Abstract: An optical integrated circuit includes: a waveguide including a first part and a second part and configured to couple an electromagnetic wave propagating in the first part and an electromagnetic wave propagating in the second part; and a non-reciprocal member positioned alongside the second part in an amplitude direction of an electric field component of the electromagnetic wave. In a range where the first part and the second part are coupled with each other, deviation between a center of an energy distribution of an electric field component of the electromagnetic wave propagating in the first part and a center of an energy distribution of an electric field component of the electromagnetic wave propagating in the second part falls within a prescribed range.

Abstract: An isolator includes a substrate, a waveguide, an insulating layer, and a non-reciprocity member. The insulating layer includes a recess. The recess overlaps at least part of the waveguide. The non-reciprocity member is positioned in the recess. The waveguide includes a first waveguide and a second waveguide. The recess includes a first recess and a second recess. The non-reciprocity member includes a first non-reciprocity member positioned in the first recess and a second non-reciprocity member positioned in the second recess. A propagation direction of the electromagnetic wave in a portion of the first waveguide, the portion overlapping the first non-reciprocity member, and a propagation direction of the electromagnetic wave in a portion of the second waveguide, the portion overlapping the second non-reciprocity member, are different from each other.

Abstract: A nonreciprocal waveguide includes a substrate, a light propagation path, a magnetic member, an insulating layer, and a mask. The light propagation path is positioned at the substrate along a substrate surface. The magnetic member is positioned at the substrate along part of the light propagation path in a longitudinal direction. The insulating layer is positioned at the substrate and contains the light propagation path and the magnetic member. Inside the insulating layer, the mask is positioned further away than the light propagation path from the substrate. As seen from a direction perpendicular to the substrate surface, the mask overlaps at least part of the light propagation path in a width direction from a side of the light propagation path opposite to the magnetic member in the width direction. The mask is positioned in at least a range in which the magnetic member is positioned in the longitudinal direction.

Abstract: A nonreciprocal waveguide includes a substrate, a light propagation path, a magnetic member, an insulating layer, and a mask. The light propagation path is positioned at the substrate along a substrate surface. The magnetic member is positioned at the substrate along part of the light propagation path in a longitudinal direction. The insulating layer is positioned at the substrate and contains the light propagation path and the magnetic member. Inside the insulating layer, the mask is positioned further away than the light propagation path from the substrate. As seen from a direction perpendicular to the substrate surface, the mask overlaps at least part of the light propagation path in a width direction from a side of the light propagation path opposite to the magnetic member in the width direction. The mask is positioned in at least a range in which the magnetic member is positioned in the longitudinal direction.