WO2015030251A1 - 光増幅器、光増幅システム、波長変換器および光通信システム - Google Patents
光増幅器、光増幅システム、波長変換器および光通信システム Download PDFInfo
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- 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
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
- H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
- H01S3/1083—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering using parametric generation
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- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
- G02B6/0283—Graded index region external to the central core segment, e.g. sloping layer or triangular or trapezoidal layer
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- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
- G02B6/0365—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - - +
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- 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
- G02B6/27—Optical coupling means with polarisation selective and adjusting means
- G02B6/2753—Optical coupling means with polarisation selective and adjusting means characterised by their function or use, i.e. of the complete device
- G02B6/2773—Polarisation splitting or combining
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- 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
- H01S3/06725—Fibre characterized by a specific dispersion, e.g. for pulse shaping in soliton lasers or for dispersion compensating [DCF]
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- 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
- H01S3/06729—Peculiar transverse fibre profile
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- 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
- H01S3/094042—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser
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- 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
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/10007—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers
- H01S3/10023—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers by functional association of additional optical elements, e.g. filters, gratings, reflectors
- H01S3/1003—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers by functional association of additional optical elements, e.g. filters, gratings, reflectors tunable optical elements, e.g. acousto-optic filters, tunable gratings
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- 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
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/102—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
- H01S3/1028—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation by controlling the temperature
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- 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
- H04B10/293—Signal power control
- H04B10/294—Signal power control in a multiwavelength system, e.g. gain equalisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0221—Power control, e.g. to keep the total optical power constant
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- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
- G02B6/02219—Characterised by the wavelength dispersion properties in the silica low loss window around 1550 nm, i.e. S, C, L and U bands from 1460-1675 nm
- G02B6/02247—Dispersion varying along the longitudinal direction, e.g. dispersion managed fibre
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- 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
- H01S2301/00—Functional characteristics
- H01S2301/02—ASE (amplified spontaneous emission), noise; Reduction thereof
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- 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
- H01S2301/00—Functional characteristics
- H01S2301/04—Gain spectral shaping, flattening
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- 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
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- 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
- H01S3/23—Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
- H01S3/2375—Hybrid lasers
Definitions
- the present invention relates to an optical amplifier, an optical amplification system, a wavelength converter, and an optical communication system.
- optical amplifiers are indispensable.
- EDFAs Erbium-Doped Fiber Amplifiers
- Raman amplifiers Raman amplification systems
- EDFAs Erbium-Doped Fiber Amplifiers
- Raman amplification systems have been put to practical use as optical amplifiers or optical amplification systems in the optical communication band.
- an optical parametric amplifier that utilizes a nonlinear effect in an optical fiber for optical amplification as disclosed in Patent Document 1 can reduce noise compared to an EDFA.
- OPA optical parametric amplifier
- PSA Phase Sensitive Amplifier
- OPA has not been put to practical use because the amplification band is narrow and the gain spectrum is not flat.
- the present invention has been made in view of the above, and provides an optical amplifier, an optical amplification system, a wavelength converter, and an optical communication system with higher gain while realizing gain spectrum flatness and broadband characteristics. For the purpose.
- an optical amplifier includes an amplification optical fiber and a signal light input to the amplification optical fiber that is nonlinear with the amplification optical fiber.
- a pump light source that supplies pump light for parametric amplification by an optical effect to the optical fiber for amplification, and the optical fiber for amplification has a variation of zero dispersion wavelength in the range of 0.5 nm / 100 m in the longitudinal direction. It is characterized by being.
- the amplification optical fiber includes a central core portion, an outer core layer formed around the central core portion and having a lower refractive index than the central core portion, and the central core.
- a core part formed between the outer core layer and the outer core layer, and having a refractive index lower than that of the central core part and higher than that of the outer core layer, and the outer core A cladding portion formed around the layer and having a refractive index lower than that of the central core portion and higher than that of the outer core layer, and having an effective core area of 18 ⁇ m 2 or less at a wavelength of 1550 nm.
- the optical amplifier according to one aspect of the present invention the amplification optical fiber, the effective core area at the wavelength of 1550nm is at 10.27Myuemu 2 or more 18 [mu] m 2 or less, the relative refractive index difference with respect to the cladding portion of the central core portion Is 1.8% or more and 3.0% or less, and the relative refractive index difference of the outer core layer with respect to the cladding is ⁇ 1.2% or more and ⁇ 0.2% or less, and the cladding of the buffer core layer
- the relative refractive index difference with respect to the portion is 0.1% to 0.6%
- the outer diameter of the outer core layer is 9.4 ⁇ m to 21.4 ⁇ m
- the ratio of the diameter of the portion is 0.20 or more and 0.40 or less
- the ratio of the outer diameter of the buffer core layer to the outer diameter of the outer core layer is 0.24 or more and 0.80 or less
- An optical amplifier includes a temperature adjustment mechanism that adjusts a temperature of the amplification optical fiber or a tension adjustment mechanism that adjusts a tension applied to the amplification optical fiber.
- An optical amplifier includes a temperature adjustment mechanism for adjusting a temperature of a semiconductor laser element in the pump light source or a drive current adjustment mechanism for adjusting a drive current of the semiconductor laser element.
- An optical amplifier includes a temperature adjustment mechanism for adjusting a temperature of the fiber Bragg grating or a tension adjustment mechanism for adjusting a tension applied to the fiber Bragg grating, wherein the phase shifter is a fiber Bragg grating. It is characterized by that.
- the amplification optical fiber is configured such that the zero difference wavelength at an ambient temperature is flat when the wavelength of the pump light is set to a predetermined pump light wavelength.
- the temperature adjustment mechanism is positioned on the short wavelength side by 5 nm or less from the first zero dispersion wavelength at which the gain band is maximized, and the temperature adjustment mechanism is configured so that the zero difference wavelength of the amplification optical fiber approaches the first zero dispersion wavelength. And adjusting the temperature of the amplification optical fiber.
- An optical amplifier includes a gain flattening filter for flattening a gain wavelength characteristic of the optical amplifier, in which a zero dispersion wavelength of the amplification optical fiber is shorter than the pump wavelength. .
- the signal light and the pump light are input, and the signal light and the pump light are separated into polarization components having polarization states orthogonal to each other, and the orthogonal to each other
- the polarization components to be amplified are input to the amplification optical fiber so that the amplification optical fiber propagates in opposite directions, and are amplified by propagating in the amplification optical fiber in opposite directions.
- a polarization multiplexer / demultiplexer that combines components with polarization is provided.
- the optical amplifier according to an aspect of the present invention further includes a relative phase shifter that is inserted between the plurality of amplification optical fibers and changes a relative phase of input light.
- the optical amplifier according to an aspect of the present invention is characterized in that an intensity ratio between the intensity of the pump light input to the optical amplifier and the total intensity of the signal light is 24 dB or more.
- An optical amplifier includes an amplification optical fiber and pump light for parametrically amplifying the wavelength-division multiplexed signal light input to the amplification optical fiber by a nonlinear optical effect of the amplification optical fiber.
- the optical amplifier according to an aspect of the present invention is characterized in that the pump light wavelength of the pump light is set to be 5 nm or more away from the wavelength of the wavelength multiplexed signal light.
- An optical amplification system includes the optical amplifier according to an aspect of the present invention.
- a wavelength converter according to an aspect of the present invention includes the optical amplifier according to an aspect of the present invention.
- An optical communication system includes the optical amplifier according to an aspect of the present invention.
- the gain is further increased while realizing flatness and wide bandwidth of the gain spectrum.
- FIG. 1 is a schematic configuration diagram of an optical amplifier and its amplification characteristic measurement system according to the first embodiment.
- FIG. 2 is a schematic cross-sectional view of the amplification optical fiber shown in FIG.
- FIG. 3 is a diagram schematically showing a refractive index profile of the amplification optical fiber shown in FIG.
- FIG. 4 is a diagram showing an example of the distribution in the longitudinal direction of the zero dispersion wavelength of the original optical fiber for preparing the amplification optical fiber shown in FIG.
- FIG. 5 is a schematic configuration diagram of a temperature adjustment mechanism applicable to the amplification optical fiber shown in FIG.
- FIG. 6 is a diagram illustrating the wavelength dependence of the gain and NF of the manufactured optical amplifier according to the first embodiment.
- FIG. 1 is a schematic configuration diagram of an optical amplifier and its amplification characteristic measurement system according to the first embodiment.
- FIG. 2 is a schematic cross-sectional view of the amplification optical fiber shown in FIG.
- FIG. 3 is a diagram schematically showing a
- FIG. 7 is a diagram showing an ASE spectrum when the pump light wavelength and the temperature of the optical fiber for amplification are adjusted by the manufactured optical amplifier of the first embodiment.
- FIG. 8 is a diagram illustrating the gain of the manufactured optical amplifier of Example 1 and the dependence of NF on the input signal light intensity.
- FIG. 9 is a diagram illustrating the wavelength dependence of gain and NF when the relative phase shifter is omitted in the configuration of the manufactured optical amplifier according to the first embodiment.
- FIG. 10 is a schematic configuration diagram of an optical amplifier and its amplification characteristic measurement system according to a modification of the first embodiment.
- FIG. 11 is a diagram illustrating the wavelength dependence of the gain and NF of the manufactured optical amplifier according to the second embodiment.
- FIG. 12 is a diagram illustrating the wavelength dependence of gain and NF when the zero-dispersion wavelength is adjusted in the manufactured optical amplifier according to the second embodiment.
- FIG. 13 is a schematic configuration diagram of an optical amplifier according to the second embodiment.
- FIG. 14 is a schematic configuration diagram of a three-stage optical amplifier.
- FIG. 15 is a schematic configuration diagram of the optical amplifier according to the first embodiment and its WDM amplification characteristic measurement system.
- FIG. 16 is a diagram showing a spectrum of 8-channel WDM signal light to be input.
- FIG. 17 is a diagram showing a spectrum of amplified 8-channel WDM signal light.
- FIG. 18 is a diagram showing a spectrum of amplified 8-channel WDM signal light.
- FIG. 16 is a diagram showing a spectrum of 8-channel WDM signal light to be input.
- FIG. 19 is a diagram showing a spectrum of amplified 8-channel WDM signal light.
- FIG. 20 is a diagram showing a spectrum of amplified 8-channel WDM signal light.
- FIG. 21 is a diagram showing a spectrum of amplified 8-channel WDM signal light.
- FIG. 22 is a diagram showing a spectrum of amplified 8-channel WDM signal light.
- FIG. 23 is a diagram illustrating the wavelength dependence of the gain and NF when the 8-channel WDM signal light is input to the optical amplifier according to the first embodiment.
- FIG. 24 is a diagram illustrating the wavelength dependence of the gain and NF when a 4-channel WDM signal light is input to the optical amplifier according to the first embodiment.
- FIG. 25 is a schematic configuration diagram of the disclosed optical amplifier and its amplification characteristic measurement system.
- FIG. 26 is a diagram showing the wavelength dependence of the gain and NF of the optical amplifier shown in FIG.
- the present inventors have disclosed an OPA that realizes flatness of gain spectrum and broadband characteristics by quasi phase matching.
- the gain was about 10 dB and the 0.3 dB gain band was about 30 nm.
- the present inventors have made a multistage OPA in order to realize a gain of 20 dB and gain flatness within 1 dB in the C band (for example, 35 nm from 1530 nm to 1565 nm). The experiment was conducted.
- OPA in this specification means the following optical amplifiers. That is, the pump light and the signal light that is the amplified light are input to the amplification optical fiber that is the amplification medium.
- the amplification optical fiber idler light is generated from the pump light and the signal light by the nonlinear optical effect of the amplification optical fiber. Further, the signal light is parametrically amplified.
- the wavelength ⁇ idler [nm] of the idler light has the following relationship with the wavelength ⁇ pump [nm] of the pump light and the wavelength ⁇ signal [nm] of the signal light.
- PSA in this specification means the following optical amplifier. That is, in the PSA, in addition to the pump light and the signal light, idler light having a power 1/10 to 10 times that of the signal light is input to the amplification optical fiber. At the output of the amplification optical fiber, pump light, parametric amplified signal light, and parametric amplified idler light are output. The wavelength of this idler light is determined by the following relationship, similar to the idler light of OPA.
- FIG. 1 is a schematic configuration diagram of an optical amplifier 100 and its amplification characteristic measurement system according to Embodiment 1 of the present invention.
- an optical amplifier 100 that is an OPA includes an optical amplifying body 10, a pump light source unit 20, and an optical multiplexer / demultiplexer 30.
- a signal light source 41 composed of a wavelength tunable laser device for measurement is connected to the optical multiplexer / demultiplexer 30 of the optical amplifier 100 via a polarization controller 42.
- An optical spectrum analyzer 300 for measuring spectrum, gain, and NF is connected to the amplification optical fiber 12 of the optical amplifier 100 via an optical attenuator 200.
- the configuration of the optical amplifier 100 will be described more specifically in the order of the pump light source unit 20, the optical amplifying body 10, and the optical multiplexer / demultiplexer 30.
- the pump light source unit 20 includes a pump light source 21, a phase modulator 22, an optical fiber amplifier 23, an optical bandpass filter 24, a white noise source 25, and a broadband RF amplifier 26.
- the pump light source 21, the phase modulator 22, the optical fiber amplifier 23, and the optical bandpass filter 24 are connected by an optical fiber.
- the optical fiber used for this connection is preferably a polarization maintaining optical fiber.
- the pump light source 21 outputs pump light having a predetermined pump light wavelength to be supplied to the optical amplifying body 10.
- the pump light source 21 is composed of a tunable laser device, but may be composed of a distributed feedback (DFB) laser, a Fabry-Perot (FP) laser, or a vertical cavity surface emitting laser (VCSEL).
- the white noise source 25 outputs a 1.2 GHz broadband white noise signal as an electrical signal.
- the white noise source 25 may output a white noise signal of 2 GHz, or may output a plurality of sine waves having different frequencies as a white noise signal.
- the broadband RF amplifier 26 amplifies the white noise signal output from the white noise source 25 and outputs it to the phase modulator 22.
- the phase modulator 22 receives the pump light and the amplified white noise signal, phase-modulates the pump light with a predetermined degree of phase modulation with the amplified white noise signal, and outputs it to the optical fiber amplifier 23. Note that, by modulating the phase of the pump light, the spectral width of the pump light is widened, so that the generation or intensity of SBS (stimulated Brillouin scattering) in the optical amplifier 10 can be suppressed. If the pump light source 21 uses an FP laser or VCSEL having a wide spectrum width, the degree of phase modulation may be lower than when a DFB laser is used.
- the optical fiber amplifier 23 is, for example, EDFA or EYDFA (Erbium Ytterbium Doped Fiber Amplifier), and optically amplifies the pump light phase-modulated by the phase modulator 22 and outputs the amplified light to the optical bandpass filter 24.
- the optical bandpass filter 24 has a transmission center wavelength that matches the pump light wavelength, and removes an ASE (Amplified Spontaneous Emission) component generated in the optical fiber amplifier 23 from the pump light amplified by the optical fiber amplifier 23. Output.
- the transmission wavelength band of the optical bandpass filter 24 is preferably as narrow as 1 nm or less, for example.
- an optical isolator may be inserted at an arbitrary position ahead of the pump light source 21.
- the optical amplifying body 10 is a two-stage optical amplifying body that includes amplification optical fibers 11 and 12 and a relative phase shifter 13 inserted between the amplification optical fibers 11 and 12.
- FIG. 2 is a schematic cross-sectional view of the amplification optical fiber 11 shown in FIG.
- FIG. 3 is a diagram schematically showing a refractive index profile of the amplification optical fiber 11 shown in FIG. Since the amplification optical fiber 12 has the same configuration as the amplification optical fiber 11, description thereof is omitted.
- the amplification optical fiber 11 includes a central core portion 11aa, an outer core layer 11ac formed around the central core portion 11aa and having a lower refractive index than the central core portion 11aa, and between the central core portion 11aa and the outer core layer 11ac.
- the amplification optical fiber 11 has a coating 11c formed around the cladding portion 11b (see Patent Document 3).
- the core part 11a and the clad part 11b are based on SiO 2 glass.
- the distribution of the addition amount of the refractive index adjusting dopant such as GeO 2 and fluorine (F) added to adjust the refractive index, the distribution amount of the addition amount in the radial direction, and the like can be adjusted.
- a refractive index profile can be formed. At this time, when GeO 2 is added, the refractive index can be increased, and when F is added, the refractive index can be decreased.
- the clad portion 11b is made of, for example, pure SiO 2 glass, but a refractive index adjusting dopant such as GeO 2 or F may be added to obtain a desired refractive index.
- the phrase “consisting essentially of pure SiO 2 glass” means that no refractive index adjusting dopant is included, and a Cl element that does not affect the refractive index may be included.
- the coating 11c is usually made of two layers of ultraviolet curable resin, but is not particularly limited.
- the outer diameter of the clad portion 11b is usually 125 ⁇ m, but can be 100 ⁇ m or less. In that case, the diameter when the amplification optical fiber 11 is wound around a bobbin or the like can be reduced.
- the outer diameter of the coating 11c is usually 250 ⁇ m, but can be made 150 ⁇ m or less by reducing the outer diameter of the cladding. In that case, the volume of the amplification optical fiber 11 is reduced. Therefore, if the amplification optical fiber 11 is wound around a small-diameter bobbin and accommodated in a housing, a small nonlinear optical device can be realized.
- the central core portion 11aa has a diameter d1, has a refractive index profile P1, and has a maximum refractive index nc1.
- the outer core layer 11ac has an outer diameter of d3, a refractive index profile P3, and a minimum refractive index of nc3.
- the buffer core layer 11ab has an outer diameter of d2, a refractive index profile P2, and a maximum refractive index of nc2.
- the clad part 11b has a refractive index profile P4, and the refractive index is ncl.
- ng is the refractive index of pure SiO 2 glass.
- a profile parameter characterizing the refractive index profile of the amplification optical fiber 11 is defined.
- d1 / d3 which is the ratio of the diameter d1 of the central core portion 11aa to the outer diameter d3 of the outer core layer 11ac, is Ra11
- d2 / is the ratio of the diameter d2 of the buffer core layer 11ab to the outer diameter d3 of the outer core layer 11ac.
- d3 is defined as Ra12.
- the maximum relative refractive index difference of the central core portion 11aa relative to the cladding portion 11b is ⁇ 11
- the minimum relative refractive index difference of the outer core layer 11ac relative to the cladding portion 11b is ⁇ 12
- the maximum relative refractive index of the buffer core layer 11ab relative to the cladding portion 11b is defined as ⁇ 14.
- the relative refractive index difference of the clad portion 11b with respect to the refractive index of pure SiO 2 glass is represented by ⁇ clad.
- ⁇ clad is 0%.
- ⁇ 11, ⁇ 12, ⁇ 14, and ⁇ clad are defined by equations (1) to (4).
- ⁇ 11 [(nc1-ncl) / nc1] ⁇ 100 (%) (1)
- ⁇ clad [(ncl-ng) / ncl] ⁇ 100 (%) (4)
- the ratio of the outer diameter of the buffer core layer 11ab to the diameter of the central core portion 11aa, that is, d3 / d1 is 1.2 or more and 2.0 or less. ⁇ 11 is 1.8% or more, more preferably 2.2% or more, and 3.0% or less.
- the outer core layer 11ac has an outer diameter of 9.4 ⁇ m or more and 21.4 ⁇ m or less. Further, the ratio of the diameter of the central core portion 11aa to the outer diameter of the outer core layer 11ac, that is, d1 / d3 is not less than 0.20 and not more than 0.40.
- the ratio of the outer diameter of the buffer core layer 11ab to the outer diameter of the outer core layer 11ac, that is, d2 / d3 is 0.24 or more and 0.80 or less.
- ⁇ 12 is ⁇ 1.2% or more and ⁇ 0.2% or less, and more preferably ⁇ 1.2% or more and ⁇ 0.4% or less.
- ⁇ 14 is 0.1% or more and 0.6% or less, and more preferably 0.3% or more and 0.6% or less.
- the central core portion 11aa and the buffer core layer 11ab have a so-called ⁇ -type refractive index profile, and have ⁇ values of ⁇ 11 and ⁇ 14, respectively.
- the ⁇ value is an index representing the shape of the refractive index profile, and is defined by Expression (5) and Expression (6). As the ⁇ value increases, the central portion of the refractive index profile of the core becomes rounder, that is, shifts from a triangle to a quadrangle. *
- n 2 (r) nc1 2 ⁇ 1-2 ( ⁇ 11 / 100) ⁇ (2r / d1) ⁇ ⁇ 11 ⁇ (5) However, 0 ⁇ r ⁇ d1 / 2
- n 2 (r) nc2 2 ⁇ 1-2 ( ⁇ 14 / 100) ⁇ ((r ⁇ r14max) / (d2 / 2 ⁇ r14max)) ⁇ ⁇ 14 ⁇ (6)
- r14max ⁇ r ⁇ d2 / 2
- r indicates the position in the radial direction from the center of the optical fiber.
- N (r) represents the refractive index at the position r.
- the cut-off wavelength is less than 1500 nm in order to transmit signal light having a wavelength of 1500 nm or more in a single mode.
- the variation of the zero dispersion wavelength in the longitudinal direction is within a range of 0.5 nm (0.5 nm / 100 m) per 100 m length, preferably 0.2 nm / 100 m, and the wavelength dispersion in the longitudinal direction at a wavelength of 1550 nm. Since the fluctuation range is 1 ps / nm / km or less per 1 km length, the chromatic dispersion characteristics are stable in the longitudinal direction even if the optical fiber length is increased, and the nonlinear optical phenomenon can be used efficiently.
- the absolute value of chromatic dispersion at a wavelength of 1550 nm is 5 ps / nm / km or less, and more preferably 1 ps / nm / km or less, the generation efficiency of nonlinear optical phenomena such as FWM is high. Further, in the range where the absolute value of the chromatic dispersion at the wavelength of 1550 nm is 5 ps / nm / km or less, the chromatic dispersion at the wavelength of 1550 nm when the outer diameter of the outer core layer 11ac (that is, the outer diameter of the core portion 11a) varies by 1%.
- the optical fiber Since the fluctuation is 0.7 ps / nm / km or less, the optical fiber has an absolute value of chromatic dispersion that is stably small in the longitudinal direction. In addition, since the absolute value of the chromatic dispersion slope is 0.02 or more and 0.06 ps / nm 2 / km or less at the wavelength of 1550 nm, the optical fiber has a small absolute value of chromatic dispersion in a wide wavelength band. In addition, since the transmission loss is 1.5 dB / km or less at the wavelength of 1550 nm, the loss of light is small and the generation efficiency of the nonlinear optical phenomenon is high.
- n 2 is a nonlinear refractive index
- a eff is an effective core area
- the cutoff wavelength ( ⁇ c) is the ITU-T (International Telecommunication Union) G.I. This refers to the fiber cutoff wavelength defined in 650.1.
- Effective core area is ITU-T G.
- the effective core area defined by 650.2 is measured by ITU-T G. The measurement was performed in the same manner as the mode field diameter (MFD) measurement method defined in 650.1. Calculated according to the definition of 650.2. For other terms not specifically defined in this specification, see ITU-T G.C. It shall follow the definition and measurement method in 650.1.
- the non-linear coefficient (n 2 / Aeff) used in this specification is a measured value by the XPM method.
- FIG. 4 is a diagram showing an example of the distribution in the longitudinal direction of the zero dispersion wavelength of the original optical fiber for preparing the amplification optical fibers 11 and 12 shown in FIG.
- the original optical fiber having a length of 2000 m has a portion in which the variation of the zero-dispersion wavelength in the longitudinal direction is within a range of 0.5 nm / 100 m.
- Optical fibers 11 and 12 can be prepared.
- the distribution in the longitudinal direction of the zero dispersion wavelength of the optical fiber can be obtained by measuring the fluctuation of the chromatic dispersion in the longitudinal direction of the optical fiber by the nonlinear OTDR method disclosed in Non-Patent Document 4. .
- the relative phase shifter 13 is composed of, for example, a fiber Bragg grating (FBG), and the Bragg wavelength is set in the vicinity of the zero dispersion wavelength of the amplification optical fibers 11 and 12.
- FBG fiber Bragg grating
- the optical multiplexer / demultiplexer 30 connects the pump light source unit 20, the optical amplifying body 10, and the signal light source 41.
- the optical multiplexer / demultiplexer 30 has a function of multiplexing pump light and signal light.
- the optical multiplexer / demultiplexer 30 is, for example, a 20 dB optical coupler or an optical bandpass filter, but is not particularly limited.
- the optical multiplexer / demultiplexer 30 is a 20 dB optical coupler, the pump light source unit 20 and the optical amplifier 10 are connected with low optical loss, and the optical amplifier 10 and the signal light source 41 are connected with optical loss of about 20 dB.
- the pump light source unit 20 outputs pump light (hereinafter simply referred to as “pump light”) that has been phase-modulated and optically amplified and from which the ASE component has been removed.
- pump light pump light
- the wavelength of the pump light is set in the vicinity of the zero dispersion wavelength of the amplification optical fibers 11 and 12.
- the signal light source 41 outputs signal light.
- the wavelength of the signal light is set to a wavelength within the amplification band of the optical amplifier 100.
- the optical multiplexer / demultiplexer 30 combines the pump light and the signal light and causes the optical amplifying body 10 to input from the amplification optical fiber 11.
- the optical amplifying body 10 parametrically amplifies the signal light by the nonlinear optical effect of the amplification optical fibers 11 and 12 to which the pump light is input, and outputs the signal light from the amplification optical fiber 12 side.
- the relative phase shifter 13 changes the relative phase ⁇ rel of the light propagating from the amplification optical fiber 11 in accordance with the power of the input pump light, the length of the amplification optical fibers 11 and 12, the nonlinear coefficient, the dispersion characteristic, and the like. Shift it by an appropriate amount.
- the length and dispersion of the amplification optical fibers 11 and 12 are appropriately set according to the required gain spectrum waveform.
- the relative phase shifter 13 has a relative phase ⁇ rel of 0.5 ⁇ of light output from the amplification optical fiber 11 of the amplification stage connected to the front side of the relative phase shifter 13 as shown in Patent Document 2 and the like.
- the product ⁇ PL of the nonlinear constant ⁇ , the length L of the amplification optical fiber 11 and the input power P of the pump light is set so as to be larger, and the relative phase shifter 13 sets the relative phase ⁇ rel to 0.5 ⁇ . Is also changed to a smaller value and output to the amplification optical fiber 12 at the subsequent stage.
- the installation of the relative phase shifter 13 realizes flatness of the gain spectrum that cannot be obtained without inserting the relative phase shifter between the amplification optical fibers 11 and 12. At the same time, a lower noise figure (NF: Noise Figure) can be obtained than when there is no relative phase shifter.
- NF Noise Figure
- the relative phase ⁇ rel is an amount described by the following equation using the phase ⁇ signal [radian] of the signal light, the phase ⁇ idler [radian] of the idler light, and the phase ⁇ pump [radian] of the pump light.
- ⁇ rel ⁇ k + ⁇ signal + ⁇ idler-2 ⁇ pump [radian]
- ⁇ k ksignal + kidler ⁇ 2kpump.
- ksignal, kidler and kpump are wave numbers of each light.
- the relative phase ⁇ rel is an amount defined by a plurality of light phases. Therefore, as a relative phase shifter, for example, one that shifts only the phase of pump light, one that shifts only the phase of signal light, one that shifts only the phase of idler light, or the phase of pump light, phase of signal light, idler light Any of the phases that shift two or more may be used.
- the relative phase shifter 13 in the first embodiment shifts only the phase of the pump light.
- this optical amplifier 100 as the amplification optical fibers 11 and 12, dispersion-stable light whose longitudinal zero-dispersion wavelength variation is in the range of 0.5 nm / 100 m, preferably in the range of 0.2 nm / 100 m.
- the gain characteristic of higher gain is realized while realizing the flatness of the gain spectrum and the broadband property.
- FIG. 5 is a schematic configuration diagram of a temperature adjustment mechanism applicable to the amplification optical fibers 11 and 12 shown in FIG.
- This temperature adjustment mechanism 14 is attached to the bobbin 14a, a bobbin 14a made of a material having high thermal conductivity, such as aluminum, for winding the amplification optical fiber 11 or 12, a heater wire 14b wound around the bobbin 14a, and the bobbin 14a.
- a case 14d, 14e made of a heat insulating material having a recess for accommodating the bobbin 14a.
- the amplifying optical fiber 11 or 12 is wound around the bobbin 14a, and the bobbin 14a is housed in the casings 14d and 14e with the heater wire 14b wound around the bobbin 14a. Then, a current is supplied from a power source (not shown) to the heater wire 14b to generate heat, and the amplification optical fiber 11 or 12 is heated to a predetermined set temperature. The temperature of the amplification optical fiber 11 or 12 is measured by the temperature detection element 14c. The temperature of the amplification optical fiber 11 or 12 is preferably adjusted to be within the set temperature ⁇ 2 ° C. by adjusting the current flowing through the heater wire 14b based on the measured temperature.
- the zero dispersion wavelength of the amplification optical fiber 11 or 12 is shifted to the longer wavelength side when the temperature is increased. Accordingly, the zero dispersion wavelength can be adjusted by adjusting the temperature of the amplification optical fiber 11 or 12. Therefore, for example, when it is desired to use a desired pump light wavelength, the zero dispersion wavelength at an ambient temperature (for example, room temperature of 25 ° C.
- ⁇ 5 ° C. is within a range of 5 nm from the desired pump light wavelength (for example, 1
- the zero-dispersion wavelength can be adjusted to be close to the optimum value (for example, the value at which the gain band of the optical amplifier 100 is maximized) with respect to the desired pump light wavelength, and preferably matched.
- the adjustment of the zero dispersion wavelength by such temperature adjustment may be performed only on one of the amplification optical fibers 11 and 12, but it is preferable to be performed on both. When both amplification optical fibers 11 and 12 are used, optimum adjustments can be made to shift to the desired optimum zero dispersion wavelength in accordance with the zero dispersion wavelength at each ambient temperature. More preferred.
- the zero dispersion wavelength of the amplification optical fibers 11 and 12 is It is desirable that the wavelength of the pump light and the wavelength of the relative phase shifter 13 that shifts the phase of the pump light (for example, the wavelength at which the wavelength change rate of the phase shift is maximized) coincide with each other in a range of about ⁇ 1 nm. More specifically, with respect to the amplification optical fibers 11 and 12, the zero dispersion wavelength can be adjusted by temperature adjustment or tension adjustment.
- the oscillation wavelength can be adjusted by adjusting the temperature of the semiconductor laser element or adjusting the driving current.
- the relative phase shifter 13 is an FBG
- the Bragg wavelength of the FBG can be adjusted by temperature adjustment or tension adjustment.
- the optical amplifier 100 includes a tension adjustment mechanism that adjusts the tension applied to the amplification optical fibers 11 and 12, a temperature adjustment mechanism that adjusts the temperature of the semiconductor laser element, or a drive current adjustment mechanism that adjusts the drive current of the semiconductor laser element, Alternatively, it is preferable to provide a temperature adjusting mechanism for adjusting the temperature of the FBG or a tension adjusting mechanism for adjusting the tension applied to the FBG.
- a temperature adjusting mechanism for adjusting the temperature of the FBG or a tension adjusting mechanism for adjusting the tension applied to the FBG.
- the zero dispersion wavelength of the amplification optical fibers 11 and 12 is set to the Bragg wavelength of the FBG by the above mechanism. It can be adjusted to match the oscillation wavelength of the semiconductor laser element.
- the above mechanism adjusts the Bragg wavelength of the FBG that constitutes the relative phase shifter 13 and the oscillation wavelength of the semiconductor laser element to thereby obtain a zero dispersion wavelength.
- the FBG is disposed on a Peltier element or heater as a temperature adjustment mechanism via a heat sink made of copper, aluminum, ceramic, or the like so as to be in thermal contact with the Peltier element or heater.
- a temperature sensor such as a thermistor on the heat sink and adjusting the temperature while monitoring the temperature, the temperature can be adjusted more precisely.
- Example 1 an optical amplifier of Example 1 in which the temperature adjustment mechanism 14 was applied to the optical amplifier 100 according to the first embodiment was manufactured, and its characteristics were measured using the measurement system shown in FIG.
- the amplification optical fibers 11 and 12 had a zero dispersion wavelength of 1562.6 nm at a room temperature of 25 ° C., but were heated to 126.5 ° C. by the temperature adjustment mechanism 14 to change the zero dispersion wavelength to 1565. Adjusted to 6 nm.
- the dispersion slope at a wavelength of 1550 nm was 0.04 ps / nm 2 / km, the transmission loss at a wavelength of 1550 nm was 1.2 dB / km, and the nonlinear constant at a wavelength of 1550 nm was 21.4 / W / km.
- the lengths of the amplification optical fibers 11 and 12 were 100 m and 130 m, respectively.
- the fluctuation of the zero dispersion wavelength in the longitudinal direction of the amplification optical fibers 11 and 12 was in the range of 0.5 nm / 100 m.
- These amplifying optical fibers 11 and 12 are ITU-T G. It was possible to fuse with a standard single mode optical fiber for communication conforming to 652 with a connection loss of 0.1 dB or less.
- the power of the pump light input to the optical amplifying body 10 was about 31.76 dBm, and the pump light wavelength was 1565.6 nm.
- the transmission wavelength band of the optical bandpass filter 24 in the pump light source unit 20 was 0.8 nm.
- the power of the signal light input to the optical amplifying body 10 was about ⁇ 20 dBm.
- the relative phase shifter 13 is FBG, has a Bragg wavelength of 1565.9 nm, and is longer by 0.3 nm than the zero dispersion wavelength after the temperature adjustment of the amplification optical fibers 11 and 12.
- the reflection band width of the FBG was 0.65 nm, and the transmission loss at the Bragg wavelength was -39 dB. At this time, it is considered that the phase of the pump light is shifted by about 0.35 ⁇ ⁇ 0.15 ⁇ .
- FIG. 6 is a graph showing the gain and NF wavelength dependence of the manufactured optical amplifier of Example 1.
- the horizontal axis indicates the wavelength of the input signal light.
- the gain and NF characteristics are values excluding the influence of optical loss such as an optical multiplexer / demultiplexer, that is, the net value of the optical amplifier.
- the gain is 20.7 dB
- the 1 dB gain band is 38 nm that can cover the C band
- the NF within the 1 dB gain band is 4.5 dB or less.
- the amplification characteristics were obtained.
- the manufactured optical amplifier of Example 1 extremely high gain spectrum flatness, wide bandwidth capable of covering the C band, and high gain of 20 dB or more were realized, and extremely low NF was obtained.
- the gain characteristic is realized with higher gain while achieving flatness of the gain spectrum and wider bandwidth. Has been.
- FIG. 7 is a diagram showing an ASE spectrum when the pump light wavelength and the temperature of the amplification optical fibers 11 and 12 are adjusted by the manufactured optical amplifier of the first embodiment. Signal light is not input.
- a solid line indicates a case where the temperature of the amplification optical fibers 11 and 12 is set to room temperature and the pump light wavelength is set to 1562.6 nm (that is, zero dispersion wavelength at room temperature).
- the broken line indicates a case where the temperature of the amplification optical fibers 11 and 12 is set to 128.7 ° C. and the pump light wavelength is set to 1565.0 nm, which is 2.4 nm longer than that at room temperature.
- the broadband spectrum around the peak indicating pump light indicates the ASE spectrum of the optical amplifier.
- the shape of the ASE spectrum substantially corresponds to the shape of the gain spectrum.
- the shape in which the intensity decreases toward the long wavelength side in the ASE spectrum is a characteristic that the optical attenuation amount (about ⁇ 20 dB) of the optical attenuator 200 in the measurement system increases toward the long wavelength side. Is reflected.
- the ASE spectrum is almost overlapped with the solid line and the broken line. This is because, when the pump light wavelength is changed from the state where the zero dispersion wavelength and the pump light wavelength coincide with each other at room temperature, the temperature of the amplification optical fibers 11 and 12 is adjusted accordingly, and the zero dispersion is obtained. By shifting the wavelength and bringing it closer to the pump light wavelength, an ASE spectrum (or gain spectrum) having the same shape as the ASE spectrum (or gain spectrum) in which the zero dispersion wavelength and the pump light wavelength coincide with each other at room temperature can be obtained. It is shown that. According to the technique of adjusting the temperature of the amplification optical fibers 11 and 12, the pump light wavelength and the zero dispersion wavelength can be easily brought close to the range of ⁇ 0.5 nm.
- FIG. 8 is a diagram showing the gain of the manufactured optical amplifier of Example 1 and the dependence of NF on the input signal light intensity.
- the vertical axis indicates the difference between the gain and NF when the intensity of the input signal light is ⁇ 20 dBm.
- the gain and NF are almost constant, but when the intensity is ⁇ 10 dBm or more, a decrease in gain and an increase in NF are observed.
- FIG. 9 is a diagram showing the gain and NF wavelength dependence when the relative phase shifter is deleted and the amplification optical fibers 11 and 12 are directly fused and connected in the configuration of the manufactured optical amplifier of the first embodiment. .
- the flatness of the gain is lower than when the relative phase shifter shown in FIG. 6 is provided, but NF is improved.
- FIG. 25 is a schematic configuration diagram of the disclosed optical amplifier and its amplification characteristic measurement system.
- This optical amplifier 1000 has a configuration in which the optical amplifier 10 is replaced with the optical amplifier 1010 in the optical amplifier 100 according to the first embodiment shown in FIG.
- the optical amplifying body 1010 is a three-stage optical amplifying body including amplification optical fibers 1011, 1012, 1013 and relative phase shifters 1014, 1015 inserted between the amplification optical fibers 1011, 1012, 1013. It is.
- the amplification optical fibers 1011, 1012, 1013 had a zero dispersion wavelength of 1567.0 nm at room temperature.
- the dispersion slope at a wavelength of 1550 nm was 0.017 ps / nm 2 / km, the transmission loss at a wavelength of 1550 nm was 0.8 dB / km, and the nonlinear constant at a wavelength of 1550 nm was 12 / W / km.
- the lengths of the amplification optical fibers 1011, 1012, and 1013 were 120 m, 150 m, and 200 m, respectively.
- the fluctuation of the zero dispersion wavelength in the longitudinal direction of the amplification optical fibers 1011, 1012, 1013 was larger than 0.5 nm / 100 m.
- the power of the pump light input to the optical amplifying body 1010 was about 32.2 dBm, and the pump light wavelength was 1567.2 nm.
- the transmission wavelength band of the optical bandpass filter 24 in the pump light source unit 20 was 0.8 nm.
- the power of the signal light input to the optical amplifying body 1010 was about ⁇ 20 dBm.
- the relative phase shifters 1014 and 1015 were all-pass dielectric multilayer filters.
- the insertion loss of the relative phase shifters 1014 and 1015 was 1.0 dB and 1.2 dB at the wavelength of 1550 nm, respectively, but these insertion losses were almost the same values for the wavelengths of the pump light and the signal light. .
- FIG. 26 is a diagram showing the wavelength dependence of the gain and NF of the optical amplifier shown in FIG.
- the horizontal axis indicates the wavelength of the input signal light.
- “1st HNLF out”, “2nd HNLF out”, and “3rd HNLF out” indicate the characteristics on the output side of the amplification optical fibers 1011, 1012, and 1013, respectively.
- the optical amplifier 1000 achieves a gain of 21 dB exceeding the practical gain of 20 dB by adopting a three-stage configuration, but the gain 1 dB band is 25 nm, It was not possible to cover the C band.
- FIG. 10 is a schematic configuration diagram of an optical amplifier 100A and its amplification characteristic measurement system according to a modification of the first embodiment of the present invention. As shown in FIG. 10, an optical amplifier 100A according to this modification is obtained by replacing the optical multiplexer / demultiplexer 30 with an optical multiplexer / demultiplexer 30A in the optical amplifier 100 according to the first embodiment.
- the optical multiplexer / demultiplexer 30A includes a three-port optical bandpass filter.
- This optical bandpass filter has a characteristic of passing the pump light and reflecting light other than the wavelength of the pump light.
- the optical bandpass filter may be replaced with a C / L band optical coupler.
- the C / L band optical coupler is an optical coupler having a function of combining light of both C band and L band (for example, 1565 nm to 1620 nm) using a low pass filter or a high pass filter.
- the pump light is input from the L band port side of the optical multiplexer / demultiplexer 30A.
- the optical multiplexer / demultiplexer 30A By using the optical multiplexer / demultiplexer 30A, the optical loss of the pump light at the time of multiplexing with the signal light can be reduced as compared with the case where the optical multiplexer / demultiplexer 30 which is a 20 dB optical coupler is used. Intense pump light can be input to the optical amplifying body 10.
- an optical amplifier of Example 2 in which the temperature adjustment mechanism 14 was applied to the optical amplifier 100A according to the present modification was manufactured, and the characteristics thereof were measured using the measurement system shown in FIG.
- the optical amplifier according to the second embodiment is implemented except that the optical multiplexer / demultiplexer 30A is configured by a three-port optical bandpass filter and the intensity of the pump light input to the optical amplifying body 10 is high by 0.5 dB.
- the configuration was the same as that of the optical amplifier of Example 1, and measurement was performed under the same measurement conditions. However, the temperature adjustment of the amplification optical fibers 11 and 12 was performed with higher accuracy.
- FIG. 11 is a graph showing the gain and NF wavelength dependence of the manufactured optical amplifier of Example 2.
- the horizontal axis indicates the wavelength of the input signal light.
- the gain is 23 dB
- the 1 dB gain band is very wide and 50 nm (1515 nm to 1565 nm) can sufficiently cover the C band, and within the 1 dB gain band.
- An amplification characteristic of NF of 4.5 dB or less was obtained.
- the manufactured optical amplifier of Example 2 achieves extremely high gain spectrum flatness, extremely wide bandwidth capable of sufficiently covering the C band, and high gain of 20 dB or more, and extremely low NF. It was.
- the temperature of the amplification optical fibers 11 and 12 was adjusted, and the zero dispersion wavelength was shifted from the pump light wavelength by 0.1 nm to 0.2 nm toward the short wavelength side.
- the following characteristics were obtained:
- FIG. 12 is a diagram showing the gain and NF wavelength dependence when the zero-dispersion wavelength is adjusted in the manufactured optical amplifier of the second embodiment. As shown in FIG. 12, when the zero-dispersion wavelength is adjusted, the flatness of the gain is reduced as compared with the case of FIG. 11, but the NF is greatly improved and is about 3 dB in a wide range from 1525 nm to 1560 nm. became.
- the output side of the optical amplifier in the state of FIG. 12 has a transmission wavelength characteristic obtained by inverting the gain wavelength characteristic of FIG. 12 (for example, a wavelength characteristic with low transmittance at a high gain wavelength), and a gain wavelength after output. If a gain flattening optical filter that flattens the characteristics is arranged, a gain of 20 dB or more can be realized in a very wide band, and an optical amplifier with a very low NF can be realized.
- MI modulation instability
- FIG. 13 is a schematic configuration diagram of an optical amplifier according to Embodiment 2 of the present invention.
- an optical amplifier 100B that is an OPA according to the second embodiment includes an optical amplifying body 10, a pump light source unit 20A, an optical multiplexer / demultiplexer 30, an optical multiplexer / demultiplexer 31, and an optical circulator. 51, a polarization multiplexer / demultiplexer 52, and connection polarization maintaining optical fibers 61 and 62.
- the pump light source unit 20A includes a pump light source 21A, an optical isolator 22A, a polarizer 23A, and a wave plate 24A.
- the pump light source 21A has the same configuration as the pump light source unit 20 shown in FIG. 1, for example, and outputs pump light having a predetermined pump light wavelength to the optical isolator 22A.
- the optical isolator 22A transmits the pump light to the polarizer 23A side and blocks input of the return light propagating from the polarizer 23A side to the pump light source 21A.
- the polarizer 23A converts the pump light transmitted through the optical isolator 22A into linearly polarized light.
- the wave plate 24A is a half-wave plate or a quarter-wave plate, and rotates the polarization direction of the pump light that is linearly polarized.
- the rotation angle of the polarization direction of the pump light by the wave plate 24A can be adjusted by adjusting the angle of the wave plate 24A.
- the optical multiplexer / demultiplexer 30 has a function of combining the pump light input from the pump light source unit 20 ⁇ / b> A and the signal light input from the outside and outputting to the optical circulator 51.
- the optical multiplexer / demultiplexer 30 is, for example, a 20 dB optical coupler or a C / L band optical coupler, but is not particularly limited.
- a three-port optical bandpass filter may be used as in the optical multiplexer / demultiplexer 30A.
- the optical circulator 51 receives the pump light and the signal light from the optical multiplexer / demultiplexer 30 and transmits them to the polarization multiplexer / demultiplexer 52.
- the polarization multiplexer / demultiplexer 52 separates the signal light and the pump light into polarization components having polarization states orthogonal to each other, and outputs them to the connected polarization maintaining optical fibers 61 and 62, respectively.
- connection polarization maintaining optical fibers 61 and 62 are connected to both ends of the optical amplifying body 10. That is, the connection polarization maintaining optical fiber 61 is connected to the amplification optical fiber 11 side of the optical amplifying body 10, and the connection polarization maintaining optical fiber 62 is connected to the amplification optical fiber 12 side of the optical amplification body 10. Yes.
- the angular polarization components of the signal light and the pump light separated by the polarization multiplexer / demultiplexer 52 are input to the optical amplifying body 10 from the amplification optical fiber 11 side and the amplification optical fiber 12 side, respectively.
- the optical fibers 11 and 12 for amplification propagate in opposite directions.
- the amplification optical fibers 11 and 12 parametrically amplify the signal light being propagated.
- Each polarization component amplified while propagating in opposite directions is output from the amplification optical fiber on the opposite side to the input side of the optical amplifying body 10, and propagates through the connected polarization maintaining optical fibers 61 and 62, respectively.
- the polarization multiplexer / demultiplexer 52 receives the respective polarization components propagated through the connected polarization maintaining optical fibers 61 and 62, combines them, and outputs them to the optical circulator 51.
- the optical circulator 51 outputs the input polarization combined and amplified signal light and the polarization combined pump light to the optical multiplexer / demultiplexer 31.
- the optical multiplexer / demultiplexer 31 is, for example, a 20 dB optical coupler or a C / L band optical coupler, but is not particularly limited. For example, a three-port optical bandpass filter may be used as in the optical multiplexer / demultiplexer 30A.
- the optical multiplexer / demultiplexer 31 demultiplexes the amplified signal light and pump light input from the optical circulator 51, and outputs them from different ports. For example, the optical multiplexer / demultiplexer 31 outputs the amplified signal light from a port indicated by a straight line in the drawing, and outputs the pump light from a port indicated by a curved line in the drawing.
- the pump light is usually high-intensity light of 1 W or more, it is processed by a known light processor after being output from the port.
- a known light processor has a function of absorbing light, converting the energy into heat, and radiating the converted heat, for example.
- the optical amplifier 100B includes amplification optical fibers 11 and 12 with little variation in the zero-dispersion wavelength in the longitudinal direction.
- the optical amplifier 100B separates the input pump light and signal light by polarization, and amplifies the optical fiber 11 so that the orthogonal polarization components propagate in the amplification optical fibers 11 and 12 in opposite directions. , 12 and propagating through the amplification optical fibers 11 and 12 in opposite directions to amplify the polarization components orthogonal to each other and amplified.
- the optical amplifier 100B has the effects obtained in the first embodiment, and can provide a gain with little polarization dependency even if the input signal light has an arbitrary polarization state.
- the polarization direction of the pump light to be input is preferably set to such a polarization direction that the polarization dependency of the optical amplifier 100B is low, preferably the minimum state, by adjusting the angle of the wave plate 24A.
- the optical amplifying body 10 is preferably configured to have central symmetry. For example, if the amplification optical fibers 11 and 12 are optical fibers having the same characteristics, the amplification optical fibers 11 and 12 have the same length, and the relative phase shifter 13 is disposed at the center in the longitudinal direction of the optical amplification body 10. It is preferred that
- the optical amplifier according to the first or second embodiment or the modification thereof includes the two-stage optical amplifying body 10 in which one relative phase shifter 13 is inserted between the amplification optical fibers 11 and 12. Yes.
- the optical amplifier is not limited to a two-stage configuration, and may be a one-stage configuration or a three-stage configuration or more.
- an optical amplifying body 10A in which relative phase shifters 13 and 16 are inserted between amplification optical fibers 11, 12, and 15 may be used as the optical amplifying body, as shown in FIG. 14, an optical amplifying body 10A in which relative phase shifters 13 and 16 are inserted between amplification optical fibers 11, 12, and 15 may be used.
- Such an optical amplifying body 10A is an optical amplifying body having a three-stage configuration including amplification stages ST1, ST2, and ST3.
- the amplification optical fiber 15 may have the same configuration as the amplification optical fibers 11 and 12, and the relative phase shifter 16 may have the same configuration as the relative phase shifter 13.
- the amplification characteristics and length of the amplification optical fiber and the phase shift amount of the relative phase shifter are the same as in the case of the two-stage configuration. And the like are preferably configured and arranged so as to be symmetrical with respect to the longitudinal direction.
- each amplification optical fiber when they have the same characteristics, it is preferable that the amplification optical fibers disposed on both sides have the same length and the amplification optical fiber disposed in the center is longer than that.
- the polarization component propagating in any direction can be compensated for by reducing the gain caused by the insertion loss of the relative phase shifter by lengthening the central amplification optical fiber.
- the relative phase shifter is not limited to the one using FBG, and an all-pass filter type relative phase shifter constituted by a dielectric multilayer filter and a reflection type module may be used.
- Such an all-pass filter type relative phase shifter can adjust the phase shift amount by adjusting the pump light wavelength. Moreover, since there is no reflection of a specific wavelength, it is preferable.
- the optical fiber used as the pigtail fiber has a zero dispersion wavelength in the range of the pump light wavelength to be used ⁇ 10 nm or a dispersion slope of 0.06 ps /
- An optical fiber having characteristics of nm 2 / km or less or both is desirable. The reason for this is to prevent the relative phase from fluctuating due to the chromatic dispersion of the pigtail fiber and destroying the phase matching state.
- the mode field diameter (MFD) of the pigtail fiber is in the range of ⁇ 50% of the MFD of the amplification optical fiber. This is because the fusion splicing loss between the pigtail fiber and the amplification optical fiber can be reduced to 0.5 dB or less by matching the MFD within this range.
- WDM wavelength multiplexed
- FWM four-wave mixing
- Non-Patent Document 3 as a result of investigating NF characteristics by FWM light in OPA using ASE light as signal light instead of WDM signal light, the difference in intensity between pump light intensity and amplified ASE light is 20 dB or more. For example, it is reported that the increase in NF is suppressed.
- the present inventors diligently examined, and in OPA, when the intensity ratio between the intensity of the pump light input to the optical amplifier and the total intensity of the WDM signal light is 24 dB or more, it is practically used. It was found that the amount of degradation of WDM signal light was sufficient.
- FIG. 15 is a schematic configuration diagram of the optical amplifier according to the first embodiment and its WDM amplification characteristic measurement system.
- the WDM signal light sources are output from the signal light sources 41-1 to 41-8 in which the polarization controllers 42-1 to 42-8 are connected to the eight signal light sources 41-1 to 41-8, respectively.
- the signal light having different wavelengths are combined by the AWG 43 to generate WDM signal light of 8 channels, and the optical amplifier 100 according to Embodiment 1 I entered it.
- the manufactured optical amplifier of Example 1 was used as the optical amplifier 100 according to the first embodiment.
- the pump light wavelength of the pump light is set to be 5 nm or more away from the wavelength of the 8-channel WDM signal light.
- FIG. 16 is a diagram showing a spectrum of 8-channel WDM signal light to be input.
- Each of the polarization controllers 42-1 to 42-8 was adjusted so that the gain of each signal light in the optical amplifier was maximized.
- the other conditions were the same as in the experiment whose results are shown in FIG.
- the intensity of the input pump light was 32.2 dBm.
- 17 to 22 are diagrams showing spectra of the amplified 8-channel WDM signal light.
- the optical intensity per channel of the WDM signal light input to the optical amplifier is -11 dBm / ch, -16 dBm / ch, -21 dBm / ch, -26 dBm / ch, and -41 dBm / ch, respectively. , ⁇ 51 dBm / ch.
- the actual light intensity output from the optical amplifier Is a value obtained by adding 19 dB or 20 dB to the numerical value on the vertical axis of each figure.
- the intensity difference between the 8-channel WDM signal light and the FWM light is 20 dB or more, and the generated amount of FWM light can be used as a practical optical amplifier. there were.
- the intensity of the 8-channel WDM signal light was lower than ⁇ 21 dBm / ch, the generation amount of FWM light was significantly reduced.
- the intensity ratio between the intensity of the pump light input to the optical amplifier and the total intensity of the WDM signal light is 24 dB or more, the amount of degradation of the WDM signal light is sufficient for practical use.
- FIG. 23 is a diagram illustrating the wavelength dependence of the gain and NF when the 8-channel WDM signal light is input to the optical amplifier according to the first embodiment.
- the intensity of the signal light per channel is changed from ⁇ 56 dBm / ch to ⁇ 11 dBm / ch.
- the optical amplifier of Example 1 obtained a sufficient gain even when an 8-channel WDM signal light was input.
- interval between the signal lights of 8-channel WDM signal light is narrow, since the noise floor was measured larger than the actual, it is thought that it is larger than an actual value. Therefore, a similar WDM amplification characteristic experiment was conducted using a 4-channel WDM signal light (within an interval of about 2.4 nm within the range of 1550 nm to 1560 nm) instead of the 8-channel WDM signal light.
- FIG. 24 is a diagram illustrating the wavelength dependence of the gain and NF when a 4-channel WDM signal light is input to the optical amplifier according to the first embodiment.
- the intensity of the signal light per channel is changed from ⁇ 56 dBm / ch to ⁇ 11 dBm / ch.
- an NF smaller than 4.5 dB was obtained in the case of ⁇ 21 dBm / ch assumed in actual use.
- the intensity of the signal light is larger than ⁇ 21 dBm / ch, it is considered that the noise floor is larger than the actual value because it is measured larger than the actual value.
- the optical amplifier according to the above-described embodiment may be installed in the front stage of the EDFA or the rear stage of the optical amplification system using the Raman effect to constitute the optical amplification system.
- Such an optical amplification system is an optical amplification system with low noise and high output in the entire system due to the low noise characteristics of the optical amplifier according to the embodiment.
- the optical amplifier according to the above embodiment can be used as a wavelength converter or a PSA.
- the optical amplifier, optical amplification system, wavelength converter, and optical communication system according to the present invention are suitable mainly for use in the field of optical communication.
- SYMBOLS 10, 10A Optical amplifier 11, 12, 15 Amplifying optical fiber 11a Core part 11aa Center core part 11ab Buffer core layer 11ac Outer core layer 11b Cladding part 11c Coating 12 Outer core layer 13, 16 Relative phase shifter 14 Temperature adjustment mechanism 14a Bobbin 14b Heater wire 14c Temperature detection element 14d Housing 20, 20A Pump light source unit 21, 21A Pump light source 22 Phase modulator 22A Optical fiber amplifier 23A Polarizer 24 Optical bandpass filter 24A Wavelength plate 25 White noise source 26 Broadband RF amplifier 30, 30A, 31 Optical multiplexer / demultiplexer 41, 41-1 to 41-8 Signal light source 42, 42-1 to 42-8 Polarization controller 51 Optical circulator 52 Polarization multiplexer / demultiplexer 61, 62 Connected polarization Holding optical fiber 100, 100A, 00B optical amplifier 200 an optical attenuator 300 optical spectrum analyzer ST1, ST2, ST3 amplifier stage
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Abstract
Description
図1は、本発明の実施の形態1に係る光増幅器100およびその増幅特性測定系の模式的な構成図である。図1に示すように、OPAである光増幅器100は、光増幅体10と、ポンプ光源部20と、光合分波器30とを備えている。
ただし、0≦r<d1/2
ただし、r14max≦r<d2/2
ここで、Δk=ksignal+kidler-2kpumpで定義される。ksignal、kidler、kpumpは各光の波数である。
より具体的には、増幅用光ファイバ11および12については、温度調節や張力調節により零分散波長を調節できる。ポンプ光源21がDFBレーザやFPレーザやVCSELなどの半導体レーザ素子で構成される場合、半導体レーザ素子の温度調節や駆動電流の調節によりその発振波長を調節することができる。また、相対位相シフタ13がFBGの場合は、FBGのブラッグ波長を温度調節や張力調節により調節することができる。これらの3つの特性波長(零分散波長、発振波長、ブラッグ波長)の1つから3つを、任意に組み合わせて調節することにより、光増幅器100において平坦かつ広帯域な利得スペクトルを得ることができる。従って、光増幅器100は、増幅用光ファイバ11および12に掛かる張力を調整する張力調整機構、半導体レーザ素子の温度を調整する温度調整機構または半導体レーザ素子の駆動電流を調整する駆動電流調整機構、またはFBGの温度を調整する温度調整機構もしくはFBGに掛かる張力を調整する張力調整機構を備えることが好ましい。
たとえば、相対位相シフタ13を構成するFBGとして反射波長の温度依存性をキャンセルしたアサーマルFBGを用いる場合は、上記機構により、該FBGのブラッグ波長に、増幅用光ファイバ11および12の零分散波長と、半導体レーザ素子の発振波長とを合わせるように調節することができる。また、増幅用光ファイバ11および12の零分散波長を固定した場合は、上記機構により、相対位相シフタ13を構成するFBGのブラッグ波長と半導体レーザ素子の発振波長とを調節して、零分散波長に合わせるようにすることができる。
なお、ここで、FBGは、温度調整機構としてのペルチェ素子やヒータなどの上に、銅、アルミ、セラミックなどからなるヒートシンクを介して配置し、ペルチェ素子やヒータなどに熱的に接触するように固定することで、温度調節することができる。また、サーミスタなどの温度センサをヒートシンク上に設け、温度をモニタしながら温度調節をすることで、より精密に温度調節を行うことができる。
図10は、本発明の実施の形態1の変形例に係る光増幅器100Aおよびその増幅特性測定系の模式的な構成図である。図10に示すように、本変形例に係る光増幅器100Aは、実施の形態1に係る光増幅器100において、光合分波器30を光合分波器30Aに置き換えたものである。
図13は、本発明の実施の形態2に係る光増幅器の模式的な構成図である。図13に示すように、本実施の形態2に係るOPAである光増幅器100Bは、光増幅体10と、ポンプ光源部20Aと、光合分波器30と、光合分波器31と、光サーキュレータ51と、偏波合分波器52と、接続偏波保持光ファイバ61、62とを備えている。
11、12、15 増幅用光ファイバ
11a コア部
11aa 中心コア部
11ab 緩衝コア層
11ac 外側コア層
11b クラッド部
11c 被覆
12 外側コア層
13、16 相対位相シフタ
14 温度調整機構
14a ボビン
14b ヒータ線
14c 温度検出素子
14d 筐体
20、20A ポンプ光源部
21、21A ポンプ光源
22 位相変調器
22A 光アイソレータ
23 光ファイバ増幅器
23A 偏光子
24 光バンドパスフィルタ
24A 波長板
25 白色雑音源
26 広帯域RF増幅器
30、30A、31 光合分波器
41、41-1~41-8 シグナル光源
42、42-1~42-8 偏波コントローラ
51 光サーキュレータ
52 偏波合分波器
61、62 接続偏波保持光ファイバ
100、100A、100B 光増幅器
200 光減衰器
300 光スペクトラムアナライザ
ST1、ST2、ST3 増幅段
Claims (16)
- 増幅用光ファイバと、
前記増幅用光ファイバに入力されるシグナル光を前記増幅用光ファイバの非線形光学効果によってパラメトリック増幅するためのポンプ光を前記増幅用光ファイバに供給するポンプ光源と、
を備え、前記増幅用光ファイバは、長手方向において零分散波長の変動が0.5nm/100mの範囲内であることを特徴とする光増幅器。 - 前記増幅用光ファイバは、
中心コア部と、
前記中心コア部の周囲に形成され前記中心コア部よりも屈折率が低い外側コア層と、
前記中心コア部と前記外側コア層との間に形成され前記中心コア部よりも屈折率が低くかつ前記外側コア層よりも屈折率の高い1以上の緩衝コア層と、
を有するコア部と、
前記外側コア層の周囲に形成され前記中心コア部よりも屈折率が低くかつ前記外側コア層よりも屈折率が高いクラッド部と、
を有し、波長1550nmにおける有効コア断面積が18μm2以下であることを特徴とする請求項1に記載の光増幅器。 - 前記増幅用光ファイバは、
波長1550nmにおける有効コア断面積が10.27μm2以上18μm2以下であり、
前記中心コア部の前記クラッド部に対する比屈折率差が1.8%以上3.0%以下であり、
前記外側コア層の前記クラッド部に対する比屈折率差が-1.2%以上-0.2%以下であり、
前記緩衝コア層の前記クラッド部に対する比屈折率差が0.1%以上0.6%以下であり、
前記外側コア層の外径が9.4μm以上21.4μm以下であり、
前記外側コア層の外径に対する前記中心コア部の直径の比が0.20以上0.40以下であり、
前記外側コア層の外径に対する前記緩衝コア層の外径の比が0.24以上0.80以下であり、
波長1550nmにおける波長分散の絶対値が5ps/nm/km以下の範囲において、前記外側コア層の外径が1%変動したときの波長1550nmにおける波長分散の変動が、0.7ps/nm/km以下であることを特徴とする請求項2に記載の光増幅器。 - 前記増幅用光ファイバの温度を調整する温度調整機構または前記増幅用光ファイバに掛かる張力を調整する張力調整機構を備えることを特徴とする請求項1~3のいずれか一つに記載の光増幅器。
- 前記ポンプ光源内の半導体レーザ素子の温度を調整する温度調整機構または前記半導体レーザ素子の駆動電流を調整する駆動電流調整機構を備えることを特徴とする請求項1~3のいずれか一つに記載の光増幅器。
- 前記位相シフタがファイバブラッググレーティングであって、前記ファイバブラッググレーティングの温度を調整する温度調整機構または前記ファイバブラッググレーティングに掛かる張力を調整する張力調整機構を備えることを特徴とする請求項1~3のいずれか一つに記載の光増幅器。
- 前記増幅用光ファイバは、周囲温度における前記零分差波長が、前記ポンプ光の波長を所定のポンプ光波長に設定した場合に当該光増幅器の平坦な利得帯域が最大となる第1零分散波長よりも5nm以下だけ短波長側に位置し、
前記温度調整機構は、前記増幅用光ファイバの前記零分差波長が前記第1零分散波長に近づくように前記増幅用光ファイバの温度を調整することを特徴とする請求項4に記載の光増幅器。 - 前記増幅用光ファイバの零分散波長は前記ポンプ波長よりも短く、
当該光増幅器の利得波長特性を平坦にする利得平坦化フィルタを備えることを特徴とする請求項1~7のいずれか一つに記載の光増幅器。 - 前記シグナル光および前記ポンプ光が入力され、前記シグナル光および前記ポンプ光を互いに直交する偏波状態を有する偏波成分に偏波分離し、前記互いに直交する偏波成分を前記増幅用光ファイバを互いに逆向きに伝搬するように前記増幅用光ファイバに入力させ、前記増幅用光ファイバを互いに逆向きに伝搬して増幅された前記互いに直交する偏波成分を偏波合成する偏波合分波器を備えることを特徴とする請求項1~8のいずれか一つに記載の光増幅器。
- 前記複数の増幅用光ファイバの間に挿入され、入力された光の相対位相を変化させる相対位相シフタをさらに備えることを特徴とする請求項1~9のいずれか一つに記載の光増幅器。
- 当該光増幅器に入力される前記ポンプ光の強度と前記シグナル光の総強度との強度比が24dB以上であることを特徴とする請求項1~10のいずれか一つに記載の光増幅器。
- 増幅用光ファイバと、
前記増幅用光ファイバに入力される波長多重シグナル光を、前記増幅用光ファイバの非線形光学効果によってパラメトリック増幅するためのポンプ光を前記増幅用光ファイバに供給するポンプ光源と、
を備え、当該光増幅器に入力される前記ポンプ光の強度と前記波長多重シグナル光の総強度との強度比が24dB以上であることを特徴とする光増幅器。 - 前記ポンプ光のポンプ光波長が前記波長多重シグナル光の波長に対して5nm以上離間して設定されていることを特徴とする請求項12に記載の光増幅器。
- 請求項1~13のいずれか一つに記載の光増幅器を備えたことを特徴とする光増幅システム。
- 請求項1~13のいずれか一つに記載の光増幅器を備えたことを特徴とする波長変換器。
- 請求項1~13のいずれか一つに記載の光増幅器を備えたことを特徴とする光通信システム。
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108139648A (zh) * | 2015-10-13 | 2018-06-08 | 古河电气工业株式会社 | 光放大器、光放大系统、波长变换器以及光通信系统 |
WO2018155017A1 (ja) * | 2017-02-24 | 2018-08-30 | 国立研究開発法人産業技術総合研究所 | 波長変換方法および波長変換器 |
JP2021022622A (ja) * | 2019-07-25 | 2021-02-18 | 株式会社フジクラ | ファイバレーザ、及び、レーザ光の出力方法 |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9843410B2 (en) * | 2015-11-18 | 2017-12-12 | Fujitsu Limited | Low-noise optical phase sensitive amplifier using a semiconductor nonlinear optical device |
US9997887B1 (en) * | 2017-02-07 | 2018-06-12 | Fujitsu Limited | Optical phase-sensitive amplifier with fiber bragg grating phase shifter |
US10498102B2 (en) | 2017-06-20 | 2019-12-03 | Fujitsu Limited | Optical phase-sensitive amplifier with signal noise removal |
US10847945B2 (en) * | 2018-01-11 | 2020-11-24 | Fujitsu Limited | Phase shifter for an optical phase-sensitive amplifier |
WO2020056264A1 (en) * | 2018-09-13 | 2020-03-19 | Ofs Fitel, Llc | Bismuth doped fiber amplifier |
CN109298425B (zh) * | 2018-11-13 | 2023-12-05 | 华中光电技术研究所(中国船舶重工集团有限公司第七一七研究所) | 多功能激光传感系统 |
US10523334B1 (en) | 2018-12-07 | 2019-12-31 | Fujitsu Limited | Controlling gain modulation in optical communication networks |
US11757248B2 (en) * | 2019-07-19 | 2023-09-12 | Raytheon Company | System and method for spectral line shape optimization for spectral beam combining of fiber lasers |
US11387912B2 (en) * | 2020-11-19 | 2022-07-12 | Fujitsu Limited | Wavelength converter and fiber optic transmission system |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007072182A (ja) * | 2005-09-07 | 2007-03-22 | Sumitomo Electric Ind Ltd | 光ファイバおよびそれを用いた光デバイス |
JP2007225734A (ja) | 2006-02-21 | 2007-09-06 | Furukawa Electric Co Ltd:The | 非線形光ファイバおよび非線形光デバイスならびに光信号処理装置 |
JP2010272636A (ja) * | 2009-05-20 | 2010-12-02 | Sumitomo Electric Ind Ltd | 光ファイバ増幅モジュールおよび光源装置 |
WO2012121223A1 (ja) | 2011-03-04 | 2012-09-13 | 古河電気工業株式会社 | 光増幅器、光増幅システム、波長変換器、光増幅方法および光通信システム |
WO2013153687A1 (ja) * | 2012-04-12 | 2013-10-17 | 古河電気工業株式会社 | 光増幅器、光増幅システム、波長変換器、光増幅方法および光通信システム |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7483614B2 (en) * | 2005-09-07 | 2009-01-27 | Sumitomo Electric Industries, Ltd. | Optical fiber and optical device using the same |
-
2014
- 2014-09-02 EP EP14839281.4A patent/EP3043205B1/en active Active
- 2014-09-02 JP JP2015531184A patent/JP5877280B2/ja active Active
- 2014-09-02 WO PCT/JP2014/073006 patent/WO2015030251A1/ja active Application Filing
-
2016
- 2016-02-24 US US15/052,315 patent/US9948057B2/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007072182A (ja) * | 2005-09-07 | 2007-03-22 | Sumitomo Electric Ind Ltd | 光ファイバおよびそれを用いた光デバイス |
JP2007225734A (ja) | 2006-02-21 | 2007-09-06 | Furukawa Electric Co Ltd:The | 非線形光ファイバおよび非線形光デバイスならびに光信号処理装置 |
JP2010272636A (ja) * | 2009-05-20 | 2010-12-02 | Sumitomo Electric Ind Ltd | 光ファイバ増幅モジュールおよび光源装置 |
WO2012121223A1 (ja) | 2011-03-04 | 2012-09-13 | 古河電気工業株式会社 | 光増幅器、光増幅システム、波長変換器、光増幅方法および光通信システム |
WO2013153687A1 (ja) * | 2012-04-12 | 2013-10-17 | 古河電気工業株式会社 | 光増幅器、光増幅システム、波長変換器、光増幅方法および光通信システム |
Non-Patent Citations (8)
Title |
---|
J.C.BOGGIO ET AL.: "A novel method for measuring longitudinal variations of the zero dispersion wavelength in optical fibers", EUROPEAN CONFERENCE ON OPTICAL COMMUNICATIONS (ECOC), 2006, 24 September 2006 (2006-09-24), pages 1 - 2, XP031437051 * |
MASASHI ONISHI ET AL.: "Recent Technologies on Optical Nonlinearity of Optical Fibers", IEICE COMMUNICATIONS SOCIETY CONFERENCE 2007 KOEN RONBUNSHU, vol. 2, 29 August 2007 (2007-08-29), pages S-13 - S-14, XP008182827 * |
OPTICS LETTERS, vol. 21, 1996, pages 1724 - 1726 |
ROBERT ELSCHNER ET AL.: "Characterization ofFWM-Induced Crosstalk for WDM Operation of a Fiber-Optical Parametric Amplifier", ECOC 2011 |
S. TAKASAKA ET AL.: "Flat and Broad Amplification by Quasi-Phase-Matched Fiber Optical Parametric Amplifier", OFC/NFOEC 2012, 2012 |
S. TAKASAKA ET AL.: "FOPA with Flat 21-dB Gain and NF less than 4-dB using Alternately Concatenated Pump-Phase Shifters and HNLF", OFC/NFOEC 2013, 2013 |
S. TAKASAKA ET AL.: "FOPA with flat 21-dB gain and NF less than 4-dB using alternately concatenated pump-phase shifters and HNLFs", OPTICAL FIBER COMMUNICATION CONFERENCE AND EXPOSITION AND THE NATIONAL FIBER OPTIC ENGINEERS CONFERENCE (OFC/NFOEC) TECHNICAL DIGEST, 2013, vol. JTH2A.13, 17 March 2013 (2013-03-17), pages 1 - 3, XP032679217 * |
S.TAKASAKA ET AL.: "Flat and broad amplification by quasi-phase-matched fiber optical parametric amplifier", OPTICAL FIBER COMMUNICATION CONFERENCE AND EXPOSITION (OFC/NFOEC), 2012 AND THE NATIONAL FIBER OPTIC ENGINEERS CONFERENCE TECHNICAL DIGEST, vol. OTHCL.4, 4 March 2012 (2012-03-04), pages 1 - 3, XP032340556 * |
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EP3364244A4 (en) * | 2015-10-13 | 2019-06-12 | Furukawa Electric Co., Ltd. | OPTICAL AMPLIFIER, OPTICAL AMPLIFICATION SYSTEM, WAVE LENGTH CONVERTER AND OPTICAL COMMUNICATION SYSTEM |
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US20160172818A1 (en) | 2016-06-16 |
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