Patent ID: 9239426
Filing Date: 2016-01-19
CPC Classification: G02B,G03F

Claim Text:
1. An optical waveguide, comprising: a core layer comprising a resin material forming a core portion, a first side cladding portion and a second side cladding portion such that the first side cladding portion and the second side cladding portion are formed on lateral sides of the core portion and that the core portion and the first and second side cladding portions are aligned in a width direction of the core layer; a first cladding layer provided over one vertical side of the core layer; and a second cladding layer provided over the other vertical side of the core layer, wherein the core layer has a cross-sectional plane having a horizontal refractive index distribution curve W in the width direction, the horizontal refractive index distribution curve W continuously changes and has a region such that first and second local minimum values, a local maximum value, and first and second local secondary maximum values smaller than the local maximum value, are aligned in an order of the first local secondary maximum value, the first local minimum value, the local maximum value, the second local minimum value, and the second local secondary maximum value in the region, the region has a section defined between the first and second local minimum values corresponding to the core portion, a section including the first local secondary maximum value and corresponding to the first side cladding portion, and a section including the second local secondary maximum value and corresponding to the second side cladding portion, the first and second local minimum values are smaller than an average refractive index of each of the first and second side cladding portions, the cross-sectional plane of the optical waveguide has a vertical refractive index distribution curve T in a thickness direction of the core portion, the vertical refractive index distribution curve T has a core section including a third local maximum value, a first outer section on one outer side of the core section, and a second outer section on the other outer side of the core section such that a refractive index in the core section continuously decreases from the third local maximum value toward each of the first and second outer sections and a refractive index in each of the first and second outer sections is substantially constant, the core section corresponds to the core portion, the first outer section corresponds to the first cladding layer, and the second outer section corresponds to the second cladding layer.