EP0091738A2
Expired / Lapsed
EP
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Precise positioning of optical fibers
Assignee: Nortel Networks Ltd
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Filing: 1983-03-17
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Granted: —
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Expires: 2003-03-17
Abstract
Abstract Before splicing optical fibers (10) having cladding (12) and core (14) of differing refractive index, have their cores (14) axially aligned. The fiber ends (18, 20) are held apart with the fibers approximately coaxial. The fiber end surfaces (18, 20) are then illuminated and reflected light is monitored. Since reflectivity is a function of refractive index, the position of the core (14) in the reflectivity profile of each surface can be readily identified. The fiber ends (18, 20) can then be manoeuvred transverse of the fiber axes to bring the fiber core centers into registration with a datum line. The fiber ends are then brought close together for splicing. Previously, fibers having nominally identical outside diameters were aligned simply by pressing them into a common V groove (24), the optical transmission efficiency then depending on fiber/core concentricity. Alternatively, light was injected into the far end of one fiber, monitored at the far end of the other fiber, and the fibers at their near end manipulated to maximize monitored optical power. The present invention provides an easier and cheaper method of ensuring core alignment especially for monomode fibers.
Inventors
- 👤 Koichi Abe
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 17:20
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/26; G01B11/27; G02; G02B; G02B6/00; G02B6/24; G02B6/255; G02B6/2551
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
102 words
A method of positioning one end of an optical fiber relative to a datum line, the fiber having an end surface cleaved generally mirror flat and having an abrupt change in reflectivity at a region thereof, the method characterised by directing light at the fiber end surface (18), monitoring light reflected from the end surface (18) to identify the region of abrupt change in reflectivity, and moving the fiber end in a plane perpendicular to the longitudinal axis of the fiber to a position at which the region of abrupt change in reflectivity has a predetermined disposition relative to the datum line.
Claim 2
Independent Claim
102 words
A method of positioning one end of an optical fiber relative to a datum line, the fiber having an end surface cleaved generally mirror flat and having an abrupt change in reflectivity at a region thereof, the method characterised by directing light at the fiber end surface (18), monitoring light reflected from the end surface (18) to identify the region of abrupt change in reflectivity, and moving the fiber end in a plane perpendicular to the longitudinal axis of the fiber to a position at which the region of abrupt change in reflectivity has a predetermined disposition relative to the datum line.
Claim 3
Dependent Claim
66 words
A method of coaxially aligning a pair of fibers, the method further characterised by positioning a first fiber (10) using the method defined in claim 1, so that the first fiber extends along the datum line in one direction and positioning a second fiber (10) using the method defined in claim 1, so that the second fiber extends along the datum line in the opposite direction.
Claim 4
Dependent Claim
110 words
A method as claimed in claim 1, further characterised in that the fiber has an external cladding (12) and a central core (14), the refractive index, and thus the reflectivity of the core (14), being greater than those of the cladding (12), wherein the light reflected from the end surface is monitored to identify the position of the higher reflectivity core (14) in the reflectivity profile of the fiber end surface (18, 20), and the fiber end is moved in a plane perpendicular to the longitudinal axis of the fiber (10) to a position at which the high reflectivity core (14) has a predetermined disposition relative to the datum line.
Claim 5
Dependent Claim
77 words
A method as claimed in claim 3, further characterised in that the high reflectivity core (14) has a low reflectivity central dip (15) and the light reflected from the end surface (18, 20) is monitored to identify the position of the reflectivity dip (15), and the fiber end is moved in a plane perpendicular to the longitudinal axis of the fiber (10) to a position at which the reflectivity dip (15) is aligned with said datum line.
Claim 6
Dependent Claim
113 words
Apparatus for positioning one end of an optical fiber relative to a datum line, the fiber having an end surface of known reflectivity profile, the apparatus characterised by directing means for directing light at the fiber end surface (18), monitoring means (34, 36, 38) for monitoring light reflected from the end surface (18) to identify the region of an abrupt change in reflectivity of the end surface (18), and adjustment means for moving the fiber end in a plane perpendicular to a longitudinal axis of the fiber (10) to a position at which the region of abrupt change in reflectivity of the end surface has a predetermined disposition relative to the datum line.
Claim 7
Dependent Claim
113 words
Apparatus for positioning one end of an optical fiber relative to a datum line, the fiber having an end surface of known reflectivity profile, the apparatus characterised by directing means for directing light at the fiber end surface (18), monitoring means (34, 36, 38) for monitoring light reflected from the end surface (18) to identify the region of an abrupt change in reflectivity of the end surface (18), and adjustment means for moving the fiber end in a plane perpendicular to a longitudinal axis of the fiber (10) to a position at which the region of abrupt change in reflectivity of the end surface has a predetermined disposition relative to the datum line.
Claim 8
Dependent Claim
44 words
Apparatus according to claim 5, further characterised in that the directing means comprises a light source (40) located off the axis of the fiber and a mirror device (30, 32) to direct light from the source generally perpendicular to the fiber end surface (18).
Claim 9
Dependent Claim
39 words
Apparatus as claimed in claim 6, particularly for coaxially aligning a pair of fibers, the apparatus further characterised by means (28) for mounting the mirror device (30, 32) between the opposed end surfaces (18, 20) of the fibers (10).
Claim 10
Dependent Claim
83 words
Apparatus as claimed in claim 7, further characterised in that the mirror device comprises a pair of prisms (30, 32) located side-by-side, the device being drivable between two positions, in a first of which, a surface of one prism (30) directs light from said source (40) into the end surface (18) of one fiber (10) and, in a second position, a surface of the other prism (32) directs light from the source (40) into the end surface (18) of the other fiber (10).
Claim 11
Dependent Claim
74 words
Apparatus according to claim 7, further characterised in that the mirror device is a plane mirror (50) mounted on a rotatable carriage (52) angularly movable between a first position in which the mirror (50) reflects light from the source (40) into the end surface (18) of one fiber (10) and a second position in which the mirror (50) reflects light from the source (40) into the end surface (20) of the other fiber (10).
Claim 12
Dependent Claim
33 words
Apparatus as claimed in claim 7, further characterised by a jig having two supporting heads (22), each supporting head (22) having a V-groove (24) in a surface thereof, the V-grooves being approximately aligned.
Claim 13
Dependent Claim
17 words
Apparatus according to claim 10, further characterised by X, Y and Z microscrew adjustors for driving the
Claim 14
Dependent Claim
24 words
. Apparatus as claimed in claim 6 further characterised in that the monitoring means includes a microscope objective (36) and an eye-piece lens (34).
Claim 15
Dependent Claim
39 words
Apparatus as claimed in claim 12, further characterised by a beam splitter (38) is mounted on the microscope optic axis to direct light from the light source (40) through the objective lens (36) to the mirror device (30, 32).
References Cited (Backward Citations)
No citation records indexed.
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