High-speed si/ge-based photodiodes for optical interconnect applications

Owing to the ever-increasing need for higher bandwidths, optical interconnect (OI) technologies for rack-to-rack, board-to-board, and chip-to-chip signal transmission have received a great deal of attention in recent years [1,2]. The MAUI project (funded in part by the DARPA, United States) has successfully demonstrated a 500-Gbps parallel wavelength-division multiplexed OI [1] with 48 channels of 10.42-Gbps data transmitted over a parallel 12-fiber ribbon at 4 wavelengths per fiber. This device was developed in order to carry the bandwidth load needed for board-to-board and processor-to-processor capabilities in high-end computer systems. High-speed, high-efficiency, and low-power-consumption vertical-cavity surface-emitting lasers (VCSELs) [3-5], modulators, and photodiodes (PDs) [6,7] that operate at a wavelength of 850 nm or around 1000 nm have lately attracted much attention due to their suitability for applications in the OI system. Silicon (Si) photonic technology [8,9], which includes Si-based light sources, modulators, and PDs, can be used to realize these key active components in the OI system, because Si-based optoelectronic (OE) devices have the potential to be monolithically integrated with Si-based integrated circuits (ICs). Figure 22.1 depicts a 4 × 10-Gb/s, 0.13 µm complementary metal-oxide-semiconductor (CMOS) silicon-on-insulator (SOI) integrated OE transceiver chip copackaged with a single, externally modulated continuous-wave (CW) laser [10].