WO2004025354A1 - 光アイソレータ、及びこれを用いたレーザ発振器 - Google Patents
光アイソレータ、及びこれを用いたレーザ発振器 Download PDFInfo
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- WO2004025354A1 WO2004025354A1 PCT/JP2003/011228 JP0311228W WO2004025354A1 WO 2004025354 A1 WO2004025354 A1 WO 2004025354A1 JP 0311228 W JP0311228 W JP 0311228W WO 2004025354 A1 WO2004025354 A1 WO 2004025354A1
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- faraday rotator
- component
- optical isolator
- faraday
- light
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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
Definitions
- the present invention relates to a magneto-optical device used for an optical communication system or the like, and in particular, an optical isolator suitable for preventing light emitted from a light source from being reflected on an end face of an optical element and returning to the light source, and
- the present invention relates to a laser oscillator.
- CD-R which is now commonly used as an optical recording medium, uses a laser beam with a wavelength of 770 nm to 790 nm, enabling higher density recording and a wavelength range of 633 nm.
- Recording methods such as DVD-R, DVD-RW, DVD-RAM, etc., that can handle the video, are emerging.
- it is required to increase the recording density by using more laser light, and for example, writing with one light of blue-violet laser has been proposed.
- BI u-ray it has been proposed to use a blue-violet laser beam of about 405 nm to 410 nm, and the recording density has become increasingly popular. Is being done.
- optical isolators which had been required to be used in the past, have come to attract attention again.
- This optical isolator is a magneto-optical device that transmits light in one direction and does not transmit light in the other direction.
- This optical isolator is composed of at least a Faraday rotator, a polarizer and an analyzer, and the polarizer and the analyzer are arranged before and after the Faraday rotator with respect to the light incident direction.
- This optical isolator utilizes the property (Faraday effect) that when a magnetic field is applied to a Faraday rotator and light is incident on the Faraday rotator, its polarization plane rotates in the Faraday rotator. . More specifically, of light incident from one direction and having the same polarization plane as the polarizer, the Faraday rotation The light is emitted at a rotation of 45 ° with respect to the traveling direction of the light.
- the analyzer for the return light incident from the opposite direction to the incident direction, only the return light having the same polarization plane passes through the analyzer.
- the return light from the analyzer is further polarized in the Faraday rotator with respect to the first incident direction. As it rotates, it becomes a plane of polarization perpendicular to the polarizer and the light does not pass through the polarizer.
- Faraday rotation angle is conventionally ferromagnetic as a magnetic material of the Faraday rotator as mentioned above (theta f) is greater
- I Tsu Bok Riu ⁇ garnet Bok Structure Single of (Y 3 Fe 5 0 12 hereinafter abbreviated as YIG) Crystals were used.
- the YIG single crystal can only transmit light in the wavelength range of 1000 nm to 5000 ⁇ m, and is the recording wavelength of CD_R as well as the visible light range of 400 nm to 600 nm, which is the recording wavelength of the next-generation recording method. There was a problem that it could not be used in nm.
- Verdet constant (V) is large, as the magnetic material having high light transmittance in the visible light region, paramagnetic garnet containing at least Tb and AI: the (Tb 3 AI 5 0 12 hereinafter abbreviated as TAG)
- TAG the (Tb 3 AI 5 0 12 hereinafter abbreviated as TAG)
- This TAG single crystal has the highest Welde constant (V) among the paramagnetic materials, and can obtain a sufficiently high light transmittance over a wide range of light wavelengths from 500 nm to 1400 nm, especially when the light wavelength is 400 nm. It is clear that high transmittance can be obtained even in the visible light range of ⁇ 600 nm.
- Japanese Patent Application Laid-Open No. 9-68675 discloses that four permanent magnets are provided on both sides of the Faraday rotator, that is, a total of eight permanent magnets are provided.
- An optical isolator is disclosed.
- Japanese Patent Application Laid-Open No. 2001-209006 discloses an optical isolator using a cylindrical permanent magnet that encloses the entire Faraday rotator.
- An object of the present invention is to solve the above-mentioned problems.
- An optical isolator in particular, a TAG single crystal having a characteristic that the Verdet constant (V) is large and the light transmittance is high even in a visible light region is provided.
- An optical isolator used for a Faraday rotator which provides an optical isolator with a high magnetic field strength applied to the Faraday rotator, a uniform magnetic field, and a compact size, and a laser transmitter using the same. Is to do. Disclosure of the invention
- An optical isolator includes a Faraday rotator made of a paramagnetic material, a first component and a second component each having at least one or more permanent magnets, and a polarizer.
- An optical isolator comprising: an analyzer; and the Faraday rotator is disposed along the optical axis direction between the first component and the second component, and An end surface on the Faraday terminal side of the component and the second component and an end surface of the Faraday rotator are arranged on the same plane, and an optical axis passing through the Faraday rotator; It is characterized in that the first component and the second component are provided so that the direction of magnetization applied to the Faraday rotator is parallel.
- the Faraday rotator can be easily controlled so that the Faraday rotation angle (0 f ) becomes a desired rotation angle, and the size of the Faraday rotator can be reduced.
- the optical isolator according to the second invention of the present application includes a Faraday rotator made of a paramagnetic material, a first component and a second component each having at least two or more permanent magnets, and a polarizer.
- An optical isolator comprising: an analyzer, wherein the Faraday rotator is between the first component and the second component, and the first component and the second component are arranged between the first component and the second component.
- the second component and the Faraday rotator are disposed so as to have a predetermined clearance along the optical axis direction, and an optical axis passing through the Faraday rotator; the first component and the first component.
- At least one of the second components is provided so that the direction of magnetization applied to the Faraday rotator is parallel. This further increases the Faraday rotator And the magnetic field distribution can be made uniform. As a result, the Faraday rotation angle ⁇ f ) can be further adjusted to a desired rotation angle, and the size of the Faraday rotator and thus the optical isolator can be reduced.
- the optical isolator according to the third aspect of the present invention may further include a spacer provided between an end surface of the first component and the second component on the Faraday rotator side and an end surface of the Faraday rotator. Preferably. This makes it easy to adjust the strength of the magnetic field applied to the Faraday rotator.
- the Faraday rotator has a cylindrical shape
- the permanent magnet has a cylindrical shape. This makes it possible to make the magnetic field distribution in the Faraday rotator more uniform. This makes it possible to adjust the Faraday rotation angle ( ⁇ f ) to a desired rotation angle, and to provide an optical isolator with high insertion loss (I.S.) and isolation (I.so).
- the Faraday rotator is made of a paramagnetic garnet single crystal containing at least Tb and AI.
- a paramagnetic garnet single crystal containing at least Tb and AI as a Faraday rotator, for example, a TAG single crystal, it is possible to return light even in the visible light region having a wavelength of 400 to 600 nm. It is possible to provide an optical isolator capable of suppressing the above.
- the optical isolator according to the sixth aspect of the present invention provides the Faraday rotator according to the fifth aspect of the present invention, wherein the crystal orientation in the optical axis direction has an angle of 0 ° to 10 ° with respect to the ⁇ 110> orientation. It is preferable that As a result, a magnetic field is applied in a direction parallel to the magnetic field at an angle of 0 ° to 10 ° with respect to the ⁇ 110> direction. At this time, the present inventors have found that the effective Welde constant of the optical isolator is larger than that when a magnetic field is applied in parallel to the other crystal orientations.
- the desired angle is determined as the Faraday rotation angle (0 f )
- the larger the effective Werde constant is, the smaller the magnetic field intensity can be, and the longer the Faraday rotator length is. Can be shortened. This enables a small size optical isolator.
- a laser oscillator is configured such that a semiconductor laser serving as a light source, a condenser lens, and the optical isolator according to any one of the first to sixth aspects of the present application are arranged in series.
- a semiconductor laser serving as a light source, a condenser lens, and the optical isolator according to any one of the first to sixth aspects of the present application are arranged in series.
- FIG. 1 is a schematic sectional view of an optical isolator according to one embodiment of the present invention.
- FIG. 2 is a schematic sectional view of an optical isolator according to another embodiment of the present invention.
- FIG. 3 is a schematic diagram of an optical device for explaining an applied magnetic field according to the present invention.
- FIG. 4 is a schematic sectional view of a laser oscillator according to one embodiment of the present invention.
- FIG. 5 is a schematic sectional view of an optical isolator according to a comparative example of the present invention.
- FIG. 6 is a schematic sectional view of an optical isolator of another comparative example of the present invention.
- FIG. 1 is a schematic sectional view of an optical isolator 1 of the present invention. It comprises a Faraday rotator 2, a first component 3a and a second component 3b, a polarizer 4 and an analyzer 5.
- the Faraday rotator 2 is provided between the first component 3a and the second component 3b along the optical axis direction. That is, the first component 3a, the Faraday rotator 2, and the second component 3b are linearly arranged in this order along the optical axis direction.
- the Faraday rotator 2 forms an optical axis P through which light passes, and is fixed by a support member 7 so that the optical axis passes through the center of the Faraday rotator 2.
- Faraday rotator 2 as used herein, (Hg, Cd) T e , Z n S e, but B i 12 G e O 20, T b 3 G a 5 0 can be used 12 and the like, at least T b It is preferable to be made of a terbinium aluminum-based paramagnetic garnet single crystal containing chromium and AI. Specifically, Tb 3 AI 5 0 12 or the Tb rhino Bok Dy, H o, E r, and may be used as substituted with rare-earth elements of Tm, etc., large Vuerude constant, 400-500 T b 3 AI 5 0 to obtain a suitable light transmittance in the visible light region of 600 nm, 2 is most preferred.
- the Faraday rotator 2 preferably has a magnetic permeability of 12 or more. Such permeability By having the ratio, the magnetic flux is easily converged in the Faraday rotator, and the magnetic field intensity applied to the Faraday rotator can be increased.
- the end face of the Faraday rotator 2 is a plane perpendicular to the optical axis of the Faraday rotator, and indicates a plane on which light enters and exits.
- the crystal orientation of the Faraday rotator 2 in the optical axis direction is ⁇ 1. It is preferable to set the azimuth at an angle of 0 ° to 10 ° with respect to the 10> azimuth.
- the azimuth that forms an angle of 0 ° to 10 ° with respect to the ⁇ 110> azimuth means that the solid angle centered on the ⁇ 110> azimuth or the ⁇ 110> azimuth is 10 °. It indicates that the direction is within.
- the Faraday rotator can be miniaturized with the same magnetic field strength, and thus the optical isolator can be miniaturized.
- the Faraday rotator has the same length, an optical isolator with excellent accuracy can be provided even with a smaller magnetic field strength.
- first component 3a and the second component 3b used here only need to have at least one or more permanent magnets.
- each of the first component 3a and the second component 3b may be composed of one permanent magnet, or the first component 3a and the second component 3a
- Each of b may have a plurality of permanent magnets. If at least one or more permanent magnets are provided in each component, a magnetic material such as Fe, Co, or Ni can generate a magnetic field due to the magnetization exerted by the permanent magnets. May be provided.
- end surface in each component means a surface perpendicular to the optical axis direction of each component, and indicates a surface on which light enters and exits.
- the permanent magnets provided in the first component 3a and the second component 3b are provided with holes 6 for introducing light.
- the first component 3a and the second component 3b are provided so that light passes through the hole 6 and the hole 6 and the optical axis P are parallel to each other. With such a configuration, the magnetic field M is generated parallel to the optical axis P.
- the holes 6 are preferably larger than the cross section of the light beam. This is to prevent the incident light from being reflected off the first constituent part 3a and the second constituent part 3b other than the holes 6 and irregularly reflected.
- a predetermined clearance is provided in the optical axis direction between the first rotor 2 and the Faraday terminal end faces of the first component 3a and the second component 3b and the Faraday rotation. It is preferable that the Faraday rotator 2 and the first component 3a and the second component 3b are juxtaposed with no gap as shown in FIG. .
- the first component 3a when a TAG single crystal is used as the Faraday rotator 2 and a neodymium-based one is used as the first component 3a and the second component 3b, the first component 3a
- the distance from the end face of the second component 3b on the Faraday rotator side to the end face of the Faraday rotator 2 is preferably about 0 to 1000 tm. This distance can be adjusted as appropriate according to the size and strength of the permanent magnet used, and the Verdet constant of the magnetic material of the Faraday rotator 2, but with this configuration, the Faraday rotator 2 Such a magnetic field strength can be further increased.
- the polarizer 4 and the photon 5 are provided before the light enters the Faraday rotator 2 and after the light is emitted from the Faraday rotator 2. More specifically, the polarizer 4 may be provided on either the light incident side of the first component 3a or the Faraday rotator 2 as long as the polarizer 4 is on the end face side of the first component 3a. good. In addition, the analyzer 5 may be provided on either the Faraday rotator 2 side or on the emission side of the light obtained by performing JI on the Faraday rotator as long as the analyzer 5 is on the end face side of the second component 3b.
- the polarizer 4 and the photon 5 it is only necessary that the polarizer 4 and the photon 5 have a cross section larger than the diameter of the hole 4 of the first component 3a and the second component 3b. Further, it is preferable to apply an antireflection coating to the surfaces of the polarizer 4 and the fiber photon 5 in order to reduce reflection loss. Then, in order to fix the Faraday rotator 2, the first component 3a and the second component 3b, the polarizer 4, and the analyzer 5 arranged in this manner, the Faraday rotator 2 is fixed by a holder 8. You may leave.
- the polarizer 4 and the analyzer 5 used herein may be used a stretched polymer or rutile and calcite (C a C 0 3) single crystal polarizers, etc. made of the like.
- a plurality of thin metal wires may be prepared, and the adjacent wires may be arranged in a plate so as to be parallel in a certain direction.
- the holding member 7 used here may or may not be provided, but when provided, a holding member that does not transmit light and has high hardness is preferable.
- a resin, a solder, a low-melting-point metal, and a glass having low permeability can be used, but the magnetic permeability of the holding material is preferably about the same as that of air, or about one.
- This holding member 7 holds the center of the Faraday rotator 2 between the first component 3a and the second component 3b so that the center of the Faraday rotator 2 passes through the optical axis. A certain distance from the second component 3b can be maintained.
- the holding material 7 when a resin such as an epoxy resin is used as the holding material 7, before adjusting the shape of the TAG single crystal, which is the Faraday rotator 2, cover the resin with the above resin and dry it to a certain solid material, and then form the solid with the TAG single crystal. Can be processed. In this case, very small Even a single TAG single crystal can be easily processed, and the thickness of the Faraday rotator 2 can be easily kept constant.
- each of the first component 3a and the second component 3b has at least one permanent magnet, a magnetic field is generated in parallel with the optical axis.
- This magnetic field concentrates on the paramagnetic Faraday rotator, and produces a strong and uniform magnetic field in the direction of the optical axis.
- the principle is explained in detail. For example, in the case of the configuration of Patent Document 2 ((B) in FIG. 3), the lines of magnetic force applied to the Faraday rotator 42 greatly rotate on the outer side and the inner side of the cylindrical permanent magnet 43.
- the Faraday rotator 42 provided inside the center of the cylindrical permanent magnet 43 generates only a weak magnetic field.
- the Faraday rotator 2 is disposed between the first component 3a and the second component 3b having the permanent magnet. Provided along the optical axis direction, the end faces of the first component 3a and the second component 3 on the Faraday rotator 2 side and the end face of the Faraday rotator 2 exist on the same plane.
- a magnetic field is also generated from the end face of one component on the Faraday rotator side to the end face of the other component on the Faraday rotator side.
- the generated magnetic field is more converged and passes through the inside of the Faraday rotator 2 having a higher magnetic permeability than that of a low-permeability t ⁇ resin holder or in air.
- a Faraday rotator 2 (see FIG. 3C) which is formed by providing a predetermined clearance between the first component 3a and the second component 3b. )),
- the magnetic field generated from the end face on the Faraday rotator side of one component toward the end face on the Faraday rotator side of the other component, as indicated by the lines of magnetic force, has a high magnetic permeability. Occurs parallel to the length direction of child 2.
- the average value of the magnetic field strength applied to the Faraday rotator 2 must be increased because the magnetic field is applied in parallel to the optical axis direction even at the corners of the Faraday rotator 2 due to the provision of the clearance. Can be.
- the magnetic flux is concentrated on the paramagnetic Faraday rotator 2, and a strong and uniform magnetic field is generated in the optical axis direction. Therefore, light having the same polarization plane as the polarizer 4 can pass through the polarizer 4 and rotate the incident light to 45 ° with respect to the optical axis with high precision in the Faraday rotator 2. Become. The light rotated by 45 ° passes through the analyzer 5 as it is and is emitted. Also, a strong and uniform magnetic field is generated parallel to the optical axis for the return light that enters from the opposite direction to the incident direction.
- the Faraday rotator Even when the light passes through 2, the plane of polarization is accurately rotated by the influence of the strong magnetic field and further rotated by 45 ° with respect to the incident light. As a result, the return light that has passed through the Faraday rotator 2 has a plane of polarization that is perpendicular to the polarizer 4, so that the light is not emitted from the polarizer 4.
- the permanent magnet provided in the first component 3a and the second component 3b in the present invention may have any shape as long as it has a hole 6 through which light passes. It is preferably in the form. With such a shape, a magnetic field is uniformly applied to the Faraday rotator 2. Further, it is preferable that the shape of the Faraday rotator 2 is also cylindrical, in accordance with the first component 3a and the second component 3 that are cylindrical. When the Faraday rotator 2 having such a shape is used, not only processing is easy, but also the magnetic field generated from the cylindrical permanent magnets of the first component 3a and the second component 3b is the object to be rotated. This is preferable because a magnetic field is uniformly applied to the Faraday rotator 2.
- the inner diameter of the permanent magnet and the Faraday rotation It is preferable that the diameter of the Faraday rotator 2 is smaller than that of the Faraday rotator 2.
- the diameter of the Faraday rotator is large, the inner diameter of the permanent magnet is not preferable because the strength of the magnetic field applied to the Faraday rotator is weakened.
- FIG. 2 is a schematic sectional view showing an optical array 11 according to another embodiment of the present invention.
- the difference between FIG. 2 and FIG. 1 is that the configuration of FIG. 1 is further different between the first component 13 a and the Faraday rotator 12, and between the second component 13 b and the Faraday rotator 12.
- a spacer 19 is provided between the two. By providing the spacer 19, a predetermined clearance formed between the first component 13a and the second component 13b and the Faraday rotator 12 can be kept constant. Easy to keep. Therefore, the intensity of the magnetic field applied by the first component 13a and the second component 13b can be easily adjusted and stabilized.
- the spacer 19 is used to adjust the width between the end faces of the first component 13 a and the second component 13 b and the end face of the Faraday rotator 12. It is made of a material having a magnetic permeability of about 1 and does not affect the magnetic field, and has a uniform thickness with a hole at the position of the optical axis. Specifically, a film, a resist coating, an adhesive, a cellophane tape, or the like can be used, but is not limited thereto.
- TAG single crystal As starting materials for paramagnetic garnet Bok polycrystalline, T b 4 0 7 (99, 9%) and AI 2 0 3 as a prepared (purity 99. 99%) Tb 3 AI 5 0 12 Weighed.
- pure water was added to the mixed powder of the prepared starting materials, and the mixture was mixed with the cobblestone for about 24 hours.
- the mixed powder was dried overnight with an aspire.
- the dried mixed powder was passed through a mesh to adjust the particle size of the mixed powder, and calcined at 1200 ° C for 2 hours using an electric furnace.
- the mixed powder After pulverizing the mixed powder obtained by calcining, the mixed powder was mixed with an A binder and a solvent and mixed with a cobblestone for several hours to obtain a slurry mixture. After this mixture is formed into a cylindrical shape by a molding machine,
- TAG polycrystal By firing at 1 600 ° C for 2 hours, a columnar TAG polycrystal was obtained. The density of the obtained TAG polycrystal was 68%. The density here indicates the relative density of the starting material composition to the theoretical density.
- the obtained column-shaped polycrystalline AG was used as a raw material rod, and a TAG single crystal was separately prepared as a seed crystal.
- a CO 2 laser FZ (Floating Zone) device shown in Japanese Patent Application No. 2002-242047 the end of the TAG polycrystal is heated and melted by irradiating a CO 2 laser beam in the air atmosphere, and The fused part of the AG polycrystal and the end of the seed crystal were fused and joined to form a melt zone.
- t ⁇ Te moving the region of C 0 2 laser beam at a rate 30 mm / Time to TAG polycrystalline side.
- TbA I 0 3 phase was confirmed to have deposited on the porous portion of the TAG polycrystal.
- the melt zone on the seed crystal side was solidified by natural cooling, and a TAG single crystal was obtained. This way-obtained TAG single crystal was confirmed to be pure TAG single crystal TbA I 0 3 phase is not precipitated.
- the obtained TAG single crystal was cut and polished to obtain a Faraday rotator.
- the wavelength of the laser light is 1300 nm, and 1500 ⁇
- the refractive index at m is calculated separately, and the refractive index at each wavelength is calculated by Cauchy fitting.
- Table 1 shows that the Faraday rotator made of a TAG single crystal has a high effective Verdet constant even in the visible light range of 400 to 680 nm.
- the light absorption coefficient is 1 cm- 1 or less, which indicates that the Faraday rotator is transparent.
- BI u-ray has attracted attention as a next-generation recording method because it has a sufficiently high effective Wohlde constant in the wavelength range of 400 to 420 m and has a low light absorption rate. It can be seen that it is suitably used for suppressing return light.
- the magnetic field strength, the standard deviation value, and the CV value of the optical isolator according to the first and second embodiments of the present invention and the comparative example are compared.
- the TAG single crystal obtained in Experimental Example 1 was used as a Faraday rotator and processed into a columnar shape having a length of 2.8 mm and a cross-sectional diameter of 1 mm.
- the crystal orientation in the optical axis direction (longitudinal direction) of the Faraday rotator was set to 100>.
- the magnetic permeability of the TAG single crystal was 13.
- the first As component and second component, N d 2 F e 1 4 B Karanari, intensity of magnetization was 1.3 chome of providing two permanent magnets.
- This permanent magnet was machined into a cylindrical shape with a length of 3 mm, an inner diameter of 1 mm, and an outer diameter of 5 mm, and the holes of the two permanent magnets and the end face of the Faraday rotator were straightened. They were arranged so as to be sandwiched by permanent magnets. Further, a polarizer made of rutile was provided on the light incident surface side of the end face of the permanent magnet corresponding to the first component. Further, an analyzer made of the same rutile as the polarizer was provided at an angle of 45 ° with respect to the polarizer on the light emission surface side of the end face of the permanent magnet corresponding to the second component.
- the two permanent magnets and the Faraday rotator are configured so that there is no gap between the Faraday terminal end face of each permanent magnet and the end face of the Faraday rotator.
- Example 1 was an optical isolator obtained by fixing.
- the TAG single crystal obtained in Experimental Example 1 was used as a Faraday rotator and processed into a columnar shape having a length of 2.8 mm and a cross-sectional diameter of 1 mm.
- the crystal orientation of the Faraday rotator in the optical axis direction (longitudinal direction) was set to 100>.
- the magnetic permeability of the TAG single crystal was 13.
- intensity of magnetization was two prepared permanent magnet of 1 ⁇ 3 T.
- This permanent magnet was machined into a cylindrical shape with a length of 3 mm, an inner diameter of 1 mm, and an outer diameter of 5 mm, so that the holes of the two permanent magnets and the end face of the Faraday rotator were linear. They were arranged so as to be sandwiched by 7 magnets. Further, a polarizer made of rutile was provided on the light incident surface side of the end face of the permanent magnet corresponding to the first component. Further, an analyzer made of the same rutile as the polarizer was provided at an angle of 45 ° with respect to the polarizer on the light emitting surface side of the end face of the permanent magnet corresponding to the second component.
- An optical isolator obtained by fixing a PET film 100 m as a spacer between the end face of each permanent magnet and the end face of the Faraday rotator and fixing the two permanent magnets and the Faraday rotator was used.
- Example 2 was set.
- optical isolators of the following comparative examples were manufactured.
- an optical isolator 31 having the same configuration as in FIG. Specifically, prepared Ding AG single crystal having the same magnetic permeability 1 3 Example as a Faraday rotator 3 2, N d 2 F e having a strength similar magnetization and examples as the permanent magnet 3 3, the 4 B was eight available.
- Four permanent magnets 33 were formed before and after the Faraday rotator 32 in the light incident direction. Each of the permanent magnets 33 is formed so as to surround the end face of the Faraday rotator 32, and a part of the Faraday rotator 32 enters the permanent magnet 33.
- the magnetization direction of the permanent magnet 33 disposed in front of the Faraday rotator 32 with respect to the light incident direction is perpendicular to the optical axis and directed away from the optical axis.
- the magnetization direction of the permanent magnet 33 disposed rearward is perpendicular to the optical axis and is directed in the direction toward the optical axis.
- An optical isolator 31 made by using the same method as that of the embodiment except for the above configuration was used as a comparative example 1.
- an optical isolator 41 having the same configuration as in FIG. Specifically, a TAG single crystal having the same magnetic permeability 13 as that of the example was prepared as the Faraday rotator 42, and processed into a columnar shape having a length of 2.8 mm and a cross-sectional diameter of 1 mm. In addition, one Nd-B-Fe system permanent magnet 43 with a magnetization strength of 1.3 was prepared. Each of the permanent magnets 43 was machined into a cylindrical shape having a length of 8.8 mm, an inner diameter of 1 mm, and an outer diameter of 5 mm. The columnar Faraday rotator 42 was inserted so as to be located at the center of the cylinder of the permanent magnet 43 obtained in this manner. An optical isolator 41 manufactured by using the same method as that of the embodiment except for the above configuration was used as a comparative example 2.
- Example 1 Example 2, Comparative Example 1, and Comparative Example 2 obtained as described above.
- Example 1, Example 2, Comparative Example, and Comparative Example 2 were measured as follows.
- Each of the optical isolators obtained as described above was calculated by computer simulation using the finite element method.
- the radial direction and the optical axis direction of the Faraday rotator were cut into a mesh at intervals of 0.1 mm, and the magnetic field strength in the optical axis direction at each point was calculated.
- the average value was measured for magnetic field strength (k AZm), standard deviation (k A / m), and CV value (%). The results are shown in Table 2.
- the magnetic field strength was 180 °. In addition to the high kAZm or higher, the standard deviation and CV value show that the magnetic field distribution is uniform.
- the magnetic field strength is strong because a plurality of magnets are formed, but when two or more magnets are combined in the magnetization direction, the magnets easily repel each other because the magnets repel each other. Cannot be stabilized. Therefore, it can be seen that the magnetic field distribution is non-uniform.
- the magnetic field strength was 60 kAZm, which indicates that the magnetic field strength was extremely lower than in Example 1. Therefore, when trying to obtain the same magnetic field as the optical isolator of the present invention, the Faraday rotator is required to be at least 9.4 mm in length, and it is difficult to reduce the size as necessary.
- Example 1 and Example 2 of the present invention are excellent in magnetic field strength, standard deviation and CV value, and therefore have excellent insertion loss (Nishi) and isolation (Iso). You can see that. As a result, it can be seen that even in the wavelength region of 400 nm to 680 nm, more preferably 400 to 420 nm, it is possible to sufficiently cope with optical isolation. You.
- Example 2 In addition to Example 2, Examples 3 to 7 were prepared, and the relationship between the crystal orientation in the longitudinal direction of the Faraday rotator and the effective Weerde constant was compared.
- the Faraday rotator was prepared and produced in the same manner as in Example 2 except that the crystal orientation in the optical axis direction (longitudinal direction) of the Faraday rotator was set to an angle of 10 ° with respect to the ⁇ 110> orientation. In Example 5, the optical isolator was used.
- the Faraday rotator was fabricated and produced in the same manner as in Example 2, except that the crystal orientation in the optical axis direction (longitudinal direction) of the Faraday rotator was an angle of 15 ° with respect to the ⁇ 110> orientation.
- the optical isolator was used.
- Example 7 was an optical isolator obtained in the same manner as in Example 2 except that the crystal orientation in the optical axis direction (longitudinal direction) of the Faraday rotator was ⁇ 11 1>.
- the Faraday rotation angle (0 f ) of the Faraday rotator was measured as follows.
- a Faraday rotation angle measuring device For the measurement, a Faraday rotation angle measuring device was used. Specifically, a laser device having an output of 25 mW and a wavelength range of 408 nm, a polarizer, a permanent magnet serving as a first component, a Faraday rotator, and a permanent magnet serving as a second component The analyzer and the photodetector, which were placed on the rotating holder, were arranged in this order. Next, while applying a magnetic field (H) of 1 kOeEll, light was emitted from the laser device in parallel with the longitudinal direction of the Faraday rotator, and the Faraday rotation angle (6 f ) was measured from the analyzer rotation angle.
- H magnetic field
- the effective Verdet constant was measured using a laser device with an output of 25 mW and a wavelength range of 633 nm and 810 nm. The results are shown in Table 3.
- FIG. 4 is a schematic sectional view of a laser oscillator according to one embodiment of the present invention.
- the laser oscillator 20 of the present invention includes the optical isolator 21 of the present invention, a condenser lens 22, and a semiconductor laser 23.
- the optical isolator 21, the condenser lens 22, and the semiconductor laser 23 are connected in series such that the optical axes of the laser beams emitted from the semiconductor laser 23 coincide.
- the semiconductor laser 23 and the optical isolator 21 are fixed by a housing 25, and the condenser lens 22 is held by a lens holder 24.
- Laser light oscillated from the semiconductor laser 23 is condensed through the condenser lens 22 and is incident on the optical isolator 21.
- the polarization direction of the incident laser light is formed in a direction that matches the inclination of the polarizer.
- the semiconductor laser 23 used in the present invention is preferably a GaN semiconductor or a GaN semiconductor.
- a laser using an SHG crystal can be used.
- a laser beam was applied to the optical disk using the laser oscillator 20 having the above-described configuration, and the change in the output value of the laser oscillator 20 was measured for the returned light that was reflected and returned. According to this, it was found that the fluctuation of the output value of the laser oscillator 20 was within 5%. This indicates that the laser oscillator 20 using the optical isolator 21 of the present invention has a small output fluctuation and can perform stable oscillation.
- the optical isolator according to the present invention and the laser oscillator using the same are useful for preventing return light of laser light in data storage and reading of an optical communication system. It is suitable for use as a part of information equipment that stores and reads data.
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Abstract
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AU2003261894A AU2003261894A1 (en) | 2002-09-09 | 2003-09-03 | Optical isolator, and laser oscillator using this |
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JP2002-263176 | 2002-09-09 | ||
JP2002263176 | 2002-09-09 |
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PCT/JP2003/011228 WO2004025354A1 (ja) | 2002-09-09 | 2003-09-03 | 光アイソレータ、及びこれを用いたレーザ発振器 |
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WO (1) | WO2004025354A1 (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006330197A (ja) * | 2005-05-24 | 2006-12-07 | Murata Mfg Co Ltd | 光アイソレータ |
CN101546051B (zh) * | 2008-03-24 | 2013-01-16 | 住友金属矿山株式会社 | 法拉第旋转器 |
JP2018097350A (ja) * | 2016-12-15 | 2018-06-21 | 日本電気硝子株式会社 | 磁気光学素子 |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5441251U (ja) * | 1977-08-26 | 1979-03-19 | ||
JPH02102517U (ja) * | 1989-01-30 | 1990-08-15 | ||
JPH04233510A (ja) * | 1990-12-28 | 1992-08-21 | Hoya Corp | 光アイソレータ |
JP2000298247A (ja) * | 1998-10-29 | 2000-10-24 | Tokin Corp | 光アイソレータ及び非可逆相反部品 |
JP2001226196A (ja) * | 2000-02-17 | 2001-08-21 | Tokin Corp | テルビウム・アルミニウム・ガーネット単結晶およびその製造方法 |
-
2003
- 2003-09-03 WO PCT/JP2003/011228 patent/WO2004025354A1/ja not_active Application Discontinuation
- 2003-09-03 AU AU2003261894A patent/AU2003261894A1/en not_active Abandoned
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5441251U (ja) * | 1977-08-26 | 1979-03-19 | ||
JPH02102517U (ja) * | 1989-01-30 | 1990-08-15 | ||
JPH04233510A (ja) * | 1990-12-28 | 1992-08-21 | Hoya Corp | 光アイソレータ |
JP2000298247A (ja) * | 1998-10-29 | 2000-10-24 | Tokin Corp | 光アイソレータ及び非可逆相反部品 |
JP2001226196A (ja) * | 2000-02-17 | 2001-08-21 | Tokin Corp | テルビウム・アルミニウム・ガーネット単結晶およびその製造方法 |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006330197A (ja) * | 2005-05-24 | 2006-12-07 | Murata Mfg Co Ltd | 光アイソレータ |
CN101546051B (zh) * | 2008-03-24 | 2013-01-16 | 住友金属矿山株式会社 | 法拉第旋转器 |
JP2018097350A (ja) * | 2016-12-15 | 2018-06-21 | 日本電気硝子株式会社 | 磁気光学素子 |
CN110073276A (zh) * | 2016-12-15 | 2019-07-30 | 日本电气硝子株式会社 | 磁光学元件 |
EP3557312A4 (en) * | 2016-12-15 | 2020-07-22 | Nippon Electric Glass Co., Ltd. | MAGNETO-OPTICAL ELEMENT |
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AU2003261894A1 (en) | 2004-04-30 |
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