GaAs/In _0.5Ga _0.5P laser power converter with undercut mesa for simultaneous high-speed data detection and DC electrical power generation

We demonstrate novel GaAs/In _0.5Ga _0.5P high-speed laser power converters (LPCs), which not only can detect the envelope of incoming high-speed optical data but also can efficiently convert its optical dc component to dc electrical power. By utilizing the graded p-type GaAs and n-type In _0.5Ga _0.5P layers as photoabsorption (P) and collector (C) layers, respectively, the problem of slow-motion holes under 830-nm-optical-wavelength excitation and the conduction-band-offset-induced electron blocking effect between the P/C layers, which seriously limit the high-speed performance of LPC, can both be eliminated. Furthermore, by using the undercut mesa structure of the In _0.5Ga _0.5P C layer to further reduce the large junction capacitance under forward operation, we can achieve invariable high-speed performance (∼9 GHz) from zero to near turn-on voltage (+0.8 V), which corresponds to the operation point of our LPC with the maximum power conversion efficiency (∼ 15%).