An ultrafast InP/InGaAs Poptical modulator

Embedding a Bragg reflector in an optoelectronic modulator could overcome the 40GBit/s speed limit. Direct-bandgap III-V semiconductor materials based on InP al-low monolithic integration of optical functionality with elec-tronic circuitry for optical communication applications.1 The quaternary III-V alloy, InGaAsP, is particularly important be-cause its bandgap can be tuned to different wavelength win-dows by adjusting its composition, while keeping its lattice matched to InP. Optoelectronic modulators, which translate elec-trical pulses into light pulses, are a critical component for com-munications. Here we show how, by electrically inducing a 2.5mm-long Distributed Bragg Reflector2 in an InP/InGaAsPrib waveguide, we can theoretically realize a modulator capable of a switching speed over 40GHz. The proposed device, shown in cross section in Figure 1, is a vertical InP/InGaAsP p-i-n diode