Cascadability Performance of Continuous Spectrum WB/WSS at 10/40/160 Gb/s

Abstract

Optical switching technologies such as reconfigurable add/drop multiplexers and cross-connects (OADMs/OXCs) have the ability to perform wavelength routing, provisioning protection/restoration and traffic management thus enabling to cope with the dynamic nature of the data traffic that is met especially in the metro environment. Wavelength Selective Switches (WSS) and Wavelength Blockers (WB) are crucial elements in this kind of nodes offering flexible connectivity between the add/drop and through ports as well as the ability to selectively block the transit traffic. For the so called ? Continuous Spectrum? WB/WSS (CS-WB/WSS), the overall filtering pass-band of the WSS device can be adjusted in a quasi-continuous way by grouping two or more adjacent pixels offering enhanced switching flexibility at arbitrary channel spacing or multi line rates. However loss and group delay ripples appear at each slot boundary causing degradations to the transmitted signal. In this work a system perspective analytical modelling has been developed and through detailed simulation studies we identify the relative impact of each imperfection on the overall cascadability of the WB/WSS. Different switching scenarios at various line rates (10 Gb/s, 40 Gb/s, 160 Gb/s) have been investigated and the corresponding specifications for the WSS device have been identified.