Patent ID: 7315673

Claim:
An optical multiplexer/demultiplexer comprising: a substrate; a base groove formed on the substrate; a first linear positioning groove formed on the substrate, the first positioning groove being formed on a first side of the base groove at a predetermined angle to the base groove; a second linear positioning groove formed on the substrate, the second positioning groove being formed on a second side of the base groove oppositely to and coaxially with the first positioning groove; a third linear positioning groove formed on the substrate and on the first side of the base groove such that it is at a smaller distance to the first positioning groove as it becomes closer to the base groove; an optical element provided in the base groove for multiplexing or/and demultiplexing light; a first optical fiber with a lens provided in the first positioning groove, the first optical fiber having a graded index lens attached to an end thereof and facing the base groove at an end face thereof; a second optical fiber with a lens provided in the second positioning groove, the second optical fiber having a graded index lens attached to an end thereof and facing the base groove at an end face thereof; a third optical fiber with a lens provided in the third positioning groove, the third optical fiber having a graded index lens attached to an end thereof and facing the base groove at an end face thereof; and an inclination adjusting member for adjusting the inclination of the optical element relative to a plane in which the optical fibers are disposed such that light which has excited the first optical fiber with a lens is coupled to the third optical fiber with a lens.