ore, the sweet spot for the carrier is 100-Mbps TLS. As a result, the equipment cost has to be in the range of $2,500 per building. These figures clearly throw the design in the direction of CWDM (or CWDM-like price points). Coarse Wavelength Division Multiplexing (CWDM) Technology A metro carrier needs to find more than one customer in a building to be viable. Although some carriers have publicly stated that they need/want 67 broadband (FE/GbE) customers per building, we find this totally untenable. A much more reasonable assumption is that a carrier will find three cus- tomers per building. This would open up the budget for the edge equipment to some extent, but when you also consider the CO costs and the required profit figure (which needs to be at least 15 to 25 percent of the gross), you are left, once again, with some tight requirements on the building equip- ment, throwing the design in the direction of CWDM-like price points. The price of DWDM transceivers is typically four to five times more expensive than that of their CWDM counterparts. The higher DWDM transceiver costs are attributed to a number of factors related to the lasers. The manufacturing wavelength tolerance of a DWDM laser die compared to a CWDM die is a key factor. Typical wavelength tolerances for DWDM lasers are on the order of +0.1 nm, whereas manufacturing wavelength tol- erances for a CWDM laser die are +2 to 3 nm. Lower die yields thus drive up the costs of DWDM lasers relative to CWDM lasers. In addition, pack- aging a DWDM laser die for temperature stabilization with a Peltier cooler and thermister in a butterfly package is more expensive than uncooled CWDM coaxial laser packaging. The cost difference between DWDM and the CWDM multiplexers and demultiplexers based on thin-film filter technology contributes to lower overall system costs in favor of CWDM as well. CWDM filters are inher- ently less expensive to manufacture than DWDM filters due to the fewer number of layers in the filter design. Typically, there are approximately 150 l