Patent ID: 7313307

Claim:
A waveguide comprising: a plurality of linear defects of a three-dimensional photonic crystal, wherein the three-dimensional photonic crystal includes: a first layer including a plurality of columnar structures disposed at a predetermined interval; a second layer including a plurality of columnar structures disposed at the predetermined interval, the columnar structures extending in a direction different from that in which the columnar structures in the first layer extend; a third layer including a plurality of columnar structures disposed at the predetermined interval, the columnar structures extending in the same direction as the columnar structures in the first layer; and a fourth layer including a plurality of columnar structures disposed at the predetermined interval, the columnar structures extending in the same direction as the columnar structures in the second layer, wherein the first layer and the third layer are stacked such that the positions at which the columnar structures contained in the first layer are disposed are shifted by one-half the predetermined interval with respect to the positions at which the columnar structures contained in the third layer are disposed in a direction perpendicular to the direction of extension of the columnar structures, and the second layer and the fourth layer are stacked such that the positions at which the columnar structures contained in the second layer are disposed are shifted by one-half the predetermined interval with respect to the positions at which the columnar structures contained in the fourth layer are disposed in a direction perpendicular to the direction of extension of the columnar structures, wherein the plurality of linear defects include a first linear defect formed by changing the medium of some of the columnar structures to a medium different from that of the unchanged columnar structures and a second linear defect formed by shifting the position or changing the shape of some of the columnar structures extending in the same direction as the first linear defect, and wherein the first linear defect and the second linear defect are disposed apart by 0.5 times the out-of-plane lattice period or more in the stacking direction of the three-dimensional photonic crystal.