Optical printed circuit board with two light waveguide layers optically coupled to each other

1. An optical printed circuit board (PCB), comprising:

a substrate layer defining a receiving groove;

a first light waveguide layer on the substrate layer;

a second light waveguide layer on the substrate layer, the second light waveguide layer being optically coupled with the first light waveguide layer; and

an interconnecting light waveguide layer received in the receiving groove of the substrate layer and positioned between the first light waveguide layer and the second light waveguide layer, the first light waveguide layer optically coupled with the second light waveguide layer via the interconnecting light waveguide layer;

wherein the first light waveguide layer comprises a first tapered end facing toward the second light waveguide layer, the second light waveguide layer comprises a second tapered end facing toward the first light waveguide layer, and the first light waveguide layer and the second light waveguide layer are optically coupled with each other via the first tapered end and the second tapered end.

2. The optical PCB of claim 1 , wherein the interconnecting light waveguide layer comprises a third tapered end and a fourth tapered end opposite to the third tapered end, the first tapered end overlaps the third tapered end, the second tapered end overlaps the fourth tapered end, a bottom surface of the first tapered end contacts a surface of the interconnecting light waveguide layer, and a bottom surface of the second tapered end contacts a surface of the interconnecting light waveguide layer.

3. The optical PCB of claim 2 , wherein the first tapered end comprises a first inclined surface connecting the bottom surface of the first tapered end, the second tapered end comprises a second inclined surface connecting the bottom surface of the second tapered end, the third tapered end comprises a third inclined surface, the fourth tapered end comprises a fourth inclined surface, the first inclined surface is optically coupled with the third inclined surface, and the second inclined surface is optically coupled with the fourth inclined surface.

4. The optical PCB of claim 3 , wherein the first inclined surface is substantially parallel to the first inclined surface, and the fourth inclined surface is substantially parallel to the second inclined surface.

5. The optical PCB of claim 4 , wherein the substrate layer comprises a first surface and a second surface opposite to the first surface, the receiving groove is defined in the first surface, and the bottom surface of the first light waveguide layer and the bottom surface of the second light waveguide layer are positioned on the first surface.

6. The optical PCB of claim 5 , wherein the optical PCB further comprises a reflecting layer covering the first light waveguide layer, the second light waveguide layer, and the interconnecting waveguide layer.

7. The optical PCB of claim 5 , wherein an orthogonal projection of the third tapered end on the first surface substantially coincides with an orthogonal projection of the first tapered end on the first surface, and an orthogonal projection of the fourth tapered end on the first surface substantially coincides with an orthogonal projection of the second tapered end on the first surface.

8. The optical PCB of claim 4 , wherein the substrate layer comprises a first surface and a second surface opposite to the first surface, the receiving groove of the substrate layer passes through the substrate layer, the bottom surface of the first light waveguide layer is positioned on the first surface, and the bottom surface of the second light waveguide layer is positioned on the second surface.

9. The optical PCB of claim 8 , wherein the optical PCB further comprises a first reflecting layer and a second reflecting layer, the first reflecting layer covers the first light waveguide layer and the first surface, and the second reflecting layer covers the second light waveguide layer and the second surface.

10. The optical PCB of claim 9 , wherein the first reflecting layer and the second reflecting layer are made of materials with high reflectivity.

11. The optical PCB of claim 4 , wherein a thickness of the interconnecting light waveguide layer is substantial equal to that of the substrate layer.

12. The optical PCB of claim 4 , wherein the substrate layer comprises a first surface and a second surface opposite to the first surface, the substrate layer defines a first receiving groove in the first surface, a second receiving groove in the second surface and the receiving groove communication with the first receiving groove and the second receiving groove, the receiving groove is defined in a side surface of the substrate layer substantially perpendicular to the first surface and the second surface, the first light waveguide layer is received in first receiving groove, the second light waveguide layer is received in the second receiving groove, and the interconnecting light waveguide layer is engaged into the receiving groove from the side surface of the substrate layer.

13. The optical PCB of claim 12 , wherein the first receiving groove comprises a first tapered portion corresponding to the first tapered end, the second receiving groove comprises a second tapered portion corresponding to the second tapered portion, the first tapered end is engaged into the first tapered portion, and the second tapered end is engaged into the second tapered portion.