Patent ID: 7382958

Claim:
An optical instrument for splitting optical spectrum, comprising: a plurality of hollow core optical wave guide stages comprising an input end and an output end connected in series by optical couplers, said couplers being capable of transmitting a broad band incident optical signal from each stage of hollow core optical waveguide to the next stage of hollow core optical waveguide in series; wherein each stage comprises: a photonic crystal optical waveguide comprising an input end and an output end, said photonic crystal optical waveguide being capable of transmitting a predetermined narrow band optical signal; wherein a said photonic crystal optical waveguide is mounted inside the respective hollow core optical wave guide; wherein each of the said photonic crystal optical waveguides has a bend at the output end such that it exits the hollow core optical waveguide at a predetermined angle such that the selected narrow band component of the incident optical spectrum is guided out of the hollow core optical waveguide.