$\hbox{GaAs/In}_{0.5}\hbox{Ga}_{0.5}\hbox{P}$ Laser Power Converter With Undercut Mesa for Simultaneous High-Speed Data Detection and DC Electrical Power Generation

We demonstrate novel GaAs/In
_0.5
Ga
_0.5
P 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
_0.5
Ga
_0.5
P 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
_0.5
Ga
_0.5
P 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%).