GB1569614A

GB1569614A - Optical fibre connectors

Info

Publication number: GB1569614A
Application number: GB417476A
Authority: GB
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1976-02-03
Filing date: 1976-02-03
Publication date: 1980-06-18
Also published as: DE2703887A1; AU505125B2; FR2340558B1; FR2340558A1; AU2182277A; CH613529A5; ES455578A1

Abstract

The end piece is provided with a virtually spherical lens, e.g. a ball lens (13) and the uncovered fibre end (14) is arranged in front of the lens (13) in such a way that the light bundle emerging from the fibre end (14) is converted into a parallel beam. A pair of such end pieces can be used as a ray coupler. <IMAGE>

Description

(54) OPTICAL FIBRE CONNECTORS (71) We, STANDARD TELEPHONES AND CABLES LIMITED, a British Company, of 190 Strand, London, W.C.2., England, do hereby declare Ithe invention, for which we pray ;that a patent rnay be granted b us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to lens terminations for optical fibres.

According to the invention there is provided an optical fibre termination for a coated fibre, including a substantially cylindrical transparent plastics body member having a convex lens surface formed integral and coaxial therewith, and having a coaxial guide taper adapted to receive the bared fibre end and leading to a central bore which bore locates the fibre end, and in which the central bore and the lens are so arranged that, when a fibre is fitted to the termination, light emitted from the fibre end is refracted into a substantially parallel beam by the lens.

Embodiments of the invention will now be described with reference to the drawings accompanying the Provisional Specification in which: Fig. 2 shows a lens termination having a guide Itaper for receiving a coated or clad fibre; Fig. 3 shows a pair of the terminations of Fig. 2 arranged in a coupler or connector assembly; and Fig. 5 shows a lens termination/beam splitter.

Fig. 2 shows a demountable fibre termination which includes an integral lens.

The termination includes a transparent cast or moulded cylindrical plastics body 21 having a coaxial guide taper 22 adapted to receive the prepared end of a coated optical fibre 23, which fibre may advantageously be of the plastics coated silica type. The guide taper 22 leads to a central bore 24 which receives and locates the bared end 25 of the fibre 23. In some applications the fibre end 25 may be secured in the bore 24 by a refractive index matched adhesive.

The termination is provided with a spherical lens surface 26 on the end face 27 opposite the taper entry and coaxial with ;the taper 22 and bore 24. The lens 26 and bore 24 are so arranged that when a fibre end 25 is located in the bore 24 the end of the core is at Ithe optical centre d the lens 26, i.e. such that light from the fibre is refracted by the lens 26 into a parallel beam.

'Fig. 3 shows how a pair of fibre terminations 311 and 32 of the type shown in Fig. 2 may be arranged to form a connector or coupler assembly. The two terminations, which are separated ;by a spacer ring 33, are mounted on a ferrule 34 which engages a machined or moulded surface on each termination so as to maintain the termina- tions in axial alignment. Due to the beam expanding effect of the ball lenses, however a small lateral tolerance between the terminations is permissible.

Fig. 5 shows demountaible fibre termination which may be employed as a beam splitter or combiner. The beam splitter of Fig. 5 has a plastics body similar to that of the termination of Fig. 2, but has one end of the body cut at an angle of approximately 45" to the body axis, the angled face 52 being half silvered. Further lens material is secured to the half silvered face so that the face 52 is effeotively embedded in the lens material. A ball lens surface 53 is formed around the end of the plastics body so as to receive the two light beams produced at the half silvered surface 52.

In s'ome applications ;the central bore of the terminations of Figs. 2, 3 and 5 which receives the fibre core may be provided with an accurately trilled jewel insert, which insert is advantageously secured in the plastics body during the moulding and casting process.

WHAT WE CLAIM IS: - 1. An optical fibre termination for a coated fibre, including a substantially cylindrical transparent plastics body member having a convex lens surface formed integral and coaxial therewith, and having a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. (54) OPTICAL FIBRE CONNECTORS (71) We, STANDARD TELEPHONES AND CABLES LIMITED, a British Company, of 190 Strand, London, W.C.2., England, do hereby declare Ithe invention, for which we pray ;that a patent rnay be granted b us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to lens terminations for optical fibres. According to the invention there is provided an optical fibre termination for a coated fibre, including a substantially cylindrical transparent plastics body member having a convex lens surface formed integral and coaxial therewith, and having a coaxial guide taper adapted to receive the bared fibre end and leading to a central bore which bore locates the fibre end, and in which the central bore and the lens are so arranged that, when a fibre is fitted to the termination, light emitted from the fibre end is refracted into a substantially parallel beam by the lens. Embodiments of the invention will now be described with reference to the drawings accompanying the Provisional Specification in which: Fig. 2 shows a lens termination having a guide Itaper for receiving a coated or clad fibre; Fig. 3 shows a pair of the terminations of Fig. 2 arranged in a coupler or connector assembly; and Fig. 5 shows a lens termination/beam splitter. Fig. 2 shows a demountable fibre termination which includes an integral lens. The termination includes a transparent cast or moulded cylindrical plastics body 21 having a coaxial guide taper 22 adapted to receive the prepared end of a coated optical fibre 23, which fibre may advantageously be of the plastics coated silica type. The guide taper 22 leads to a central bore 24 which receives and locates the bared end 25 of the fibre 23. In some applications the fibre end 25 may be secured in the bore 24 by a refractive index matched adhesive. The termination is provided with a spherical lens surface 26 on the end face 27 opposite the taper entry and coaxial with ;the taper 22 and bore 24. The lens 26 and bore 24 are so arranged that when a fibre end 25 is located in the bore 24 the end of the core is at Ithe optical centre d the lens 26, i.e. such that light from the fibre is refracted by the lens 26 into a parallel beam. 'Fig. 3 shows how a pair of fibre terminations 311 and 32 of the type shown in Fig. 2 may be arranged to form a connector or coupler assembly. The two terminations, which are separated ;by a spacer ring 33, are mounted on a ferrule 34 which engages a machined or moulded surface on each termination so as to maintain the termina- tions in axial alignment. Due to the beam expanding effect of the ball lenses, however a small lateral tolerance between the terminations is permissible. Fig. 5 shows demountaible fibre termination which may be employed as a beam splitter or combiner. The beam splitter of Fig. 5 has a plastics body similar to that of the termination of Fig. 2, but has one end of the body cut at an angle of approximately 45" to the body axis, the angled face 52 being half silvered. Further lens material is secured to the half silvered face so that the face 52 is effeotively embedded in the lens material. A ball lens surface 53 is formed around the end of the plastics body so as to receive the two light beams produced at the half silvered surface 52. In s'ome applications ;the central bore of the terminations of Figs. 2, 3 and 5 which receives the fibre core may be provided with an accurately trilled jewel insert, which insert is advantageously secured in the plastics body during the moulding and casting process. WHAT WE CLAIM IS: -

1. An optical fibre termination for a coated fibre, including a substantially cylindrical transparent plastics body member having a convex lens surface formed integral and coaxial therewith, and having a coaxial guide taper adapted to receive the bared fibre end and leading to a central bore which bore locates the fibre end, and in which the central bore and the lens are so arranged that, when a fibre is fitted to the termination, light emitted from the fibre end is refracted into a substantially parallel beam by the lens.

2, A termination as claimed in claim 2, and in which the fibre end is secured in the bore by a refractive index matching adhesive.

3. A termination as claimed in claim 2 or 3, and in which the lens is by a semi- reflecting plane so as to provide a beam splitting action

4. An optical fibre termination substantially as described herein with reference to Figs. 2 and 3, or to Fig. 5 of the drawings accompanying the Provisional Specification.

5. A method of coupling two or more optical fibres substantially as described herein with reference to Fig. 3 of the draw ings accompanying the Provisional Speoifica tion.