Optical waveguide lens and optical coupling module incorporating the same
An optical waveguide lens includes a substrate, and a planar waveguide and a media grating formed on the substrate in sequence. The media grating includes a first group of gratings located adjacent to the light source and a second group of gratings away from the light source. The first group of gratings and the second group of gratings each include a plurality of strip-shaped films arranged in parallel. The first group of gratings and the planar waveguide under the first group of gratings cooperatively define a first waveguide section. The second group of gratings and the planar waveguide under the second group of gratings cooperatively define a second waveguide section. Light radiated from a light source passes through the optical waveguide lens and is successively converged by the first waveguide section and the second waveguide section. An optical coupling module incorporating the optical waveguide lens is also provided.
1. An optical waveguide lens configured for converging light emitted from a light source, comprising:
a substrate;
a planar waveguide and a media grating formed on the substrate in sequence;
the media grating comprising a first group of gratings located adjacent to the light source and a second group of gratings away from the light source, the first group of gratings and the second group of gratings each comprising a plurality of strip-shaped films arranged in parallel and spaced from each other; and
the first group of gratings and the planar waveguide under the first group of gratings cooperatively defining a first waveguide section, the second group of gratings and the planar waveguide under the second group of gratings cooperatively defining a second waveguide section;
wherein light radiated from the light source passes through the optical waveguide lens and is successively converged by the first waveguide section and the second waveguide section;
wherein a coordinate system “oxy” is established, the origin “o” denotes an intersecting point of the optical axis of the light source and a widthwise direction of the planar waveguide, “x” axis denotes the widthwise direction of the planar waveguide, “y” axis denotes a phase difference with respect to incident light incident on the media grating in a direction inclined from the normal direction, and boundary of each strip-shaped film is set to conform following conditions:
x
n
=
±
ln
(
1
-
n
π
a
)
k
,
and wherein x n is the nth boundary of the strip-shaped films along the “x ” axis, and a and k are constants.
2. The optical waveguide lens of claim 1 , wherein the diverging light emitted from the light source is first collimated by the first waveguide section and then focused by the second waveguide section.
3. The optical waveguide lens of claim 2 , wherein the planar waveguide comprises a front face and a back face at opposite ends thereof, light emitted from the light source enters the planar waveguide through the front face, successively passes through the first waveguide section and the second waveguide section, and exits the planar waveguide through the back face.
4. The optical waveguide lens of claim 2 , wherein the planar waveguide is of rectangular parallelepiped form, the light source is arranged in a manner that an optical axis of the light source extends in a direction parallel to a lengthwise direction of the planar waveguide, the plurality of strip-shaped films of the first group of gratings and the second group of gratings are symmetrically arranged with respect to the optical axis of the light source.
5. The optical waveguide lens of claim 4 , wherein widths of the plurality of strip-shaped films of the first group of gratings and the second group of gratings decrease along a widthwise direction of the planar waveguide from the optical axis of the light source toward opposite sides of the planar waveguide.
6. The optical waveguide lens of claim 5 , wherein a distance between two adjacent strip-shaped films of the first group of gratings decreases along the widthwise direction of the planar waveguide from the optical axis of the light source toward opposite sides of the planar waveguide, and a distance between two adjacent strip-shaped films of the second group of gratings decreases along the widthwise direction of the planar waveguide from the optical axis of the light source toward opposite sides of the planar waveguide.
7. The optical waveguide lens of claim 1 , wherein the first group of gratings and the second group of gratings each comprises seven strip-shaped films, and the seven strip-shaped films in the first group of gratings are respectively aligned with the seven strip-shaped films in the second group of gratings.
8. The optical waveguide lens of claim 4 , further comprising a pair of first electrodes formed on the planar waveguide, wherein the pair of first electrodes are symmetrically arranged with respect to the optical axis of the light source and located at opposite sides of the second group of gratings, and an effective focal length of the second waveguide section can be modulated by applying an electric field between the pair of first electrodes.
9. The optical waveguide lens of claim 4 , wherein the first group of gratings is spaced from the second group of gratings.
10. The optical waveguide lens of claim 2 , wherein the planar waveguide is made of lithium niobate diffused with titanium.
11. The optical waveguide lens of claim 2 , wherein a refractive index of the media grating is larger than the refractive index of the planar waveguide.
12. An optical coupling module, comprising:
a light source; and
an optical waveguide lens optically coupled to the light source;
the optical waveguide lens comprising:
a substrate; and
a planar waveguide and a media grating formed on the substrate in sequence;
the media grating comprising a first group of gratings located adjacent to the light source and a second group of gratings away from the light source, the first group of gratings and the second group of gratings each comprising a plurality of strip-shaped films arranged in parallel and spaced from each other;
wherein the first group of gratings and the planar waveguide under the first group of gratings cooperatively define a first waveguide section, and the second group of gratings and the planar waveguide under the second group of gratings cooperatively define a second waveguide section; and
wherein light radiated from the light source passes through the optical waveguide lens and is successively converged by the first waveguide section and the second waveguide section;
wherein a coordinate system “oxy” is established, the origin “o” denotes an intersecting point of the optical axis of the light source and a widthwise direction of the planar waveguide, “x” axis denotes the widthwise direction of the planar waveguide, “y” axis denotes a phase difference with respect to incident light incident on the media grating in a direction inclined from the normal direction, and boundary of each strip-shaped film is set to conform following conditions:
x
n
=
±
ln
(
1
-
n
π
a
)
k
,
and wherein x n is the nth boundary of the strip-shaped films along the “ x ” axis, and a and k are constants.
13. The optical coupling module of claim 12 , wherein the diverging light emitted from the light source is first collimated by the first waveguide section and then focused by the second waveguide section.
14. The optical coupling module of claim 13 , wherein the planar waveguide comprises a front face and a back face at opposite ends thereof, light emitted from the light source enters the planar waveguide through the front face, successively passes through the first waveguide section and the second waveguide section, and exits the planar waveguide through the back face.
15. The optical coupling module of claim 13 , wherein the planar waveguide is of rectangular parallelepiped form, the light source is arranged in a manner such that an optical axis of the light source extends in a direction parallel to a lengthwise direction of the planar waveguide, the plurality of strip-shaped films of the first group of gratings and the second group of gratings are symmetrically arranged with respect to the optical axis of the light source.
16. The optical coupling module of claim 15 , wherein widths of the plurality of strip-shaped films of the first group of gratings and the second group of gratings decrease along a widthwise direction of the planar waveguide from the optical axis of the light source toward opposite sides of the planar waveguide.
17. The optical coupling module of claim 15 , wherein a distance between two adjacent strip-shaped films of the first group of gratings decreases along a widthwise direction of the planar waveguide from the optical axis of the light source toward opposite sides of the planar waveguide, and a distance between two adjacent strip-shaped films of the second group of gratings decreases along a widthwise direction of the planar waveguide from the optical axis of the light source toward opposite sides of the planar waveguide.
18. An optical waveguide lens configured to converge light emitted from a light source, the waveguide lens comprising:
a substantially planar substrate having;
a top surface;
a bottom surface opposite to and substantially parallel to the top surface;
a first side surface;
a second side surface opposite to and substantially parallel to the first side surface;
a front face; and
back face opposite to and substantially parallel to the front face;
the first side, second side, front face and back face each substantially perpendicular to the top surface and the bottom surface;
a planar waveguide having:
a top surface;
a bottom surface opposite to and substantially parallel to the top surface;
a first side surface;
a second side surface opposite to and substantially parallel to the first side surface;
a front face; and
a back face opposite to and substantially parallel to the front face;
the first side, second side, front face and back face each substantially perpendicular to the top surface and the bottom surface; and
the planar waveguide positioned on the top surface of the planar substrate with;
the bottom surface of the planar waveguide against the top surface of the planar substrate; and
the front substrate surface substantially contiguous with the front waveguide surface;
a first set of media gratings positioned on the top surface of the planar waveguide; and
a second set of media gratings positioned on the top surface of the planar waveguide;
wherein, the first set of media gratings and the second set of media gratings each comprise a plurality of elongated strip-shaped film elements, the elongated film elements spaced apart and arranged in parallel to the first side surface of the planar waveguide and the second side surface of the planar waveguide;
wherein, the first set of media gratings is positioned near the front face of the planar waveguide to form a first waveguide section;
wherein, the second set of media gratings is positioned away from the front face of the planar waveguide to form a second waveguide section; and
wherein, light emitted from a light source positioned at the front face of the planar waveguide is converged by the first waveguide section and then the second waveguide section;
wherein a coordinate system “oxy” is established, the origin “o” denotes an intersecting point of the optical axis of the light source and a widthwise direction of the planar waveguide, “x” axis denotes the widthwise direction of the planar waveguide, “y” axis denotes a phase difference with respect to incident light incident on the first set of media gratings and the second set of media gratings in a direction inclined from the normal direction, and boundary of each of the elongated strip-shaped film elements is set to conform following conditions:
x
n
=
±
ln
(
1
-
n
π
a
)
k
,
and wherein x n is the nth boundary of the strip-shaped film elements along the “x ” axis, and a and k are constants.