Implementation And In-band Crosstalk Research Of Bandwidth-variable ROADM

The Flexible Bandwidth Optical Networks (FBON) is a novel networkarchitecture which through flexible signal speed allocation and dynamic bandwidthallocation to improve the fiber spectrum utilization and network flexibility.This paperaims at the design and implementation of the bandwidth-variable reconfigurableoptical add-drop multiplexer（BV ROADM）which as the footstone of further FBONresearch, the investigation of how to reduce the impact of crosstalk with ROADM isalso introduced by simulation. The main contents are as follows:1. A realization program of the minimum spectral grid12.5GHz BV ROADM ispresented, based on the Wavelength Selective Switch(WSS) device.And the hardwareand software design of the BV ROADM subsystem is described in detail. The opticalpower attenuation accuracy, the insertion loss, the port isolation and the flexiblepassband spectrum width characteristics of ROADM are measured.2. The in-band crosstalk introduced by the ROADM node is analysed. A schemebased on Optical Orthogonal Frequency Division Multiplexing (OOFDM) technologyfor the improvement of signal’s performance balance is proposed, it utilizes the dropsignals of ROADM to estimate the in-band crosstalk of the express signal’s dropwavelength introduced by the isolation profile, while the adaptive signal powerdistribution technology is used for the add signals to suppress the in-band crosstalk.The technique includes three methods: the multichannel power distribution, thesubcarrier distribution and the multichannel-subcarrier allocation.3. The simulation structure of ROADM add signals’ adaptive power allocationwhich based on112Gb/s polarization-division-multiplexed coherent-detected opticalOFDM (PDM-CO-OFDM) system is build by the VPI and Matlab. The simulationresults show that the three methods can effectively inhibit the ROADM in-bandcrosstalk and improve the performance balance of ROADM’s add signals and thequality of WDM signal compared to the average power allocation. Among the three methods, the first one can adjust the performance balance of ROADM’s add signalseffectively and a4dB OSNR improvement is acquired at the cost of decreasing theother signals’ performance; the second method cannot adjust the performance balanceof ROADM’s add signals effectively but a6.2dB OSNR improvement can acquired atmost; the third method is based on the aforementioned two methods, it achieves theoptimal effect of suppressing ROADM in-band crosstalk and a7.5dB OSNRimprovement can acquired at most.