An Optimal Driving Strategy for Maximum Electro-optical Conversion Efficiency of Laser Diode in Laser Power Transmission System

Abstract

Laser Power Transmission (LPT) technique features high energy density, flexible devices and advantageous orientation ability, making itself extremely promising for realizing long-distance, high-power wireless power transmission. Laser diode (LD), a core component in LPT system’s transmitter, realizes power conversion from electricity to high-intensity laser beam. LD’s performance significantly affects the efficiency of LPT transmitter. Different driving current patterns lead to different electro-optical conversion efficiency (EOCE). The paper presents a novel LD driving strategy for optimal EOCE under different working conditions. To precisely estimate EOCE of LD, a simplified LD equivalent circuit model with only five parameters is proposed, which can readily be adopted to characterize any commercial LD using curves given in their datasheets. Though simplified, the model can still depict the power-current-voltage (P-I-V) characteristics well, and its accuracy is shown to be as close as its traditional counterparts. Based on the model, the optimal driving current strategy for maximum EOCE is derived for all optical power output conditions. A four-phase interleaved Buck converter is constructed to verify the proposed driving strategy. As all experimental results indicate, the proposed method enjoys a fine performance in improving LD’s EOCE.