GB2425647A - Transition-metal doped fiber amplifier - Google Patents

Transition-metal doped fiber amplifier Download PDF

Info

Publication number
GB2425647A
GB2425647A GB0508602A GB0508602A GB2425647A GB 2425647 A GB2425647 A GB 2425647A GB 0508602 A GB0508602 A GB 0508602A GB 0508602 A GB0508602 A GB 0508602A GB 2425647 A GB2425647 A GB 2425647A
Authority
GB
United Kingdom
Prior art keywords
doped
optical amplifier
core
optical
fiber
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
GB0508602A
Other versions
GB0508602D0 (en
GB2425647B (en
Inventor
Sheng-Lung Huang
Chia-Yao Lo
Kwang-Yao Huang
Jian-Cheng Chen
Chiang-Yuan Chuang
Chien-Chih Lai
Yen-Sheng Lin
Ping-Hui Sophia Yeh
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.)
National Sun Yat Sen University
Original Assignee
National Sun Yat Sen University
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 National Sun Yat Sen University filed Critical National Sun Yat Sen University
Priority to GB0508602A priority Critical patent/GB2425647B/en
Publication of GB0508602D0 publication Critical patent/GB0508602D0/en
Publication of GB2425647A publication Critical patent/GB2425647A/en
Application granted granted Critical
Publication of GB2425647B publication Critical patent/GB2425647B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • H01S3/06716—Fibre compositions or doping with active elements
    • 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
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • 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
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • H01S3/162—Solid materials characterised by an active (lasing) ion transition metal
    • 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
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/1601—Solid materials characterised by an active (lasing) ion
    • H01S3/162—Solid materials characterised by an active (lasing) ion transition metal
    • H01S3/1623—Solid materials characterised by an active (lasing) ion transition metal chromium, e.g. Alexandrite
    • 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
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/163—Solid materials characterised by a crystal matrix

Abstract

An optical amplifier includes an optical fiber having a core doped with transition metal ions, and at least one glass cladding enclosing the core. By using the fiber, the optical amplifier of the invention has a gain bandwidth of more than 300 nm including 1300-1600 nm band in low-loss optical communication.

Description

TRANSITION METAL DOPED FIBER AMPLIFIER
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to optical fiber amplifiers, and more particularly to a fiber amplifier having a core doped with transition metal.
2. Description of the Related Art
Many types of optical fiber amplifiers are known in the art and are suitable for various optical communication bands.
U.S. Pat. No. 6,646,796 disclosed a wide band erbium-doped fiber amplifier.
It connected two erbium-doped fiber amplifiers to achieve a super wide band amplifier.
The first erbium-doped fiber amplifier pumped by a 980 nm laser diode was used to amplify the input optical signal of the C-band, which has a wavelength ranging from 1530 nm to 1560 nm. The second erbium-doped fiber amplifier pumped by a 1480 nm laser diode was used to amplify the input optical signal of the L- band, which has a wavelength ranging from 1570 nm to 1600 nm.
The disadvantage of the above-mentioned U.S. patent is that the band of the optical signal that can be amplified falls only in the C-band and the L-band, which has a bandwidth shorter than 80 nm. This bandwidth is only a part of a 300 nm bandwidth used in the optical communication. Besides, it needs two erbium-doped fiber amplifiers and two pumping lasers of different wavelength, which increase the cost of the system.
U.S. Pat. No. 6,515,795 disclosed a thulium-doped fiber amplifier. The fiber has a borosilicate glass material cladding and a core comprising a germinate glass material doped with Tm3. It can amplify the optical signal of 1400-1540 nm with a
I
pumping source. The pumping source used in the amplifier is a semiconductor laser, having essentially a wavelength of 7 80-800 nm.
The disadvantage of the above-mentioned amplifier is that the melting point of the fiber with borosilicate glass material cladding is about 800 C such that the fiber cannot be connected by fusion to the present fused silica fiber that has a melting point of 1600 C. It increases the system cost by using additional optical elements or mechanical structures as optical couplers. In addition, the bandwidth of the optical signal that can be amplified is about 160 nm, which does not cover the whole 300 nm bandwidth of the optical communication.
U.S. Pat. No. 5,805,332 disclosed a praseodymium-doped fiber amplifier.
The fiber has a fused silica cladding and a core comprising zirconium dioxide doped with praseodymium ion. The fiber amplifier is well suited for use in the 1300 nm band when pumped with an optical source having a wavelength of about 1000 nm. However, the 1300 nm band does not cover the whole band in the optical communication.
SUMMARY OF Tlli INVENTION
The primary objective of the present invention is to provide a transition metal doped fiber amplifier, which has a gain bandwidth of more than 300 nm including the 1300-1600 nm band used in optical communication.
To achieve the objective of the present invention, an optical fiber amplifier provided by the present invention comprises an optical fiber having a core doped with transition metal ions, and at least one glass cladding enclosing the core. By using the fiber, the optical fiber amplifier of the invention has a gain bandwidth of more than 300 nm including the 1300-1600 nm band used in low-loss optical communication.
BRIEF DESCRIPTION OF TIlE DRAWINGS
FIG 1 shows a schematic drawing of an apparatus for fabricating a Cr:YAG crystal fiber according to the laser-heated pedestal growth apparatus of the present invention; FIG 2 is a schematic drawing showing the grown procedure of the crystal fiber according to the present invention; FIG 3 shows a schematic drawing of a molten zone during growth; FIG 4 is a cross-sectional view of the grown double-clad Cr44:YAG fiber; FIG 5 is a plot showing the relationship between the gross gain and the pumping power subject to various input signal powers; FIG 6 is a plot showing the gross gain and the ASE spectmm at different signal wavelength.
DETAILED DESCRIPTION OF THE INVENTION
A transition metal doped optical fiber amplifier in accordance with the present invention essentially comprises a fiber doped transition metal ion such as Cr4, y3 Ni2, or etc. The fiber provided in the preferred embodiment of the present invention is a double-clad crystal fiber doped with chromium. The method of making the fiber according to the present invention comprises a first step of growing a Cr4:YAG crystal fiber having a diameter of 6jim by using the laser-heated pedestal growth (LHPG) method, and a second step of obtaining a double-clad crystal fiber enclosed by fused silica by using codrawing laser-heated pedestal growth (CDLHPG) method.
FIG 1 is a schematic drawing showing an apparatus for fabricating a crystal fiber according to the LHPG method. CO2 laser beam 11 provided by a CO2 laser generator (not shown) is emitted to a beam splitter 12 such that the CO2 laser beam is split into a generally annular beam. A bending mirror 13 is used to reflect the annular beam from the beam splitter 12 and to project it to a paraboloidal mirror 14. The paraboloidal mirror 14 is used to reflect the annular beam from the bending mirror 13 and to focus the annular beam on one end of a source crystal rod 20, which is YAG crystal doped with Cr4 ions. Referring to FIG 2, the end of the source crystal rod 20 can be melted to form a molten zone 21 by the laser beam 11. An oriented seed 30 is fed downward to dip in the molten zone 21, and then the oriented seed 30 is pulled upward slowly, while the source crystal rod 20 is fed toward the molten zone 21 so that a new grown crystal core 40 is formed at the end of the oriented seed 30, wherein the crystal orientation of the new grown crystal core is the same as that of the oriented seed 30. Different ratio of the pull speed of the oriented seed 30 to the feed speed of the source crystal rod 20 determines the diameter of the new grown crystal fiber 40.
For example, if the ratio of the pull speed of the oriented seed 30 to the feed speed of the source crystal rod is 16:1, the diameter ratio of the new crystal fiber 40 to the source crystal rod is 1:4.
FIG 3 is a schematic drawing showing the cladding step according to the CDLHPG method. A Cr4:YAG crystal fiber having a diameter of 68 p.m made by the above-mentioned LHPG method is inserted into a fused silica tube 50 having an inner diameter of 76 pm. The fused silica tube 50 thus obtained is heated by the laser beam of the LHPG system to downwardly grow a double-clad crystal fiber 60. The method is called codrawing laser- heated pedestal growth (CDLHPG) method. By controlling suitable growth factor of the CDLHPG method, a double-clad crystal fiber enclosed by fused silica can be achieved. As shown in FIG 4, the double-clad crystal fiber thus obtain has a Cr44:YAG crystal core 61, an inner cladding 62 and an outer cladding 63.
The diameters of the core 61, the inner cladding 62 and the outer cladding 63 are 25 p.m. 100 pm and 320 p.m respectively.
In the measurement of gross gain, a 1064 nm Yb-fiber laser is used as a pump source. The pump beam is guided into a signal mode fiber by a coupled lens and combined with 1520 nm signal beam through an optical coupler, such as a wavelengthdivisionmultipleXing (WDM) coupler, and the optical coupler output is spliced to the double-clad crystal fiber by a thsion splicer. The signal light from the output of the double-clad crystal fiber was concentrated by a 10 mm-focus lens. The unabsorbed pumping light was filtered by a filter at a wavelength of 1064 nm, and than the gross gain is determined under different signal input power. The definition of the gross gain is the gain of the output signal power with pumping to the output signal power without pumping, and the contribution of the amplified spontaneous emission (ASE) has to be of course subtracted. The result of the measurement is shown in FIG 5.
As shown in FIG 5, the gross gain of 10 dB is obtained at the pump power of 0.83 W under the input signal power of -20 dBm.
On the application of the amplifier, the propagation directions of the pumping light and the outputted amplified signal light can be controlled to be same or reverse. In order to transit a signal light or pumping light in a single direction, or to prevent the reflected light caused by connection of optical elements from interfering with the signal light or pumping light, an optical isolator can be provided at the output end of the transition metal doped fiber or at the input end of the optical coupler for signal light passing. The optical isolator is but not limited to a Faraday isolator.
Besides, the gross gains to various wavelengths of the input signal lights under the pump power of about I W are measured. As shown in FIG 6, the gross gain of 16 dB is obtained at the signal wavelength of 1.47 p.m. The bandwidth of the optical amplifier of the present invention that is calculated by comparing the measured gross gain and the ASE spectrum is about 270 nm.
Cr:YAG crystal fiber used in the above-mentioned embodiment has a strong spontaneous emission that just covers the low-loss-window of the optical fiber.
The crystal fiber has a 270 nm bandwidth under a 3-dB gain condition and a 400 rim bandwidth under a 6-dB gain condition. This covers the 0-band, E-band, S-band, C-band, and L-band of the optical communication. The bandwidth of the transition metal doped fiber amplifier of the invention is far widely than that of the traditional erbium-doped fiber amplifier. In addition, the absorption spectrum of the fiber amplifier of the present invention ranges from about 0.9pm to about I.2iim so that the fiber amplifier of the invention is compatible with the pumping light of 0.98p.m used by the well-known erbium-doped fiber amplifier (EDFA).
Presently it needs to connect plural amplifiers to widen band, and no one single amplifier can fully cover the whole 1.3-1.6pm of optical communication. Under limited bandwidth the dense wavelength division multiplex has chock point about increasing channels and results in fabricating difficultly. The gain bandwidth of the transition metal doped optical fiber amplifier of the present invention is about ten times than that of a traditional erbium-doped fiber amplifier. One single transition metal doped optical fiber amplifier of the present invention can cover the whole 1.3-1.6pm of optical communication, including the low loss band around 1 4p.m. The present invention improves the disadvantage of connecting plural amplifiers for covering the whole optical communication band in the art. In addition, since the main material of the double-clad fiber is fused silica, the fiber of the present invention can be connected to the fibers currently used by fusion directly, eliminating the inconvenience of using optical coupling devices. The optical amplifier of the present invention can replace the currently existing system and has a very high useful value.

Claims (15)

  1. WHAT IS CLAIMED IS: 1. An optical amplifier comprising: an optical fiber
    comprising: a core doped with transition metal ions; and at least one cladding enclosing the core.
  2. 2. The optical amplifier as defined in claim 1, wherein said cladding is made by a material selected from a group consisting of fused silica and compounds thereof.
  3. 3. The optical amplifier as defined in claim 1, wherein the material of the core is a single crystal material doped with Cror a poly crystal material doped with Cr4.
  4. 4. The optical amplifier as defined in claim 1, wherein the material of the core is glass containing Cr4 doped single crystal or a poly crystal.
  5. 5. The optical amplifier as defined in claim 1, wherein the material of the core is a single crystal material doped with V3 or a poly crystal material doped with V3.
  6. 6. The optical amplifier as defined in claim 1, wherein the material of the core is glass containing y3 doped single crystal or a poly crystal.
  7. 7. The optical amplifier as defined in claim 1, wherein the material of the core is a single crystal material doped with Ni2 or a poly crystal material doped with Ni2t
  8. 8. The optical amplifier as defined in claim 1, wherein the material of the core is glass containing Ni2 doped single crystal or a poiy crystal.
  9. 9. The optical amplifier as defined in claim 1, wherein the material of the core is a single crystal material or a poly crystal material doped with ions selected from the group consisting of Cr4, V3, Ni2 and the combinations thereof.
  10. 10. The optical amplifier as defined in claim 1, wherein the material of the core is glass containing single crystal or a poly crystal doped with ions selected from the group consisting of Cr4, V3, Ni and the combinations thereof.
  11. 11. The optical amplifier as defined in claim 1, including a pumping light source providing a pumping light of O.8-1.2im in wavelength.
  12. 12. The optical amplifier as defined in claim 1, having a band ranging from 1.2pmto 1.65.tmatagainof3dB.
  13. 13. The optical amplifier as defined in claim 11, wherein a pumping light and an amplified signal light are propagated in the optical fiber in same or reverse propagation direction.
  14. 14. The optical amplifier as defined in claim 1, further comprising: an optical coupler coupled to an end of the optical fiber; and an optical isolator coupled to the other end of the optical fiber.
  15. 15. An optical amplifier substantially as hereinbefore described with reference to the accompanying drawings.
GB0508602A 2005-04-28 2005-04-28 Transition metal doped fiber amplifier Expired - Fee Related GB2425647B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0508602A GB2425647B (en) 2005-04-28 2005-04-28 Transition metal doped fiber amplifier

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0508602A GB2425647B (en) 2005-04-28 2005-04-28 Transition metal doped fiber amplifier

Publications (3)

Publication Number Publication Date
GB0508602D0 GB0508602D0 (en) 2005-06-01
GB2425647A true GB2425647A (en) 2006-11-01
GB2425647B GB2425647B (en) 2011-06-08

Family

ID=34640290

Family Applications (1)

Application Number Title Priority Date Filing Date
GB0508602A Expired - Fee Related GB2425647B (en) 2005-04-28 2005-04-28 Transition metal doped fiber amplifier

Country Status (1)

Country Link
GB (1) GB2425647B (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5717517A (en) * 1995-01-13 1998-02-10 The Research Foundation Of City College Of New York Method for amplifying laser signals and an amplifier for use in said method
US6297179B1 (en) * 1999-10-18 2001-10-02 Corning Incorporated Transition-metal, glass-ceramic gain media
WO2002091530A1 (en) * 2001-05-03 2002-11-14 Corning Incorporated Broadband source with transition metal ions
US6698246B1 (en) * 1999-10-18 2004-03-02 Corning Incorporated Method for making nanocrystalline glass-ceramic fibers

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5717517A (en) * 1995-01-13 1998-02-10 The Research Foundation Of City College Of New York Method for amplifying laser signals and an amplifier for use in said method
US6297179B1 (en) * 1999-10-18 2001-10-02 Corning Incorporated Transition-metal, glass-ceramic gain media
US6698246B1 (en) * 1999-10-18 2004-03-02 Corning Incorporated Method for making nanocrystalline glass-ceramic fibers
WO2002091530A1 (en) * 2001-05-03 2002-11-14 Corning Incorporated Broadband source with transition metal ions

Also Published As

Publication number Publication date
GB0508602D0 (en) 2005-06-01
GB2425647B (en) 2011-06-08

Similar Documents

Publication Publication Date Title
JP6794310B2 (en) Multi-core erbium-doped fiber amplifier
CA2056925C (en) Optical fiber amplifier and coupler
CA2021801C (en) Double active-fiber optical amplifier having a wide-band signal wavelength
JP6125971B2 (en) High power double clad (DC) pump erbium-doped fiber amplifier (EDFA)
WO1992010014A1 (en) A method and apparatus for amplifying an optical signal
CA2109765A1 (en) Fiber optic coupler and amplifier
CA2276997C (en) Optical fiber for optical amplifier and fiber optic amplifier
US5970198A (en) Optically amplifying fiber and optical fiber amplifier
JP2003124547A (en) Optical fiber amplifier
US7333263B2 (en) Transition metal doped fiber amplifier
JPH10261826A (en) Optical amplifier and optical fiber applicable to it
CA2465522A1 (en) An optical light source
Michalska et al. Thulium-doped 1940-and 2034-nm fiber amplifiers: Towards highly efficient, high-power all-fiber laser systems
US5502591A (en) Optical amplifier with a doped fluoride glass of optical fibre and process for producing said amplifier
JP7264994B2 (en) Bismuth-doped fiber amplifier
US5473713A (en) Optical amplifier having a doped fluoride glass optical fibre and process for producing this amplifier
JP3006474B2 (en) Multi-core fiber, optical amplifier using the same, and device using the amplifier
GB2425647A (en) Transition-metal doped fiber amplifier
KR100928273B1 (en) Fiber Optic Amplifier with Transition Metal
US20240072507A1 (en) Fiber optic amplifier
JPWO2004005984A1 (en) Optical fiber, optical fiber coupler using the same, erbium-doped optical fiber amplifier, optical waveguide
JP2010080884A (en) Optical fiber amplifier
Wada et al. Differential modal gain reduction of L-band 5-spatial mode EDFA with depressed core structure
JP3163566U (en) Fiber optic amplifier
Veng et al. Investigation of new erbium doped fiber design with improved splice performance

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20130428