Cascaded coupler Mach-Zehnder channel dropping filters for wavelength-division-multiplexed optical systems

We describe the design and characteristics of cascaded coupler Mach-Zehnder (CMZ) channel adding/dropping filters that select every nth channel (n=2,3,4,...) from the wavelength-division-multiplexed (WDM) optical signal. Using the truncated binomial coupling weight distribution, which appears to be optimal, such filters achieve low (>