Issued Feb 4, 2003 (filed April 4, 2001)

Titled: Structures and Methods for Aligning Fibers

Inventor: Barclay J. Tullis

Listing of Claims (as corrected by Certificate of Correction):

1. A method of positioning a first fiber comprising:
(a) providing said first fiber to be aligned, wherein said first fiber has a diameter, an axis, and a side portion;
(b) providing a first groove within a first surface of a first substrate, wherein said first groove has a first width at a first intersection where it intersects a first edge of said first substrate, and has a second width away from said first edge, and wherein said first width is larger in value than said second width, and said second width is closer in value to said diameter;
(c) urging said side portion of said first fiber against said first edge and into said first intersection;
(d) pivotally rotating more of said first fiber into said first groove; whereby said first fiber is located in said first groove with a minimum of alignment effort.

2. The method of claim 1 further including urging said first fiber along said first groove to a first final position defined relative to one of the group including a coupling position to an end of another fiber, a coupling position to a planar waveguide, a light source, a filter, a detector, an optical device, and an end of said first groove.

3. The method of claim 1 further including:
(a) providing an opposing second fiber within said first groove, wherein said second fiber ends within said first groove;
(b) urging said first fiber along said first groove to a stopping location relative to said end of said second fiber.

4. The method of claim 1 further including:
(a) attaching at least a portion of said first fiber within said first groove with a prescribed rotational orientation about said axis,
(b) providing a second substrate with a second surface having a second groove, said second groove having a second intersection with a second edge of said second surface, wherein said second groove has a third width at said second intersection, with said third width larger than a fourth width which is away from said second edge, and wherein said fourth width is closer in value to said diameter of said first fiber,
(c) urging said first fiber against said second edge and into said second intersection;
(d) pivotally urging more of said first fiber about said second intersection into said second groove while rotating said first fiber, by rotating said first substrate, to place said first and second surfaces parallel to one another;
whereby said first fiber becomes sandwiched between said first and second substrates with a prescribed rotational alignment.

5. The method of claim 4 further including:
(a) prescribing a destination position along said second groove; and
(b) sliding said first surface on said second surface along said second groove until said first fiber comes to said destination position.

6. A method of co-aligning two alignment grooves comprising:
(a) providing a fiber to be used as an alignment tool, wherein said fiber has a diameter;
(b) providing two substrates to be co-aligned, wherein each said substrate has both a first and a second surface with said second surface plane-parallel and equidistant to said first surface;
(c) providing each substrate with one of said two alignment grooves, wherein each said alignment groove spans said first surface respectively and has a first end of width approximately equal to said diameter of said fiber and a second end that has a width larger than said first end;
(d) providing a work surface on which said second surfaces of said substrates are placed slidably on said work surface;
(e) first disposing said two substrates to coarsely align said two alignment grooves to be co-axial with their said first ends close to one another;
(f) disposing said fiber to curve toward said first surfaces to contact said substrates at said second ends;
(g) urging said fiber down into said two alignment grooves starting near said second ends of said two alignment grooves and working inward toward said first ends;
(h) urging said substrates together while keeping said fiber within said two alignment grooves;
whereby said substrates become precisely aligned with their said two alignment grooves oriented co-axially and said substrates contacting one another.

7. A tunable fiber optic apparatus having an optical coupling ratio that can be adjusted, the apparatus comprising:
(a) two substrates, wherein each said substrate has a first surface with a first groove suitable for holding a fiber, wherein said first surfaces are slidable on one another, and wherein a plane of contact exists between the two said first surfaces;
(b) two optical fibers each with a mutually plane-parallel side-polished first area, wherein said first areas are sandwiched between said first surfaces, and wherein each said optical fiber lies within only one of said first grooves, and wherein said first areas of-said optical fibers are pressed against one another and lie substantially within said plane of contact;
(c) at least one alignment groove on each of said first surfaces wherein said alignment grooves are parallel and offset relative to said first grooves such that said alignment grooves together form a channel between said two first surfaces;
(d) a third fiber positioned in said channel and having a lengthwise direction, wherein said third fiber constrains substrate sliding to a direction substantially parallel to said lengthwise direction;
whereby sliding said two substrates against one another substantially along said lengthwise direction easily adjusts said optical coupling ratio.

8. The tunable fiber optic apparatus of claim 7 wherein said channel is bi-directionally tapered forming a region of narrowest channel width and a center of rotation therein, wherein at least some slidable rotation is possible about said center of rotation.

9. The tunable fiber optic apparatus of claim 8 wherein said optical coupling ratio is tunable by said rotational adjustment.

10. The tunable fiber optic apparatus of claim 7 wherein said apparatus forms at least one apparatus selected from the group including a coupler, add-drop multiplexer, tap, splitter, joiner, filter, modulator and switch.

11. The tunable fiber optic apparatus of claim 7 wherein at least one of said first surfaces further includes circuitry of type selected from the group including electrical and optical.

12. The tunable fiber optic apparatus of claim 7 wherein at least one surface selected from the group including said first surfaces and said first areas further includes at least one thin film.

13. The tunable fiber optic apparatus of claim 7 wherein said plane of contact may include a thin film of fluid.

14. A method of tuning an optical coupling ratio between two side-polished optical fibers, the method comprising:
(a) providing two substrates, wherein each said substrate has a first surface with a first groove suitable for holding a fiber, wherein said first surfaces are slidable on one another, and wherein a plane of contact exists between the two said first surfaces;
(b) providing two optical fibers each with a mutually plane-parallel side-polished first area, wherein said first areas are sandwiched between said first surfaces, and wherein each said optical fiber lies within only one of said first grooves, and wherein said side-polished first areas of said optical fibers are pressed against one another and lie substantially within said plane of contact;
(c) providing at least one alignment groove on each of said first surfaces wherein said alignment grooves are parallel and offset relative to said first grooves such that they together form a channel between said two first surfaces;
(d) providing a third fiber having a lengthwise direction;
(e) positioning said third fiber into said channel, wherein said third fiber constrains substrate sliding to a direction substantially parallel to said lengthwise direction; and
(f) sliding one said side-polished first area against the other by sliding said substrates against one another substantially along said lengthwise direction; whereby said optical coupling is easily tuned.

15. The method of claim 14 further including:
(a) providing said alignment grooves with a bi-directional taper in said plane of contact to form a region of narrowest channel width and a center of rotation therein;
(b) tuning said optical coupling ratio by slidably rotating said substrates about said center of rotation.

16. A fiber holder for guiding and positioning a portion of at least one fiber, said fiber holder comprising:
(a) a substrate made of a rigid material,
(b) a first surface on said substrate;
(c) a first edge defining at least a portion of said first surface;
(d) at least a first groove in said first surface, of sufficient size to hold a portion of said fiber;
(e) a first location on said first surface where said first groove intersects said first edge;
(f) a first groove width and a first groove depth at said first location;
(g) a second location on said first surface along said first groove away from said first location.
(h) a second groove width and a second groove depth at said second location;
(i) a first groove length between said first location and said second location;
(j) a third location on said first surface along said first groove away from both said first location and said second location;
(k) a third groove width and a third groove depth at said third location;
(l) a second groove length between said second location and said third location;
(m) first additional groove widths and first additional groove depths along said first groove length, wherein at least one of the group including said first additional groove widths and first additional groove depths increases continuously, smoothly and more rapidly than linearly along at least a portion of said first groove length in direction away from said second location and toward said first location;
(n) second additional groove widths and second additional groove depths along said second groove length, wherein at least one of the group including said second additional groove widths and second additional groove depths stays constant along at least a portion of said second groove length;
wherein said first width is substantially larger than a diameter of said fiber, and said second width and said third width are nearer that of said diameter;
whereby said first groove width, being larger than said second additional groove widths, more easily receives said fiber, making placement of said fiber into said first groove easier by commencing with pivoting said fiber about said first edge at said first location and then into said first groove at said second location and said third location, helping to precisely locate said fiber at least within said first groove over said second length and without said fiber encountering any sharp bends.

17. The fiber holder of claim 16 further including said fiber bonded to said substrate within said first groove at least somewhere along said second groove length, wherein said fiber remains free to move around within said groove along at least a portion of said first groove length;
whereby said fiber is strain relieved over at least some of said first groove length by virtue of said fiber encountering only smooth surfaces therealong and between said first groove length and said second groove length.

18. The fiber holder of claim 16 wherein said substrate is made of one of the group including a crystal material, semiconductor material, quartz material, and plastic material, and wherein at least one ratio of width to depth at one said location can be different from that at another said location.

19. The fiber holder of claim 16 wherein said substrate is made of crystal, and wherein at least a portion of said first groove is at least partially defined by a crystal plane.

20. The fiber holder of claim 19 wherein said first surface lies substantially in a crystal plane.

21. The fiber holder of claim 19 further comprising:
(a) groove cross-section perimeters; and
(b) contours of said perimeters; wherein at least a significant portion of said contours are defined by etching to lie substantially in at least one crystal plane.

22. The fiber holder of claim 21 wherein at least one of said contours is V-shaped.

23. The fiber holder of claim 21 wherein at least one of said contours has sloped sides and a flat bottom.

24. The fiber holder of claim 16 wherein at least a portion of said first surface is substantially planar.

25. The fiber holder of claim 16 further including
(a) said fiber, wherein said fiber is an optical fiber in said first groove, and,
(b) positioned along said first groove, at least one of the group including a coupling position to an end of another fiber, a coupling position to an end of a planar waveguide. a light source, a filter, a detector, an optical device, an end of said first groove at said third location, and an end of said fiber.

26. The fiber holder of claim 16 further including said fiber in said first groove. wherein said fiber is an optical fiber with a side-polished area, and, located at least somewhere along said second groove length, at least one of the group including a side-coupling to another fiber, a side-coupling to a planar waveguide, a coupler, an add-drop multiplexer, a demultiplexer, a tap, a splitter, a joiner, a filter, a polarizer, a reflector, an attenuator, a modulator, and a switch.

27. The fiber holder of claim 16 further including additional grooves for guiding and holding additional fibers.

28. The fiber holder of claim 16 further including a second intersection of said first groove with a second edge of said first surface.

29. The fiber holder of claim 16 further including a fourth location along said first groove located farther from said first edge than said third location, wherein the distance between said third location and said fourth location along the groove defines a third groove length, wherein said first groove has a fourth groove width and a fourth groove depth at said fourth location, and wherein said fourth width is substantially larger than said diameter.

30. The fiber holder of claim 29 wherein said fourth location is also the location of a second intersection of said first groove with a second edge defining at least a portion of said first surface.

31. The fiber holder of claim 29 further including:
(a) a first optical fiber inserted into said first groove, said first fiber having a first diameter and passing through said first location;
(b) a second optical fiber inserted into said first groove, said second fiber having a second diameter and passing through said fourth location;
wherein the diameters are at least approximately the same, and said first groove width and said fourth groove width are both substantially larger than these diameters;
whereby an optical connection is easily afforded between said first and second fibers at a location along said second groove length.

32. The fiber holder of claim 16 wherein at least one of the group including (a) one of the groove widths and (b) one of the groove depths varies along at least a portion of said first groove with a contour shape that is, at least approximately, one of the group including linear, parabolic, hyperbolic, elliptic, and arcuate.

33. The fiber holder of claim 25 further including a second such fiber holder with its respective optical fiber, wherein the two holders are attached to one another with their said first surfaces face-to-face.

34. The fiber holder of claim 26 further including a second such fiber holder with its respective side-polished optical fiber, wherein the two holders are attached to one another with their said first surfaces face-to-face and their side-polished areas opposing one another.

35. The fiber holder of claim 34 further including:
(a) an alignment fiber, and,
(b) within each said first surface, at least one alignment groove parallel to and offset an equal distance from its said first groove;
wherein at least one of said alignment grooves is arcuate along at least a portion of its length; wherein each alignment groove, viewed in a plan view to its respective first surface, runs parallel to its respective first groove, and wherein said alignment fiber is positioned within an alignment channel formed by oppositely facing these alignment grooves;
whereby said side-polished areas opposing one another can be finely tuned in their locations relative to one another by any of the group of actions including (a) sliding said first surfaces relative to one another along said alignment channel and (b) slight rotation of one said first surface over the other to the extent allowed by the combination of groove width tolerancing and shortening of the distance over which the alignment fiber offers restraint to such rotation.