This PDF file contains the front matter associated with SPIE Proceedings Volume 12562, including the Title Page, Copyright information, Table of Contents, and Conference Committee listings.

In this paper, we use the experimental data to verify the technology of Optical Time Domain Reflectometry (OTDR) to realize multi-branch fault monitoring in PON access network. Then the monitoring effects of the two optical splitter structures are analyzed in detail, and the dynamic monitoring of different fault degrees is realized. We prepared single-mode optical fibers, with the length of 10.282 km, 10.768 km, 14.45 km, 25.2 km and 50.38 km respectively. Optical attenuators with different optical attenuation values, like 5 dB and 2 dB, respectively corresponding to different fault degrees of optical fiber link. The fault monitoring of branches with similar distance is analyzed, and the influencing factors such as pulse width are analyzed in detail. In experiments, it can be found that the selection of scanning pulse width has little impact on the identification of event position, but when two adjacent events fold each other due to the increase of attenuation dead zone, the identification of event position cannot be realized. It is believed that these research data can provide valuable reference for the management and maintenance of optical fiber in the actual PON network, and provide valuable data for the promotion of this new technology.

Compared with traditional electrical accelerometers, the fiber optic interferometric accelerometers have the unique advantages such as high precision and anti-electromagnetic interference to be widely used. Sensitivity is an important parameter of the fiber optic interferometer accelerometers and this paper mainly studied the influence factor of sensitivity. Meanwhile, this paper focuses on analyzing the winding fiber optic length and the structure of interferometric accelerometers for the influence of sensitivity. At the same time, this paper experimented and verified the theoretical derivation calculation of factor influence of sensitivity. This paper lays the theoretical foundation for the design of specific sensitivity of fiber optic interferometric accelerometers.

The rapid development of underwater acoustic sensor networks(UASNs) will greatly improve people's ability to perceive and apply the ocean. The positional information of network nodes plays a vital role in UASNs system. Aiming at the problems of multiple access interference and location beacon selection in traditional location methods, this paper proposes a multiple access method combined with FDMA / CDMA, which optimizes the division of frequency band and orthogonal code resources according to the network topology to ensure that different beacon nodes send location signals with different frequencies and different orthogonal code compared, so as to realize conflict free multiple access of multiple location signals. This paper also proposes a network beacon autonomous switching method, which optimizes the transmission time of control command according to the position relationship between its own position and network nodes, updates the positioning beacon in real-time, and realizes the cross regional autonomous navigation and positioning of underwater mobile nodes. The method in this paper is verified by simulation and sea trial.

Peak-to-average power ratio (PAPR) is a hot issue in orthogonal frequency division multiplex (OFDM) technology. High PAPR of OFDM system limits its application in underwater acoustic communications. The DFT-s-OFDM technology has been widely used in long term evolution (LTE) and fifth-generation new radio (5G NR) uplink transmission schemes for wireless communications due to its good PAPR performance. However, it is difficult to adapt to time-varying underwater acoustic channels by using time-multiplexed training. We use the DFT-s-OFDM technology of the sideband tone reservation method to suppress the PAPR of the system. At the same time, for the DFT-s-OFDM system, it is impossible to insert data and pilots in a single symbol block at the same time to track the channels. A low-power training sequence is superimposed with symbols, and the training sequence is transmitted over all time. It is used to enhance the tracking channel capability with a small energy overhead and is used to process time-varying channels. Field experiments were carried in Qiandao Lake in 2021, and the results verify the effectiveness of the proposed scheme.

The introduction of the F5G concept defines a bright prospects for optical transmission, but there are many difficulties in the networks evolving to F5G. This paper puts forward some ideas for the network evolution of F5G, in order to provide reference for the development of F5G.

In this paper, the properties of ultra-low loss and large effective area G.654.E fiber were studied, including the optical properties and cabling performance. Based on the tests of the transmission performances of different optical fibers in nonrelay ultra-long haul optical transmission system, practical suggestions for optical fiber selection of electric communication construction were proposed. G.654.E fiber was utilized in practical engineering, verifying the theoretical research and identifying optimal direction and methods. 467 km non-relay ultra-long haul optical transmission was realized, creating a new record in electric communication network.

Blood glucose level has important significance for medical diagnosis. Blood glucose measurement in traditional methods requires collecting blood samples several times a day, which causes discomfort, environmental pollution and so on. As a "fingerprint" spectrum for molecular recognition, Raman spectroscopy has attracted attention in blood glucose measurement. However, blood glucose level is low and spectral signal of glucose is easy to be influenced by noise and other components. To improve accuracy of blood glucose concentration estimation by Raman spectroscopy, we carried out the Raman blood glucose measurement in vitro, the interferograms of blood samples in different glucose concentrations were measured by the self-developed Spatial Heterodyne Raman Spectrometer (SHRS), and converted the interferograms to one-dimensional spectroscopic data using Fourier transform. In order to get data with higher quality, we used wavelet decomposition to remove the noise and sparse representation to remove the signal baseline. Then, selected the spectroscopy at 500-2500 cm^-1 as input, and the corresponding blood glucose concentration value as label, use particle swarm optimization-support vector regression (PSO-SVR) algorithm to construct the blood glucose concentration estimation model. The results show that the R² of test set is 0.8041 and the RMSE is 1.8580. And the accuracy of blood glucose concentration estimation was evaluated by the Clark Error Grid. The model based on PSO-SVR can achieve accurate estimation of blood glucose concentration. This method has important research significance and application potential for blood glucose measurement.

In order to improve the security of ciphertext image in transmission, a scheme of using neural network is proposed to restore the encryption-hiding images by using chaotic iris phase mask and double random phase encoding encrypted. To improve encryption performance, we replace the double random phase with chaotic iris phase masks. Firstly, the plaintext image is encrypted by improved double chaotic iris phase masks encoding, and the ciphertext image is generated. Then the ciphertext image is hidden into the carrier image through the Least Significant Bit (LSB) algorithm. It can avoid the detection to a certain extent. And a large number of hidden-plaintext image pairs are produced as a dataset. Secondly, the neural network is built in the process of continuous training and testing. The neural network selected in this paper is residual network (ResNet). The neural network to learn the logical relationship between input and output more efficiently, and successfully recovered the corresponding plaintext image. Finally, the trained neural network can fit the mapping relationship between the hidden image and the plaintext image. When decrypting, it is not necessary to extract the ciphertext image from the hidden image first and then decrypt it. This scheme can directly realize the decryption of hidden images. The paper elaborates the encryption, hiding and decryption process of the scheme in detail. Simulation experiments show that the scheme is feasible and has good robustness.

Aiming at the characteristics of the self-designed and developed fiber tree bus (FTB) terminal, such as more terminals, more interactive data and various node communication protocols, This paper designs an efficient bus controller, a practical and efficient instruction list, and Constructs A high-speed data transmission system, which is used to manage and control the data transmitted on the fiber bus. FTB layered structure, bus topology and the performance of real-time transmission are introduced. According to the application requirements of military vehicle-borne photoelectric system, the model of photoelectric information transmission system based on FTB is built, and the transmission performance of FTB based on this bus controller is tested. The compared results of analysis and test show that, FTB has a variety of real-time information transmission capacity, but also verified that the bus controller is efficient and practical，Finally, Transmission Delay Index and information interaction index are analyzed and tested.

Speckle noise results in a serious quality degradation in reconstructed image of the optical implementation for image cryptosystem using a joint transform correlation (JTC) architecture. In this paper, a speckle-suppressed optical implementation for JTC-based image cryptosystem is proposed. The encryption process is performed optically, while the decryption process is performed digitally. In this paper, the distribution of objects in the input plane is optimized on basis of analysis for the inherent noise of cryptosystem, such as dark current noise of the CCD camera. Consequently, speckle noise in the reconstructed image is effectively decreased. Furthermore, less times of record are required, and there is no increase in hardware and complexity. Simulations and experimental results demonstrate the validity and effectiveness of the proposed speckle-suppressed scheme.

A new advanced suspended-core fiber sensor is proposed and demonstrated for ultrasonic detection. The free micro suspended-core fiber is fabricated by acid corrosion and fiber splicing. Significantly, two cascaded uniform fiber Bragg gratings are imprinted into the suspended-core fiber. The sensor response and spectrum stability are thus largely improved because of the using of two fiber grating reflectors for constructing a suspended-core interferometer. This paper shows the sensor fabrication in detail and presents contrastive analysis of the spectrum characteristics. Preliminary measurements are also carried out to verify the enhanced acoustic performance of the dual-FBG suspended-core fiber. The proposed sensor is a good candidate for high-fidelity ultrasonic detection in seismic physical modeling.

In this paper, a novel microstructure fiber (MSF) filled with E7 liquid crystal with polarization-maintaining and dispersion compensation characteristics is designed. The fiber is arranged and constructed in a conventional C6v structure, and the inner and outer cores are filled with liquid crystals. The rotation angle of liquid crystal molecules can be converted between 0° and 90° by using applied voltage, to realize dispersion compensation in two polarization directions. Under the external control, the effect of the effect of both polarization-maintaining and dispersion compensation can be achieved in the fiber, and the dispersion-compensation direction can be adjusted. It can not only broaden the research field of MSF and deepen the research depth of MSF polarization-maintaining characteristics and dispersion compensation characteristics, but also provide theoretical conditions for the continuous improvement of fiber communication technology.