CA1068953A - Optical fibre connector for variable signal attenuation - Google Patents

Optical fibre connector for variable signal attenuation

Info

Publication number
CA1068953A
CA1068953A CA275,742A CA275742A CA1068953A CA 1068953 A CA1068953 A CA 1068953A CA 275742 A CA275742 A CA 275742A CA 1068953 A CA1068953 A CA 1068953A
Authority
CA
Canada
Prior art keywords
fibre
optical
bore
members
accept
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA275,742A
Other languages
French (fr)
Inventor
Otto I. Szentesi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nortel Networks Ltd
Original Assignee
Northern Telecom Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Northern Telecom Ltd filed Critical Northern Telecom Ltd
Priority to CA275,742A priority Critical patent/CA1068953A/en
Application granted granted Critical
Publication of CA1068953A publication Critical patent/CA1068953A/en
Expired legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24Coupling light guides
    • G02B6/26Optical coupling means
    • G02B6/264Optical coupling means with optical elements between opposed fibre ends which perform a function other than beam splitting
    • G02B6/266Optical coupling means with optical elements between opposed fibre ends which perform a function other than beam splitting the optical element being an attenuator

Abstract

OPTICAL FIBRE CONNECTOR FOR
VARIABLE SIGNAL ATTENUATION
Abstract of the Disclosure An optical fibre connector is disclosed for variable optical signal attenuation. The attenuator comprises a connecting element with a common bore of size to accept with close sliding fit two optical fibres in end to end relationship, and a positioning means for varying the end separation of said optical fibres relative to one another.

- i -

Description

68~53 This invention relates to connecting two optical fibres in end to end relationship and more particularly to connecting two optical fibres in end to end relationship with a predetermined amount of variable end separation for providing variable optical signal attenuation.
In the testing of fibre optic communication systems it is often necessary to insert a known amount of attenuation in the optical transmission path. Fixed attenuation has been realized by installing a splice element such as described in U.S. patent no. 3,972,585, such that the axial end separation between the fibres is a predetermined value to give the required attenuation. Such an approach means that a new attenuator has to be made for each value of attenuation wanted.
An optical fibre is extremely fragile and positioning and holding must be done without damage to the fibres. An optical fibre usually comprises a light propagating core of one predetermined refractive index and having an outer cladding layer of a lower refractive indexO The materials are usually glass. An alternative form has a separate outer layer, or cladding, but the fibre has a variable refractive index across its core, the index being higher at the fibre centre and lower at the outer circumference.
The fibre is covered with a flexible material as an example plastic, for protection and ease of handling.
The present invention provides the accurate end to end connection of optical fibres with a variable end separation by positioning the fibres in a tubular connecting ~- member such as described in U.S. Patent No. 3,972,585. Generally, one fibre is permanently held in the connecting member, as by ~ crimping or bonding, and the other fibre is moved by a linear ; ' ..... -...... .. ... " ,. . , , ~

. , ;' . . . ,' . ': . ' . - , . . . ' "' i ,`
positioner which moves the fibre back and forth axially to increase and decrease the end separation of the two fibres, thus increasing and decreasing the attenuation.
Before being positioned in the connecting me~lber, khe ends of the fibres are stripped of the coatings ;~
and the end surfaces prepared to be smooth, flat and perpendicular to the axis of the fibre. -~
The invention will be readily understood by the following description of certain embodiments, by way of example, in conjunction with the accompanying drawings, in which:-Figure 1 illustrates the principal of theinvention;
Figure 2 is a cross-section of an embodiment of the invention showing zero separation;
Figure 3 is a cross-section along the line A-A of Figure 2;
Figure 4 is a cross-section along the line B-B of Figure 2; ;
Figure 5 is a cross-section of an embodiment of the invention illustrating external connections;
Figure 6 is a cross-section along the line C-C of Figure 5; ~, Figure 7 is a graph of attenuation vs separation. -Figure 1 illustrates the principal of the ` invention where the tubular connecting member ~ has at each end a bore 9 of close sliding fit over coated fibres 10 and 14 and a central bore 11 which is a close sliding fit on the opposed uncoated fibre ends 12. For ease of insertion of the uncoated fibre ends 12 an inclined surface 13 e~tends between
- 2 -. ,.

1~6~3~53 .

the central bore 11 and the end bores 9. As an example the central bore 11 may be produced by a section which is preformed :-by deforming the walls of the member inwards to define the smaller central bore 11. Fibre 14 is stripped of its coating and placed into the tubular connecting member 8 and held in place by a crimp or bond 15, the fibre 14 may be supported by support member 16. Fibre 10 is stripped of its coating and supported on an axial positioner 17 by support member 18. The ~;
axial separation 19 of the fibre 14 and 10 is increased or 10 decreased by moving the axial positioner 17 back and forth .
along the axis o~ fibre 10.
Figure 2 illustrates a housing 20 have a bore 21 for supporting section 25 of positioning member 24 and ~.
a bore 23 for supporting section 27 of positioning member 24.
Housing member 20 has a hollowed portion 22 large enough to accept captive nut 31. The positioning member 24 is a basically cylindrical shape comprised of three sections. Section 25 is :
mounted in bore 21, section 26 has a reduced diameter and is threaded to accept captive nut 31, and section 27 has a further reduced diameter and is mounted in bore 23.
Positioning member 24 has an axial bore 28 therethrough of diameter sufficient to accept connecting element 8. A bore 29 of the same diameter as that of bore 28 . is provided in the end wall 30 of housing 20 in order to allow fibre 14 to pass through.
Captive nut 31 may have a knurled sur~ace to . allow for easier rotation.

,' Figure 3 is a cross~section along the line , . .
A-A of an embodiment as illustrated in Figure 2. Housing member 20 has a generally circular cross-section with a cutoff section 32 to expose captive nut 31. Bore 23 supports ~ ,:
': ;' ``` ~06~5~S3 ..: -section 25 of the positioning member 24 of Figure 2. Connecting element 8 with fibre 10 is shown in position in the centre of section 25.
Figure 4 is a cross-section along the line B-B of Figure 2 and illustrates the cross-sectional form of the hollowed section 22, and the captive nut 31. Fibre 14 is shown in the bore 28.
Figure 5 illustrates an embodiment of the invention in which a containing member 50 surrounds a connector as illustrated in Figure 2 for protection and ease of handling.
Bulkhead optical connectors 51 are provided through the `
containing member 50 to allow for interconnection to the connector. The movement of the fibres during variation of the end separation is taken up at the bends in fibres 52. Mounting screws 53 are shown on top of housing member 20. Side 54 of the containing member 50 may be transparent in order that calibrations mark 55 may be seen from outside. A hand hole 56 is provided in side 54 for adjustment of the end separation of fibres 10 and 14 by rotating captive nut 31. A transparent or 20 otherwise cover plate 57 may cover the hand hole when not in -use.
Figure 6 illustrates a cross-section of Figure 5 at the line C-C. The containing member 50 supports housing member 20 at the mounting screws 53.
Figure 7 shows a graph of the optical attenuation vs the incremental end separation of the fibres, experimental and theoretical. The splice element was prefilled with index matching fluid for this experiment but in practice may not be.
A method of measuring the attenuation is illustrated by the dotted boxes of Figure 5. An optical : ~:

~1~685~53 signal source 70 is connected to one of the bulkhead optical connectors 51. The output optical signal Erom the attenuator is fed to an optical siynal detector 71. The output from the signal detector 71 is processed by the signal measurement circuit 72. The separation of the fibre is varied from zero separation until the desired attenuation is achieved.

:- .. : .. :... . -

Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:-
1. An optical fiber connector for variable optical signal attenuation, comprising;
a connecting element with a common bore of a size to accept with close sliding fit two uncoated optical fibers in end-to-end relationship, said connecting element including two members, one moveable axially relative to the other, a fiber secured in each member; and positioning means acting between said members to move one member axially relative to the other to vary the gap between the ends of the fibers.
2. A connector as claimed in claim 1, including two further bores, one on each end of said common bore, a first of size to accept a first coated fibre with close sliding fit and means for permanently securing said coated fibre to said element, and a second bore of size to accept a second coated optical fibre with sliding fit to allow axial movement of the fibre.
3. A connector as claimed in claim 1, wherein the positioning means comprises a captive nut in a housing, said housing forming one of said members and said nut mounted on a threaded portion on the other of said members.
CA275,742A 1977-04-06 1977-04-06 Optical fibre connector for variable signal attenuation Expired CA1068953A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA275,742A CA1068953A (en) 1977-04-06 1977-04-06 Optical fibre connector for variable signal attenuation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA275,742A CA1068953A (en) 1977-04-06 1977-04-06 Optical fibre connector for variable signal attenuation

Publications (1)

Publication Number Publication Date
CA1068953A true CA1068953A (en) 1980-01-01

Family

ID=4108345

Family Applications (1)

Application Number Title Priority Date Filing Date
CA275,742A Expired CA1068953A (en) 1977-04-06 1977-04-06 Optical fibre connector for variable signal attenuation

Country Status (1)

Country Link
CA (1) CA1068953A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2504690A1 (en) * 1981-04-27 1982-10-29 Raychem Corp METHODS, APPARATUS AND ARTICLES FOR OPTICAL FIBER SYSTEMS
WO1985001118A1 (en) * 1983-08-29 1985-03-14 American Telephone & Telegraph Company Optical fiber connector
FR2557981A1 (en) * 1981-04-27 1985-07-12 Raychem Corp Methods, apparatuses and articles for fibre-optic systems
US4664732A (en) * 1981-04-27 1987-05-12 Raychem Corp. Methods and apparatus for optical fiber systems
FR2590370A1 (en) * 1985-11-21 1987-05-22 Cit Alcatel Adjustable attenuator connector for optical fibres
US4896938A (en) * 1983-08-29 1990-01-30 American Telephone And Telegraph Company, At&T Bell Laboratories Optical fiber connector comprising glass tubes
US4934785A (en) * 1983-08-29 1990-06-19 American Telephone And Telegraph Company Optical fiber connector

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2504690A1 (en) * 1981-04-27 1982-10-29 Raychem Corp METHODS, APPARATUS AND ARTICLES FOR OPTICAL FIBER SYSTEMS
EP0063954A1 (en) * 1981-04-27 1982-11-03 RAYCHEM CORPORATION (a Delaware corporation) Methods, apparatus and articles for optical fiber systems
WO1982003922A1 (en) * 1981-04-27 1982-11-11 Ltd Raychem Methods,apparatus and articles for optical fiber systems
FR2557981A1 (en) * 1981-04-27 1985-07-12 Raychem Corp Methods, apparatuses and articles for fibre-optic systems
US4664732A (en) * 1981-04-27 1987-05-12 Raychem Corp. Methods and apparatus for optical fiber systems
WO1985001118A1 (en) * 1983-08-29 1985-03-14 American Telephone & Telegraph Company Optical fiber connector
US4896938A (en) * 1983-08-29 1990-01-30 American Telephone And Telegraph Company, At&T Bell Laboratories Optical fiber connector comprising glass tubes
US4934785A (en) * 1983-08-29 1990-06-19 American Telephone And Telegraph Company Optical fiber connector
FR2590370A1 (en) * 1985-11-21 1987-05-22 Cit Alcatel Adjustable attenuator connector for optical fibres

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