An optical dynamic gain equalization filter (DGEF) comprises a planar arrangement
of preferably "perfectly sampled" (or alternatively oversampled) waveguide grating
routers (WGR's) connected by individual optical paths each containing a Mach-Zehnder
interferometer operated in a push-pull fashion so that a positive phase change
in one interferometer arm and a corresponding negative phase change in the other
interferometer arm produces a desired change in attenuation while, at the same
time, the overall phase of the optical signals after passing through the Mach-Zehnder
interferometer is kept constant with respect to the adjacent paths. Alternatively,
the above-described arrangement is effectively "cut in half", and its size effectively
also reduced accordingly, using a mirror placed at the midpoint of the device and
an appropriate circulator to separate the input and output optical signals.
