Photonics grating coupler and method of manufacture
View Patent ↗A structure for coupling an optical signal between an integrated circuit photonic structure and an external optical fiber is disclosed as in a method of formation. The coupling structure is sloped relative to a horizontal surface of the photonic structure such that light entering or leaving the photonic structure is substantially normal to its upper surface.
1. A photonic coupler, comprising:
a substrate having an upper surface;
a photonic element disposed over the substrate;
a sloped grating disposed over the substrate for redirecting light into or out of the photonic element, the sloped grating configured to redirect light from a horizontal direction substantially parallel to the upper surface of the substrate to a vertical direction substantially orthogonal to the horizontal direction; and
a lower cladding disposed between the substrate and the photonic element, the lower cladding having a horizontal portion and a sloped portion.
2. The photonic coupler of claim 1 , further comprising an upper cladding material over the photonic element and the sloped grating, the upper cladding material having an upper surface that is substantially parallel to the upper surface of the substrate.
3. The photonic coupler of claim 1 , wherein the sloped grating comprises spaced grooves in a sloped portion of the photonic element, the spaced grooves being oriented substantially vertically relative to the upper surface of the substrate.
4. The photonic coupler of claim 3 , wherein the spaced grooves have a depth from an upper surface of the photonic element to the bottom of the grooves in the range of about 270 nm to about 280 nm.
5. The photonic coupler of claim 3 , wherein the spaced grooves have a period of about 498 nm.
6. A photonic coupler, comprising:
a photonic element provided having a horizontal portion and a sloped portion;
a sloped grating formed at sloped portion of the photonic element and configured to direct light into or out of the photonic element;
a lower cladding disposed between the substrate and the photonic element, the lower cladding having a horizontal portion and a sloped portion; and
an upper cladding disposed over the photonic element, the upper cladding having an upper surface that is substantially parallel to the horizontal portion of photonic element.
7. The photonic coupler of claim 6 , wherein the sloped grating is configured to redirect light from a horizontal direction along the horizontal portion of the photonic element to a vertical direction substantially orthogonal to the horizontal direction.
8. The photonic coupler of claim 6 , wherein the sloped grating comprises spaced grooves in the sloped portion of the photonic element, the spaced grooves being oriented substantially vertically relative to the upper surface of the substrate.
9. The photonic coupler of claim 8 , wherein the spaced grooves have a depth from an upper surface of the photonic element to the bottom of the grooves in the range of about 270 nm to about 280 nm.
10. The photonic coupler of claim 8 , wherein the spaced grooves have a period of about 498 nm.