IMPACT OF COHERENT CROSSTALK ON USABLE BANDWIDTH OF A GRATING-MZI BASED OADM

The allowable fluctuation of center frequency (AFCF) for a grating bas ed Mach-Zehnder interferometer (MZI) optical add/drop multiplexer (OAD M) might not be limited by the transfer function from the input to the drop port, but rather by the transfer function from the add port to t he drop port or the input port to the output port. We show that the si gnificant bandwidth is determined by the bandwidth in which the cohere nt crosstalk is sufficiently low. For the commercially available devic e investigated here the crosstalk reduces the AFCF by a factor of 2. F urthermore, we show an excellent prediction of the penalty due to cohe rent crosstalk based on measured transfer functions when compared to d irectly measured penalties.