Hitless multiwavelength source reconfiguration for flexible optical networks

We experimentally demonstrate hitless multiwavelength source reconfiguration for flexible optical networks. The source is a PPLN-based tunable frequency comb generator that provides equally spaced subcarriers with reconfigurable spacing. The subcarriers are filtered, DPSK modulated at 10 Gb/s, demodulated and received. A static and dynamic characterization is carried out. In the static characterization all the modulated subcarriers show error-free performance for 12.5, 25, 37.5 GHz spacing. In the dynamic characterization the BER is measured while the subcarrier spacing is changed from 37.5 to 12.5 GHz at different frequency steps. The automatic reconfiguration of the multiwavelength source, the filter and the demodulator is achieved with a Matlab script running on a personal computer connected with the devices. Error-free transmission is demonstrated during the reconfiguration interval for 0.5 GHz frequency step. The maximum allowed step is 1.25 GHz, at which the FEC limit is reached.