 A 20- to 30-dB gain and output power Bit-rate independence when designed for the highest bit rate Current bandwidth: 30 nm in the 1,530- to 1,560-nm range (80 nm is possible in the future) High bandwidth that can be extended with improved designs WDM amplifier technology has improved significantly in the past few years. It is now mature and is used in many networks. These amplifiers support the transmission of multiple OC-48 (2.5 Gbps), OC-192 (10 Gbps), and evolving OC-76815 signals over conventional and newer nonzero dispersion-shifted fiber (NZDSF). Typical repeaters enable 32 channels to be inserted and spaced 0.8 nm apart in field-deployable systems. You need flat gain performance in the bandwidth of the amplifier as well as high power. High power is critical in long-haul applications where you need to transmit over long distances. Figure 5-16 is an example of a large DWDM system (long haul). High-end DWDM systems are designed with extended reach optics support for the major fiber types in use today including OC-48 and/or OC-192 OC-48 and/or OC-192 Figure 5-16 Network Elements (up to 16) Network Elements (up to 16) Example of large DWDM system (long haul). Pre/Post Amps. Line Amps. Line Amps. (Pre/Post Amps.) (116B Working Facility with Unidirectional 1510-om OSC Couplers Protection Facility with Unidirectional 1510-om OSC DWDM Couplers Service Service Terminating or Intermediate Intermediate Terminating or Regenerator Site Regenerator Site Working and protection fibers provide Single-Ended SONET and a complete bidirectional OSC. Optical Layer Operations Access via Standard Interfaces OSC = Optical Service Channel Dense Wavelength Division Multiplexing (DWDM) Systems nondispersion-shifted fiber (NDSF), dispersion-shifted fiber (DSF), and NZDSF (for example, Lucent TrueWaveTM Classic/Plus and Corning SMF- LSTM/LEAFTM). (Fiber types were discussed in Chapter 2.) Long-haul sys- tems typically need large cabinets, as depicted in Figure 5-17. This makes the systems expensive from an equipment, power, environment