Optical fiber array alignment unit
View Patent ↗An optical fiber alignment unit for the easy precise alignment of optical fibers in and array. In a preferred embodiment the positioning array is incorporated twice in an all optical cross connect switch utilizing MEMS mirrors for cross connecting optical fibers in a first set of optical fibers to optical fibers in a second set of optical fibers. The optical fibers are preferably arranged in rectangular arrays. These arrays include array sizes such as 4×8, 16×16 and 8×16. A preferred embodiment built and tested by Applicants is a modular optical switch in which an input 8×16 array of optical fibers from sixteen eight-fiber ribbons are cross-connected into an output 8×16 array of optical fibers also from sixteen eight-fiber ribbons.
1. A fiber-microlens positioning array comprising;
A) a plurality of optical fibers at least partially contained in a smaller plurality of fiber optic ribbons,
B) a mounting plate adapted to permit the passage through the mounting plate of said optical fibers extending from said fiber optic ribbons,
C) a positioning plate comprised of a single silicon plate mounted on said mounting plate comprising a two dimensional array of lithographically-defined V-grooves for alignment of said plurality of optical fibers extending from said fiber optic ribbons to provide an array of optical fiber beam exit and/or entrance apertures, wherein each of said V-grooves are positioned in said single plate both horizontally and vertically with sub-micron accuracy, and wherein said plurality of optical fibers extending from said plurality of fiber optic ribbons are fixedly positioned in the V-grooves and
D) a microlens array comprised of a plurality of microlenses positioned to align a microlens with each optical fiber beam exit and/or entrance aperture in said array of optical fiber beam exit and/or entrance apertures.
2. A method for forming an array of optical fibers comprising:
A) providing a mounting plate adapted to permit the passage through the mounting plate of said optical fibers extending from fiber optic ribbons,
B) mounting on said mounting plate a positioning plate comprised of a single silicon plate comprising an array of lithographically-defined V-grooves positioned with sub-micron accuracy,
C) inserting optical fibers extending from said fiber optic ribbons through said mounting plate and into the V-grooves,
D) fixing the fibers in the V-grooves, and
E) positioning a microlens array comprised of a plurality of microlenses to align a microlens with each optical fiber beam exit and/or entrance aperture in said array of optical fiber beam exit and/or entrance apertures to provide a fiber-micro lens positioning array.
3. The fiber-microlens positioning array as in claim 1 wherein said array of optical fiber beam exit and/or entrance apertures is an array of optical fiber beam exit apertures.
4. The fiber-microlens positioning array as in claim 1 wherein said array of optical fiber beam exit and/or entrance apertures is an array of optical fiber beam entrance apertures.
5. The fiber-microlens positioning array as in claim 1 wherein said array of optical fiber beam exit and/or entrance apertures is an array of optical fiber beam exit and entrance apertures.
6. The fiber-microlens positioning array as in claim 1 wherein said fiber-microlens positioning array is adapted to produce an array of parallel collimated light beams.
7. The fiber-microlens positioning array as in claim 1 wherein said array is adapted to produce an array of parallel collimated cross-connect communication beam paths.
8. The fiber-microlens positioning array as in claim 7 wherein each of said communication beam paths connects each of said exit and/or entrance aperture with a MEMS mirror.
9. The fiber-microlens positioning array as in claim 1 wherein said plurality of optical fiber ribbons is a plurality of 8-fiber ribbons.
10. The fiber-microlens positioning array as in claim 1 wherein said plurality of ribbons is 16 ribbons.
11. The fiber-microlens positioning array as in claim 7 wherein said microlens array is a lithographically fabricated microlens array.
12. The fiber-microlens positioning array as in claim 7 wherein each of said microlenses in the microlens array has a diameter of about 1.1 millimeters and a focal length of about 3.7 millimeters.
13. The fiber-microlens positioning array as in claim 7 wherein said microlens array is spaced away from said array of exit and/or entrance apertures so as to create a beam waist approximately at a desired location for each beam path.
14. The fiber-microlens positioning array as in claim 7 wherein said fiber-microlens positioning array and a similar fiber-microlens positioning array are components in an optical switch module for cross connecting optical fibers in a first set of optical fibers to optical fibers in a second set of fibers, said optical switch module comprising:
A) a first MEMS mirror array comprising an array of MEMS mirrors arrayed in a first MEMS mirror pattern corresponding to said first fiber-microlens array pattern and positioned to reflect communication light beams to and/or from optical fibers arrayed in said first fiber-microlens positioning array and a second MEMS mirror array comprising an array of MEMS mirrors arrayed in a second MEMS mirror pattern corresponding to said second fiber-microlens array pattern and positioned to reflect communication light beams to and/or from optical fibers arrayed in said second fiber-microlens positioning array,
B) a first alignment beam unit for providing an alignment beam for each communication beams between said first fiber-microlens array and said first MEMS array and co-aligning said alignment beams with the communication light beams, defining a first set of alignment beams, and a second alignment beam unit for providing an alignment beam for each communication beams between said second fiber-microlens array and said second MEMS array and co-aligning said alignment beams with the communication light beams, defining a second set of alignment beams,
C) a dichroic mirror positioned and adapted to reflect communication beams from said first MEMS array to said second MEMS array and/or to reflect communication beams from said second MEMS array to said first MEMS array and to transmit said first and second set of alignment beams,
D) a first beam direction sensor positioned and adapted to sense directions of each alignment beam in said first set of alignment beams transmitted through said dichroic mirror and a second beam direction sensor positioned and adapted to sense directions of each alignment beam in said second set of alignment beams transmitted through said dichroic mirror, and
E) a MEMS control system for controlling positions of each mirror in said first and second MEMS mirror arrays in order to provide optical connections between each of the mirrors in said first set of optical fibers and any fiber in said second set of optical fibers and/or to provide optical connections between each of the mirrors in said second set of optical fibers and any fiber in said first set of optical fibers.