CN109613724B - Magneto-optical adjustable optical attenuator - Google Patents
Magneto-optical adjustable optical attenuator Download PDFInfo
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- CN109613724B CN109613724B CN201910089184.6A CN201910089184A CN109613724B CN 109613724 B CN109613724 B CN 109613724B CN 201910089184 A CN201910089184 A CN 201910089184A CN 109613724 B CN109613724 B CN 109613724B
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- 230000003287 optical effect Effects 0.000 title claims abstract description 52
- 239000013078 crystal Substances 0.000 claims abstract description 123
- 239000013307 optical fiber Substances 0.000 claims abstract description 48
- 229920006395 saturated elastomer Polymers 0.000 claims abstract description 22
- 239000000835 fiber Substances 0.000 claims description 11
- 230000006698 induction Effects 0.000 claims description 7
- ZEMPKEQAKRGZGQ-AAKVHIHISA-N 2,3-bis[[(z)-12-hydroxyoctadec-9-enoyl]oxy]propyl (z)-12-hydroxyoctadec-9-enoate Chemical compound CCCCCCC(O)C\C=C/CCCCCCCC(=O)OCC(OC(=O)CCCCCCC\C=C/CC(O)CCCCCC)COC(=O)CCCCCCC\C=C/CC(O)CCCCCC ZEMPKEQAKRGZGQ-AAKVHIHISA-N 0.000 claims description 3
- 230000007547 defect Effects 0.000 abstract description 7
- 230000005381 magnetic domain Effects 0.000 abstract description 6
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- 230000010287 polarization Effects 0.000 description 5
- 239000011521 glass Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 2
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- 238000012986 modification Methods 0.000 description 1
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Classifications
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- 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
- G02F1/093—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 used as non-reciprocal devices, e.g. optical isolators, circulators
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- 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
Abstract
The invention provides a magneto-optical adjustable optical attenuator, which adopts an assembly of a first wedge-shaped birefringent crystal, a second wedge-shaped birefringent crystal and a Faraday rotary crystal, so that the magneto-optical adjustable optical attenuator can be further miniaturized, is simpler in debugging and assembly, and improves the working efficiency. Meanwhile, a saturated permanent magnetic field perpendicular to the light path is applied to the side face by adopting a saturated magnetic field applying mechanism, and a variable magnetic field applying mechanism of a variable magnetic field is sleeved on the peripheries of the first wedge-shaped birefringent crystal, the second wedge-shaped birefringent crystal and the Faraday rotary crystal, so that the purpose of miniaturization is realized, and the defect of poor repeatability caused by unstable magnetic domain boundaries in the prior art is overcome. The technical difficulty brought by placing the birefringent crystal light beam shifter between the double optical fiber heads and the collimating lens in the prior art is also overcome, so that the manufacturing of the invention is simpler and more convenient, and the manufacturing cost is greatly reduced.
Description
Technical Field
The invention relates to the field of variable optical attenuators, in particular to a magneto-optical variable optical attenuator.
Background
The conventional magneto-optical attenuator consists of a double optical fiber head, a collimating lens, a wedge-shaped birefringent crystal, a Faraday rotator and a reflecting mirror. The Faraday rotator consists of Faraday rotary crystal, fixed magnet with variable magnetic field on its side, variable magnetic field perpendicular to the light-transmitting direction, and magnet with fixed magnetic field behind the reflector, with the magnetic field direction parallel to the light-transmitting direction. In a conventional magneto-optical attenuator, a wedge-shaped birefringent crystal is adopted in an optical path, so that a collimator and the wedge-shaped birefringent crystal form a certain angle, namely, the collimator is required to be obliquely arranged and cannot be horizontally arranged, and therefore, the assembly and the miniaturization are not facilitated. In addition, because a variable magnetic field perpendicular to the light path is applied to the side surface, and a fixed magnetic field parallel to the light path is applied behind the reflecting mirror, the structure has larger volume and is not beneficial to miniaturization of products.
The invention patent with application number 03127861.2 and issued publication number CN100334484C and issued publication day 2007.8.29 specifically discloses a magneto-optical component which comprises a double optical fiber head, a collimating lens, a wedge-shaped birefringent crystal, a Faraday rotator and a reflecting mirror. The Faraday rotator consists of Faraday rotary crystal, fixed magnet on its side to apply one saturated magnetic field parallel to the light direction and magnet with one variable magnetic field behind the reflecting mirror. The optical path is the same as the conventional magneto-optical attenuator, and the wedge-shaped birefringent crystal is adopted, so that the miniaturization is not facilitated. In addition, the side surface is provided with a fixed magnetic field parallel to the light path, a variable magnetic field is applied in the direction of the light path, and the rotation angle of the Faraday is controlled by changing the saturated magnetic domain area in the light-transmitting area, so that the defect is that the magnetic domain boundary is unstable, and the repeatability of the product is poor.
US7379226B2 discloses a variable optical attenuator consisting of a dual fiber head, a birefringent crystal displacer, a collimating lens, a faraday rotator, and a mirror. The Faraday rotator is composed of Faraday rotary crystal, and magnets with variable magnetic field on its side surface, which apply variable magnetic field perpendicular to light-passing direction, and magnets with fixed magnetic field behind reflector, and the magnetic field direction is parallel to light-passing direction. The light path adopts a birefringent crystal light beam shifter and is arranged between the double optical fiber head and the collimating lens, while overcoming the defect of the inherent flat included angle between the collimator required by the birefringent wedge-shaped crystal and the wedge-shaped birefringent crystal in the conventional technology. However, because the birefringent crystal beam displacer is disposed between the dual-fiber head and the collimating lens, the assembly process of the actual product is complex and the cost is high.
Disclosure of Invention
The invention aims to solve the technical problem of providing a magneto-optical adjustable optical attenuator, which adopts two wedge-shaped birefringent crystals and a Faraday crystal assembly, and overcomes the defects that a collimator and the wedge-shaped birefringent crystals form a certain included angle and are unfavorable for miniaturization and debugging assembly caused by single wedge-shaped birefringent crystals which are mostly adopted in conventional and other patents.
The invention is realized in the following way: a magneto-optical tunable optical attenuator comprises a first wedge-shaped birefringent crystal, a second wedge-shaped birefringent crystal, a Faraday rotary crystal, a saturated magnetic field applying mechanism for applying a saturated magnetic field to the Faraday rotary crystal, a variable magnetic field applying mechanism for applying a variable magnetic field, and a dual-fiber collimator for transmitting optical signals and receiving optical signals;
the first wedge-shaped birefringent crystal comprises a first wedge angle surface and a second wedge angle surface; the second wedge-shaped birefringent crystal comprises a third wedge angle surface and a fourth wedge angle surface, and the third wedge angle surface is parallel to the second wedge angle surface;
the dual-fiber collimator comprises a first optical fiber for inputting optical signals, a second optical fiber for outputting optical signals and a collimating lens; the first optical fiber and the second optical fiber are arranged in parallel, the collimating lens is arranged behind the emergent end surfaces of the first optical fiber and the second optical fiber, the first wedge-shaped birefringent crystal, the second wedge-shaped birefringent crystal and the Faraday rotary crystal are sequentially and closely arranged, the second wedge-angle surface and the third wedge-angle surface are closely arranged, the optical axis of the first wedge-shaped birefringent crystal is in the plane where the horizontal axis and the normal line are located, the azimuth angle of the optical axis of the first wedge-shaped birefringent crystal and the horizontal axis form an angle theta, and the optical axis of the second wedge-shaped birefringent crystal is perpendicular to the plane where the horizontal axis and the normal line are located;
the saturated magnetic field applying mechanism is arranged on the side edge of the Faraday rotary crystal, and the direction of the applied saturated magnetic field is perpendicular to the horizontal axis; the variable magnetic field applying mechanism is sleeved outside the first wedge-shaped birefringent crystal, the second wedge-shaped birefringent crystal, the Faraday rotary crystal and the saturated magnetic field applying mechanism, and the direction of the variable magnetic field applied by the variable magnetic field applying mechanism is parallel to the horizontal axis.
Further, the first wedge-shaped birefringent crystal, the second wedge-shaped birefringent crystal and the Faraday rotary crystal are connected into a whole.
Further, an incident angle of incident light entering the first wedge-shaped birefringent crystal is beta, and an inclination angle of the first wedge angle surface is alpha 1; the inclination angles of the second wedge angle surface and the third wedge angle surface are alpha 2; the inclination angle of the fourth wedge angle surface is alpha 3; α1, α2, α3, θ, and β satisfy the following relational expression:
wherein, the sign of the wedge angle surface inclination angle is defined as clockwise inclination is negative, and anticlockwise inclination is positive; n is n o Is the refractive index of the birefringent crystal O light, n e For the refractive index of the birefringent crystal E light, θe is the included angle between the normal line of the E light wave and the horizontal axis, n (θe) is the refractive index of the E light when the E light propagates in the normal direction of the birefringent crystal wave, and n (θe) and θe are obtained by the following two equations:
sin(α 1 -β)＝n(θe)·sin(α1-(θ-θe)) (2)。
further, the saturated magnetic field applying mechanism is composed of two permanent magnets, and the two permanent magnets are arranged on the upper side and the lower side of the Faraday rotary crystal in a one-to-one correspondence mode.
Further, the variable magnetic field applying mechanism is an induction coil.
Further, the faraday rotator is a faraday rotator with no magnetic field, and a reflecting film layer is arranged on the rear end face of the faraday rotator to serve as a reflecting mirror face.
The invention has the following advantages: the magneto-optical adjustable optical attenuator can be further miniaturized, is simpler to debug and assemble and improves the working efficiency due to the adoption of the assembly of the first wedge-shaped birefringent crystal, the second wedge-shaped birefringent crystal and the Faraday rotary crystal. Meanwhile, a saturated permanent magnetic field perpendicular to the light path is applied to the side face by adopting a saturated magnetic field applying mechanism, and a variable magnetic field applying mechanism of a variable magnetic field is sleeved on the peripheries of the first wedge-shaped birefringent crystal, the second wedge-shaped birefringent crystal and the Faraday rotary crystal, so that the purpose of miniaturization is realized, and the defect of poor repeatability caused by unstable magnetic domain boundaries in the prior art is overcome. The technical difficulty brought by placing the birefringent crystal light beam shifter between the double optical fiber heads and the collimating lens in the prior art is also overcome, so that the manufacturing of the invention is simpler and more convenient, and the manufacturing cost is greatly reduced.
Drawings
The invention will be further described with reference to examples of embodiments with reference to the accompanying drawings.
In the description of the present invention, it should be noted that, if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like are used, the indicated azimuth or positional relationship is based on the azimuth or positional relationship shown in the drawings, only for convenience of description and simplification of the description, and does not indicate or imply that the apparatus or element to be referred must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like, as used herein, are used for descriptive purposes only and are not to be construed as indicating or implying any relative importance.
Fig. 1 is a schematic view of the structure and optical path of a conventional magneto-optical attenuator in the related art.
Fig. 2 is a schematic diagram of the structure and optical path of the magneto-optical tunable optical attenuator of the present invention.
Fig. 3 is a side view of a magneto-optical tunable optical attenuator of the present invention.
Fig. 4 is a top view of a magneto-optical tunable optical attenuator of the present invention.
In the figure: 1. the optical fiber comprises a double optical fiber head 2, a collimating lens 3, a wedge-shaped birefringent crystal 4, a Faraday rotator 5, a reflecting mirror 6 and a permanent magnet;
100. light rays emitted by the first optical fibers, 110, first polarized light beams, 111, first reflected light beams, 112, first light beams, 113, third light beams, 120, second polarized light beams, 121, second reflected light beams, 122, second light beams, 123 and fourth light beams;
200. a dual-fiber collimator 201, a first wedge-shaped birefringent crystal, 2011, a first wedge angle surface, 2012, a second wedge angle surface, 202, a second wedge-shaped birefringent crystal, 2021, a third wedge angle surface, 2022, a fourth wedge angle surface, 203, a faraday rotation crystal, 2031, a reflective film layer, 204, a saturated magnetic field applying mechanism, 205, a variable magnetic field applying mechanism, 206, a first optical fiber, 207, a second optical fiber, 208, a collimating lens, 209, an optical axis of the first wedge-shaped birefringent crystal, 210, an optical axis of the second wedge-shaped birefringent crystal, 211, a glass capillary; b1, the direction of the magnetic field applied by the saturated magnetic field applying mechanism, and B2, the direction of the magnetic field applied by the variable magnetic field applying mechanism.
Detailed Description
Referring to fig. 2 to 4, the present invention provides a magneto-optical tunable optical attenuator, which includes a first wedge-shaped birefringent crystal 201, a second wedge-shaped birefringent crystal 202, a faraday rotator 203, a saturation magnetic field applying mechanism 204 for applying a saturation magnetic field to the faraday rotator 203, a variable magnetic field applying mechanism 205 for applying a variable magnetic field, a first optical fiber 206 for emitting an optical signal, and a second optical fiber 207 for receiving an optical signal;
the first wedge-shaped birefringent crystal 201 includes a first wedge angle surface 2011 and a second wedge angle surface 2012; the second wedge-shaped birefringent crystal 202 comprises a third wedge angle surface 2021 and a fourth wedge angle surface 2022, the third wedge angle surface 2021 being parallel to the second wedge angle surface 2012;
the dual-fiber collimator 200 includes a first optical fiber 206 for optical signal input, a second optical fiber 207 for optical signal output, and a collimator lens 208; the first optical fiber 206 and the second optical fiber 207 are arranged in parallel, and the collimating lens 208 is arranged behind the emergent end surfaces of the first optical fiber 206 and the second optical fiber 207; the first wedge-shaped birefringent crystal 201, the second wedge-shaped birefringent crystal 202 and the faraday rotator 203 are sequentially and closely arranged, the second wedge-angle surface 2012 and the third wedge-angle surface 2021 are closely arranged, the optical axis 209 of the first wedge-shaped birefringent crystal 201 is in a plane where a horizontal axis and a normal line are located, an azimuth angle of the optical axis 209 of the first wedge-shaped birefringent crystal 201 and the horizontal axis form an angle θ, and the optical axis 210 of the second wedge-shaped birefringent crystal 202 is perpendicular to the plane where the horizontal axis and the normal line are located. In a specific embodiment, the first optical fiber 206 and the second optical fiber 207 are placed in parallel in the glass capillary 211, and the collimating lens 208 is installed behind the glass capillary 211, the exit end surfaces of the first optical fiber 206 and the second optical fiber 207, so as to be connected as a whole as the dual-fiber collimator 200, and the collimating lens 208 is used for collimating the divergent light exiting from the first optical fiber 206 and converging the reflected collimated light onto the second optical fiber 207.
The first wedge-shaped birefringent crystal 201, the second wedge-shaped birefringent crystal 202, and the faraday rotator crystal 203 are connected as a unit, and in a specific implementation, they are bonded as a unit by, for example, gluing, bonding, or optical contact.
The saturation magnetic field applying mechanism 204 is disposed at a side of the faraday rotation crystal 203, in fig. 2, at an upper side and a lower side, and a direction B1 of the applied saturation magnetic field is perpendicular to a horizontal axis; the variable magnetic field applying mechanism 205 is sleeved outside the first wedge-shaped birefringent crystal 201, the second wedge-shaped birefringent crystal 202, the faraday rotator 203 and the saturation magnetic field applying mechanism 204, and the direction B2 of the variable magnetic field applied by the variable magnetic field applying mechanism 205 is parallel to the horizontal axis.
The incident angle of the incident light entering the first wedge-shaped birefringent crystal 201 is β (i.e. the angle between the light ray 100 emitted from the first optical fiber and the horizontal axis), and the inclination angle of the first wedge-angle surface 2011 is α1; the second wedge angle surface 2012 and the third wedge angle surface 2021 have inclination angles of alpha 2; the inclination angle of the fourth wedge angle surface 2022 is alpha 3; α1, α2, α3, θ, and β satisfy the following relational expression:
wherein, the sign of the wedge angle surface inclination angle is defined as clockwise inclination is negative, and anticlockwise inclination is positive; n is n o Is the refractive index of the birefringent crystal O light, n e For the refractive index of the birefringent crystal E light, θe is the included angle between the normal line of the E light wave and the horizontal axis, n (θe) is the refractive index of the E light when the birefringent crystal propagates along the direction of the wave normal, and n (θe) and θe are obtained by the following two equations:
sin(α 1 - β) =n (θe) ·sin (α1- (θ - θe)) (2). Wherein, alpha 1, alpha 2, alpha 3, theta and beta adopt uniform angle units, namelyIt may, for example, be in degrees.
The saturation magnetic field applying mechanism 204 is two permanent magnets 204, and the two permanent magnets 204 are arranged on the upper side and the lower side of the faraday rotary crystal 203 in a one-to-one correspondence manner, so that the faraday rotary crystal 203 is always in the saturation magnetic field, the problem of poor product repeatability caused by instability of magnetic domain boundaries when the faraday rotary crystal is in a variable magnetic field in the prior art is solved, and the repeatability of the invention is greatly improved.
The variable magnetic field applying mechanism 205 is an induction coil 205.
The faraday rotator 203 is a faraday rotator 203 with no magnetic field, and a reflective film layer 2031 is provided on the rear end surface of the faraday rotator 203 as a mirror surface, and has a function of a mirror, for example, in a specific implementation, a high reflective film layer in an operating wavelength range is directly plated on the rear end surface of the faraday rotator 203 as a mirror surface.
Working principle: the light beam 100 emitted from the output fiber 206 of the dual-fiber collimator 200 propagates along the rectangular coordinate system Z axis, and is incident on the first wedge-shaped birefringent crystal 201, and is split into the first polarized light beam 110 and the second polarized light beam 120 having polarization directions perpendicular to each other. And then passes through the second wedge-shaped birefringent crystal 202 such that the first and second polarized light beams 110 and 120 are collected on the reflective surface of the faraday rotator crystal 203.
As shown in fig. 3 and 4, when the induction coil 205 is energized to make the magnetic field components of the variable magnetic field B2 and the saturation magnetic field B1 of the two permanent magnets 204 in the light passing direction equal to or larger than the saturation magnetic field requirement of the faraday rotator, the light beam is reflected by the faraday rotator, and the polarization planes of the first reflected light beam 111 and the second reflected light beam 121 are rotated by 90 ° in total. When the first reflected light beam 111 enters the first wedge-shaped birefringent crystal 201, it propagates along the beam path of the first light beam 112, and is received by the second optical fiber 207 after being converged by the collimator lens 208. When the second reflected light beam 121 enters the first wedge-shaped birefringent crystal 201, it propagates in the beam path of the second light beam 122, is converged by the collimator lens 208, and is received by the second optical fiber 207. Thereby a loss-free optical transmission of the polarization-independent optical signal from the entrance port to the exit port is achieved.
As shown in fig. 3 and 4, when the induction coil 205 is energized, the variable magnetic field B2 thereof and the saturation magnetic field B1 of the two permanent magnets 204 have a magnetic field component in the light passing direction smaller than that required by the faraday rotator crystal, the light beam is reflected by the faraday rotator 203, and the polarization planes of the first reflected light beam 111 and the second reflected light beam 121 are rotated by less than 90 ° in total. When the first reflected light beam 111 enters the first wedge-shaped birefringent crystal 201, a part of the first reflected light beam propagates along the beam path of the first light beam 112, is converged by the collimator lens 208 and is received by the second optical fiber 207, and a part of the first reflected light beam propagates along the beam path of the third light beam 113, and cannot be coupled into the second optical fiber 207. Similarly, when the second reflected light beam 121 enters the first wedge-shaped birefringent crystal 201, a part of the second reflected light beam propagates through the beam path of the second light beam 122, is converged by the collimator lens 208 and is received by the second optical fiber 207, and a part of the second reflected light beam propagates through the beam path of the fourth light beam 123, and cannot be coupled into the second optical fiber collimator. The transmission of the magnetic control light attenuation quantity of the polarization-independent optical signal from the incident port to the emergent port is realized.
The invention adjusts the current of the induction coil to further adjust the size of the variable magnetic field, thereby realizing the adjustment of the attenuation of the optical signal.
The invention adopts the assembly of the first wedge-shaped birefringent crystal 201, the second wedge-shaped birefringent crystal 202 and the Faraday rotary crystal 203, thereby overcoming the defects that the collimator and the wedge-shaped birefringent crystal form a certain included angle and the collimator needs to form an included angle with the horizontal axis in the conventional and other patents and is not beneficial to miniaturization and debugging and assembly. Therefore, the first optical fiber collimator, the second optical fiber collimator or the integral double-optical fiber collimator 200 can be arranged in a mode parallel to the horizontal axis, so that the magneto-optical tunable optical attenuator can be further miniaturized, is simpler in debugging and assembly, and improves the working efficiency.
Meanwhile, compared with the patent CN100334484C, the invention adopts the permanent magnetic field which is saturated and is vertical to the light path, namely the saturated magnetic field B1, and the induction coil 205 which is sleeved with the variable magnetic field at the periphery of the first wedge-shaped birefringent crystal 201, the second wedge-shaped birefringent crystal 202 and the Faraday rotary crystal 203, thereby not only realizing the purpose of miniaturization, but also overcoming the defect of poor repeatability caused by unstable magnetic domain boundaries of the technology of the CN 100334484C.
Compared with US patent 7379226B2, the present invention uses two wedge-shaped birefringent crystals and one faraday crystal assembly, overcoming the process difficulties associated with US patent 7379226B2 in placing a birefringent crystal beam displacer between a dual fiber head and a collimating lens. The invention has the advantages of simpler and more convenient manufacture and greatly reduced manufacturing cost.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that the specific embodiments described are illustrative only and not intended to limit the scope of the invention, and that equivalent modifications and variations of the invention in light of the spirit of the invention will be covered by the claims of the present invention.
Claims (5)
1. A magneto-optical tunable optical attenuator, characterized by: the optical fiber collimator comprises a first wedge-shaped birefringent crystal, a second wedge-shaped birefringent crystal, a Faraday rotary crystal, a saturated magnetic field applying mechanism for applying a saturated magnetic field to the Faraday rotary crystal, a variable magnetic field applying mechanism for applying a variable magnetic field, and a double optical fiber collimator for transmitting optical signals and receiving optical signals;
the first wedge-shaped birefringent crystal comprises a first wedge angle surface and a second wedge angle surface; the second wedge-shaped birefringent crystal comprises a third wedge angle surface and a fourth wedge angle surface, and the third wedge angle surface is parallel to the second wedge angle surface;
the dual-fiber collimator comprises a first optical fiber for inputting optical signals, a second optical fiber for outputting optical signals and a collimating lens; the first optical fiber and the second optical fiber are arranged in parallel, the collimating lens is arranged behind the emergent end surfaces of the first optical fiber and the second optical fiber, the first wedge-shaped birefringent crystal, the second wedge-shaped birefringent crystal and the Faraday rotary crystal are sequentially and closely arranged, the second wedge-angle surface and the third wedge-angle surface are closely arranged, the optical axis of the first wedge-shaped birefringent crystal is in the plane where the horizontal axis and the normal line are located, the azimuth angle of the optical axis of the first wedge-shaped birefringent crystal and the horizontal axis form an angle theta, and the optical axis of the second wedge-shaped birefringent crystal is perpendicular to the plane where the horizontal axis and the normal line are located;
the saturated magnetic field applying mechanism is arranged on the side edge of the Faraday rotary crystal, and the direction of the applied saturated magnetic field is perpendicular to the horizontal axis; the variable magnetic field applying mechanism is sleeved outside the first wedge-shaped birefringent crystal, the second wedge-shaped birefringent crystal, the Faraday rotary crystal and the saturated magnetic field applying mechanism, and the direction of the variable magnetic field applied by the variable magnetic field applying mechanism is parallel to the horizontal axis;
the incident angle of the incident light entering the first wedge-shaped birefringent crystal is beta, and the inclination angle of the first wedge angle surface is alpha 1; the inclination angles of the second wedge angle surface and the third wedge angle surface are alpha 2; the inclination angle of the fourth wedge angle surface is alpha 3; α1, α2, α3, θ, and β satisfy the following relational expression:
wherein, the sign of the wedge angle surface inclination angle is defined as clockwise inclination is negative, and anticlockwise inclination is positive; n is n o Is the refractive index of the birefringent crystal O light, n e For the refractive index of the birefringent crystal E light, θe is the included angle between the normal line of the E light wave and the horizontal axis, n (θe) is the refractive index of the E light when the E light propagates in the normal direction of the birefringent crystal wave, and n (θe) and θe are obtained by the following two equations:
sin(α 1 -β)＝n(θe)·sin(α1-(θ-θe)) (2)。
2. a magneto-optical tunable optical attenuator according to claim 1, wherein: the first wedge-shaped birefringent crystal, the second wedge-shaped birefringent crystal and the Faraday rotary crystal are connected into a whole.
3. A magneto-optical tunable optical attenuator according to claim 1, wherein: the saturated magnetic field applying mechanism is composed of two permanent magnets, and the two permanent magnets are arranged on the upper side and the lower side of the Faraday rotary crystal in a one-to-one correspondence mode.
4. A magneto-optical tunable optical attenuator according to claim 1, wherein: the variable magnetic field applying mechanism is an induction coil.
5. A magneto-optical tunable optical attenuator according to claim 1, wherein: the Faraday rotary crystal is a Faraday rotary piece without a magnetic field, and a reflecting film layer is arranged on the rear end surface of the Faraday rotary piece to serve as a reflecting mirror surface.
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| CN201910089184.6A CN109613724B (en) | 2019-01-30 | 2019-01-30 | Magneto-optical adjustable optical attenuator |
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| US6631238B2 (en) * | 2001-03-16 | 2003-10-07 | Primanex Corporation | Variable optical attenuator |
| JP2003098500A (en) * | 2001-09-26 | 2003-04-03 | Fdk Corp | Reflection type variable optical attenuator |
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| CN204496133U (en) * | 2015-04-03 | 2015-07-22 | 福建华科光电有限公司 | A kind of polarized light beam combining device of reverse isolation |
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| CN109613724A (en) | 2019-04-12 |
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