On the basis of the temperature-controlled phase change properties of vanadium dioxide (VO₂), a dual-functional terahertz metamaterial device is proposed. The device can be switched between an absorber and a polarization converter. Simulation results demonstrate that the device acts as a terahertz wave absorber when the VO₂ is in the metallic state, and the reflected extinction ratio is less than −15 dB in the frequency range between 1.07 and 1.19 THz. Moreover, the absorption performance is insensitive to polarization. When the VO₂ is in the insulated state, the device behaves as a polarization converter, which can convert line-polarized light to cross-polarized light. The polarization conversion rate of the device is over 90% in the frequency range between 1.43 and 1.51 THz. The proposed dual-functional metamaterial device with tunable and diverse functions has broad and potentially useful uses in areas such as terahertz detection, modulation, and switching.

The primary factor influencing semiconductor laser performance is photoelectric conversion efficiency. In this study, a heat sink structure in the form of a laminated DC-mount package was created using Solidworks 2018 in accordance with the semiconductor laser C-mount packaging structure specifications. The Workbench 17.0 program theoretically derived the link between the device’s junction temperature and power, and then optimized the size of its heat sink. The primary characteristics of semiconductor laser devices with various C-type and DC-type heat sink architectures were then packaged and compared. Results demonstrate that thermal resistance decreased by 31%, the power of the semiconductor laser device with a DC packaging structure increased by 0.5 W, and photoelectric conversion efficiency increased to over 60%, thereby lowering the temperature at the device junction and thermal resistance. at least to a certain point. the effect of the parasitic parameters of the package is effectively improved. Finally, the 3000 h life test confirmed this package construction’s stability.

In order to realize effective laser communication on underwater mobile platforms, the active tracking and alignment technology of underwater laser communication (UWLC) is studied. Firstly, the servo control principle of the UWLC system is analyzed. Secondly, aiming at underwater disturbance, an adaptive fuzzy PID controller is designed to realize parameter self-tuning, thereby improving the system’s anti-disturbance ability. The designed algorithm was simulated, and the simulation results show that the adaptive fuzzy PID algorithm has better anti-disturbance ability and tracking performance than the traditional PID. Finally, an experimental platform was built for dynamic tracking experiments, and the results show that the dynamic tracking accuracy of the designed control algorithm was improved by 30.29% compared with the traditional control algorithm, which provides a certain reference for the development of laser communication on underwater moving platforms.

Silicon-based optical waveguides exhibit high Brillouin gain, enabling the realization of Brillouin lasers directly on silicon substrates. These lasers hold significant promise for applications such as tunable-frequency laser emission, ultrafast pulse generation via mode-locking techniques, and other advanced photonic functionalities. However, a key challenge in silicon-based Brillouin lasers is the requirement for long waveguide lengths to achieve sufficient optical feedback and reach the lasing threshold. This study proposes a novel floating waveguide architecture designed to significantly enhance the Brillouin gain in silicon-based systems. Furthermore, we introduce a breakthrough method for achieving wide-range phonon frequency tunability, enabling precise control over stimulated Brillouin scattering (SBS) dynamics. By strategically engineering the waveguide geometry (shape and dimensions), we demonstrate a tunable SBS phonon laser, offering a versatile platform for on-chip applications. Additionally, the proposed waveguide system features adjustable operating frequencies, unlocking new opportunities for compact Brillouin devices and integrated microwave photonic signal sources.

In order to improve the imaging quality of the vehicle photoelectric servo system, image motion compensation under the vehicle platform is studied. Based on the principle of image motion compensation, combined with coordinate system transformation and velocity vector decomposition, the angular velocity compensation formula of a fast mirror in dynamic scanning imaging of a vehicle photoelectric servo system is obtained. A discrete sliding mode control algorithm based on the Kalman filter is proposed. The proposed algorithm and the discrete sliding mode control algorithm are simulated and compared to verify the system control performance. The simulation results show that the designed algorithm improves control accuracy by 76.3%, reduces overshoot by 75%, and improves response time by 31.25% compared with the discrete sliding mode control algorithm. The experimental platform is built to verify the experimental results. The experimental results show that the speed stability accuracy of the fast mirror is better than 19 μrad, which is 74.37% higher than that of the traditional control scheme. This study provides a reference for the follow-up study of image motion compensation in a vehicle photoelectric servo system.