Realization of GHz band integrated optical links in a radio frequency Si Ge bipolar process operating at 650 to 850 nm wavelength

A series of on-chip optical links of 50-μm length, utilizing 650 to 850 nm propagation wavelength, with Si avalanche-mode optical sources, silicon nitride-based waveguides, and Si Ge detectors, have been designed and realized, with a 0.35-μm SiGe radio frequency bipolar integrated circuit process. The optical coupling between the optical source and the detectors was realized by a set of dedicated designed optical waveguides, which were all fabricated with components of the SiGe radio frequency process. All components were fully integrated on the same silicon chip. The Si avalanche-mode light-emitting diodes (Si AMLEDs) emitted in the 650- to 850-nm wavelength regime. Correspondingly, small microdimensioned detectors utilize SiGe detector technology with detection efficiencies of up to 0.85 in the same wavelength regime and with a transition frequency of up to 20 GHz. Best performances for the optical links as realized show optical coupling of up to 5 GHz with a total optical link budget loss of -40 dB. A set of link results are presented and several interpretations are given on current realizations. The technology is particularly suitable for realization of low-cost on-chip optical signal processing, optical interconnects, and various types of on-chip microsensors.