55% efficient high-power multijunction photovoltaic laser power converters for power beaming applications at 1075nm

High-efficiency multijunction laser power converters are demonstrated at high power for optical inputs around 1075nm. The InP-based photovoltaic power-converting III–V heterostructures are designed with eight lattice-matched InGaAsP subcells (PT8-1070nm). Conversion efficiencies of 55% were obtained with ~ 20W of output power. Endurance testing was performed for over 1000h of continuous operation. For example, an average output power of 13.2W at an input wavelength of 1064nm for long duration testing. An average steady-state efficiency of 54.4% at an ambient temperature of ~20 °C was obtained for that duration. The results demonstrate that 1cm2 optical power converter devices can produce electrical outputs of 20W at maximum power voltages around Vmpp ~6V, thus retaining an optimal load near Rmpp at ~2 ohms. Efficiencies between 57.9% and 59.0% were also obtained for smaller 0.029cm2 chips for input intensities between 35 and 69W/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 1080nm.