A photonic circuit includes a tunable drop filter arrangement that includes a
plurality
of resonators. The drop filter arrangement is tuned to remove a selected frequency
from an input data stream from a waveguide. A wavelength sensor coupled to the
drop filter to monitor the selected frequency to which the drop filter arrangement
has been tuned. A tunable laser presents a new signal of a defined frequency indicative
of a signal to be added to the input data stream. A modulator coupled to the tunable
laser for receiving the new signal and forming a modulated signal. An add filter
arrangement coupled to the modulator for receiving the modulated signal and adding
the modulated signal to the data stream.
