GB2128766A - Single-mode optical fibre attenuator - Google Patents

Single-mode optical fibre attenuator Download PDF

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Publication number
GB2128766A
GB2128766A GB08229637A GB8229637A GB2128766A GB 2128766 A GB2128766 A GB 2128766A GB 08229637 A GB08229637 A GB 08229637A GB 8229637 A GB8229637 A GB 8229637A GB 2128766 A GB2128766 A GB 2128766A
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GB
United Kingdom
Prior art keywords
fibre
attenuator
diffusion
attenuation
heat
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.)
Granted
Application number
GB08229637A
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GB2128766B (en
Inventor
Andrew Baxter Harding
Alexander John Robertson
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.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
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 Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Priority to GB08229637A priority Critical patent/GB2128766B/en
Publication of GB2128766A publication Critical patent/GB2128766A/en
Application granted granted Critical
Publication of GB2128766B publication Critical patent/GB2128766B/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/255—Splicing of light guides, e.g. by fusion or bonding
    • G02B6/2552—Splicing of light guides, e.g. by fusion or bonding reshaping or reforming of light guides for coupling using thermal heating, e.g. tapering, forming of a lens on light guide ends
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/02—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the intensity of light
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/255—Splicing of light guides, e.g. by fusion or bonding
    • G02B6/2551—Splicing of light guides, e.g. by fusion or bonding using thermal methods, e.g. fusion welding by arc discharge, laser beam, plasma torch
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/264—Optical coupling means with optical elements between opposed fibre ends which perform a function other than beam splitting

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Coupling Of Light Guides (AREA)

Abstract

To make a single-mode optical fibre attenuator, the fibre is heated at the point at which the attenuator is needed, which causes the core material to diffuse into the cladding. Hence the attenuation to which light propagating in the fibre is subjected is increased. The amount of attenuation depends on the temperature and the time for which it is applied. This can be done when making a fusion splice by applying the heat for a period after the splice has been made. For large value attenuators, two or more closely-spaced attenuators are made by the above method. <IMAGE>

Description

SPECIFICATION Optical attenuators This invention relates to the attenuation of light in a single-mode fibre.
In the development of optical fibre systems the need has arisen for a cheap and compact fixed single-mode attenuator.
According to the invention, there is provided a method of making a single-mode optical fibre attenuator, which includes applying heat to the fibre at the point at which the attenuator is wanted to cause the core material to partially diffuse into the cladding, the extent of the diffusion being dependent on the temperature to which the fibre is heated and the time for which that heat is applied, the diffusion causing the attenuation of light propagating along the fibre to be increased.
An embodiment of the invention will now be described with reference to the accompanying highly schematic drawing.
A known method of splicing two optical fibre ends together is to place the ends together in abutting relation and apply heat.
This fuses the ends together. In the present arrangement when the ends have been satisfactorily fused together from the jointing aspect the heating is continued. This causes the core region to partially diffuse into the cladding material, see the accompanying drawing, which affects the light guiding properties of the fibre. Hence when the fibre has finally cooled down it is found that light propagating in the fibre is attenuated as a result of the partial diffusion just mentioned.
The degree of diffusion, and hence the degree of attenuation produced, is dependent on the temperature of the fibre and the time for which the fibre is at that temperature.
To produce attenuators of varying values we have found that the easiest way is to keep the temperature constant and to vary the time for which the fibre is maintained at that temperature. Thus for a standard monomode fibre, to make a 4dB attentuator, the splice region is maintained at 2000 C for 70 secs. To make an 8dB attenuator the splice region is maintained at 2000"C for 1 50 secs.
The diffusion rate is exponential, so that when an attenuator with a greater attenuation than 8dB is to be made, the hot zone is moved to a different area of the fibre and the process repeated. Thus two or more smaller attenuators will be produced. Hence to make a 24dB attenuator we produce a number of 4dB or 8dB attenuators in series in the fibre.
In doing this the points at which the heating is applied can be separated to give separate and distinct "sub-attenuators", or can be close enough to produce a diffused zone if the latter is preferred.
Thus it will be seen that an attenuator can also be made by applying heat to a section of the fibre other than a spliced joint. The case of the splice is convenient in that the continuation of the application of heat serves two purposes, to joint the fibres and to produce an attenuator.
It will be appreciated that the figures quoted above are experimental values for a particular fibre; for other fibres routine experiment is needed to get the desired attenuation.
Such an attenuator is not polarisation sensitive and does not result in reflected optical power affecting the stability of the light source.
1. A method of making a single-mode optical fibre attenuator, which includes applying heat to the fibre at the point at which the attenuator is wanted to cause the core material to partially diffuse into the cladding, the extent of the diffusion being dependent on the temperature to which the fibre is heated and the time for which that heat is applied, the diffusion causing the attenuation of light propagating along the fibre to be increased.
2. A method as claimed in claim 1, and in which to produce an attenuator with a relatively high attenuation the heating is performed at two or more points along the fibre.
3. A method of making a single-mode optical fibre attenuator, which includes placing two optical fibre ends together in abutting relation so that the two cores abut, applying heat to the abutting ends to cause them to fuse together, and continuing the application of heat after the ends have been fused to cause the core material to partially diffuse into the cladding, the extent of the diffusion being dependent on the temperature to which the fibre is heated and the time for which the heat is applied, the diffusion causing the attentuation of light propagating along the fibre to be increased.
4. A method as claimed in claim 3, and in which to produce an attenuator with a relatively high attenuation the heating is performed at two or more separated points along the fibre.
5. A method of making a single-mode optical fibre attenuator, substantially as described with reference to the accompanying drawings.
6. A single-mode optical fibre attenuator, made by the method of any one of the preceding claims.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Optical attenuators This invention relates to the attenuation of light in a single-mode fibre. In the development of optical fibre systems the need has arisen for a cheap and compact fixed single-mode attenuator. According to the invention, there is provided a method of making a single-mode optical fibre attenuator, which includes applying heat to the fibre at the point at which the attenuator is wanted to cause the core material to partially diffuse into the cladding, the extent of the diffusion being dependent on the temperature to which the fibre is heated and the time for which that heat is applied, the diffusion causing the attenuation of light propagating along the fibre to be increased. An embodiment of the invention will now be described with reference to the accompanying highly schematic drawing. A known method of splicing two optical fibre ends together is to place the ends together in abutting relation and apply heat. This fuses the ends together. In the present arrangement when the ends have been satisfactorily fused together from the jointing aspect the heating is continued. This causes the core region to partially diffuse into the cladding material, see the accompanying drawing, which affects the light guiding properties of the fibre. Hence when the fibre has finally cooled down it is found that light propagating in the fibre is attenuated as a result of the partial diffusion just mentioned. The degree of diffusion, and hence the degree of attenuation produced, is dependent on the temperature of the fibre and the time for which the fibre is at that temperature. To produce attenuators of varying values we have found that the easiest way is to keep the temperature constant and to vary the time for which the fibre is maintained at that temperature. Thus for a standard monomode fibre, to make a 4dB attentuator, the splice region is maintained at 2000 C for 70 secs. To make an 8dB attenuator the splice region is maintained at 2000"C for 1 50 secs. The diffusion rate is exponential, so that when an attenuator with a greater attenuation than 8dB is to be made, the hot zone is moved to a different area of the fibre and the process repeated. Thus two or more smaller attenuators will be produced. Hence to make a 24dB attenuator we produce a number of 4dB or 8dB attenuators in series in the fibre. In doing this the points at which the heating is applied can be separated to give separate and distinct "sub-attenuators", or can be close enough to produce a diffused zone if the latter is preferred. Thus it will be seen that an attenuator can also be made by applying heat to a section of the fibre other than a spliced joint. The case of the splice is convenient in that the continuation of the application of heat serves two purposes, to joint the fibres and to produce an attenuator. It will be appreciated that the figures quoted above are experimental values for a particular fibre; for other fibres routine experiment is needed to get the desired attenuation. Such an attenuator is not polarisation sensitive and does not result in reflected optical power affecting the stability of the light source. CLAIMS
1. A method of making a single-mode optical fibre attenuator, which includes applying heat to the fibre at the point at which the attenuator is wanted to cause the core material to partially diffuse into the cladding, the extent of the diffusion being dependent on the temperature to which the fibre is heated and the time for which that heat is applied, the diffusion causing the attenuation of light propagating along the fibre to be increased.
2. A method as claimed in claim 1, and in which to produce an attenuator with a relatively high attenuation the heating is performed at two or more points along the fibre.
3. A method of making a single-mode optical fibre attenuator, which includes placing two optical fibre ends together in abutting relation so that the two cores abut, applying heat to the abutting ends to cause them to fuse together, and continuing the application of heat after the ends have been fused to cause the core material to partially diffuse into the cladding, the extent of the diffusion being dependent on the temperature to which the fibre is heated and the time for which the heat is applied, the diffusion causing the attentuation of light propagating along the fibre to be increased.
4. A method as claimed in claim 3, and in which to produce an attenuator with a relatively high attenuation the heating is performed at two or more separated points along the fibre.
5. A method of making a single-mode optical fibre attenuator, substantially as described with reference to the accompanying drawings.
6. A single-mode optical fibre attenuator, made by the method of any one of the preceding claims.
GB08229637A 1982-10-16 1982-10-16 Single-mode optical fibre attenuator Expired GB2128766B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08229637A GB2128766B (en) 1982-10-16 1982-10-16 Single-mode optical fibre attenuator

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08229637A GB2128766B (en) 1982-10-16 1982-10-16 Single-mode optical fibre attenuator

Publications (2)

Publication Number Publication Date
GB2128766A true GB2128766A (en) 1984-05-02
GB2128766B GB2128766B (en) 1985-12-24

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GB08229637A Expired GB2128766B (en) 1982-10-16 1982-10-16 Single-mode optical fibre attenuator

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0161826A2 (en) * 1984-05-11 1985-11-21 Stc Plc Single mode optical fibre attenuators
WO1989010332A1 (en) * 1988-04-29 1989-11-02 British Telecommunications Public Limited Company Connecting optical waveguides
FR2633727A1 (en) * 1988-06-29 1990-01-05 Furukawa Electric Co Ltd OPTICAL COMPONENT FOR TRANSMISSION LINES AND METHOD FOR MANUFACTURING THE SAME
EP0356872A2 (en) * 1988-08-25 1990-03-07 Alcatel SEL Aktiengesellschaft Method for changing the waist diameter of monomode step index fibres
EP0575009A1 (en) * 1992-06-19 1993-12-22 SIRTI S.p.A. Method for fusion-forming an optical signal attenuator
US5319733A (en) * 1992-01-02 1994-06-07 Adc Telecommunications, Inc. Variable fiber optical attenuator
EP0740171A1 (en) * 1995-04-28 1996-10-30 Telefonaktiebolaget LM Ericsson (publ) Optical fiber attenuator
US5588087A (en) * 1992-01-02 1996-12-24 Adc Telecommunications, Inc. Overlapping fusion attenuator
WO2000016138A1 (en) * 1998-09-16 2000-03-23 The University Of Sydney In-fibre optical attenuator
EP1017140A2 (en) * 1998-12-29 2000-07-05 Nortel Networks Corporation Optical amplifier manufacture

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0161826A3 (en) * 1984-05-11 1986-12-30 Stc Plc Single mode optical fibre attenuators
US4728170A (en) * 1984-05-11 1988-03-01 Standard Telephones And Cables Public Limited Co. Single mode optical fibre attenuators
AU571082B2 (en) * 1984-05-11 1988-03-31 Stc Plc Optical fibre attenuators
EP0161826A2 (en) * 1984-05-11 1985-11-21 Stc Plc Single mode optical fibre attenuators
WO1989010332A1 (en) * 1988-04-29 1989-11-02 British Telecommunications Public Limited Company Connecting optical waveguides
EP0340042A1 (en) * 1988-04-29 1989-11-02 BRITISH TELECOMMUNICATIONS public limited company Connecting optical waveguides
US5142603A (en) * 1988-04-29 1992-08-25 British Telecommunications Public Limited Company Method of connecting high numerical aperture optical waveguides
FR2633727A1 (en) * 1988-06-29 1990-01-05 Furukawa Electric Co Ltd OPTICAL COMPONENT FOR TRANSMISSION LINES AND METHOD FOR MANUFACTURING THE SAME
EP0356872A2 (en) * 1988-08-25 1990-03-07 Alcatel SEL Aktiengesellschaft Method for changing the waist diameter of monomode step index fibres
EP0356872A3 (en) * 1988-08-25 1991-09-25 Alcatel SEL Aktiengesellschaft Method for changing the waist diameter of monomode step index fibres
US5588087A (en) * 1992-01-02 1996-12-24 Adc Telecommunications, Inc. Overlapping fusion attenuator
US5319733A (en) * 1992-01-02 1994-06-07 Adc Telecommunications, Inc. Variable fiber optical attenuator
EP0575009A1 (en) * 1992-06-19 1993-12-22 SIRTI S.p.A. Method for fusion-forming an optical signal attenuator
US5382275A (en) * 1992-06-19 1995-01-17 Sirtl S.P.A. Method for fusion-forming an optical signal attenuator
EP0740171A1 (en) * 1995-04-28 1996-10-30 Telefonaktiebolaget LM Ericsson (publ) Optical fiber attenuator
US5897803A (en) * 1995-04-28 1999-04-27 Telefonaktiebolaget Lm Ericsson Optical fiber attenuator made by fusion splicing offset fiber ends with extended heating after fusing
WO2000016138A1 (en) * 1998-09-16 2000-03-23 The University Of Sydney In-fibre optical attenuator
EP1017140A2 (en) * 1998-12-29 2000-07-05 Nortel Networks Corporation Optical amplifier manufacture
US6166851A (en) * 1998-12-29 2000-12-26 Nortel Networks Limited Optical amplifier manufacture
EP1017140A3 (en) * 1998-12-29 2003-07-30 Nortel Networks Limited Optical amplifier manufacture

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Publication number Publication date
GB2128766B (en) 1985-12-24

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Legal Events

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732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19931016