venue for the first half of 2001 was only $90,000. This page intentionally left blank. CHAPTER Optics Primer Chapter 2 This chapter provides a short primer on optical technologies and lays the groundwork for the rest of the book. Commercial applications of optical fiber technology for telecommunications purposes were first introduced in the field in 1977. This original system supported a DS3 link that was 2 km (1.5 miles) long. Today 10 Gbps can be supported on a single beam of light1,2 (and work that aims at supporting 40 Gbps is underway). Multiplexing sys- tems enable the carriage of several dozen beams onto a single fiber or fiber pair. Although unrepeated distances have increased significantly over the years, the use of repeaters creates virtually unlimited distances. Figure 2-1 positions optical communication in the electromagnetic spectrum. The basic components of a fiber-optic system are a transmitter (laser diode [LD] or light-emitting diode [LED]), a fiber-optic waveguide (single- mode or multimode fiber), and a receiver (photodetector diode), as shown in Figure 2-2. Most commercially deployed systems today are unidirectional (that is, one fiber is used to transmit and another fiber is used to receive). Typically, termination-multiplexing equipment is at the end of the link to support tributary lower-speed signals. This transmission/multiplexing equipment generates electrical signals that the fiber-optic transmitter con- verts to optical signals for transmission over the optical fiber. The far-end receiver converts the optical signals back to electrical signals for distribu- tion to the various ancillary devices. When originally introduced, fiber-optic systems were implemented for long-distance applications based on very traditional cost-of-transmission- versus-cost-of-multiplexing economic trade-off considerations. As the costs of the fiber media and multiplexers decreased over time, Local Exchange Carriers (LECs) identified cost-effective applications for fiber-optic systems in the metropolitan (metro