WO2002075976A1 - Erbium doped fibre amplifier having a tuneable pump laser - Google Patents

Erbium doped fibre amplifier having a tuneable pump laser Download PDF

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Publication number
WO2002075976A1
WO2002075976A1 PCT/GB2002/001301 GB0201301W WO02075976A1 WO 2002075976 A1 WO2002075976 A1 WO 2002075976A1 GB 0201301 W GB0201301 W GB 0201301W WO 02075976 A1 WO02075976 A1 WO 02075976A1
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WO
WIPO (PCT)
Prior art keywords
laser
pump laser
amplifier
pump
fibre
Prior art date
Application number
PCT/GB2002/001301
Other languages
French (fr)
Inventor
Lloyd Langley
Stephen John Taylor
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 WO2002075976A1 publication Critical patent/WO2002075976A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/29—Repeaters
    • H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form

Definitions

  • the present invention relates to an optical amplifier, in particular an erbium doped fibre amplifier (EDFA), having control means to compensate for non optimum performance.
  • EDFA erbium doped fibre amplifier
  • the fibre length In an optical amplifier, such as an EDFA, for a given pump power, to obtain the maximum amount of gain for a given erbium concentration in the fibre core, the fibre length should be increased to the point at whic the pump power becomes equal to the intrinsic pump threshold. This determines the optimum length of the fibre to maximise the signal gain for the amplifier. However, for other applications, the fibre length may need to be optimised for other parameters such as the noise figure or output saturation power.
  • the fibre length may prove to be sub-optimal. It is known to compensate for sub-optimal performance of an optical amplifier by increasing the pump power. It is also known to tailor the gain of a WDM amplifier by an appropriate choice of the fibre length.
  • the present invention seeks to provide an optical amplifier with control means which control means is adapted to modify the gain in situ.
  • an optical amplifier having a pump laser, which pump laser is adapted to pump an optical fibre in an optical circuit via an opto-coupier, Wuerein t .e pump aser is a tuneable laser.
  • the amplifier is an erbium doped fibre amplifier.
  • the pump laser is a ITJ-N semiconductor tuneable laser.
  • the ability to tune the wavelength of the pump laser allows the laser wavelength to be matched to the assembled components. This is particularly advantageous as it is simpler to tune the laser than to change the length of fibre in the amplifier once the amplifier has been assembled.
  • Fig.l shows a schematic representation of an EDFA DETAILED DESCRIPTION OF THE EMBODIMENT
  • the amplifier is connected between an optical fibre input line 1 and an output line 2, the fibres being formed of a silica core of 7nm diameter surrounded by an outer sleeve of silica having a different refractive index of approximately 120nm.
  • the amplifier is intended for the transmission of optical signals at a frequency of approximately 1530nm to form a telecornmunication transmission signal.
  • the input line 1 is optically connected to a dichroic coupler 3, which, in turn, is connected to the output line 2 via a fibre coil 4.
  • the fibre coil 4 is doped with erbium which, when excited by an applied signal at the right frequency, is amplified.
  • a tuneable laser 5 is connected optically to the dichroic coupler 3 so that when an electrical signal is applied to the laser 5, a light signalis transmitted to the fibre coil 4 through the dichroic coupler 3.
  • the erbium ions in the erbium doped optical fibre coil 4 are inverted by the pumped signal to generate a signal gain.
  • the pump laser 5 is a wavelength tuneable laser having sampled gratings at the front and rear of its gain region.
  • the gratings produce slightly different reflection combs which provide feedback into the device.
  • the gratings can be current tuned in wavelength with respect to each other. Co-incidence of a maximum from each of the front and rear gratings is referred to as a supermode.
  • To switch the device between super modes requires a small electrical current into one of the gratings to cause a different pair of maxima to co-incide in the manner of a vernier. By applying different electrical currents to the two gratings, continuous tuning wilhin a supermode can be achieved.
  • a tuneable laser as a pump laser enables the pump laser to also fulfil a function as a control means not simply for power. This enables the wavelength of the pump laser to be matched to the assembled components in the EDFA to optimise performance rather than having to re-splice the fibre with the concomitant risks of fibre damage and further deterioration in amplifier performance.
  • the laser 5 has been described as a Segmented Grating-DBR, it would be possible to use other types of tuneable laser such as a Phase Shift Grating Distributed Bragg Reflector laser. It would also be possible to use non current driven tuneable lasers in appropriate circumstances.

Abstract

An erbium doped fibre amplifier having a pump laser, which pump laser is adapted to pump an optical fibre in an optical circuit via a coupler, wherein the pump laser is a tuneable laser.

Description

ERBIUM DOPED FIBRE AMPLIFIER HAVING A TUNEABLE PUMP LASER
Figure imgf000003_0001
The present invention relates to an optical amplifier, in particular an erbium doped fibre amplifier (EDFA), having control means to compensate for non optimum performance.
BACKGROUND ART
In an optical amplifier, such as an EDFA, for a given pump power, to obtain the maximum amount of gain for a given erbium concentration in the fibre core, the fibre length should be increased to the point at whic the pump power becomes equal to the intrinsic pump threshold. This determines the optimum length of the fibre to maximise the signal gain for the amplifier. However, for other applications, the fibre length may need to be optimised for other parameters such as the noise figure or output saturation power.
For a number of reasons, when an optical amplifier has been assembled, the fibre length may prove to be sub-optimal. It is known to compensate for sub-optimal performance of an optical amplifier by increasing the pump power. It is also known to tailor the gain of a WDM amplifier by an appropriate choice of the fibre length.
However, the known approaches suffer from the problem that the pump laser is often working near its maximum power for performance reasons and it is also clearly not ideal to have to re-splice optical fibre more than is necessary.
SUMMARY OF THE INVENTION
The present invention seeks to provide an optical amplifier with control means which control means is adapted to modify the gain in situ.
According to the invention, there is provided an optical amplifier having a pump laser, which pump laser is adapted to pump an optical fibre in an optical circuit via an opto-coupier, Wuerein t .e pump aser is a tuneable laser.
Preferably, the amplifier is an erbium doped fibre amplifier. Preferably the pump laser is a ITJ-N semiconductor tuneable laser.
This has the advantage that the length of fibre is no longer critical to the optimum performance and the amplifier performance can be compensated for by tuning the pump laser. The ability to tune the wavelength of the pump laser allows the laser wavelength to be matched to the assembled components. This is particularly advantageous as it is simpler to tune the laser than to change the length of fibre in the amplifier once the amplifier has been assembled.
BRIEF DESCRIPTION OF THE DRAWINGS
An exemplary embodiment of the invention will now be described in greater detail with reference to the drawings, in which:
Fig.l shows a schematic representation of an EDFA DETAILED DESCRIPTION OF THE EMBODIMENT
The amplifier is connected between an optical fibre input line 1 and an output line 2, the fibres being formed of a silica core of 7nm diameter surrounded by an outer sleeve of silica having a different refractive index of approximately 120nm. The amplifier is intended for the transmission of optical signals at a frequency of approximately 1530nm to form a telecornmunication transmission signal. The input line 1 is optically connected to a dichroic coupler 3, which, in turn, is connected to the output line 2 via a fibre coil 4. The fibre coil 4 is doped with erbium which, when excited by an applied signal at the right frequency, is amplified. A tuneable laser 5 is connected optically to the dichroic coupler 3 so that when an electrical signal is applied to the laser 5, a light signalis transmitted to the fibre coil 4 through the dichroic coupler 3. The erbium ions in the erbium doped optical fibre coil 4 are inverted by the pumped signal to generate a signal gain.
The pump laser 5 is a wavelength tuneable laser having sampled gratings at the front and rear of its gain region. The gratings produce slightly different reflection combs which provide feedback into the device. The gratings can be current tuned in wavelength with respect to each other. Co-incidence of a maximum from each of the front and rear gratings is referred to as a supermode. To switch the device between super modes requires a small electrical current into one of the gratings to cause a different pair of maxima to co-incide in the manner of a vernier. By applying different electrical currents to the two gratings, continuous tuning wilhin a supermode can be achieved.
The use of a tuneable laser as a pump laser enables the pump laser to also fulfil a function as a control means not simply for power. This enables the wavelength of the pump laser to be matched to the assembled components in the EDFA to optimise performance rather than having to re-splice the fibre with the concomitant risks of fibre damage and further deterioration in amplifier performance.
Although the laser 5 has been described as a Segmented Grating-DBR, it would be possible to use other types of tuneable laser such as a Phase Shift Grating Distributed Bragg Reflector laser. It would also be possible to use non current driven tuneable lasers in appropriate circumstances.

Claims

1. An optical amplifier having a pump laser, which pump laser is adapted to pump an optical fibre in an optical circuit via a coupler, wherein the pump laser is a tuneable laser.
2. An optical amplifier according to Claim 1, wherein the amplifier is an erbium doped fibre amplifier
3. An optical amplifier according to Claim 1 or Claim 2, wherein the pump laser is a HI-N semiconductor tuneable laser.
4. An optical amplifier according to any one of Claims 1 to 3, wherein the pump laser is a segmented grating distributed Bragg reflector laser.
5. An optical amplifier substantialb' as described herein with reference to and as illustrated in the accompanying drawing.
PCT/GB2002/001301 2001-03-19 2002-03-19 Erbium doped fibre amplifier having a tuneable pump laser WO2002075976A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0106769.3 2001-03-19
GB0106769A GB2377814A (en) 2001-03-19 2001-03-19 Optical amplifier with tunable pump laser

Publications (1)

Publication Number Publication Date
WO2002075976A1 true WO2002075976A1 (en) 2002-09-26

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Country Status (2)

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GB (1) GB2377814A (en)
WO (1) WO2002075976A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1848073A1 (en) 2006-04-19 2007-10-24 Multitel ASBL Switchable laser device and method for operating said device

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0721261A1 (en) * 1995-01-09 1996-07-10 AT&T Corp. Self-amplified optical networks
US6178036B1 (en) * 1997-01-14 2001-01-23 California Institute Of Technology Opto-electronic devices and systems based on brillouin selective sideband amplification
EP1076429A2 (en) * 1999-08-10 2001-02-14 Lucent Technologies Inc. Band conversion apparatus for optical transmission systems
WO2001016642A2 (en) * 1999-09-02 2001-03-08 Agility Communications, Inc. Integrated opto-electronic wavelength converter assembly

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5539571A (en) * 1992-09-21 1996-07-23 Sdl, Inc. Differentially pumped optical amplifer and mopa device
US5912910A (en) * 1996-05-17 1999-06-15 Sdl, Inc. High power pumped mid-IR wavelength systems using nonlinear frequency mixing (NFM) devices
US6144486A (en) * 1998-01-30 2000-11-07 Corning Incorporated Pump wavelength tuning of optical amplifiers and use of same in wavelength division multiplexed systems

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0721261A1 (en) * 1995-01-09 1996-07-10 AT&T Corp. Self-amplified optical networks
US6178036B1 (en) * 1997-01-14 2001-01-23 California Institute Of Technology Opto-electronic devices and systems based on brillouin selective sideband amplification
EP1076429A2 (en) * 1999-08-10 2001-02-14 Lucent Technologies Inc. Band conversion apparatus for optical transmission systems
WO2001016642A2 (en) * 1999-09-02 2001-03-08 Agility Communications, Inc. Integrated opto-electronic wavelength converter assembly

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1848073A1 (en) 2006-04-19 2007-10-24 Multitel ASBL Switchable laser device and method for operating said device

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Publication number Publication date
GB0106769D0 (en) 2001-05-09
GB2377814A (en) 2003-01-22

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