Design constraints for wavelength-division-multiplexed filters with minimal side-channel impairment

The design of wavelength-division-multiplexed (WDM) filters requires contro l of both the attributes of the filter within the reflection band and the f ilter's effects on adjacent bands. Causality arguments are used to give the minimum dispersion that can be achieved in the transmission of an adjacent channel in terms of the bandwidth, sidelobe suppression, and channel spaci ng of WDM filters. The ripple in the side-channel dispersion is also relate d to the sidelobe properties. Results for a synthesized grating design and its calculated spectrum are compared with the theoretical limits on dispers ion. (C) 2001 Optical Society of America OCIS codes: 050.1950, 000.3860, 12 0.2440.