Optical WDM technology for networking and switching applications

Optical wavelength-division multiplexing (WDM) is arguably the most attractive technique for accessing the vast bandwidth of the optical fiber. By combining a large number of independently modulated optical wavelengths, one can envision networking and switching systems with an overall throughput that is virtually unattainable by any other means. This potentiality induced many researchers to vigorously investigate optical WDM technology over the past decade. Early work on the subject was based on circuit-switched local-area network architectures utilizing a broadcasting medium (e.g., a star or a bus) to which laser-based transmitters and coherent or filter-based direct-detection receivers are attached. It was recognized that, in such networks, full interconnectivity among the various nodes can be achieved by tuning either the transmitters or the receivers. It was envisioned that the potential number of optical wavelength would be up to a few thousands.