Abstract: A core layer (13) of an optical waveguide (1) includes a plurality of core groups (140) disposed so as to mutually intersect on the same plane, each core group (140) being an assembly of a plurality of core portions (14), at least some of which are arranged in parallel, and side cladding portions (15) provided so as to adjoin the side surfaces of each core portion (14). A transverse cross-section of the optical waveguide (1) includes a high refractive index region (WH) in a position corresponding with each core portion (14) and having a relatively high refractive index, and a low refractive index region (WL) in a position corresponding with each side cladding portion (15) and having a lower refractive index than the high refractive index region (WH), and a refractive index distribution is formed in which the refractive index varies continuously across the entire distribution.

Abstract: An optical waveguide has: a core layer which includes at least one core portion for transmitting a light signal and at least two side cladding portions respectively provided at lateral sides of the core portion so as to be opposed to each other; and two cladding layers respectively provided at vertical sides of the core layer. The core layer is configured to have a horizontal refractive index distribution curve W in a width direction of a cross-sectional plane of the core layer. The horizontal refractive index distribution curve W has a region including at least two local minimum values, at least one first local maximum value and at least two second local maximum values smaller than the first local maximum value. A refractive index in whole of the horizontal refractive index distribution curve W continuously varies.

Abstract: An optical waveguide including a first cladding layer; a core layer, including first and second core sections with cladding sections on sides thereof in the in-layer direction; and a second cladding layer. A refractive index distribution in the in-layer direction in the core layer, from the first core section to an adjacent cladding section, has a continuous change and a region with a first peak, a first dip, and a second peak in this order; the first peak at a position of the first core section, the second peak with a maximum value of refractive index smaller than of the first peak, at a position of the cladding section, and a portion, from the first cladding layer to the first core section, corresponded to a refractive index distribution in the layer-stacking direction, discontinuously changing at the boundary between the first cladding layer and first core section.

Abstract: A core layer (13) of an optical waveguide (1) includes a plurality of core groups (140) disposed so as to mutually intersect on the same plane, each core group (140) being an assembly of a plurality of core portions (14), at least some of which are arranged in parallel, and side cladding portions (15) provided so as to adjoin the side surfaces of each core portion (14). A transverse cross-section of the optical waveguide (1) includes a high refractive index region (WH) in a position corresponding with each core portion (14) and having a relatively high refractive index, and a low refractive index region (WL) in a position corresponding with each side cladding portion (15) and having a lower refractive index than the high refractive index region (WH), and a refractive index distribution is formed in which the refractive index varies continuously across the entire distribution.

Abstract: An electrical optical circuit-board (10) is provided with an optical circuit-board (40) provided with an optical waveguide (42) and an electrical wiring board (70) that contains a conductor layer (72) and is laminated on the optical circuit-board (40). In the electrical optical circuit-board (10), the electrical wiring board (70) is provided with extending portions (74) formed extending beyond the optical circuit-board (40) laterally with respect to the extending direction of the optical waveguide (42), and conductive portions (50) are provided in a middle portion M of the electrical wiring board (70) in the extending direction thereof that connect the conductor layer (72) and the back side of the electrical optical circuit-board (10).

Abstract: An optical waveguide has: a core layer which includes at least one core portion for transmitting a light signal and at least two side cladding portions respectively provided at lateral sides of the core portion so as to be opposed to each other; and two cladding layers respectively provided at vertical sides of the core layer. The core layer is configured to have a horizontal refractive index distribution curve W in a width direction of a cross-sectional plane of the core layer. The horizontal refractive index distribution curve W has a region including at least two local minimum values, at least one first local maximum value and at least two second local maximum values smaller than the first local maximum value. A refractive index in whole of the horizontal refractive index distribution curve W continuously varies.

Abstract: An optical waveguide including a first cladding layer; a core layer, including first and second core sections with cladding sections on sides thereof in the in-layer direction; and a second cladding layer. A refractive index distribution in the in-layer direction in the core layer, from the first core section to an adjacent cladding section, has a continuous change and a region with a first peak, a first dip, and a second peak in this order; the first peak at a position of the first core section, the second peak with a maximum value of refractive index smaller than of the first peak, at a position of the cladding section, and a portion, from the first cladding layer to the first core section, corresponded to a refractive index distribution in the layer-stacking direction, discontinuously changing at the boundary between the first cladding layer and first core section.