Method of manufacturing optical waveguide, optical waveguide and optical transmission device
A method for manufacturing an optical waveguide which includes a core configured to transmit an optical signal, and a mirror portion configured to reflect the optical signal, the method includes: forming a mask layer patterned in a predetermined shape, on a first crystal plane of a substrate made of a crystalline material; etching the first crystal plane by a wet-etching using the mask layer to form a groove having a plurality of crystal planes; providing a metallic reflection film on at least one of the plurality of crystal planes to form the mirror portion; and providing the groove with a core material to form the core.
1. An optical waveguide comprising:
a groove having at least four crystal planes formed by wet-etching a first crystal plane of a substrate made of a crystalline material, the groove having a cross-sectional shape that defines an inverted trapezoid or an inverted triangle;
a mirror portion configured to reflect an optical signal, the mirror being formed by providing a metallic reflection film on the entire surface of the groove such that the metallic reflection film covers the at least four crystal planes;
a core configured to transmit an optical signal, the core being provided on the groove with a core material; and
a clad layer formed on an upper surface of the core.
2. The optical waveguide according to claim 1 , wherein the mirror portion includes two mirrors that are formed by providing the metallic reflection film on two of the crystal planes that oppose defining an angle of 90°.
3. The optical waveguide according to claim 1 , wherein:
the crystalline material is a silicon single-crystal;
the first crystal plane is a (100)-plane;
the at least four crystal planes are (110)-planes; and
an alkaline etchant is used as an etchant of the wet-etching.
4. An optical transmission device comprising:
an optical waveguide including:
a groove having at least four crystal planes formed by wet-etching a first crystal plane of a substrate made of a crystalline material, the groove having a cross-sectional shape that defines an inverted trapezoid or an inverted triangle;
first and second mirrors that are formed by providing a metallic reflection film on the entire surface of the groove such that the metallic reflection film covers the at least four crystal planes and two of the crystal planes oppose at an angle of 90°;
a core configured to transmit an optical signal, the core being provided on the groove with a core material; and
a clad layer formed on an upper surface of the core;
a light emitting element disposed on the substrate, the light emitting element being configured to project the optical signal to the first mirror; and
a light receiving element disposed on the substrate, the light receiving element being configured to receive the optical signal reflected by the first mirror and then reflected by the second mirror.