A transparent WDM network featuring shared virtual rings

We propose and demonstrate a transparent wavelength division multiplexing ( WDM) metro ring architecture in which optics enables simultaneous provision ing of dedicated wavelengths for high-end users, while low-end users share wavelengths on "virtual rings". All wavelengths are sourced by the network and remotely modulated at customer End Stations (ES) by low-cost semiconduc tor optical amplifiers (SOAs), which also serve as transmission amplifiers. Measured bit error rate (BER) data for three different ring configurations show negligible power penalties associated with upstream transmission arou nd a 120-km 3-node ring through as many as four cascaded SOA/modulators. Pr eliminary tests indicate that the SOAs are suitable modulators for packet t ransmission over the network.