WO2002075871A1 - Optical fibre amplifiers - Google Patents

Optical fibre amplifiers Download PDF

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Publication number
WO2002075871A1
WO2002075871A1 PCT/GB2002/001300 GB0201300W WO02075871A1 WO 2002075871 A1 WO2002075871 A1 WO 2002075871A1 GB 0201300 W GB0201300 W GB 0201300W WO 02075871 A1 WO02075871 A1 WO 02075871A1
Authority
WO
WIPO (PCT)
Prior art keywords
laser
casing
amplifier
optical fibre
amplifier according
Prior art date
Application number
PCT/GB2002/001300
Other languages
French (fr)
Inventor
Christopher Mark Hardingham
Original Assignee
Bookham Technology
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 Bookham Technology filed Critical Bookham Technology
Publication of WO2002075871A1 publication Critical patent/WO2002075871A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06754—Fibre amplifiers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/02—Constructional details
    • H01S3/04—Arrangements for thermal management
    • H01S3/042—Arrangements for thermal management for solid state lasers
    • 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
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4251—Sealed packages
    • G02B6/4253—Sealed packages by embedding housing components in an adhesive or a polymer material
    • 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
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4266—Thermal aspects, temperature control or temperature monitoring
    • G02B6/4268—Cooling
    • G02B6/4269—Cooling with heat sinks or radiation fins
    • 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
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4266—Thermal aspects, temperature control or temperature monitoring
    • G02B6/4268—Cooling
    • G02B6/4272—Cooling with mounting substrates of high thermal conductivity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06704—Housings; Packages
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light

Definitions

  • This invention relates to optical fibre amplifiers.
  • a pumped laser to amplify optical signals of 1530 - 1610nrn using an erbium doped silica core via a dichroic fibre coupler. It is crucial for the efficient operation of the amplifier for the temperature of the laser to be kept as constant as possible, since the output frequency from the laser varies significantly with temperature. It is critical that the output power and frequency of the laser be kept constant to ensure that the excitation of the erbium is kept high enough to generate the required signal gain. Since operation of the laser generates a significant amount of heat, this heat must be dissipated from the laser. Typically, 1 watt of heat must be removed from the laser during operation through a contact area of the order of 4mm by 4mm.
  • the present invention seeks to provide a solution to this problem.
  • an optical fibre amplifier including a casing and a pump laser for generating amplifying signals to the optical fibre, the pump laser being in communication with an outer surface of the casing.
  • the laser is physically mounted to the outside of the casing.
  • the optical fibre and electrical connectors of the laser lead into the casing are encapsulated, preferably by means of a resin or similar potting compound.
  • the pump laser may have a heat spreader or heat sink connected to the laser crystal, the heat sink being secured to, and in good thermal contact with, the casing of the amplifier.
  • the heat sink may be connected to further heat dissipation means which may also form a protective shield for the laser.
  • the laser is mounted in a recess so that its exterior is generally flush with the exterior of the casing.
  • Figure 1 shows a schematic side view of a first embodiment of the invention
  • Figure 2 shows a schematic side view of a second embodiment of the invention
  • Figure 3 shows a schematic side view of a third embodiment of the invention.
  • Figure 4 shows a schematic side view of a fourth embodiment of the invention.
  • FIG 1 there is shown a schematic side view of an optical fibre amplifier having a casing 1 and a laser 2.
  • the laser 2 is mounted on the outside of the casing 1.
  • the laser has a heat spreader 3 designed to absorb and dissipate the heat generated by the laser crystal and the spreader 3 is positioned with good thermal contact, for maximum thermal conduction, on the outer casing 1 of the amplifier.
  • the laser has a plurality of leads 4, comprising optical fibres and electrical leads which extend from the laser into the interior of the casing 1.
  • the leads are encapsulated in a resin or similar potting compound 5 for protection.
  • the heat spreader of the laser is arranged to be in contact with an external heat sink, which may be a rack in which the amplifier is located.
  • the amplifier may have an external heat dissipater in the form of a plate-like body 6 spaced from the outer casing.
  • the dissipater 6 is connected to the casing through legs 7 fastened to the casing 1 by, e.g. screw fasteners.
  • the laser 2 is connected, through its heat spreader 3, to the underside of the plate-like body 6 so that the heat from the laser is transmitted through the heat spreader 3 to the dissipater 6.
  • the external face of the dissipater may be finned or it may be connected to a larger source of conduction such as the rack in which the amplifier is mounted. Cooling is further assisted by convection by air flowing over both sides of the plate-like body. The efficiency of the convection may be improved by appropriate shaping of the cooling fins.
  • the dissipater 6 also serves to protect the laser from external knocks.
  • the embodiment shown in figure 2 is particularly applicable to the use of an external dissipater. In this embodiment, as shown, the laser 2 is located in a recess 8 in the amplifier casing 1.
  • the laser 2 may be secured to the casing 1 with the heat spreader 3 facing outwardly as shown in dotted outline at 3 a, preferably to lie substantially flush with the outer profile of the casing 1.
  • the embodiment of figure 3 shows the laser mounted in a recess with heat spreader secured to the underside of a metal shield 6a so that electrical leads and the optical fibres leading from the laser 2 are protected by the metal shield 6a attached to the heat spreader 3 which also serves to secure the laser 2 to the casing 1.
  • the laser is separated from the casing by an air gap which enables cooling of the laser 2 by convection. This convection can be enhanced if the heat spreader is secured to the underside of an external heat dissipater 6 spaced from the casing periphery as shown in Figure 4.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Lasers (AREA)

Abstract

An optical fibre amplifier including a casing 1 and a pump laser 2 for generating amplifying signals to the optical fibre, the pump laser 2 being mounted on the outside of the casing 1.

Description

OPTICAL FIBRE AMPLIFIERS
FIELD OF THE INVENTION
This invention relates to optical fibre amplifiers.
BACKGROUND ART
hi a known form of optical fibre amplifier it is known to use a pumped laser to amplify optical signals of 1530 - 1610nrn using an erbium doped silica core via a dichroic fibre coupler. It is crucial for the efficient operation of the amplifier for the temperature of the laser to be kept as constant as possible, since the output frequency from the laser varies significantly with temperature. It is critical that the output power and frequency of the laser be kept constant to ensure that the excitation of the erbium is kept high enough to generate the required signal gain. Since operation of the laser generates a significant amount of heat, this heat must be dissipated from the laser. Typically, 1 watt of heat must be removed from the laser during operation through a contact area of the order of 4mm by 4mm.
Since the laser is a sensitive and expensive electrical component, it is normally secured safely inside the casing of the amplifier but this leads to problems in dissipating the heat generated during use. The present invention seeks to provide a solution to this problem.
SUMMARY OF THE INVENTION
According to the present invention there is provided an optical fibre amplifier including a casing and a pump laser for generating amplifying signals to the optical fibre, the pump laser being in communication with an outer surface of the casing.
Preferably, the laser is physically mounted to the outside of the casing.
Advantageously, the optical fibre and electrical connectors of the laser lead into the casing and are encapsulated, preferably by means of a resin or similar potting compound.
The pump laser may have a heat spreader or heat sink connected to the laser crystal, the heat sink being secured to, and in good thermal contact with, the casing of the amplifier. Alternatively, the heat sink may be connected to further heat dissipation means which may also form a protective shield for the laser.
In another form, the laser is mounted in a recess so that its exterior is generally flush with the exterior of the casing.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: -
Figure 1 shows a schematic side view of a first embodiment of the invention;
Figure 2 shows a schematic side view of a second embodiment of the invention;
Figure 3 shows a schematic side view of a third embodiment of the invention; and
Figure 4 shows a schematic side view of a fourth embodiment of the invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Referring now to figure 1, there is shown a schematic side view of an optical fibre amplifier having a casing 1 and a laser 2. In accordance with the invention, the laser 2 is mounted on the outside of the casing 1. The laser has a heat spreader 3 designed to absorb and dissipate the heat generated by the laser crystal and the spreader 3 is positioned with good thermal contact, for maximum thermal conduction, on the outer casing 1 of the amplifier. The laser has a plurality of leads 4, comprising optical fibres and electrical leads which extend from the laser into the interior of the casing 1. The leads are encapsulated in a resin or similar potting compound 5 for protection.
In a modified embodiment, the heat spreader of the laser is arranged to be in contact with an external heat sink, which may be a rack in which the amplifier is located. Alternatively, as shown in Figures 3 and 4, the amplifier may have an external heat dissipater in the form of a plate-like body 6 spaced from the outer casing. In the embodiment of Figure 4, the dissipater 6 is connected to the casing through legs 7 fastened to the casing 1 by, e.g. screw fasteners. The laser 2 is connected, through its heat spreader 3, to the underside of the plate-like body 6 so that the heat from the laser is transmitted through the heat spreader 3 to the dissipater 6.
In this embodiment, little heat is transmitted to the casing by conduction because of the small contact area of the legs 7, whilst cooling of the dissipater 6 can be achieved in several ways. The external face of the dissipater may be finned or it may be connected to a larger source of conduction such as the rack in which the amplifier is mounted. Cooling is further assisted by convection by air flowing over both sides of the plate-like body. The efficiency of the convection may be improved by appropriate shaping of the cooling fins. The dissipater 6 also serves to protect the laser from external knocks. The embodiment shown in figure 2 is particularly applicable to the use of an external dissipater. In this embodiment, as shown, the laser 2 is located in a recess 8 in the amplifier casing 1. i an alternative form, the laser 2 may be secured to the casing 1 with the heat spreader 3 facing outwardly as shown in dotted outline at 3 a, preferably to lie substantially flush with the outer profile of the casing 1. The embodiment of figure 3 shows the laser mounted in a recess with heat spreader secured to the underside of a metal shield 6a so that electrical leads and the optical fibres leading from the laser 2 are protected by the metal shield 6a attached to the heat spreader 3 which also serves to secure the laser 2 to the casing 1. In this way, the laser is separated from the casing by an air gap which enables cooling of the laser 2 by convection. This convection can be enhanced if the heat spreader is secured to the underside of an external heat dissipater 6 spaced from the casing periphery as shown in Figure 4.

Claims

1. An optical fibre amplifier including a casing and a pump laser for generating amplifying signals to the optical fibre, the pump laser being in communication with an outer surface of the casing.
2. An amplifier according to claim 1, wherein the pump laser is mounted on the outside of the casing.
3. An amplifier according to claim 1 or 2, wherein the optical fibre and electrical connector leads of the laser lead into the casing and are encapsulated.
4. An amplifier according to claim 3, wherein the leads are encapsulated by means of a resin or similar potting compound.
5. An amplifier according any preceding claim, wherein the pump laser has a heat spreader or heat sink in communication with the laser crystal.
6. An amplifier according to claim 5, wherein the heat spreader or heat sink is secured to, and in thermal contact with, the casing of the amplifier.
7. An ampUfier according to claim 5 or 6, wherein the heat spreader or heat sink is connected to further heat dissipation means.
8. ■ An amplifier according to claim 7, wherein the heat dissipation means forms a protective shield for the laser.
9. An amplifier according to claim 7 or 8, wherein the heat dissipation means is spaced from the outer surface of the casing.
10. An amplifier according to any one of the preceding claims, wherein the laser is mounted in a recess in the casing.
11. An amplifier according to claim 10, wherein the exterior profile of the laser is generally flush with the exterior profile of the casing.
12. An optical fibre amplifier substantially as described herein with reference to and as illustrated in the ccompanying drawings.
13. An optical communications system including an optical fibre amplifier as claimed in any preceding claim.
PCT/GB2002/001300 2001-03-19 2002-03-19 Optical fibre amplifiers WO2002075871A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0106765.1 2001-03-19
GBGB0106765.1A GB0106765D0 (en) 2001-03-19 2001-03-19 Optical fibre amplifiers

Publications (1)

Publication Number Publication Date
WO2002075871A1 true WO2002075871A1 (en) 2002-09-26

Family

ID=9911008

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2002/001300 WO2002075871A1 (en) 2001-03-19 2002-03-19 Optical fibre amplifiers

Country Status (2)

Country Link
GB (1) GB0106765D0 (en)
WO (1) WO2002075871A1 (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04216529A (en) * 1990-12-18 1992-08-06 Fujitsu Ltd Optical amplifier
JPH06283789A (en) * 1993-03-26 1994-10-07 Shin Etsu Chem Co Ltd Light amplifier
JPH0955556A (en) * 1995-08-17 1997-02-25 Oki Electric Ind Co Ltd Optical amplifier module
EP0840411A2 (en) * 1996-10-31 1998-05-06 Kenichi Ueda Optical fiber laser device
JPH10190110A (en) * 1996-12-25 1998-07-21 Kyocera Corp Optical fiber amplifier
JPH11195827A (en) * 1997-12-26 1999-07-21 Furukawa Electric Co Ltd:The Optical fiber type light amplifier

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04216529A (en) * 1990-12-18 1992-08-06 Fujitsu Ltd Optical amplifier
JPH06283789A (en) * 1993-03-26 1994-10-07 Shin Etsu Chem Co Ltd Light amplifier
JPH0955556A (en) * 1995-08-17 1997-02-25 Oki Electric Ind Co Ltd Optical amplifier module
EP0840411A2 (en) * 1996-10-31 1998-05-06 Kenichi Ueda Optical fiber laser device
JPH10190110A (en) * 1996-12-25 1998-07-21 Kyocera Corp Optical fiber amplifier
JPH11195827A (en) * 1997-12-26 1999-07-21 Furukawa Electric Co Ltd:The Optical fiber type light amplifier

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 016, no. 565 (P - 1457) 7 December 1992 (1992-12-07) *
PATENT ABSTRACTS OF JAPAN vol. 1995, no. 01 28 February 1995 (1995-02-28) *
PATENT ABSTRACTS OF JAPAN vol. 1997, no. 06 30 June 1997 (1997-06-30) *
PATENT ABSTRACTS OF JAPAN vol. 1998, no. 12 31 October 1998 (1998-10-31) *
PATENT ABSTRACTS OF JAPAN vol. 1999, no. 12 29 October 1999 (1999-10-29) *

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Publication number Publication date
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