Isolator, optical switch, optical transmitter and receiver, data center, and isolator manufacturing method

An isolator comprising:

• a substrate with a substrate surface;
• a first waveguide and a second waveguide each extending on the substrate surface and causing an electromagnetic wave in a TM mode to propagate therethrough along an extension direction;
• an insulating layer positioned on the substrate surface and surrounding at least part of each of the first waveguide and the second waveguide;
• and
• a first non-reciprocity member and a second non-reciprocity member,
• wherein the insulating layer has a surface positioned above an upper surface of the first waveguide and an upper surface of the second waveguide, the insulating layer including a first recess and a second recess,
• the first recess is defined by a bottom surface positioned lower than the surface of the insulating layer and by side surfaces positioned between the bottom surface and the surface of the insulating layer the first recess overlapping at least part of the first waveguide in a plan view of the substrate surface,
• the second recess is defined by a bottom surface positioned lower than the surface of the insulating layer and by side surfaces positioned between the bottom surface and the surface of the insulating layer the second recess overlapping at least part of the second waveguide in the plan view of the substrate surface,
• the first non-reciprocity member is positioned on the bottom surface of the first recess and overlaps at least part of the first waveguide in the plan view of the substrate surface,
• the second non-reciprocity member is positioned on the bottom surface of the second recess and overlaps at least part of the second waveguide in the plan view of the substrate surface, and
• a propagation direction of the electromagnetic wave in a portion of the first waveguide, the portion overlapping the first non-reciprocity member in the plan view of the substrate surface, and a propagation direction of the electromagnetic wave in a portion of the second waveguide, the portion overlapping the second non-reciprocity member in the plan view of the substrate surface, are different from each other.