Silicon-based group-IV O-E-O devices for gain, logic and wavelength conversion

Using the strip-guided "manufacturable" SOI/GeSn group-IV integrated-photonics platform operating at 1550 nm, we propose an optical-to-electrical-to-optical (O-E-O) device that can work either as an amplifierless optical repeater with gain, as a linear-optics wavelength-converter repeater, or as a new "optical-optical" logic (OOL) gate. An interconnected array of such linear-optics gates performs complicated digital-logic functions. The OEO comprises a photodetector (PD), an electro-optical modulator (EOM), and an electrical biasing-and-interconnect circuit. A digitally modulated optical signal is sent into a waveguided photoconductive GeSn PIN PD whose electrical output is compatible with the electrical input of a resonant bus-coupled Si PN-depletion microdisk EOM modulating a CW optical input beam. Our self-consistent physical model takes into account N and P doping effects. Assuming a peak optical input power of 0.5 mW and 3 V DC bias, our 1.55 mu m simulations predict successful repeater-converter operation at 6.5 GHz (13 Gbit/s) and successful OOL functioning at 4.7 GHz (9.4 Gbit/s), with 12-to-16 dB extinction ratio and switching energy in the 5.8 to 9.6 fJ/bit range. A further increase of the OOL bit rate to 14 Gbit/s is available at the expense of an increased optical signal power.