Fig. 1. (a) Transversal schematics (x-y plane) of the pin photodetector with a lateral Si-Ge-Si heterojunction architecture. Inset: electric field profile of the fundamental TE-polarized optical mode in a 0.260-μm-thick and 1-μm-wide hetero-structured photodetector. (b) Longitudinal view (y-z plane) of the optical intensity distribution in the 1-μm-wide and 40-μm-long butt-waveguide-coupled pin Si-Ge-Si photodetector, as obtained from 3D FDTD simulations. The fundamental TE mode is injected from the Si waveguide on the left-hand side.

Fig. 2. (a) Static current-voltage (I–V) characteristics of 1-μm-wide by 40-μm-long hetero-structured pin photodetector in dark- and light-illuminated states. Inset: leakage dark-current evolution as a function of device junction area. Photodetectors were biased at −1  V. (b) Photo-responsivity as a function of the reverse voltage for different device lengths. (c) Quantum efficiency as a function of the device length under −0.5  V reverse bias. The shadowed region denotes a range of quantum efficiencies for an estimated power uncertainty of ±0.24  dB.

Fig. 3. (a) Small-signal RF measurements of the S21 responses of the 1-μm-wide×40-μm-long hetero-structured Si-Ge-Si photodetector, under different bias conditions in a range from 0 V to −4  V. Inset: S21 RF traces of different length Si-Ge-Si pin waveguide photodetectors biased at −1  V. (b) Opto-electrical bandwidth versus reverse bias for different device lengths. (c) Product of the quantum efficiency by the RF bandwidth versus reverse bias for Si-Ge-Si pin waveguide photodetectors with different lengths. The shadowed regions denote ranges of efficiency-bandwidth product for an estimated power uncertainty of ±0.24  dB.

Fig. 4. Evolution of eye diagram apertures within a low-reverse-bias range at 10 Gbps, 20 Gbps, 25 Gbps, 28 Gbps, 32 Gbps, and 40 Gbps. Here, x [ps/div] and y [mV/div] correspond to the horizontal and vertical scope axes within the particular measurement setting. 1-μm×40-μm (Ge width×Ge length) Si-Ge-Si photodetector.

Fig. 5. Bit-error-rate measurements of the Si-Ge-Si pin waveguide photodetector as a function of the input optical power. BER assessments performed (a) at 10 Gbps under low-reverse-bias states and (b) at 10 Gbps, 20 Gbps, and 25 Gbps, all biased at −3  V. 1-μm×40-μm (Ge width×Ge length) Si-Ge-Si photodetector.