Patent ID: 7242839

Claim:
An optical delay element, comprising: a line defect optical waveguide formed in a photonic crystal structure, the photonic crystal structure including, a medium having a first refractive index, and an array of hole portions filled with material having a second refractive index less than the first refractive index, the array of hole portions being arranged in the medium so as to have a center to center pitch along a straight line between adjacent hole portions of a distance “a,” wherein a width “D” of the line defect optical waveguide is greater than 0.7 times 3 0.5 (“a”) and less than 0.9 times 3 0.5 (“a”), wherein “D”=3 0.5 (“a”) is the width of a common line defect optical waveguide formed from a single line defect photonic crystal, and wherein a waveguide band of said line defect optical waveguide has a refractive index confinement mode and a photonic bandgap confinement mode, and the line defect optical waveguide guides light having a frequency higher than a frequency corresponding to the photonic bandgap confinement mode.