Optimal dispersion of optical filters for WDM systems

The phase response of optical filters determines their dispersive properties and impacts wavelength-division multiplexing (WDM) system performance. We present a general analysis of the phase response of optical filters used in WDM systems and suggest ways to minimize the detrimental dispersive effects of these filters. Some filters are found to be inherently linear phase filters and in principle are dispersionless. We also show that some filters may be realized for the phase correction of dispersive filters. Experimental system results demonstrate the negative effects of filter dispersion on system performance.