A photonic crystal drop filter apparatus and a method for tuning a photonic
crystal drop filter. The photonic crystal drop filter has a photonic
crystal having first waveguide for transmitting light having a frequency
within a bandgap of the photonic crystal, and a second waveguide. The
second waveguide is connected to the first waveguide by a resonant cavity
for extracting at least one wavelength of the light transmitted by the
first waveguide and redirecting the extracted light to the second
waveguide. A tuning device is included in the apparatus to tune the
wavelength of the extracted light over a full range of wavelengths. The
apparatus is particularly suitable as an extraction device for optical
communications systems such as a WDM communications system wherein it is
necessary to extract one or more carrier signals from a plurality of
carrier signals.
