To give electromagnetic energy distribution having a high symmetry to emission light from a three-dimensional photonic crystal.
The waveguide region of the photonic crystal has a first basic structure and a first defect part, the mode transformation region of the photonic crystal has second and third basic structures and a second defect part. The unit structure of the photonic crystal is not reflectionally symmetrical with respect to a straight line parallel to a second axis and reflectionally symmetrical with respect to a straight line parallel to a third axis. When the directions intersecting at right angle with the first direction in which light propagates are defined as second and third directions, the first to the third directions of the first and the second basic structures coincide with the first to the third axial directions of the unit structure. On a first cross section, the second basic structure is disposed at a side of the third direction and connected to the third basic structure. On the first cross section, the third basic structure is reflectionally symmetrical with respect to the second basic structure. The mode transformation region is reflectionally symmetrical with respect to straight lines extending in the second and the third directions on the first cross section.
IKEMOTO MASAO
Atsushi Mizumoto