Research on the output characteristics of laser wireless power transmission system with nonuniform laser irradiation

Laser wireless power transmission (LWPT), which can realize long-range power transmission, has been received widespread attention in recent years. The influence of high-power laser nonuniform irradiation on the output power and conversion efficiency of photocells has attracted much attention. This article conducted simulations and experiments on nonuniform irradiation with a constant power density and on nonuniform irradiation with constant incident power. The current I, voltage V, output power PL, conversion efficiency ηL, internal resistance R0, and maximum power point resistance RLmax of a 1 cm × 1 cm single-junction gallium arsenide photocell under nonuniform irradiation were studied. Under the condition of nonuniform irradiation with a constant laser power density, the conversion efficiency of the photocell remained constant, but R0 increased nonlinearly from 0.5 to 5 Ω. The ηL decreased from 45% to 5% when the load resistance is constant. Under the condition of nonuniform irradiation with constant laser power, the photoelectric conversion efficiency and R0 changed little, and the ηL remained about 45%, for it is not affected by nonuniform irradiation. The output characteristics of the photocells under uniform irradiation were also studied, and the results were consistent with the above conclusions. When the photocells with constant temperature were irradiated in-homogeneously, it was also revealed that the internal resistance increased and that the conversion efficiency decreased due to the irradiation power variation. The empirical formula was derived through circuit transformation and curve fitting.