Gb / s Optical Transceivers : Fundamentals and Emerging Technologies

Continued demand for higher bandwidth in data networks along with an industry need for standardized network components has driven the need for 10 Gb/s optical transceivers into the long haul, metro core, and enterprise/storage environments. In response to this demand, the functionality and performance of these modules have increased significantly, while the size, cost, and power consumption have been dramatically reduced. While each transceiver application has unique systemlevel requirements, performance criteria, and cost sensitivities, the structure of each transceiver is much the same. This paper presents a discussion of the basic transceiver architecture including analog and digital electronic ICs and process choices, optical components and packaging, and control, monitoring, and interface circuitry. With each component, the critical performance criteria and cost-reduction opportunities are highlighted. More detail is presented on a full C-band wavelength tunable long-haul optical transceiver for Dense Wavelength Division Multiplexed (DWDM) systems, including the DWDM system requirements and design issues that arise in amplified, high-power, multi-channel links. The functionality and performance of a tunable 10 Gb/s transceiver are explored in more depth with a focus on transmitter and receiver front-end design. Finally, an application of Electronic Dispersion Compensation (EDC) is presented, and we show how it can be used to compensate for fiber limitations to enable extended 10 Gb/s links over modal bandwidth limited legacy multimode fiber in enterprise systems. Figure 1: 10 Gb/s optical transceivers for DWDM line side and metro client-side interfaces. Pictured from the left are the 300-pin, XFP, and small form factor 300-pin MSA modules.