High-performance laser power converts for direct-energy applications

Six-junction GaAs laser power converts (LPCs) were designed and fabricated. Each subcell is vertically connected by p++-AlGaAs: C/n++-AlGaAs: Si: Te (1:2) tunnel junction with good thermal stability and a record peak tunneling current density of 1867 A/cm². The I-V characteristics of LPCs with an aperture of 10×10 mm² were investigated as a function of laser power and temperature. Maximum conversion efficiency and output power of 57.7% and 15.4 W, respectively, and a continuous stable operation at 22.9 W for over 550 hours were demonstrated. The temperature coefficient of conversion efficiency and open-circuit voltage were -0.197%abs/°C and -8.15 mV/°C, respectively, under 808 nm laser illumination of 21.0 W. Furthermore, an array of 100 large-scale (41×46 mm²) LPCs with an output power of 179 W under 1 kW laser irradiation at 20 m wireless transmission was developed.