Resin optical waveguide
A resin optical waveguide containing a core, an under cladding and an over cladding having refractive indices lower than that of the core, in which the resin optical waveguide has, at one end side thereof, a core-exposed section at which the over cladding is not present and the core is exposed and, of the under cladding, a portion corresponding to the core-exposed section has a core-neighboring region that satisfies the following (1) and (2): (1) the core-neighboring region is a region whose distance from the core is within x, and x is 5 μm or more and 20 μm or less; and (2) the core-neighboring region has a refractive index distribution that the refractive index at a side of an interface with the core is high and the refractive index at a far side from the interface with the core is low.
1. A resin optical waveguide comprising a core, an under cladding and an over cladding having refractive indices lower than that of the core,
wherein the resin optical waveguide comprises, at one end side thereof, a core-exposed section at which the over cladding is not present and the core and the under cladding adjacent to the core are exposed and,
of the under cladding, a portion corresponding to the core-exposed section comprises a core-neighboring region that satisfies the following (1) and (2):
(1) the core-neighboring region is a region whose distance from the core is within x, and x is 5 μm or more and 20 μm or less; and
(2) the core-neighboring region has a refractive index distribution that a refractive index at a side of an interface with the core is high and the refractive index at a far side from the interface with the core is low.
2. The resin optical waveguide according to claim 1 , wherein the core-exposed section has a length of 100 μm or more in a light propagation direction.
3. The resin optical waveguide according to claim 1 , wherein the refractive index distribution in the core-neighboring region is 0.00004/μm or more.
4. The resin optical waveguide according to claim 1 , having a difference (n max −n min ) between a maximum value n max and a minimum value n min of the refractive index of the under cladding in the core-neighboring region being 0.0001 or more.
5. The resin optical waveguide according to claim 1 , having a difference (n′ max −n max ) between a maximum value n′ max of a refractive index of the core and a maximum value n max of the refractive index of the under cladding in the core-neighboring region being from 0.008 to 0.02.
6. The resin optical waveguide according to claim 1 , wherein, of the portion of the under cladding corresponding to the core-exposed section, a portion other than the core-neighboring region has a refractive index being equal to or less than a minimum value n min of the refractive index of the under cladding in the core-neighboring region.
7. The resin optical waveguide according to claim 1 , wherein the resin optical waveguide is a single-mode optical waveguide at a wavelength of at least one of 1,310 nm and 1,550 nm.
8. The resin optical waveguide according to claim 1 , wherein the resin optical waveguide has a core size of from 1 to 10 μm.
9. The resin optical waveguide according to claim 1 , wherein the core of the resin optical waveguide is composed of a resin containing fluorine.
10. A resin optical waveguide comprising a core, an under cladding having a refractive index lower than that of the core, and an over cladding,
wherein the resin optical waveguide comprises, at one end side thereof, a core-exposed section at which the over cladding is not present and the core and the under cladding adjacent to the core are exposed, and the core-exposed section has a length of 500 μm or more in a light propagation direction of the resin optical waveguide, and
of the under cladding, a portion corresponding to the core-exposed section has a core-neighboring region that satisfies the following (1) to (3):
(1) the core-neighboring region is a region whose distance from the core is within x, and x is 10 μm or more and 20 μm or less;
(2) the core-neighboring region has a refractive index distribution that a refractive index at a side of an interface with the core is high and the refractive index at a far side from the interface with the core is low; and
(3) a difference (n max −n min ) between a maximum value n max and a minimum value n min of the refractive index of the under cladding in the core-neighboring region is 0.001 or more.
11. A silicon photonics interface comprising the resin optical waveguide according to claim 1 and a silicon optical waveguide, wherein the resin optical waveguide is connected with the silicon optical waveguide at the core-exposed section.
12. A silicon photonics interface comprising the resin optical waveguide according to claim 10 , and a silicon optical waveguide, wherein the resin optical waveguide is connected with the silicon optical waveguide at the core-exposed section.