Laser wireless power transfer technology, due to its high energy density, strong directionality, and long-distance transmission capability, is regarded as one of the ideal solutions to the power supply problem of small indoor devices. However, the commercialization of this technology has always been limited by safety protection issues. Existing safety solutions, such as distributed laser resonators, deep learning-based visual recognition, or multi-beam protection mechanisms, although each has its advantages, generally suffer from inherent drawbacks such as slow response speed, complex system structure, high hardware cost, or difficulties in miniaturized integration. To overcome these challenges, this study aims to develop a novel laser wireless charging system that combines high energy transmission efficiency, millisecond-level fast response, and a highly compact structure, thereby achieving the unification of safety and energy transfer efficiency and promoting the practical application and commercialization of this technology.

This study designed a laser wireless charging system with fast protection function based on corner-cube prism feedback. The transmitter of the system employed an 808 nm fiber-coupled semiconductor laser as the light source, and a self-designed Galilean dual-spherical lens collimation system was used to shape and expand the output laser beam, ensuring that the spot size matched the photovoltaic cell at the receiver within a transmission distance of 1 m to 5 m, thereby maximizing the utilization of laser energy. The core innovation of this system lay in the design of the receiver. Multi-junction gallium arsenide photovoltaic cells and a corner-cube prism were compactly stacked to form a composite module that combined both energy reception and signal feedback functions. The system utilized the redundant optical energy from the main transmission laser beam that was not absorbed by the photovoltaic cells and was retro-reflected by the corner-cube prism back to the transmitter as a feedback control signal. After this signal was received by the silicon photovoltaic cell at the transmitter, it output an electrical signal to control the on/off switching of the driver module, thereby establishing an optoelectronic feedback protection mechanism that did not require an independent protection light source. Through theoretical analysis, optical simulation, and experimental testing, key performance indicators such as the collimated spot, photoelectric conversion efficiency, and protection response time of the system were comprehensively verified.

Through experimental testing and data analysis, the system demonstrated several outstanding performance indicators. In terms of energy transmission, by optimizing the collimation optical system, the system achieved a maximum photoelectric conversion efficiency of 45.4% within a working distance of 3 m to 5 m, and under the optimal matched load, the output electrical power was stable at approximately 189.8 mW (see Table 1 for detailed data). In terms of structural integration, the designed integrated “photovoltaic cell-corner cube prism” receiver module achieved an optimized theoretical package volume of 13 mm × 13 mm × 10 mm, demonstrating significant miniaturization advantages and commercial integration potential. The physical implementation of this integrated structure was shown in Fig.6. In terms of safety protection performance, to accurately measure the response speed of the system, dynamic testing using a 7000 fps high-speed camera system showed that when the feedback optical path was completely blocked by a foreign object, the feedback protection response time of the system from signal loss to complete laser shutdown was only 0.72 ms (Fig.11), which was better than most reported solutions and provided millisecond-level safety assurance for indoor application scenarios.

This study successfully designs and validates a laser wireless charging system based on corner-cube prism feedback with millisecond-level fast protection. Through the unique integrated design of the receiver, the system revolutionizes the traditional safety protection approach and achieves the functional reuse of energy transmission and safety protection.