POLARIZATION ROTATION CIRCUIT

摘要

Polarization rotators of conventional techniques require forming a silicon nitride layer, which is not employed in usual fabrication of a silicon waveguide circuit. In order to employ a polarization rotator function in an optical integrated circuit, a process of forming a silicon nitride layer is added just for that purpose. This increases the fabrication time and complicates the fabrication equipment. In a polarization rotator of the present invention, the waveguide width of a center core portion of a polarization converter (104) is made small. Thus, the intensity of an optical wave does not concentrate only at the center core portion and is more influenced by structural asymmetry. With the configuration of the polarization rotator of the present invention, it is possible to efficiently cause polarization conversion with a structure including only a silicon waveguide and no silicon nitride layer or the like formed thereon.