An integrated circuit has an optical waveguide configured to carry a
plurality of optical channels, which in a particular embodiment are
optical clock signals generated by an optical clock generator. The
integrated circuit includes an optical crossbar having a first output, a
second output, a first optical ring resonator, and a second optical ring
resonator. In a further embodiment, the optical crossbar is an optical
crossbar switch and an output path in the optical crossbar switch
includes another tunable optical ring resonator and an intermediate
waveguide, which allows isolating the output from any optical channel on
the on-chip optical waveguide by tuning the first ring resonator to a
first wavelength, and tuning the other ring resonator to another
wavelength.