67.5% Efficient InP-Based Laser Power Converters at 1470 nm at 77 K
Simon Fafard, Denis Masson
Abstract
Recent developments in long wavelength and cryogenic laser power converters have unlocked record performances in both areas. Here, devices for an optical input at ~1470 nm are studied for cryogenic applications, combining these cryogenic and long-wavelength attributes. Multijunction laser power converters are demonstrated to have a high-efficiency operation at 77 K. The photovoltaic-power-converting III-V semiconductor devices are designed with InGaAs-absorbing layers, here with 10 thin subcells (PT10), connected by transparent tunnel junctions. Unprecedented conversion efficiencies of up to 67.5% are measured at liquid nitrogen temperatures with an output power of Pmpp = 1.35 W at an average optical input intensity of ~62 W/cm2. A remarkably low bandgap voltage offset value of Woc~50 mV is obtained at an average optical input intensity of ~31 W/cm2.