Optical devices and methods
View Patent ↗A fiber optic device comprises an optical lens element having a focal length greater than 2 mm, and an optical signal source or receiver mounted at the focal plane of the optical lens element and operative to communicate optical signals with a selectively transparent interference filter through the optical lens element. Methods for the production and use of the fiber optic devices are also disclosed.
1. A fiber optic device comprising, in combination:
an optical lens element having a focal length;
an optical fiber mounted at the focal plane of the optical lens element; and
a selectively transparent interference filter operative to communicate optical signals with the optical fiber through the optical lens element, the optical lens element and the interference filter cooperatively defining an optic axis substantially normal to the plane of the interference filter; wherein the optical fiber is positioned off-axis and the angle of incidents of an expanded beam signal between the off-axis optical fiber and the lens is not greater than 1.5 degrees.
2. The fiber optic device of claim 1 wherein the selectively transparent interference filter has a spectral response suitable for 50 GHz channel spacing.
3. The fiber optic device of claim 1 wherein the optical fiber is positioned off-axis and the spectral response of the selectively transparent interference filter has pass bands centered on the ITU Grid.
4. The fiber optic device of claim 1 wherein the selectively transparent interference filter has a spectral response suitable for 25 GHz channel spacing.
5. The fiber optic device of claim 3 wherein the selectively transparent interference filter has channels centered on the ITU Grid.
6. The fiber optic device of claim 1 wherein the selectively transparent interference filter has a spectral response suitable for channel spacing not greater than 12.5 GHz.
7. The fiber optic device of claim 5 wherein the selectively transparent interference filter has channels centered on the ITU Grid.
8. The fiber optic device of claim 1 wherein the selectively transparent interference filter comprises at least five coherently coupled cavities.
9. The fiber optic device of claim of claim 1 further comprising a housing, the optical lens element being secured within the housing and the optical fiber being mounted in an optical fiber ferrule secured within the housing.
10. The fiber optic device of claim 9 wherein the housing is substantially tubular.
11. The fiber optic device of claim 1 wherein the angle of incidence of an expanded beam signal between the off-axis optical fiber and the lens is not greater than 1.2 degrees.
12. The fiber optic device of claim 1 wherein the angle of incidence of an expanded beam signal between the off-axis optical fiber and the lens is not greater than 1 degree.
13. The fiber optic device of claim 1 wherein the optical lens element has a focal length of at least 3 mm.
14. The fiber optic device of claim 1 wherein the optical lens element has a focal length of at least 4 mm.
15. The fiber optic device of claim 1 further comprising an optical fiber ferrule, wherein the off-axis optical fiber is one of multiple off-axis optical fibers mounted together in a ferrule at the focal plane of the optical lens element.
16. The fiber optic device of claim 15 wherein at,least two off-axis optical fibers are mounted in contact with each other.
17. The fiber optic device of claim 15 wherein at least two off-axis optical fibers are mounted in the ferrule less than 10 micron spacing from each other.
18. The fiber optic device of claim 15 wherein at least two off-axis optical fibers are mounted in the ferrule with less than 100 micron spacing from each other.
19. The fiber optic device of claim 15 wherein the off-axis optical fibers mounted together in the ferrule each has reduced cladding in an area of contact with the other.
20. The fiber optic device of claim 19 wherein the off-axis optical fibers mounted together in the ferrule have core-to-core spacing of less than 125 um.
21. The fiber optic device of claim 1 wherein:
the selectively transparent interference filter is a high Q filter having a spectral response suitable for 50 GHz channel spacing on the ITU Grid;
the optical lens element has a focal length of at least 3 mm;
the angle of incidence of an optical signal passed between the off-axis optical fiber and the lens is not greater than 1.2 degrees; and
the optical fiber is operative as a single mode fiber for 1550 nm optical signals.
22. The fiber optic device of claim 1 wherein the first optical lens element comprises an aspheric lens.
23. The fiber optic device of claim 21 wherein the aspheric lens is a drum lens.
24. The fiber optic device of claim 1 wherein the optical lens element comprises a spherical lens.
25. The fiber optic device of claim 1 wherein the focal length of the optical lens element is between 2 mm and 8 mm.
26. The fiber optic device of claim 1 wherein the focal length of the optical lens element is between about 3.5 mm and 4.5 mm.
27. A fiber optic device comprising, in combination:
an optical lens element and having a focal length greater than 2 mm:
an optical signal element having an optical surface at the focal plane of the optical lens element: and
a selectively transparent interference filter operative to communicate optical signals with the optical surface of the optical signal element through the optical lens element, the optical lens element and the optical signal element cooperatively defining an optic axis substantially normal to the plane of the interference filter wherein the optical surface of the optical signal element is positioned off-axis.
28. An optical multiplexing device comprising:
a first optical lens element;
a first optical fiber ferrule comprising at least first and second optical fibers mounted together in the ferrule at the focal plane of the first optical lens element;
a selectively transparent interference filter;
a second optical fiber ferrule comprising at least a third optical fiber mounted in the second ferrule; and
a second optical lens element;
wherein:
the interference filter has a spectral response suitable for channel spacing not greater than 50 GHz and is operative
to receive optical signals passed to the interference filter from the first optical fiber through the first optical lens element,
to reflect at least selected optical signals back through the first optical lens element to the second optical fiber, and
to pass at least selected optical signals to the third optical fiber through the second optical lens element,
each of the optical lens elements has a focal length greater than 3 mm,
the angle of incidence of optical signals passed between the optical fibers and the lens elements is not greater than 1.2 degrees, and
each of the optical fibers is operative as a single mode fiber for 1550 nm optical signals.
29. A fiber optic device comprising:
a housing;
a first optical lens element positioned within the housing and having a focal length greater than 2 mm;
a first optical signal element having an optical surface in the housing at the focal plane of the first optical lens element;
a selectively transparent interference filter positioned within the housing and operative to communicate optical signals with the first optical signal element through the first optical lens element, the first optical lens element and the interference filter cooperatively defining an optic axis substantially normal to the plane of the interference filter;
a second optical lens element mounted within the housing and having a focal length greater than 2 mm; and
a second optical signal element having an optical surface in the housing at the focal plane of the second optical lens element and operative to receive optical signals passed by the interference filter.
30. The fiber optic device of claim 29 wherein the first optical signal element comprises an optical fiber.
31. The fiber optic device of claim 29 wherein the first optical signal element comprises an optical detector.
32. The fiber optic device of claim 29 wherein the first optical signal element comprises an optical signal waveguide.
33. The fiber optic device of claim 29 wherein the first optical signal element comprises a light source operative to emit optical signals at the optical surface.
34. The fiber optic device of claim 33 wherein the light source comprises a laser.
35. The fiber optic device of claim 33 wherein the light source comprises a semiconductor optical amplifier.
36. The fiber optic device of claim 33 wherein the light source comprises an edge emitting light emitting diode.
37. The fiber optic device of claim 29 wherein the selectively transparent interference filter comprises a sputter-deposited film stack comprising alternating layers of a first material and a second material, the first material having a different refractive index than the second material.