A photonic crystal comprising a waveguide made of material. The waveguide has
a
periodic set of holes. The material proximate to at least one of the holes in the
periodic set of holes exhibits an index of refraction that has been modified by
the application of laser energy relative to the material proximate to other holes
in the periodic set of holes. The photonic crystal is tuned to temporarily transmit
a specific wavelength of light to create an on-off switch for the specific wavelength.
Multiple photonic crystals are used to form a multiplexer and a demultiplexer.
