Analysis of terabit/second-class inter-chip parallel optoelectronic transceiver

Abstract

Electrical copper-based interconnect has been suffering from fundamental physical loss mechanism and its current infrastructure will not be able to meet the increasing demand for data rates due to reaching the limit of the transmission bandwidth-distance product. Optical interconnect has been known as the candidate for taking over the obsolete electrical counterpart owing to the capability of transmitting data at high rates with low loss and the feasibility for parallel integration. Optoelectronic transceiver is one of the essential elements in optical interconnect system. This thesis scrutinizes a complete set of constituent technologies developed for a novel inter-chip parallel optoelectronic (OE) transceiver (known as Terabus transceiver) which is able to communicate data at the speed in the range of Terabit/second. A novel packaging hierarchy and a creative design for an optical coupling mechanism devised to bring high-level integration and high-speed performance to a final package have been analyzed: Two 4x12 arrays (each < 9 mm2) of CMOS transmitter and receiver ICs have been flip-chip bonded to a silicon carrier interposer of 1.2-cm2 size. Other two 4x12 arrays of OE devices (VCSELs and photodiodes) with comparable size are then flip-chip bonded to the corresponding CMOS arrays attached to the silicon carrier, forming the Optochip assembly. The Optochip is in interface with an Optocard by the flip-chip bonding process between the silicon carrier and an organic card patterned with 48 integrated waveguides at density of 16-channel/mm and total length of 30 cm. The 985-nm operating wavelength of the lasers allows a simple optical design with emission and illumination through arrays of relay lenses directly etched into the backside of the OE Ill-V substrate. A novel design of 45*-tilted and Au-coated mirrors fabricated in 125-ptmpitch acrylate waveguides is to perpendicularly couple the light in and out of the core of these Optocard waveguides. Per-channel performance of up to 20 Gb/s for transmitter and of up to 14 Gb/s for receiver have been realized. Lastly, the thesis has analyzed the market opportunity of the transceiver by reviewing the market situation, identifying contemporary competing technologies, assessing the market prospect and predicting the cost.