160-Gb/s Bidirectional Parallel Optical Transceiver Module for Board-Level Interconnects Using a Single-Chip CMOS IC

Abstract

We report here on the design, fabrication and high-speed performance of a novel parallel optical module with sixteen 10-Gb/s transmitter and receiver channels for a 160-Gb/s bidirectional aggregate data rate. The module utilizes a single-chip CMOS optical transceiver containing both transmitter and receiver circuits. 16-channel high-speed photodiode (PD) and VCSEL arrays are flip-chip attached to the low-power CMOS IC. The substrate emitting/illuminated VCSEL and PD arrays operate at 985 nm and include collimating lenses integrated into the backside of the substrate. The IC-OE assembly is then flip-chip attached to a high density organic package forming the transceiver optical module. The exclusive use of flip-chip packaging for both the IC-to-optoelectronic (OE) devices and for the IC-toorganic package minimizes the module footprint and associated packaging parasitics. The OE-on-IC assembly achieves a high area efficiency of 9.4 Gb/s/mm2 [1]. The complete organic carrier transceiver package provides a lowcost, low-profile module similar to a conventional chip-carrier that can be directly surface mounted to a circuit board using a conventional BGA solder process. SLC transceiver modules with transmitter and receiver OE-IC arrays were assembled and characterized. Operation of all 16 transmitters in the transceiver module was demonstrated at data rates >10 Gb/s. Similarly, all 16 receiver channels operated error-free at >10 Gb/s. The receiver eye-diagrams were generated using a second transceiver source and therefore constitute a full transceiver optical link.

The viability of 25 Gb/s on-board signalling

“…We first present results for the maximum achievable data rate for electrical interconnects, then compare them to results for optical on-board interconnects published previously [2]. Besides the particular electrical 11 Gb/s link implemented in hardware and extrapolated performance of this link to higher data rates, we considered the ideal case for each technology (either no IC parasitics for the electrical, or the channel limit only for the optical interconnects) to gain insight into the possible room for speed improvements.…”

“…We then present active link measurements at 11 Gb/s and show the correlation with end-to-end link simulations. Finally, we use these hardware-correlated models in simulations to predict the performance of dense buses running at 25 Gb/s rates, and compare this to recent work [2] on on-board optical interconnects.…”

300-Gb/s 24-channel bidirectional Si carrier transceiver Optochip for board-level interconnects

“…1. The dual-lens optical system is similar to that reported earlier in references [2,3]. The design relies on nearly collimated light between the 2 lenses which provides greatly relaxed alignment tolerances.…”

“…We had previously demonstrated a highly-integrated parallel optical transceiver module utilizing 985nm VCSEL and photodiode arrays flip-chip attached to a single-chip CMOS IC [1]. These "Optochips" were designed for direct coupling to polymer waveguides integrated in optical PCBs, and a full 160 Gb/s bidirectional link through 32 polymer waveguides was recently demonstrated [2,3]. Although the substrate emitting 985nm optoelectronic devices enabled transceiver assemblies with simplified packaging and high area efficiency, these optical modules rely on custom optoelectronic components that are not commercially available.…”

“…The 850nm transceiver Optomodule provides a low-cost, lowprofile module that utilizes key aspects of the Terabus technology: 1) high-speed, low-power CMOS analog amplifier circuits, 2) dense, efficient two-dimensional arrays of high-speed photodiodes and VCSELs, 3) predominant use of flip-chip packaging onto the high density, high speed Si carrier to minimize both the module footprint and associated packaging parasitics. The 850nm transceiver Optochip is designed for flip-chip attachment to an organic laminated high density carrier that can be directly surface mounted to an FR4 circuit board with integrated waveguides [2,3]. A photograph of the assembled transceiver Optochip using a probe-able Si carrier is depicted in Figure 1.…”