Optical coupling element and optical module having the same
An optical coupling element, for coupling a light emitting element to a light transmission element, includes a light guide element. The light guide element has a light incident part, a total reflection surface and a light output part. The light incident path is formed at the light incident part corresponding to the light emitting element. The light reflection path is formed at the light output part corresponding to the light transmission element. The first included angle θ 1 is formed between the light incident path and the total reflection surface and is not equal to 45 degrees. The light emitting element is adapted to emit a beam toward the total reflection surface along the light incident path by passing through the light guide element from the light incident part. Moreover, the beam is reflected by the total reflection surface and is outputted toward the light transmission element.
1. An optical coupling element, for coupling a light emitting element to a light transmission element, comprising:
a light guide element, wherein the light guide element includes:
a light incident part;
a total reflection surface; and
a light output part having a light output surface, a light incident path is formed at the light incident part corresponding to the light emitting element, a light reflection path is formed at the light output part corresponding to the light transmission element, a first included angle θ 1 is formed between the light incident path and the total reflection surface, the first included angle θ 1 is not equal to 45 degrees, and a second included angle θ 2 is formed between the light output surface and the light incident path, wherein the light output surface and the light incident path are not parallel;
wherein the light emitting element is adapted to emit a beam toward the total reflection surface along the light incident path by passing through the light guide element from the light incident part, then the beam is reflected by the total reflection surface, and the beam is outputted toward the light transmission element from the light output part.
2. The optical coupling element according to claim 1 , wherein the light incident part comprises a light incident surface and at least one first lens, the first lens disposed on the light incident surface is adapted to receive the beam emitted by the light emitting element, the light output part further comprises at least one second lens, and the second lens disposed on the light output surface is adapted to output the beam reflected by the total reflection surface.
3. The optical coupling element according to claim 2 , wherein the second included angle θ 2 satisfies a condition: θ=90°−2θ 1 .
4. The optical coupling element according to claim 2 , wherein the first lens has a first bottom surface and a first spherical surface, the first bottom surface is contacted with the light incident part, the first spherical surface protrudes toward the light emitting element and is connected to the first bottom surface, the second lens has a second bottom surface and a second spherical surface, the second bottom surface is contacted with the light output part, and the second spherical surface protrudes toward the light transmission element and is connected to the second bottom surface.
5. The optical coupling element according to claim 4 , wherein a radius of the first bottom surface is equal to a radius of the second bottom surface.
6. The optical coupling element according to claim 2 , wherein a radius of a light spot formed by the beam passing through the first lens is greater than or equal to a radius of a light spot formed by the beam passing through the second lens.
7. The optical coupling element according to claim 2 , wherein the light incident path is perpendicular to the light incident surface.
8. The optical coupling element according to claim 1 , further comprising a shell, the light guide element is disposed in the shell, and the shell has two guide posts for fixing a relative position of the light transmission element and the light guide element.
9. An optical module, comprising:
a light emitting element for emitting a beam;
a light transmission element; and
an optical coupling element for coupling the light emitting element to the light transmission element, wherein the optical coupling element comprises a light guide element, the light guide element has a light incident part, a total reflection surface and a light output part, the light output part having a light output surface, a light incident path is formed at the light incident part corresponding to the light emitting element, a light reflection path is formed at the light output part corresponding to the light transmission element, a first included angle θ 1 is formed between the light incident path and the total reflection surface, the first included angle θ 1 is not equal to 45 degrees and a second included angle θ 2 is formed between the light output surface and the light incident path, wherein the light output surface and the light incident path are not parallel;
wherein the light emitting element is adapted to emit a beam toward the total reflection surface along the light incident path by passing through the light guide element from the light incident part, then the beam is reflected by the total reflection surface, and the beam is outputted toward the light transmission element from the light output part.
10. The optical module according to claim 9 , wherein the light emitting element comprises a light emitting surface, the light transmission element comprises an optical coupling surface, an axis of the light transmission element passes through the optical coupling surface, the light incident part comprises a light incident surface and at least one first lens, the light incident surface faces the light emitting surface, the first lens disposed on the light incident surface is adapted to receive the beam emitted by the light emitting element, the light output part faces the optical coupling surface and further comprises at least one second lens, and the second lens disposed on the light output surface is adapted to output the beam reflected by the total reflection surface.
11. The optical module according to claim 10 , wherein the second included angle θ 2 satisfies a condition: θ 2 =90°−2θ 1 .
12. The optical module according to claim 11 , wherein a third included angle θ 3 is formed between the axis of the light transmission element and a normal line of the light output surface, and the third included angle θ 3 is equal to the second included angle θ 2 .
13. The optical module according to claim 12 , wherein a fourth included angle θ 4 is formed between the optical coupling surface and the light incident path, a refraction index of the light transmission element is n 1 , and the third included angle θ 3 satisfies a condition:
θ 3 =arcsin(n 1 *sin θ 4 )−θ 4 .
14. The optical module according to claim 13 , wherein the fourth included angle θ 4 is 8 degrees.
15. The optical module according to claim 10 , wherein a first interval is formed between the light emitting surface and the light incident surface, and the first interval is greater than a focal length of the first lens.
16. The optical module according to claim 15 , wherein a second interval is formed between the axis of the light transmission element and the light output surface, and the second interval is greater than the first interval.
17. The optical module according to claim 10 , wherein the first lens has a first bottom surface and a first spherical surface, the first bottom surface is contacted with the light incident part, the first spherical surface protrudes toward the light emitting element and is connected to the first bottom surface, the second lens has a second bottom surface and a second spherical surface, the second bottom surface is contacted with the light output part, and the second spherical surface protrudes toward the light transmission element and is connected to the second bottom surface.
18. The optical module according to claim 17 , wherein a radius of a light spot formed by the beam passing through the first lens is greater than or equal to 0.6 times a radius of the first bottom surface, and the radius of the light spot is less than or equal to 0.8 times the radius of the first bottom surface.