WO2003073156A1 - Modulateur d'attenuateur optique - Google Patents

Modulateur d'attenuateur optique Download PDF

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Publication number
WO2003073156A1
WO2003073156A1 PCT/JP2003/002150 JP0302150W WO03073156A1 WO 2003073156 A1 WO2003073156 A1 WO 2003073156A1 JP 0302150 W JP0302150 W JP 0302150W WO 03073156 A1 WO03073156 A1 WO 03073156A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical attenuator
electromagnet
magnetic field
yoke
rotation angle
Prior art date
Application number
PCT/JP2003/002150
Other languages
English (en)
Japanese (ja)
Inventor
Teruhisa Sahashi
Isao Kojima
Tsuguo Tokumasu
Kiyohito Ono
Yoshio Matsuo
Original Assignee
Fdk Corporation
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 Fdk Corporation filed Critical Fdk Corporation
Publication of WO2003073156A1 publication Critical patent/WO2003073156A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/09—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on magneto-optical elements, e.g. exhibiting Faraday effect
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/48—Variable attenuator

Definitions

  • the present invention relates to a magneto-optical device having a variable optical attenuator structure in which a polarizer is arranged on the optical axis of a Faraday rotation angle varying device. More specifically, a highly saturated yoke of an electromagnet for controlling the rotation angle of a Faraday element is provided.
  • the present invention relates to an optical attenuator modulator that uses a magnetic flux density ferrite, has a variable optical attenuation function, and is capable of modulating the intensity of a transmitted light signal in an arbitrary optical attenuation state by a high-frequency electrical signal.
  • An optical attenuator is a device that controls the amount of transmitted light in an optical communication system or an optical measurement system.
  • a polarizer and an analyzer are placed before and after (input side and output side) on the optical axis of the Faraday rotation angle variable device.
  • the configuration is common.
  • the built-in Faraday rotation angle variable device applies an external magnetic field to a Faraday element (such as a magnetic garnet single crystal film having a Faraday effect) using an electromagnet and changes the external applied magnetic field to change the Faraday element. It controls the Faraday rotation angle of the plane of polarization of the transmitted light beam.
  • the optical attenuator variably controls the amount of light attenuation by controlling the Faraday rotation angle.
  • the electromagnet has a structure in which a coil is wound around a C-type yoke made of silicon steel, and a Faraday element is inserted into a gap of the yoke.
  • the reason why the yoke is made of silicon steel is that it is a material that has a high saturation magnetic flux density in direct current, is small, and can obtain a high magnetic field.
  • an optical modulator is a device that modulates a transmitted light beam with an electric signal (controls the transmitted light beam into an optical signal having the same shape as the electric signal).
  • the modulation method includes electro-optic modulation There are key modulation, magneto-optical modulation, and acousto-optic modulation, but when high-frequency modulation is required, the electro-optical modulation method that uses the Pockels effect or the force effect is generally used.
  • an electromagnet is used as a variable magnetic field generator of the optical isolator.
  • the electromagnet When the electromagnet is energized, the light beam passes through the isolator, and when the current to the electromagnet is cut off, the light beam is blocked. In this way, by turning on / off the electrical signal, the optical signal is also turned on / off and digital optical modulation is performed.
  • a movable structure permanent magnet may be used as the variable magnetic field generator.
  • silicon steel is used for the yoke of the electromagnet.
  • the drive current of the electromagnet coil usually requires only a current change close to DC, so this yoke material is preferable, and the structure operates without any trouble.
  • an electro-optic modulation method is adopted in a high frequency region, and only modulation in a very low frequency region is attempted.
  • An object of the present invention is to provide an optical attenuator modulator having both a variable attenuation function and an optical modulation function and capable of modulating an electric signal having a frequency of 10 kHz or more.
  • Another object of the present invention is to provide a magneto-optical type optical modulator which is highly reliable because it has no moving parts, and which is particularly useful as a variable attenuator and modulator for undersea optical communication requiring high reliability. It is to provide. Disclosure of the invention
  • One embodiment of the present invention is an optical attenuator modulator, which includes a Faraday rotation angle varying device that varies a rotation angle of a plane of polarization of light transmitted through a Faraday element by a variable magnetic field by an electromagnet,
  • the electromagnet includes a polarizer and an analyzer arranged, and the electromagnet includes a yoke formed of soft magnetic ferrite, and a coil wound around the yoke and supplied with a high-frequency modulation signal.
  • an optical attenuator modulator comprising: a Faraday rotation angle variable device that varies a rotation angle of a plane of polarization of light transmitted through a Faraday element by a variable magnetic field by an electromagnet;
  • the electromagnet includes a polarizer and a mirror arranged, and the electromagnet includes a yoke formed of soft magnetic ferrite, and a coil wound around the yoke and supplied with a high-frequency modulation signal.
  • a further aspect of the present invention is an optical attenuator modulator, which comprises a first permanent magnet, a polarizer made of a birefringent crystal plate, and a rotation angle of a plane of polarization of light transmitted through the Faraday element, which is controlled by a variable magnetic field generated by an electromagnet.
  • the electromagnet has a yoke formed of a soft magnetic ferrite, and a coil wound around the yoke and supplied with a high-frequency modulation signal.
  • FIG. 1 is an explanatory diagram showing an embodiment of an optical attenuator modulator according to the present invention
  • FIG. 2 is a graph showing frequency characteristics of ferrite and silicon steel
  • FIG. 3 is an explanatory view showing an example of a Faraday rotation angle varying device
  • Figure 4 shows the circuit diagram of the modulation drive circuit.
  • Figure 5 is a graph showing the attenuation characteristics
  • Figure 6 shows the observed waveform of the optical modulation output.
  • FIG. 7 is an explanatory diagram showing another embodiment of the optical attenuator modulator according to the present invention
  • FIG. 8 is an explanatory diagram showing still another embodiment of the optical attenuator modulator according to the present invention.
  • FIG. 1 is an explanatory diagram showing an embodiment of an optical attenuator modulator according to the present invention.
  • FIG. 1A shows the entire configuration
  • FIG. 1B shows a part of a Faraday rotation angle varying device.
  • the optical attenuator modulator is a Faraday rotation angle varying device that varies the rotation angle of the plane of polarization of light passing through the first permanent magnet 10, the polarizer 12, and the Faraday element 14 by a variable magnetic field generated by the electromagnet 16. 18, an analyzer 20, and a second permanent magnet 22.
  • the polarizer 12 and the analyzer 20 are disposed before and after (the input side and the output side) on the optical axis (indicated by broken lines) of the Faraday rotation angle varying device 18.
  • the polarizer 12 and the analyzer 20 are made of a birefringent crystal plate such as rutile.
  • the Faraday element 14 is made of, for example, a Bi-substituted rare earth iron garnet LPE crystal film.
  • the first and second permanent magnets 10 and 22 are ring-shaped and magnetized in the height direction (the optical axis direction in the figure), and are arranged in the same magnetization direction before and after on the optical axis. Thus, a configuration is adopted in which a fixed magnetic field in the optical axis direction is applied to the Faraday element 14.
  • the electromagnet 16 includes a C-shaped yoke 24 for applying a magnetic field to the Faraday element 14 in a concentrated manner, and a coil 26 wound around the yoke 24.
  • a co I le 2 6 that ⁇ to the yoke 2 4 is in the high saturation flux density soft magnetic ferrite, a co I le 2 6 that ⁇ to the yoke 2 4, a high frequency modulation signal is superimposed on the direct current from the modulation driving circuit 2 8
  • the structure is supplied.
  • the ferrite used in this example is a Mn-Zn-based material, and has a standard ring core (FR25Z15 / 5: outer diameter / inner diameter height) of 100 OA / m.
  • the saturation magnetic flux density is 40 O mT or more with respect to the magnetic field, and the frequency is 100
  • the relative loss factor in k H z (tan S / i ) is the following 1 X 1 0- 4.
  • the basic optical attenuator function is such that the Faraday element 14 which is magnetically saturated by the fixed magnetic field in the optical axis direction by the front and rear permanent magnets 10 and 22 is connected to the electromagnet 1 Since the Faraday element 14 is obtained by changing the magnetization direction with a variable magnetic field in the lateral direction (perpendicular to the optical axis) according to 6, a sufficient and sufficient variable magnetic field must act on the Faraday element 14.
  • the transverse magnetic field (variable magnetic field generated by the electromagnet) applied to the Faraday element 14 becomes insufficient, and the Faraday rotation angle variable reaches a peak, and further attenuation is obtained. Can not be.
  • the saturation magnetic flux density is sufficient in there DC drive 1 0 0 0 mT or more, does not work because the eddy current loss increases as if AC driving at 1 k H Z or more frequency as the modulator .
  • the saturation magnetic flux density is low, so it is more likely to be magnetically saturated than silicon steel, and the material properties must be carefully considered. The response speed does not deteriorate because the relative loss coefficient is low.
  • Fig. 2 shows the frequency characteristics of conventional silicon steel and the Mn-Zn ferrite used in the present invention.
  • impedance R s corresponding to eddy current loss
  • inductance L s decreases, and it can be seen that their characteristics deteriorate rapidly at higher frequencies.
  • the inductance L s is almost constant up to 100 kHz, and the increase in the impedance R s is very small.
  • the force at which magnetic saturation occurs at a magnetic flux density B 50 O mT In the unsaturated region, the linearity of the BH curve is good.
  • FIGS. 3A and 3B A preferred example of the Faraday rotation angle varying device used in the present invention is shown in FIGS. 3A and 3B.
  • FIG. 3A mainly shows a state where the yoke is disassembled into each element
  • FIG. 3B shows a state after assembly.
  • Yoke made of soft magnetic ferrite has dimensional accuracy and Machining ⁇
  • the combination of L type and I type is considered in consideration of ease of assembly work. That is, this electromagnet has a pair of L-shaped cores 32 and 34 symmetrically arranged so that their respective front end surfaces are in contact with the Faraday element, and an I-shaped core whose rear end surfaces are in contact with the side surfaces.
  • the yoke has a structure in which coils 36 and 38 are wound around both the L-shaped cores 30.32 respectively. These coils 36, 38 are connected individually after the winding force, which is continuously wound in series. Then, a modulation drive circuit 28 that generates a high-frequency modulation signal superimposed on the DC current is connected to the coils 30 and 32.
  • the joint surface between the L-shaped core and the I-shaped core and the tip surface (the surface facing the Faraday element) of the L-shaped core are polished. Normally, it is desirable that the gap between the yoke and the Faraday element be within 0.1 mm. Glue to the core. Therefore, the I-shaped core is set slightly longer in consideration of the displacement of the L-shaped core.
  • the cross-sectional area of the L-shaped core must be increased to some extent, and the portion near the tip is machined into a tapered shape that tapers toward the outer shape of the Faraday element. Is desirable. As a result, the magnetic field concentrates on the Faraday element, and the electromagnetic field can be applied efficiently.
  • the coil wound directly on the ferrite yoke the coil may be wound on a bobbin and can be easily mounted on the L-shaped core.
  • Figure 4 shows an example of the modulation drive circuit used for the measurement.
  • Combine two amplifiers A 2 connect an electromagnet coil to the position of coil L, and drive with transistor Q.
  • Attenuation adjustment is controlled by the voltage applied to the B (bias) terminal, and modulation is performed by applying an AC signal to the AC terminal.
  • a continuous light beam with a constant intensity was supplied to the optical attenuator modulator, the transmitted output light was converted into a voltage by photoelectric conversion, and the attenuation and output fluctuation were observed with an oscilloscope.
  • Figure 5 shows that the attenuation characteristics were obtained by changing only the voltage applied to the B terminal without inputting the modulation signal (maintaining 0 V). Wavelength used is 550 nm, measurement temperature is 25 ° C It is. As shown in the figure, this optical attenuator modulator has a drive current dependency of the amount of attenuation, similarly to a normal variable optical attenuator.
  • FIG. 6 shows the oscilloscope screen.
  • CH2 channel 2 is a modulated electrical signal waveform
  • CH1 channel 1 is a ⁇ 5% optical modulation waveform with 6 dB attenuation. It can be seen from FIG. 6 that the transmitted output light is modulated by completely following the low-voltage drive signal having the modulation frequency of 100 kHz.
  • FIG. 7 is an explanatory view showing another embodiment of the optical attenuator modulator according to the present invention, which has a fiber input / output structure. Since the main body may be the same as those shown in FIGS. 1A and 1B, the same reference numerals are given to the corresponding parts, and the description thereof will be omitted.
  • An optical fiber 40 with a ferrule is located on the input side, and is collimated by a collimator lens 42 and input to the main body.
  • the attenuated light from the main body is collected by a collimator lens 44 and output through an optical fiber 46 with a ferrule located on the output side.
  • the permanent magnet is arranged so that a fixed magnetic field is applied in the direction of the optical axis.
  • the direction perpendicular to the optical axis ( ⁇ , also perpendicular to the direction of application of the variable magnetic field by the electromagnet) (Direction) may be applied.
  • the application direction of the fixed magnetic field by the permanent magnet may be arbitrary as long as it is different from the application direction of the variable magnetic field by the electromagnet.
  • the electromagnet yoke has a functionally C-shaped configuration, and may have any configuration in which the Faraday element can be arranged in the gap. Therefore, the shape of the filament core and the manner of thread joining are not limited to the structure shown in FIG. 3, but can be freely deformed. You.
  • FIG. 8 shows still another embodiment of the present invention.
  • the optical attenuator modulator shown in Fig. 8 is a Faraday rotation angle variable device 18 that varies the rotation angle of the plane of polarization of light passing through the Faraday element 14 by a variable magnetic field generated by the electromagnet 16, and is disposed before and after the optical axis.
  • a mirror 50 a mirror 50. Then, the light beam incident from the input optical fiber 40a of the two-core ferrule 40 is reflected by the mirror 50 via the polarizer 12 and the lens 46, and is returned to the lens 46 and the polarizer 12 again.
  • the electromagnetic stone 16 has a yoke 24 made of soft magnetic ferrite, and is configured to supply a high-frequency modulated signal to the coil 26 wound around the yoke 24. You. Also in this case, it is preferable to apply a fixed magnetic field in a direction different from the variable magnetic field by the permanent magnets 10 and 22. Industrial applicability
  • the soft magnetic ferrite is used for the electromagnet yoke of the Faraday rotation angle varying device.
  • an optical attenuator is constructed by arranging a polarizer and an analyzer before and after on the optical axis of such a Faraday rotation angle varying device, and supplying a high-frequency modulation signal to a coil wound around an electromagnet yoke. It is possible to develop a variable attenuation characteristic and add an optical modulation function.
  • the optical attenuator modulator according to the present invention is a magneto-optical type and has a high reliability because it has essentially no movable parts, and is therefore particularly suitable as a variable attenuation and modulation device for submarine optical communication that requires high reliability. Useful.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

L'invention concerne un modulateur d'atténuateur optique comprenant un dispositif de variation d'angle rotationnel de Faraday destiné à faire varier l'angle rotationnel du plan de polarisation de la lumière passant à travers l'élément de Faraday par utilisation d'un champ magnétique variable produit par un électro-aimant ainsi qu'un polariseur et un analyseur disposés devant et derrière le dispositif de variation de l'angle rotationnel de Faraday le long de l'axe optique du dispositif, l'électro-aimant possédant un bloc de bobinage fabriqué à partir de ferrite magnétique souple et une bobine enroulée autour du bloc et alimentée d'un signal de modulation haute fréquence.
PCT/JP2003/002150 2002-02-28 2003-02-26 Modulateur d'attenuateur optique WO2003073156A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2002-54692 2002-02-28
JP2002054692A JP4093533B2 (ja) 2002-02-28 2002-02-28 光アッテネータ変調器

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WO2003073156A1 true WO2003073156A1 (fr) 2003-09-04

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024087685A1 (fr) * 2022-10-28 2024-05-02 华为技术有限公司 Régulateur de puissance optique, ensemble optique, module optique et équipement de réseau optique

Families Citing this family (10)

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JP2007047359A (ja) * 2005-08-09 2007-02-22 Sumitomo Metal Mining Co Ltd 光デバイス
JP4863371B2 (ja) * 2005-09-21 2012-01-25 Ｆｄｋ株式会社 ファラデー回転角可変装置及びそれを用いる可変光アッテネータ
US20130293191A1 (en) 2011-01-26 2013-11-07 Panasonic Corporation Non-contact charging module and non-contact charging instrument
JP4900525B1 (ja) * 2011-03-09 2012-03-21 パナソニック株式会社 非接触充電モジュール及びこれを備えた送信側非接触充電機器と受信側非接触充電機器
CN106888038A (zh) 2011-06-14 2017-06-23 松下电器产业株式会社 通信装置
CN103918192A (zh) 2011-11-02 2014-07-09 松下电器产业株式会社 非接触无线通信线圈、传输线圈、以及便携式无线终端
US10204734B2 (en) 2011-11-02 2019-02-12 Panasonic Corporation Electronic device including non-contact charging module and near field communication antenna
JP2013169122A (ja) 2012-02-17 2013-08-29 Panasonic Corp 非接触充電モジュール及びそれを備えた携帯端末
JP6112383B2 (ja) 2012-06-28 2017-04-12 パナソニックＩｐマネジメント株式会社 携帯端末
JP6008237B2 (ja) 2012-06-28 2016-10-19 パナソニックＩｐマネジメント株式会社 携帯端末

Citations (3)

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Publication number Priority date Publication date Assignee Title
JPH08211347A (ja) * 1995-02-02 1996-08-20 Fuji Elelctrochem Co Ltd 偏波面切替器及びそれを用いた光スイッチ
US5812304A (en) * 1995-08-29 1998-09-22 Fujitsu Limited Faraday rotator which generates a uniform magnetic field in a magnetic optical element
WO2001038930A1 (fr) * 1999-11-26 2001-05-31 3M Innovative Properties Company Element de circuit optique et procede de fabrication correspondant

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08211347A (ja) * 1995-02-02 1996-08-20 Fuji Elelctrochem Co Ltd 偏波面切替器及びそれを用いた光スイッチ
US5812304A (en) * 1995-08-29 1998-09-22 Fujitsu Limited Faraday rotator which generates a uniform magnetic field in a magnetic optical element
WO2001038930A1 (fr) * 1999-11-26 2001-05-31 3M Innovative Properties Company Element de circuit optique et procede de fabrication correspondant

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024087685A1 (fr) * 2022-10-28 2024-05-02 华为技术有限公司 Régulateur de puissance optique, ensemble optique, module optique et équipement de réseau optique

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JP2003255288A (ja) 2003-09-10
JP4093533B2 (ja) 2008-06-04

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