The rest is recent history, with tens of millions of Internet users driving a demand for bandwidth that could be satisfied only from the use of optical fiber. Team-Fly® Fiber in the WAN INITIAL WAN ARCHITECTURE The initial architecture associated with the use of optical fiber in the WAN remained a sequence of point- to-point transmission systems until the late 1990s. Electrical signals would be converted by a laser at one end of a fiber, while a photodetec- tor at the other end would convert the light signals back into an electri- cal form. Once converted back into an electrical format, the electronics could process and switch signals among different paths or simply serve as a temporary conversion point for regeneration of the signal. Thus, the optical-to-electrical conversion followed by an electrical-to-optical recon- version functioned as an amplifier. BROADBAND WDM The first development of WDM based on the use of lasers is referred to as broadband WDM. Broadband WDM took advantage of the fact that it was relatively easy to use lasers that operate in the 1300- and 1500-nm optical windows and couple their output onto a common single-mode optical fiber. During 1994 the output of lasers operating at 1310 and 1550 nm were combined onto a common optical fiber. Each laser operated at 2.5 Gbits/s, resulting in a transmission capac- ity of 5 Gbits/s obtained on a single fiber. Although a transmission capacity of 5 Gbits/s does not begin to compare to the transmission capacity obtainable just a half decade later, at the time it provided com- munications carriers with an inexpensive alternative to installing new fiber to meet customers' expanding transmission requirements. Thus, instead of having to physically install a new optical fiber, it became pos- sible to add a second laser input and a coupler to double system capacity. Similar to a child in a candy store, communications carriers were able to taste the economic advantages associated with broadband WDM and provided a ready market for more modern systems. WDM AND D