To address the issues of high construction costs and low measurement accuracy in lidar systems, a lidar communication and ranging integrated solution based on differential pulse position modulation （DPPM） is proposed. This scheme uses different pulse slot positions in DPPM to represent communication and ranging frame information. The receiver can demodulate the communication signals based on the pulse slot positions and achieve ranging using a time-of-flight ranging module. Additionally, to address the issue of low signal-to-noise ratio （SNR） in echo signals, a pulse accumulation algorithm is used to frame the echo signals and improve their SNR. Finally, the integrated communication and ranging system is built by field programmable gate array （FPGA） and tested. The experimental results show that the system can not only achieve a range of 300 cm with an average ranging error of ±2.04 cm, but also achieve a communication rate of 5 Mb/s.

In response to the lack of methods for calculating the aperture averaging function of optical receivers with arbitrary shapes in existing research, a novel two-dimensional mapping method is proposed. Firstly, the mathematical shape of the receiver is mapped into a two-dimensional matrix, and based on this matrix, a reference aperture and a displacement aperture are constructed, and the displacement range is determined. Then, a series of variable displacement matrices are obtained by gradually moving the displacement aperture. Subsequently, by calculating the same elements between the displacement matrix and the reference matrix, the aperture overlap area under different centroid spacing vectors is obtained, thereby accurately calculating the aperture averaging function of the receiver. Finally, taking the calculation of the aperture averaging function of a Cassegrain telescope as an example, it is mapped into a 300×300 matrix and compared with the theoretical calculation results. The comparison results show that the method has extremely small errors in calculating the aperture averaging function, verifying the accuracy and reliability of the proposed method.

Aiming at the issues that monochromatic optical communication is not suitable for lighting and the frequency spectrum utilization of ordinary white light communication is low, a visible light color division multiplexing communication system is de vised. The system not only maintains the normal lighting function of the light emitting diode （LED）, but also possesses the function of information transmission. At the transmitting end, three types of LEDs with fixed wavelengths are utilized for modulation. At the receiving end, narrow-band filters matching the wavelength of the transmitting end are employed to separate the optical signals of each channel. The separated optical signals are converted by a monolithic photodiode into electrical signals, which are then compared with a preset threshold and received and decoded by the microcontroller. The test results indicate that the narrow-band filter at the receiving end can effectively distinguish the broadcast signals from the three specific wavelengths of the LED. When the transmission rate is lower than 50 kHz, the eye image effect is favorable and stable communication can be achieved. However, when the transmission rate is increased to more than 50 kHz, images will present wrong color blocks and offset distortion.

Symmetrical the meter-shaped lighting layout scheme is proposed to address the issues of uneven power distribution and poor communication quality in indoor visible light sources. This scheme involves creating an objective function related to the received power and integrates logistic chaos, reversal strategies, nonlinear functions, and adaptive mechanisms. Considering single-reflection conditions, it employs a chaotic reverse initialization adaptive weight Harris Hawk optimization algorithm （referred to as the LRNA-HHO algorithm） to achieve the optimal design of light emitting diode （LED） positions and power parameters. Simulation results show that the lighting layout designed using the LRNA-HHO algorithm distributes power more evenly within a 5 m×5 m×3 m room area, with a received power variance of 0.018 dBm and illumination uniformity reaching 0.925, the signal-to-noise ratio ranges from 23.62 to 23.91 dB, significantly improving communication quality.

In order to improve the limited bandwidth resource allocation performance of indoor visible light networks in a simple and effective manner, a network access and maintenance method based on time division multiple access （TDMA） mechanism was designed, and the user competition network access process and network maintenance mechanism were described in detail. By designing specific frame structures, the probability of users accessing the network was analyzed. The experimental results show that the network access and maintenance method can support flexible access and dynamic resource allocation for multiple mobile users. The total time required for all five terminals to access is only 25 ms. This method is easy to implement in engineering and can effectively improve resource utilization.

In order to enhance the bandwidth utilization of the communication network, a service efficiency optimization algorithm founded on supermartingale theory is devised for the visible light communication （VLC） uplink system to fulfill the differentiated demands of terminal services regarding the network quality of service （QoS）. Firstly, the network queue system model based on the Markov modulated on-off （MMOO） process and the ALOHA random access process is established, and the probability of each terminal device accessing the coordinator is derived. Then, the supermartingale theory is employed to assess the delay performance of the system, and the multi-user QoS efficient guarantee issue is transformed into a service rate minimization problem constrained by the martingale domain delay bound. Finally, the honey badger algorithm （HBA） is utilized to solve the problem. The simulation results demonstrate that the algorithm can satisfy the diverse QoS requirements of terminal services and optimize service efficiency of the network.

In order to improve the physical layer security of visible light communication（VLC） system, a physical security method based on liquid crystal reconfigurable intelligent surface（LC-RIS） assistance is proposed. LC-RIS with controllable refractive index is introduced into the receiving end of the traditional VLC system, and the difference between the legitimate channel and the eavesdropping channel is increased by adjusting the refractive index of the incident optical link with applied electric field, so as to increase the reachable safe transmission rate of the VLC system. The simulation results show that compared with the traditional VLC system, the reachable safe transmission rate of the proposed VLC system is increased by 1 bit/ channel use, and the security performance of the communication is effectively improved. LC-RIS index optimization algorithm based on particle swarm optimization （PSO） algorithm has good robustness.

A graph representation learning based on optical network computing power scheduling method is proposed to address the problem of resource scheduling mismatch caused by the independent management of existing computing power resources and optical networks. This method constructs node and edge feature maps and uses graph convolutional networks for clustering, forming a bipartite graph to map the source nodes of computing power services to the destination nodes. By introducing learning factors to optimize the mapping relationship in the bipartite graph, with the goal of minimizing latency, efficient computing power scheduling can be achieved. The simulation results show that the proposed method significantly reduces the blocking rate and average processing delay of services in a multi granularity computing power coexistence environment, and improves resource utilization.

In order to tackle the issue of high integration and mutual feedback enhancement of the resources of multi-satellite and inter-satellite communication and computing systems, an integrated satellite routing algorithm OISL-DDPG is proposed based on optical inter-satellite link-optical service unit（OISL-OSU）. OISL-DDPG adopts the deep deterministic policy gradient （DDPG） optimization method to enhance the quality of service（QoS） performance of satellite optical networks. The simulation experiments indicat that the network slicing method based on time windows is consistent with the actual network operation status of domestic low-orbit constellations. Additionally, the proposed algorithm achieves higher link utilization and link occupancy rates at the cost of increasing slight delay than the minimum hop algorithm, and gets a better convergence rate, lower latency, and lower packet loss rate than the multi-constrained shortest path first（MCSPF） algorithm.

In order to significantly improve the energy efficiency of elastic optical forward（EOF） networks, a functional segmentation selection and resource allocation optimization scheme in EOF is proposed. This scheme solves the complex time averaged stochastic optimization problem in functional segmentation and resource allocation by introducing improved Lyapunov drift technology, achieving dynamic and efficient allocation of network resources. In addition, the positive effects of increasing the number of antenna ports and refining the fiber spectrum granularity on the performance of the scheme were also thoroughly explored. The simulation results show that compared with the traditional cloud wireless access network based on optical fronthaul（C-RAN）, this solution not only significantly reduces average power consumption by up to 70%, but also ensures that the forward latency is maintained below 250 s, demonstrating excellent performance advantages.

A novel high birefringence sensitivity photonic crystal fiber（PCF） for liquid sensing is designed to address the issues of complex structure, difficulty in manufacturing, and low sensitivity of existing PCF. The core of this optical fiber introduces two different sizes of elliptical air holes, and the cladding is composed of circular air holes of the same size arranged in a square-lattice. By combining finite element method with perfectly matched layer boundary conditions, the PCF is numerically simulated using COMSOL Multiphysics simulation software. Water is injected into the fiber core as a sensing liquid, and the birefringence, confinement loss, and sensitivity of the fiber are analyzed within the working wavelength range of 1.3~1.8 m. The research results indicate that as the wavelength increases, the birefringence of the new PCF reaches the order of 10-2. At a wavelength of 1.3 m, its sensitivity is as high as 54.4%, which is 1.1~2.5 times higher than the existing PCF.

Due to the narrow frequency response range of traditional optical microphones based on diaphragm or cantilever beam, and the different frequency ranges of sound waves detected in different environments and requirements, a wideband optical microphone based on a dual diaphragm structure has been designed. This optical microphone is composed of single-mode fiber, metamaterial membrane, and waveguide membrane. Theoretical analysis is conducted on the influence of the structural parameters of two membranes on the performance of the sensor. COMSOL Multiphysics is used for simulation, and the prepared optical microphone is tested. The simulation results show that the designed optical microphone has a flat frequency response within the frequency range of 1~100 kHz, with a resonant frequency of 170 kHz.

In order to analyze the impact of the absorption and turbulence characteristics of seawater on the transmission performance of vortex beams, an analytical expression for the detection probability of the orbital angular momentum （OAM） mode of anomalous vortex beams is derived, taking into account both the absorption and turbulence effects of seawater. The influence of absorbing turbulent seawater on the spiral phase spectrum, detection probability, and crosstalk probability of anomalous vortex beams is discussed in detail. The simulation results indicate that the absorption effect of seawater cannot be ignored, as it can lead to a decrease in detection probability. Absorbing ocean turbulence can lead to the expansion of the spiral phase spectrum, and as the number of OAM modes increases, the degree of expansion of the spiral phase spectrum becomes greater. As the temperature variance dissipation rate, temperature salinity contribution ratio, and turbulence energy dissipation rate of ocean turbulence decrease, the detection probability of OAM mode increases and the crosstalk probability decreases.

Aiming at the attenuation problem in the scattering transmission of ultraviolet light on the sea surface, a Monte Carlo simulation model based on partially uniform sampling is proposed. The model takes into account the low visibility caused by the high concentration of particles in the air at sea level, and adopts the importance sampling method for the distance parameter and the uniform sampling method for the zenith angle in the direction parameter. The simulation results show that compared with the traditional Monte Carlo simulation model, the proposed model significantly improves computational efficiency while maintaining the same performance. The computational efficiency is improved by approximately five orders of magnitude, making it very suitable for practical transmission scenarios involving distances on the order of kilometers at sea.

In order to accurately measure the morphology information of objects, an imaging system based on lensless Fourier transform digital holography is proposed. Firstly, the imaging principle of lensless Fourier transform digital holography was analyzed, and a tilt plane correction method was introduced. Then, an imaging system platform was built and the imaging performance of the system was verified through experiments. The experimental results show that the actual resolution of the system is 57.02 lp/mm. The relative error of the measurement results is only 3.95%, fully verifying the excellent imaging performance of the system.

Aiming at the problems of large volume and low integration of conventional balanced photodetectors for microwave photonics applications, a miniaturized, high-isolation balanced photodetector array based on hybrid photoelectric package technology is designed. By integrating multiple balanced photodiode chips and their bias and matching circuits, the balanced photodetector function of 4 independent channels is realized. The average volume of each channel is only 588 mm3. In addition, a test system is set up to test the performance of the balanced photodetector array. The test results show that the response of each channel of the balanced photodetector array is greater than 0.9 A/W, the bandwidth of 3 dB is about 12 GHz, the channel consistency in the bandwidth range is better than ±0.43 dB, the common mode rejection ratio is greater than 30 dB, the channel isolation is greater than 50 dBc, and the saturated input optical power at 10 GHz is greater than 8.4 dBm.

To address the application bottlenecks of bright laser pulses in optical communications and fiber optic sensing, a mode-locked fiber ring laser based on semiconductor optical amplifiers（SOA） is designed. This laser consists of an SOA, a polarization controller, a filter, and a polarizer. The mechanism of the gain ratio and phase difference changes in transverse electric/transverse magnetic（TE/TM） mode optical fields when passing through SOA is analyzed. The relationship between total dispersion management within the ring cavity and dynamic gain of SOA is investigated, resulting in stable output of bright pulses and dark pulses, as well as the dynamic evolution process of both types of pulses. The experimental results show that when the operating current of SOA is 242 mA, bright pulses with a pulse width of 1.1 ns and dark pulses with a pulse width of 0.95 ns are successfully obtained at repetition rates of 14.83 MHz, respectively. It is also verified that under the same operating current conditions, the intensity of the dark pulses significantly exceeds that of the bright pulses.

This paper focuses on the research of graphene chiral metasurfaces, which is mainly concentrated in the mid-infrared band, while there are relatively few studies on devices in the terahertz band, and the problem of insufficient circular dichroism generated by the non-intrinsic structure of graphene. Based on the properties of graphene, a double-layer graphene chiral metasur-face structure is designed. There is a certain angle between the upper and lower graphene patterns of the structure. By adjusting the size of this angle and the thickness of the intermediate silicon dioxide layer, the circular dichroism of the metasurface structure is studied. In addition, the dynamic tuning ability of the metasurface structure is analyzed by changing the Fermi level and relaxation time of graphene. The simulation results show that the metasurface structure can achieve circular dichroism in the terahertz frequency band and has the ability of dynamic tuning.

In order to study the effect of temperature on the output performance of fiber lasers, a self-seeded linear cavity fiber laser is constructed. The laser uses erbium-doped fiber as the gain medium, and uses fiber Bragg grating （FBG） and fiber ring mirror to form a linear laser cavity. The laser is experimentally studied by changing the temperature of the core device in the cavity. The experimental results show that the laser wavelength increases linearly with the increase of temperature. Compared with the change of the output wavelength of the laser when the FBG itself is heated, the laser wavelength is redshifted by 0.052 43 nm. When the temperature is increased from 25℃ to 55 ℃, the output conversion efficiency of the laser is reduced by 4.878%, and the output power is reduced by 33%.