Abstract: An optical mode converter for coupling between photonic integrated circuit (PIC) and optical fiber of different mode sizes is illustrated. The optical mode converter includes a waveguide assembly including a Single waveguide structure, a Multi-layer waveguide structure, and a Transitional waveguide structure. The Single waveguide structure includes a single waveguide. The dimension and propagation constant of a first end, of the single waveguide, is similar to a waveguide of a photonic integrated circuit (PIC). Furthermore, the Multi-layer waveguide structure included a multi-layer waveguide. Further, the Transitional waveguide structure is formed at a transitional structure. The Transitional waveguide structure allows transition of an optical mode between the Single waveguide structure and Multi-layer waveguide structure.

Abstract: An optical mode converter for coupling between photonic integrated circuit (PIC) and optical fiber of different mode sizes is illustrated. The optical mode converter includes a waveguide assembly including a Single waveguide structure, a Multi-layer waveguide structure, and a Transitional waveguide structure. The Single waveguide structure includes a single waveguide. The dimension and propagation constant of a first end, of the single waveguide, is similar to a waveguide of a photonic integrated circuit (PIC). Furthermore, the Multi-layer waveguide structure included a multi-layer waveguide. Further, the Transitional waveguide structure is formed at a transitional structure. The Transitional waveguide structure allows transition of an optical mode between the Single waveguide structure and Multi-layer waveguide structure.

Abstract: An attenuator includes, on a substrate: a resistor section; an insulating film covering the resistor section; and connection terminals covering the insulating film and connected in part to the resistor section. A total thickness of the insulating film and the connection terminal in a region where the insulating film and the connection terminal overlap with the resistor section is from 50 ?m to 200 ?m.

Abstract: An attenuator includes, on a substrate: a resistor section; an insulating film covering the resistor section; and connection terminals covering the insulating film and connected in part to the resistor section. A total thickness of the insulating film and the connection terminal in a region where the insulating film and the connection terminal overlap with the resistor section is from 50 ?m to 200 ?m.