Publisher Summary This chapter outlines the system requirements, enabling technologies, and system evaluation methodologies covering the various aspects of the current status of optical transceivers in the context of passive optical network (PON) applications. PON transceivers are unique bidirectional devices that use different wavelengths to transmit and receive signals between the optical line terminal (OLT) and the optical network units (ONUs) over a single fiber. Optical transceivers rely on the use of semiconductor lasers and detectors, in conjunction with integrated circuits (ICs), and novel packaging technologies to provide cost-effective means for transmitting and receiving analog and digital signals over fiber-optic cables. The different types of PONs, i.e., BPON, EPON, and G-PON, differ in the up- and downstream transmission bit-rates, reaches, split ratios, and burst-mode dynamics, which impacts the specifications of the respective transceivers. One of the critical issues for PON transceivers is the performance/cost ratio measured by the technical specifications and the unit cost of the optical transceivers. These new technologies are used to help in reducing the number of discrete components, improving the manufacturing yield, increasing the production throughput, and reducing overall cost. However there are technological challenges in PON transceivers which include upstream burst-mode optical transmission technologies; optical transmitter output power as well as optical receiver sensitivity to satisfy the increasing system link budget requirements; and higher date rates. Another challenge is the increase in electrical and optical cross talk between the transmitting and receiving channels.