Connection structure of optical waveguide chips
A connection structure of optical waveguide chips includes a base substrate ( 2003 ) in which grooves ( 2013 ) are formed, spacer optical fibers ( 2006 ) each disposed for a corresponding one of the grooves ( 2013 ) and fitted in the groove ( 2013 ) while partially projecting from the base substrate ( 2003 ), and silica-based PLCs ( 2001, 2002 ) that are a plurality of optical waveguide chips in each of which grooves ( 2007 ) fitted on the projecting portions of the spacer optical fibers ( 2006 ) are formed at positions of an optical waveguide layer ( 2008 ) facing the grooves ( 2013 ), and each of which is mounted on the base substrate ( 2003 ) while being supported by the spacer optical fibers ( 2006 ). The silica-based PLCs ( 2001, 2002 ) are mounted on the base substrate ( 2003 ) such that incident/exit end faces of the optical waveguide layers ( 2008 ) face each other.
1. A connection structure of optical waveguide chips, comprising:
a base substrate in which a plurality of first grooves are formed;
a plurality of first spacer members respectively fitted in the plurality of first grooves while partially projecting from the base substrate; and
a plurality of optical waveguide chips in each of which an optical waveguide layer is formed on a substrate, and second grooves fitted on the projecting portions of the first spacer members are formed at positions of the optical waveguide layer facing the first grooves, and each of which is mounted on the base substrate while being supported by the first spacer members,
wherein the plurality of optical waveguide chips are mounted on the base substrate such that incident/exit end faces of optical waveguide layers of two adjacent optical waveguide chips face each other,
wherein each optical waveguide chip includes at least two second grooves formed in a surface of the optical waveguide layer facing the base substrate such that one of an optical axis direction of light that enters from another adjacent optical waveguide chip and an optical axis direction of light that exits to the other optical waveguide chip becomes a longitudinal direction,
the base substrate includes at least two first grooves formed in a surface facing the plurality of optical waveguide chips such that the first grooves correspond to the at least two second grooves, respectively, and
each of the first grooves and the second grooves is fitted on a first spaces member at a central portion, and width becomes wider than the first spacer member as a point separates from the central portion along the longitudinal direction.
2. The connection structure of the optical waveguide chips according to claim 1 , wherein the second grooves formed in the optical waveguide layer of the optical waveguide chip are formed up to a depth at which the substrate of the optical waveguide hip is exposed, and the first spacer members fitted in the second grooves come into contact with the substrate of the optical waveguide chip.
3. The connection structure of the optical waveguide chips according to claim 1 , wherein a height of the first spacer members is higher than a sum of a depth of the first grooves and a depth of the second grooves.
4. The connection structure of the optical waveguide chips according to claim 1 , wherein each of two adjacent optical waveguide chips further comprises a pitch conversion portion configured to make an interval between cores in the incident/exit end face of an optical waveguide array formed in the optical waveguide layer narrower than an interval between cores in a portion far apart from the incident/exit end face.
5. The connection structure of the optical waveguide chips according to claim 4 , wherein each optical waveguide chip has a shape with a notch in at least one of corner portions of the incident/exit end face facing the other adjacent optical waveguide chip.
6. The connection structure of the optical waveguide chips according to claim 1 , wherein a planar shape of each of both-side ends of the first grooves and the second grooves in the longitudinal direction is such a shape that a distance from a groove center is substantially constant, and a distance between the both-side ends is set such that the both-side ends of the first grooves and the second grooves when fitted on the first spacer members come into contact with both-side ends of the first spacer members in the longitudinal direction.