55% Efficient High-Power Multijunction Photovoltaic Laser Power Converters for 1070 nm

High-efficiency multijunction laser power converters are demonstrated for the first time at high power for optical inputs around 1070 nm. The InP-based photovoltaic power-converting III–V heterostructures are designed with eight lattice-matched InGaAsP subcells (PT8-1070 nm). Conversion efficiencies of 55% were obtained at 18 W of output power. Endurance testing was performed for over 1000 h of continuous operation with an average output power of 13.2 W at an input wavelength of 1064 nm. An average steady-state efficiency of 54.4% at an ambient temperature of ~20 °C was obtained for that duration. The results demonstrate that 1 cm2 optical power converter devices can produce electrical outputs of 20 W at maximum power voltages around Vmpp ~6 V, thus retaining an optimal load near Rmpp at ~2 ohms. Efficiencies between 57.9% and 59.0% were also obtained for smaller 0.029 cm2 chips for input intensities between 35 and 69 W/cm2. This is an important development for power beaming applications: the unprecedented combination of power and conversion efficiency capabilities is expected to enable deployments for key wavelengths between 1040 and 1080 nm.