76.7%-efficient cryogenic laser power converters enabled by distributed Bragg reflectors

Bora Kim& Minjoo L. Lee University of Illinois Urbana-Champaign, Urbana, IL, United States

We present cryogenic GaAs laser power converters (LPCs) attaining a peak efficiency of 76.7% at 83K under 808 nm light by implementing a low-resistance distributed Bragg reflector (DBR). LPCs with an appropriately designed DBR exhibit external quantum efficiency at 808 nm (EQE808 nm) of 92.2% at 83K. We further find that p-type DBRs with barrier reduction layers and high doping maintain low and T-invariant specific series resistance <1×10-2 Ω·cm-2, contributing to high fill factor values > 90% under 808 nm laser light with input power density of 1-4 W/cm2 at 83K.