Source: http://www.google.com/patents/US6738556?dq=5251294
Timestamp: 2017-10-24 00:49:00
Document Index: 726143535

Matched Legal Cases: ['art 13', 'art 15', 'art 13', 'art 15', 'art 13', 'art 15', 'art 13', 'art 15', 'art 15', 'art 15', 'art 13', 'art 13', 'art 15', 'art 15', 'art 15', 'art 15']

Patent US6738556 - Supporting structure for optical fiber fixing and submicron fine alignment - Google Patents
The invention relates to a clip for holding an optical fiber which is enclosed in a fiber support tube, with respect to an optical source. The clip provides a rigid front part and a flexible back part in one single structure. This specific structure allows fixing and precise adjustment of the optical...http://www.google.com/patents/US6738556?utm_source=gb-gplus-sharePatent US6738556 - Supporting structure for optical fiber fixing and submicron fine alignment
Publication number US6738556 B1
Application number US 10/110,949
PCT number PCT/IB2000/001530
Publication number 10110949, 110949, PCT/2000/1530, PCT/IB/0/001530, PCT/IB/0/01530, PCT/IB/2000/001530, PCT/IB/2000/01530, PCT/IB0/001530, PCT/IB0/01530, PCT/IB0001530, PCT/IB001530, PCT/IB2000/001530, PCT/IB2000/01530, PCT/IB2000001530, PCT/IB200001530, US 6738556 B1, US 6738556B1, US-B1-6738556, US6738556 B1, US6738556B1
Inventors Peter Mueller, Bernd Valk
Patent Citations (6), Referenced by (7), Classifications (6), Legal Events (13)
Supporting structure for optical fiber fixing and submicron fine alignment
US 6738556 B1
The invention relates to a clip for holding an optical fiber which is enclosed in a fiber support tube, with respect to an optical source. The clip provides a rigid front part and a flexible back part in one single structure. This specific structure allows fixing and precise adjustment of the optical fiber alignment in a fully automated process in relatively few steps. No parts matching and multiple part handling are required when this clip is used, and final fine adjustment can be achieved by laser hammering and/or re-bending. The support tube is laser welded to the clip.
1. A fiber holding clip in an optical module for holding an optical fiber secured in a fiber support tube adjustable with respect to a light source, said clip comprising
two fiber support tube holding parts (13, 15) on a common base essentially consisting of two parallel flanges (17 a, 17 b) extending along said fiber support tube (37),
a first, essentially stiff holding part (13) located close to the fiber's light entry point, said first holding part being designed to serve as pivot point when said fiber support tube (37) is adjusted,
a second, deformable holding part (15) located downstream of said first holding part, said second holding part allowing adjustment of said fiber support tube (37) essentially perpendicular to said fiber's optical axis, and
a mounting plate (45) to which said common base is mounted by a plurality of base welding spots (41 a, 41 b, 43 a, 43 b) located such that rigidity in the area of the first, essentially stiff holding part (13) is increased, whereas rigidity in the area of the second, deformable holding part (15) is decreased.
2. The fiber holding clip according to claim 1, wherein
the base welding spots (41 a, 41 b) in the area of the first, stiff holding part (13) are positioned close to the side walls of said holding part thus increasing rigidity, and
the base welding spots (43 a, 43 b) in the area of the second, deformable holding part (15) are positioned more remote from the side walls of that back part thus increasing deformability.
3. The fiber holding clip according to claim 1 wherein each of the holding parts (13,15) comprises a pair of two parallel, opposite side walls (19 a, 19 b; 25 a, 25 b) of equal length for holding the fiber support tube (37), the side walls of each said pair are interconnected by a respective arch segment (21, 27), and
the side walls on each side of said clip are connected to the base flange (17 a, 17 b) by a respective connecting portion (23 a, 23 b, 29 a, 29 b).
4. The fiber holding clip according to claim 3, wherein
the connecting portions (23 a, 23 b) of the first, stiff holding part (13) have about the same length as the respective side walls, thus achieving rigidity, whereas the connecting portions (29 a, 29 b) of the second, deformable holding part (15) have each only a fractional length of the respective side wall, thus achieving flexibility.
5. The fiber holding clip according to claim 3, wherein
each of the side walls (19 a, 19 b, 25 a, 25 b) has a narrow protruding edge (30 a, 30 b, 32 a, 32 b, 34 a, 34 b) to which a fiber tube can be attached by spot welding (31 a, 31 b, 33 a, 33 b, 35 a, 35 b).
6. The fiber holding clip according to claim 3, wherein
the position and/or width of the arch segment (27) Interconnecting the side walls (25 a, 25 b) of the second, deformable holding part (15) leaves an upper facet (34 a) at the far end of each side wall (25 a) above the position of the respective connecting portion (29 a), so that moving the far end of the fiber support tube (37) effects deformation of said connecting portion (29 a).
7. The fiber holding clip according to claim 3, wherein
the arch segment (21) connecting the side walls (19 a, 19 b) of the first, stiff holding part (13) is shorter than the respective connecting portions (23 a, 23 b), leaving one upper facet (30 a, 30 b) on each side wall to which the fiber support tube (37) is fixed by a weld spot (31 a, 31 b), and
the arch segment (27) connecting the side walls (25 a, 25 b) of the second, deformable holding part (15) is shorter than the respective connecting portions (29 a, 29 b), leaving at least one upper facet (32 a, 34 a) at each said side wall (25 a) to which said fiber tube (37) is attached by at least one weld spot (33 a, 35 a).
8. The fiber holding clip according to claim 3 wherein
the arch segment (21) of the first, stiff holding part (13) is wider than the arch segment (27) of the second, deformable holding part (15).
9. The fiber holding clip according to claim 2 wherein each of the holding parts (13,15) comprises a pair of two parallel, opposite side walls (19 a, 19 b; 25 a, 25 b) of equal length for holding the fiber support tube (37),
the side walls of each said pair are interconnected by a respective arch segment (21, 27), and
10. The fiber holding clip according to claim 7, wherein each side wall (25 a) of the second holding part (15) comprises two upper facets (32 a, 34 a) to which said fiber tube (37) is attached by two weld spots (33 a, 35 a).
Present invention is related to fiber-optical transmission devices, and more particularly to a clip structure for fixing an optical fiber with respect to an optical source such as a laser diode.
In many modem communication networks, signals are transmitted in optical form through fibers for communication. Furthermore, optical fibers are the preferred medium to transport light from a source to the location of interaction with matter, e.g. fiber optical amplifiers, laser welders, etc. Important parts of these networks and devices are the arrangements where an optical signal, generated in a laser light source, is coupled into the transmission fiber. Optical coupling arrangements therefore have received much attention, because the energy lost in the coupling process should be minimal. Furthermore, the fabrication of such devices which have very small dimensions and tolerances is a complicated and delicate task.
Another approach is disclosed in U.S. Pat. No. 5,619,609 to Pan et al. entitled “Fiberoptic Support Clip”. The clip constitutes a channel into which the fiber sleeve is inserted from above and then, after optical adjustment, fixed by laser welding to the top edges of the walls of the channel. It appears that after initial placement of the fiber sleeve on the fiber, the sleeve must be removed and then inserted again for proper fiber adjustment and clip placement. This increases cycle time during manufacturing. Furthermore, fine adjustment after clip placement might be difficult because of the so-called slip friction.
It is an object of the invention to devise a fiber holding device which consists essentially of a single structure. A further object is to provide a fiber holding device which does not necessarily require small tolerances but still allows precise adjustment and fixing of the optical fiber in relatively few steps.
The invention for achieving this object, as defined in the claims, is a fiber holding clip for fixing an optical fiber secured in a fiber support tube, with respect to a light source, having a rigid front part and a flexible back part, so that for adjusting the position of the fiber tip, the flexible back part can be deformed to move the fiber with the fiber support tube while in the rigid front part a pivot point is available; a further aspect of the invention is an optical module subassembly for holding an optical fiber secured in a fiber support tube, with respect to a light source, the subassembly comprising a clip consisting of two fiber holding parts—a rigid front part and a flexible back part —on common base flanges, wherein welding spots fixing the base flanges to a mounting plate are specifically arranged to increase stability at the rigid front part and to increase flexibility at the flexible back part of the clip.
The invention will now be explained in more detail with reference to an embodiment illustrated in the accompanying drawings. The figures are diagrammatic and not drawn to scale, for greater clarity.
DETAILED DESCRIPTION A) Specific Clip Structure
In FIG. 1 the whole fiber holding clip structure 11 is shown. It comprises a rigid front part 13 and a flexible back part 15, both on common base flanges 17 a and 17 b. Front part 13 includes two side walls 19 a and 19 b for holding the fiber support tube (37 in FIG. 2 and FIG. 3). These side walls are connected to each other by arch segment 21, and they are connected to respective base flanges 17 a and 17 b by curved connecting portions 23 a and 23 b.
The back part 15 includes also two side walls 25 a and 25 b for holding the fiber support tube (37). These side walls are connected to each other by arch segment 27, and they are connected to the base flanges 17 a and 17 b by curved connecting portions 29 a and 29 b, respectively. It should be noted that the length, in longitudinal direction, of connecting portions 29 a/b is much shorter than that of connecting portions 23 a/b, so that the front part 13 is relatively stiffly fixed to the base flanges, whereas the back part 15 can be bent by plastic deformation of the curved connecting portions 29 a/b. The upper surfaces (facets) of side walls 19 a/b and 25 a/b have narrow edges 30 a, 30 b (front part) and 32 a, 32 b, 34 a, 34 b (back part) to which the fiber support tube can be fixed by spot welding. Clip portions which are symmetrical pairs are designated by number suffixes a and b (e.g. 25 a and 25 b). Some of them are hidden in the drawing (e.g. 25 b). Therefore it should be noted that the clip structure and fixing points are completely symmetrical with respect to the longitudinal axis of the clip.
In present example of the clip structure,.the curved connecting portions 23 a/b for holding side walls 19 a/b of rigid front part 13 have the same length (in longitudinal direction) as these side walls. The curved connecting portions 29 a/b for holding side walls 25 a/b of the flexible back part 15 have a length (in longitudinal direction) which is only a fraction (e.g. one quarter) of the length of the respective side walls 25 a/b. Arch segment 27 interconnecting side walls 25 a/b of the flexible back part 15 is located in the middle of the side wall length to allow welding spots (e.g. 33 a and 35 a) for fiber tube fixing on narrow edges (e.g. 32 a and 34 a) on both sides of this arch segment 27. In particular, weld spots 35 a/b on these narrow edges of the flexible back part 15 are located just above the connecting portions 29 a/b so as to have the best bending effect on them when the fiber support tube 37 is gripped at its far end (37×, close to back portion 15) and slightly moved for final adjustment.
Thus, an important aspect of the invention—for allowing a fast and precise adjustment of the fiber position—is the specific, one-piece structure of the clip with a relatively stiff, rigid front part, and a flexible back part easily modifiable by plastic deformation of the connecting portions joining it to the common base flanges.
B) Fixing of Fiber Holding Clip to Module Base Plate
Another aspect of the invention is the pattern of the weld spot locations for fixing the base flanges 17 a/b of the clip 13 to a base plate 45 of the fiber holding subassembly of the optical module. This is shown in particular in FIG. 5.
The weld spots for fixing the clip structure to the module's base plate 45 are located on the base flanges 17 a/b and are shown as circles 41 a, 41 b and 43 a, 43 b, respectively. In the front half of the clip, i.e. the region of the rigid front part 13, weld spots 41 a/b are situated together in a row relatively close to the side walls 19 a/b. This will hold the front part 13 tightly in place which is desired because a pivotal point for fiber support tube movement is thus more stable. In the back half of the clip, i.e. in the region of the flexible back part 15, there are fewer weld spots 43 a/b, and they are located more remote from the side walls 25 a/b than is the case for the weld spots 41 a/b (with respect to their neighboring side walls). This allows easier movement of the far end (37×) of the fiber support tube 37 by deformation of the curved connecting portions 29 a/b of back part 15.
It should be noted that at the back part 15, weld spots 35 a/b are located above connecting portions 29 a/b, to support the efficiency of bending the connecting portions 29 a/b when slightly moving the far end 37× of fiber support tube 37 for final fine adjustment (cf. FIG. 2 and FIG. 3).
C) Procedure for Fiber Fixing and Alignment by Welding
One possible example of the process steps for fiber fixing and alignment with—the above described fiber holding clip—is shown in the flow diagram of FIG. 6. Following steps are executed in the initial fixing procedure:
i) If the fixing loss is less than 15%, it is possible to secure the fiber support tube by welding it to the back part (flexible part) of the clip at weld spots 33 a/b.
j) If the fixing loss is larger than 15%, the fiber tip is moved by laser hammering at the back part of the fiber support tube (spots 35 a/b). The resulting pivoting ratio between the pivot weld and these hammer welds is ca. 1:5. This allows relatively rough laser hammering powers resulting in a small and controllable movement of the fiber tip.
D) Procedure for Final Fine Alignment (by Plastic Deformation)
After a heat treatment of the welded subassembly, the fiber tip has to be moved to its optimum position (i.e. maximum possible coupled output power) by bending. This is done by plastic deformation of the curved connecting portions 29 a/b of flexible back part 15. In order to do this, the optical module BTF is loaded again and the fiber support tube is loosely grasped around its very back end (37×) with gripping tweezers. Alternately in x-direction and y-direction, the fiber support tube is first touched by the gripper walls, then moved to the position of maximum coupled power and subsequently plastically deformed to freeze this position. This procedure will be repeated until the coupled power is more than e.g. 95% of P0 (i.e. until the fixing loss is less than −0.25 dB).
Statistical relevant quantities of samples using the inventive fiber clip show a fixing accuracy of less than 0.2 μm (equals a fixing loss of less than −0.5 db) for ˜93% and less than 0.1 μm (less than −0.25 db) for ˜80% of the samples.
JP2002323644A * Title not available
US7873254 * Apr 25, 2006 Jan 18, 2011 Fujitsu Limited Mounting member for fixedly holding cylindrical mounted part on printed wiring board
US20070145199 * Apr 25, 2006 Jun 28, 2007 Fujitsu Limited Mounting member for fixedly holding cylindrical mounted part on printed wiring board
U.S. Classification 385/137, 385/91
Cooperative Classification G02B6/4226, G02B6/4227
Owner name: NORTEL NETWORKS OPTICAL COMPONENTS (SWITZERLAND) G
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MUELLER, PETER;VALK, BERND;REEL/FRAME:013085/0405;SIGNING DATES FROM 20020604 TO 20020606