series of new generation distributed fiber sensors are investigated and designed, which consist of new generation ultra-long distributed fiber Raman and Rayleigh scattering sensors integrated with a fiber Raman amplifier (FRA), auto-correction full distributed fiber Raman temperature sensors based on Raman correlation dual sources, distributed fiber Raman temperature sensors based on a pulse coding source, distributed fiber Raman temperature sensors using a fiber Raman wavelength shifter, a new type of Brillouin optical time domain analyzers (BOTDA) integrated with a fiber Raman amplifier, distributed fiber Raman and Brillouin sensors integrated with a fiber Raman amplifier, and distributed fiber Brillouin sensors integrated with a fiber Brillouin frequency shifter. Sensor networks are important components of the internet of things. The distributed optical fiber sensor network (Rayleigh, Raman, and Brillouin scattering) is a 3S (smart materials, smart structure, and smart skill) system, which is easy to construct smart fiber sensor networks. The distributed optical fiber sensor has been applied to the power grids, railways, bridges, tunnels, roads, constructions, water supply systems, dams, oil and gas pipelines and other facilities, and can be integrated with wireless networks.

In this letter, a simple but novel temperature sensor based on an alcohol-filled photonic crystal fiber-long period grating (PCF-LPG) is proposed and studied theoretically. For the sensing principle, a section of alcohol-filled PCF-LPG works as a sensor head. As temperature changes, effective indices of the core mode and the cladding mode change obviously because of the high temperature sensitivity of the filled alcohol so that the difference of effective indices of the core mode and the cladding mode is highly affected by temperature. Therefore, the resonant wavelength which arises from light coupling from the fundamental mode to the forward-propagating cladding modes is very sensitive to temperature due to the mode couplings. By monitoring the output resonant wavelength, we can realize the detection of temperature change. Simulation analysis predicts the sensor has high temperature sensitivity, which reaches up to 8.5 nm/°C as the period of the grating is 650 μm.

A compact fiber bending sensor has been presented by superimposing a uniform fiber Bragg grating (FBG) into a tilted fiber Bragg grating (TFBG). The reflection of FBG is modulated by the same bandwidth of the cladding modes of TFBG, which is sensitive to the bending of fiber. By monitoring the differential Bragg reflection between FBG and TFBG, the sensor is insensitive to ambient temperature changes and power fluctuations from light source or fiber link during the measurement. The sensitivity of the sensor is also doubled because the signal from FBG passes through the TFBG twice.