PLANAR OPTICAL WAVEGUIDE ELEMENT, CHROMATIC DISPERSION COMPENSATOR, OPTICAL FILTER, OPTICAL RESONATOR AND METHODS FOR DESIGNING THE ELEMENT, CHROMATIC DISPERSION COMPENSATOR, OPTICAL FILTER AND OPTICAL RESONATOR

摘要

There is provided a planar optical waveguide element in which an optical waveguide comprises a core, and a gap portion that is positioned in a center of a width direction of the core so as to extend in a propagation direction of guided light, and that has a lower refractive index than that of the core; and wherein the core comprises two areas that are separated by the gap portion, and a single mode optical waveguide, in which a single mode is propagated span crossing these two areas, is formed.