AN EVALUATION OF ARCHITECTURES INCORPORATING WAVELENGTH-DIVISION MULTIPLEXING

Wavelength division multiplexing (WDM) offers the potential to transpo rt very high bit rates in access systems serving residential and small business customers. We describe the options for WDM access systems, a nd evaluate them on the basis of an international standard that is eme rging for passive optical networks (PON's) that use wavelength-indepen dent power splitting The greatest impediment to meeting the high-bandw idth potential of WDM for downstream (i.e., from the central office to the home) transmission is the need for a moderately priced multiple-w avelength light source. Implementing WDM in the upstream (home to cent ral office) direction presents greater hurdles than in the downstream, The technical aspects of overcoming these hurdles can all be met. The real challenge will be in finding technical solutions that can meet t he very stringent cost requirements of access systems, Systems I-hat u se WDM in the downstream direction only, while using wavelength-indepe ndent power-combining in a PON configuration for upstream, may prove e conomical before Full WDM systems, WDM: may also prove valuable if upg rades are needed in the future for power-splitting PON's.