in the 1,300-nm window for 10 Gigabit Ether- net (GbE). With conventional fiber, wavelengths in the 1,400-nm region suf- fer higher optical loss due to the attenuation peak caused by residual water present in most of the currently installed fiber. Although this additional loss can limit system performance for longer links, it is not an obstacle to CWDM deployment in most metro access spans. New fiber that eliminates the water attenuation peak is offered by at least two of the primary fiber vendors for use in metro links with loss budgets that mandate lower fiber attenuation. Extended wavelength band (EWB) fiber easily supports 16 channels, whereas conventional single-mode fiber (SMF) easily supports 12 channels. The advantages of EWB fibers for CWDM applications are as follows: EWB Fiber EWB fiber has identical specifications to standard single-mode fiber plus the following: 25 percent fewer fibers in the CWDM feeder 25 percent less CWDM CO floor space and apparatus require- ments Improved CWDM packaging economy Lowers installed CWDM system cost by 10 percent Opens E-band spectrum Maximum future proofing for a 25-year or more fiber plant Long-wavelength InGaAs/InP avalanche photodiodes are helping make low-cost systems a reality. The trade-off in many low-cost systems is the link budget. Although many transceivers are capable of coming close to meeting the performance specifications of long-haul equipment, the passive optical losses induced by couplers, splitters, multiplexers, and demultiplex- ers often overburden the optical link budget. In order to keep the system low cost, expensive erbium-doped fiber amplifiers (EDFAs) are not utilized; Coarse Wavelength Division Multiplexing (CWDM) Technology instead, you can make use of long-wavelength avalanche photodiode tech- nology. InGaAs/InP avalanche photodiodes have been used to increase the receiver sensitivity of long-haul communication systems. They provide cur- rent gain on the order of 10 times in the receiver front end, prior to the tran- simpedance amplifier