BANDWIDTH OPTIMIZATION OF OPTICAL ADD DROP MULTIPLEXERS USING CASCADED COUPLERS AND MACH-ZEHNDER SECTIONS

A synthesis of channel add/drop filters consisting of cascaded directional couplers and equal Mach-Zehnder sections is presented within this paper yielding a Chebyshev transmission characteristic and therefore, the optimum distribution of the coupling coefficients with respect to sidelobe suppression and filter bandwidth, It is shown that the number of selectable channels N-c grows approximately linear with the number of filter stages N, resulting in an equal number of channels and filter stages for a 20-dB sidelobe suppression.