Wavelength-selective cross connect featuring wide flat passband and high cascadability for WDM optical networks

A new reconfigurable wavelength-selective optical cross connect (OXC) featu ring wide flat passband and high cascadability is proposed. It is demonstra ted by 10-Gb/s x 8-channelwavelength-division-multiplexing (WDM) transmissi on (0.8-nm channel spacing) over 4000 km. In the transmission line end with a single OXC, the electrical signal-to-noise ratio (SNR) degradation cause d by inserting the proposed OXC is negligible, unlike the 1-dB SNR degradat ion with a conventional OXC. In the transmission line with an eight-unit OX C cascade, the bandwidths yielding 3-dB SNR degradation for the proposed OX Cs, and the conventional OXCs, are 0.6 and 0.1 nm, respectively. The cascad e of the proposed OXCs has such a wide passband, that there is nearly no na rrowing compared to the 0.8-nm channel spacing.