SUBSTRATE-TYPE OPTICAL WAVEGUIDE ELEMENT, WAVELENGTH DISPERSIVE COMPENSATING ELEMENT, OPTICAL FILTER, OPTICAL RESONATOR AND METHODS FOR DESIGNING THE ELEMENTS, OPTICAL FILTER AND OPTICAL RESONATOR

摘要

Provided is a single mode optical waveguide wherein an optical waveguide is provided with a core, and a gap section which is arranged at the center of the core in the width direction along the optical waveguide direction and has a refractive index lower than that of the core. The core is provided with two regions separated by the gap section, and single mode is propagated over the two regions.