A 160-km transparent metro WDM ring network featuring cascaded erbium-doped waveguide amplifiers

We demonstrate a 4/spl times/2.5 Gb/s WDM ring with network-sourced virtual rings comprising optically shared wavelengths. The ring's four nodes feature erbium-doped waveguide amplifiers (EDWAs), shown here for the first time in cascade, which promise future integrability.