Monolithic silicon waveguide photodiode utilizing surface-state absorption and operating at 10 Gb/s.

We have fabricated a waveguide integrated monolithic silicon infrared detector. The photodiode consists of a p-i-n junction across a silicon-on-insulator (SOI) rib waveguide. Absorption is due to surface-states at the silicon/air interface of the waveguide. A 2 mm long detector shows a response of 0.045 A/W (calculated as a function of coupled light) and is capable of operation at 10 Gb/s at a reverse bias voltage of 2 V.

10 Gbps silicon waveguide-integrated infrared avalanche photodiode.

We have fabricated monolithic silicon avalanche photodiodes capable of 10 Gbps operation at a wavelength of 1550 nm. The photodiodes are entirely CMOS process compatible and comprise a p-i-n junction integrated with a silicon-on-insulator (SOI) rib waveguide. Photo-generation is initiated via the presence of deep levels in the silicon bandgap, introduced by ion implantation and modified by subsequent annealing. The devices show a small signal 3 dB bandwidth of 2.0 GHz as well as an open eye pattern at 10 Gbps. A responsivity of 4.7 ± 0.5 A/W is measured for a 600 µm device at a reverse bias of 40 V.

Vertically-integrated multimode interferometer coupler for 3D photonic circuits in SOI.

Vertical optical coupling is demonstrated in a multimode interferometer structure fabricated using silicon-on-insulator (SOI) material. These CMOS-compatible couplers are suitable to be used to transfer optical power between stacked waveguide layers of a three-dimensional photonic circuit. Coupling between these layers can be restricted to certain regions by selectively fabricating a silicon channel between them, resulting in an isolated multimode waveguide section. Standard photolithography and etching techniques were used to fabricate proof-of-concept devices consisting of a channel waveguide coupling into a silicon waveguide that is vertically multimode. An optical coupling ratio of 93±4% between the upper and lower waveguide regions of the device was achieved with a coupler length of 241 µm.

Fabrication tolerance of asymmetric silicon-on-insulator polarization rotators.

We investigate the fabrication tolerance of novel slanted-angle silicon-on-insulator polarization rotators with asymmetric external waveguiding regions. We also minimize the input and output coupling loss between the polarization rotator and the rib waveguides through a lateral shift in the relative waveguide positions.