JP5151460B2 - Magnetic probe - Google Patents

Description

  The present invention relates to a magnetic probe.

  Conventionally, there is an optical fiber type magnetic probe that measures a magnetic field using laser light, an optical fiber, and a magneto-optical material (hereinafter, the magneto-optical material may be referred to as an MO material). And the evaluation result of the microwave circuit and antenna using such a magnetic probe is reported (nonpatent literatures 1 and 2). The probe consists of an optical fiber and an MO material formed at the tip thereof. FIG. 10 is a schematic cross-sectional view of a conventional magnetic probe. Specifically, FIG. A magnetic probe having the same shape as the probe head shown in FIG. The magnetic probe 20 is formed such that the direction of the easy axis 15 of the MO material 13 is perpendicular to the traveling direction of the probe light 14 traveling through the core 12 of the optical fiber 16. As described above, it is known that measurement in the gigahertz band is possible by using the magnetic probe 20 in which the traveling direction of the probe light 14 and the spontaneous magnetization of the MO material 13 or the direction of the easy axis 15 is perpendicular. (Non-Patent Document 2). For this reason, the application to the high frequency measurement inside the electronic device by the magnetic probe 20 is expected.

  On the other hand, when a garnet, which is a kind of MO material, is formed on the end face of an optical fiber by using the aerosol deposition (AD) method, not only an ultra-small magnetic probe is realized, but also the magnetization direction of the probe light and the MO material is changed. It has been found that the relationship is as described above, and measurement in the gigahertz band is possible (Non-Patent Document 3).

In addition, a magnetic field measuring apparatus comprising a magneto-optical crystal as a magnetic sensing element and an optical device is also known in which a condensing lens is incorporated at the tip of the apparatus (Patent Document 1). Furthermore, a first optical fiber provided with an optical crystal for detecting an electromagnetic field generated from the measurement object at the tip, and a second for measuring the displacement of the distance from the tip to the measurement object. And the first and second optical fibers are electromagnetic field detection elements that are integrally fixed in a state in which the end surfaces of the respective tip portions are aligned so as to be the same surface. Known (Patent Document 2). And the magneto-optical element which comprises a magnetic field detection apparatus is connected with the end of an optical fiber through a ferrule, The reflected light of the incident light which injects through an optical fiber and a ferrule is radiate | emitted through an optical fiber and a ferrule. It is also known to do so (Patent Document 3).
S. Wakana, T. Ohara, M. Abe, E. Yamazaki, M. Kishi, and M. Tsuchiya, “Fiber-Edge Electrooptic / Magnetooptic Probe for Spectral-Domain Analysis of Electromagnetic Field”, IEEE Trans. Microwave Theory Tech. , vol.48, no.12, pp.2611-2616,2000. E. Yamazaki, S. Wakana, H. Park, M. Kishi, and M. Tsuchiya, “High-Frequency Magneto-Optic Probe Based on BiRIG Rotation Magnetization”, IEICE Trans. Electron., Vol. E86-C, no. 7, pp. 1338-1344, 2003. M.Iwanami, M.Nakada, H.Tsuda, K.Ohashi, and J.Akedo, “Ultra small magneto-optic field probe fabricated by aerosol deposition”, IEICE Electronics Express, vol.4, no.17, pp.542 -548,2007. Japanese Patent Laying-Open No. 2005-241489 JP 2005-308455 A JP 2007-106653 A

  When a magnetic probe as shown in FIG. 10 is used, high-frequency magnetic field measurement is possible. However, according to the study by the present inventors, there is a problem that the sensitivity is insufficient for general-purpose measurement inside an electronic device. It turned out to be. Therefore, it is important to improve the sensitivity without greatly degrading the measurement band of the magnetic probe.

  The object of the present invention has been made to solve the above problems. That is, it is to provide a magnetic probe with high sensitivity while ensuring a measurement band. More specifically, an object is to provide a magnetic probe capable of measuring a high-frequency magnetic field with high sensitivity in a fine region in which electronic devices are mounted at high density.

  A magnetic probe of the present invention for solving the above-described problems has an optical fiber and a magneto-optical material formed on the end face of the optical fiber, and the direction of the easy axis of magnetization of the magneto-optical material is A magnetic probe formed perpendicular to a traveling direction of probe light traveling through a core of an optical fiber, wherein the magneto-optical material is provided so as to cover the core, and the width of the magneto-optical material is It is formed below the width.

  In a preferred aspect of the magnetic probe of the present invention, the aspect ratio of the width to the thickness of the magneto-optical material is greater than 1 and 10 or less.

  In a preferred aspect of the magnetic probe of the present invention, the optical fiber is formed of a connection part having a substantially truncated cone shape with the end face as an upper surface, and a signal transmission part provided following the connection part.

  In a preferred aspect of the magnetic probe of the present invention, the optical fiber includes a connection portion including the end face and a signal transmission portion provided following the connection portion, and an outer diameter of the connection portion is the signal transmission portion. The tip of the optical fiber is processed into a convex shape.

  In a preferred aspect of the magnetic probe of the present invention, the magneto-optical material includes a tip portion and a substrate portion provided after the tip portion, and the substrate portion is formed on the end face, and the tip The cross section of the magneto-optical material is processed into a convex shape by making the width of the portion smaller than the width of the substrate portion.

  In a preferred aspect of the magnetic probe of the present invention, the aspect ratio of the width to the thickness of the tip is greater than 1 and 10 or less.

  In a preferred aspect of the magnetic probe of the present invention, the magneto-optical material is formed using an aerosol deposition method.

  According to the magnetic probe of the present invention, it is possible to provide a highly sensitive magnetic probe while ensuring a measurement band. Specifically, it is possible to provide a magnetic probe capable of measuring a high-frequency magnetic field with high sensitivity in a fine region in which electronic devices are densely mounted. In particular, a high-frequency, high-sensitivity magnetic probe with a very small tip is realized, and as a result, magnetic field measurement can be performed in a high-density mounting area inside electronic equipment, enabling detailed evaluation of noise currents, etc. It is possible to support circuit design with high quality. Furthermore, since the magnetic probe of the present invention can be applied to the operation check and failure diagnosis of the microdevice inside the apparatus, the reliability of the product can be improved.

  Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

  The magnetic probe of the present invention has an optical fiber and a magneto-optical material formed on the end face of the optical fiber, and the direction of the easy magnetization axis of the magneto-optical material travels through the core of the optical fiber. It is formed perpendicularly to the direction of travel. A magneto-optical material is provided so as to cover the core of the optical fiber, and the width of the magneto-optical material is formed to be equal to or less than the width of the end face of the optical fiber. Specifically, in the optical fiber type magnetic probe capable of measuring in the gigahertz band, the width of the optical fiber is set so that the lateral width of the magneto-optical material formed on the end face of the optical fiber is large enough to cover the core of the optical fiber. The following. Thereby, it is possible to provide a magnetic probe with high sensitivity while ensuring a measurement band. Preferably, the aspect ratio of the thickness with respect to the lateral width of the magneto-optical material is reduced. This makes it easier to provide a fine and highly sensitive magnetic probe.

  In a specific example of the state of the tip of the magnetic probe of the present invention, the core region and its peripheral portion on the end face of the optical fiber are covered with a minute magneto-optical material. Even if the MO material is formed on the end face of the optical fiber so that the width of the magneto-optical material is about the same as the width of the optical fiber and the tip shape of the magnetic probe is a truncated cone or a convex shape, it is fine and high. Sensitive probes can be provided. Therefore, in the present invention, the principle of achieving a fine and high sensitivity by making the tip shape of the magnetic probe as described above will be described.

  FIG. 1 is a diagram schematically showing a cross section near the tip of a magnetic probe. Specifically, to explain the factors that determine the probe sensitivity to a magnetic field when an optical fiber type magnetic probe in which the traveling direction of the probe light and the direction of spontaneous magnetization of the MO material are perpendicular to each other is exposed to an external magnetic field FIG.

  In the magnetic probe 10, the spontaneous magnetization 5 in the magneto-optical material 3 precesses due to an external magnetic field, but the magnetic probe 10 becomes more sensitive as the magnetization fluctuation width at a certain magnetic field strength increases. Therefore, in order to increase the sensitivity of the magnetic probe 10, the force governing the direction of spontaneous magnetization, in other words, the magnetic anisotropy energy may be reduced.

  For the sake of convenience, the shape of the magneto-optic material in the optical fiber type magnetic probe is shown with the lateral width of the magneto-optic material 3 equal to the width of the optical fiber 9 and the thickness of the magneto-optic material 3 enlarged. However, in general, it has a thin plate shape or a film shape whose thickness is shorter than the lateral width. According to the study by the present inventors, it has been found that the sensitivity of the magnetic probe can be increased by reducing the width (lateral width) of the magneto-optical material. More specifically, if the aspect ratio of the thickness to the lateral width (width) of the magneto-optical material 3 is reduced based on the general formula of magnetic energy resulting from the shape, the amplitude of spontaneous magnetization due to an external magnetic field increases, and the magnetic It was found that the probe was highly sensitive. Therefore, this point will be described in more detail.

FIG. 2 is a conceptual diagram showing spontaneous magnetization with respect to the x, y, and z axes. With reference to the coordinate system shown in FIG. 2, when the angles formed by the spontaneous magnetization _IS and the x, y, and z axes are θ _x , θ _y , and θ _z , the magnetic energy E _d resulting from the shape is expressed.

In Formula 1, mu ₀ is the permeability of vacuum, the _{I S} is the spontaneous magnetization, Nx, Ny, Nz is, x, a y, demagnetizing factor in the z-direction. Here, it is assumed that a thin plate or film-like MO material that is infinitely spread in the x and y directions is formed at the end of the optical fiber. At this time, N _x = N _y = 0 and N _z = 1, and E _d is as shown in Equation 2.

As it can be seen from Equation 2, if the I _S is oriented in a direction parallel or in-plane direction of a thin surface becomes the minimum energy, spontaneous magnetization want orientation in that direction. If the magnetization directed in the direction parallel to the thin plate surface is directed to the vertical direction shifted by 90 degrees, energy of I _S ² / 2μ ₀ is required.

Actually, there is no thin plate or film-like MO material spreading infinitely in the x and y directions, but the direction of spontaneous magnetization of the film-like magneto-optical material is often in the in-plane direction. If it is intended to be directed in the direction perpendicular to the plane, energy proportional to I _S ² is required.

FIG. 3 is a diagram schematically showing a cross section near the tip of the magnetic probe when the width of the magneto-optical material is equal to or less than the width of the end face of the optical fiber. Specifically, consider a case where a cubic (aspect ratio: 1) magneto-optical material 3 is formed on the end face of the optical fiber. Neglecting the magnetocrystalline anisotropy of the MO material, the demagnetizing factor coefficient for the sphere can be applied, so that Nx = Ny = Nz = 1/3. As a result, E _d is expressed as shown in Equation 3.

In Equation 3, the energy difference between the spontaneous magnetization in the transverse direction and the longitudinal direction is zero, and there is no particular direction in which the magnetization wants to be directed. In other words, the energy required to direct the magnetization vertically from the in-plane is zero. . This means that amplitude of the I _S with respect to the external magnetic field is maximum.

  Since there is actually a magnetocrystalline anisotropy, there is no direction in which the magnetization tends to be directed. However, if the material is the same, the magnetic anisotropy energy due to the shape decreases as the aspect ratio decreases. , Magnetization becomes easy to move.

  From the above, to increase the sensitivity of the optical fiber type magnetic probe, it is important to reduce the magneto-optical material provided at the end of the optical fiber, while providing the magneto-optical material so as to cover the core of the optical fiber, It can be seen that it is necessary to form the width of the magneto-optical material to be equal to or less than the width of the end face of the optical fiber. Preferably, it can be seen that it is effective to reduce the aspect ratio of the thickness to the lateral width of the magneto-optical material present at the tip of the optical fiber. From such a viewpoint, it is preferable that the aspect ratio of the width to the thickness of the magneto-optical material is greater than 1 and 10 or less.

  FIG. 4 is a diagram schematically showing a cross section near the tip of the magnetic probe used in the first embodiment of the magnetic probe of the present invention. The magnetic probe 10 a has an optical fiber 9 and a magneto-optical material 3 formed on the end face 17 of the optical fiber 9, and the direction of the easy axis 5 of the magneto-optical material 3 is the core 2 of the optical fiber 9. It is formed perpendicular to the traveling direction of the probe light 4 traveling through. A magneto-optical material 3 is provided so as to cover the core 2, and the width of the magneto-optical material 3 is formed to be equal to or less than the width of the end face 17.

  More specifically, the magnetic probe 10 a is an optical fiber type magnetic probe in which the magneto-optical material 3 is formed on the end face 17 of the optical fiber 9 so as to cover the region of the core 2. As described above, by forming the magneto-optical material 3 smaller than the area of the end face 17 of the optical fiber 9, it is easy to increase the sensitivity of the magnetic probe. Preferably, the magnetic probe can be highly sensitive by reducing the aspect ratio of the thickness to the lateral width (width) of the magneto-optical material. However, when the width and thickness are equal and the aspect ratio is 1, the shape magnetic anisotropy energy becomes zero, so that the spontaneous magnetization cannot precess and high frequency measurement is impossible. For this reason, the aspect ratio of the lateral width (width) and thickness of the magneto-optical material 3 can maintain a relationship in which the direction of spontaneous magnetization or the direction of easy magnetization is perpendicular to the probe light 4, and the magnetization is precessed by an external magnetic field. It needs to be within the range where it can move. Specifically, it is desirable that the aspect ratio of the width to the thickness of the magneto-optical material 3 is greater than 1 and 10 or less. The shape of the magneto-optical material 3 may be a rectangular parallelepiped shape or a disc shape. When the shape of the magneto-optical material 3 is a rectangular parallelepiped, the lateral width (width) is the length of the long side or diagonal line, and when the shape of the magneto-optical material 3 is a disc shape, the lateral width (width) ) Is the length of the diameter (outer diameter). Further, the thickness of the magneto-optical material 3 is usually 1 μm or more and 100 μm or less.

  The magnetic probe 10a can be manufactured as follows, for example. That is, for example, a part of a yttrium iron garnet single crystal is cut and polished, and the cut crystal is used as the magneto-optical material 3. Then, the magnetic probe 10a can be obtained by adhering to the end face 17 of the optical fiber 9 so that the direction of spontaneous magnetization (magnetization easy axis) of the magneto-optical material 3 is as shown in FIG. At this time, the magneto-optical material 3 is bonded so as to completely cover the core 4 of the optical fiber 9. The shape of the crystal is, for example, a rectangular parallelepiped having a thickness of 20 μm and a lateral width of 80 μm. In this case, the aspect ratio is 4, and the fluctuation width of the spontaneous magnetization with respect to the external magnetic field is increased, so that a highly sensitive magnetic probe can be realized. Adhesion is performed using a transparent resin such as an epoxy resin adhesive in an optical communication wavelength band (around 1.55 microns). As the magneto-optical material 3, a garnet single crystal in which a part of yttrium is substituted with bismuth or another rare earth element may be used.

  The magnetic probe 10 a can also be manufactured by directly forming a film of the magneto-optical material 3 on the end face 17 of the optical fiber 9. The magneto-optical material 3 is formed by using, for example, an aerosol deposition (AD) method. A magneto-optical material such as bismuth-substituted yttrium iron garnet having a thickness of 1 μm or more and 20 μm or less can be formed on the end face 17 of the optical fiber 9 by the AD method. As described above, when the magnetic probe 10a is manufactured by forming a garnet film on the end face 17 of the optical fiber 9 by using the AD method, the direction of the easy axis of magnetization of the probe light 4 and the garnet is in a vertical relationship, and in the gigahertz band. Measurement is also possible.

  FIG. 5 is a perspective view schematically showing a method of manufacturing the magnetic probe shown in FIG. 4 by the aerosol deposition method. In FIG. 5, for convenience of explanation, the optical fiber 9 is shown as a shape cut in the middle. As shown in FIG. 5, a mask 8 having a hole larger than the area of the core 2 of the optical fiber 9 but smaller than the area of the end face of the optical fiber 9 is inserted between the end face of the optical fiber 9 and the aerosol flow 7. Thus, since the aerosol passes only through the hole region, the magneto-optical material can be deposited only on a part of the end face of the optical fiber 9. By such a film forming technique, for example, a disc-shaped bismuth-substituted yttrium iron garnet film (magneto-optic material) having a thickness of 10 μm and a width of 50 μm (aspect ratio 5) is formed on the end face of the optical fiber 9 to cover the core 2 region. Thus, a highly sensitive magnetic probe 10a can be realized.

  FIG. 6 is a diagram schematically showing a cross section near the tip of the magnetic probe used in the second embodiment of the magnetic probe of the present invention. In the magnetic probe 10b, the optical fiber 9 is formed of a connection part 18a having a substantially truncated cone shape with the end face 17 as an upper surface, and a signal transmission part 19a provided following the connection part 18a. Both the connecting portion 18a and the signal transmission portion 19a are part of the optical fiber 9, but for convenience of explanation, the respective portions are described separately.

  More specifically, in the magnetic probe 10b, the magneto-optical material 3 is formed on the end surface 17 whose area is reduced by cutting off the corner portion of the end of the optical fiber 9. The magneto-optical material 3 also has a truncated cone shape whose bottom surface has substantially the same area as the end surface 17 of the optical fiber 9. In other words, the magneto-optical material 3 has a shape that is obtained by cutting the top of the cone. The aspect ratio of the magneto-optical material 3 in this case may be the ratio of the line segment BB ′ to the line segment AA ′, and the value is preferably greater than 1 and 10 or less.

  The magnetic probe 10b can be manufactured as follows, for example. That is, the optical fiber 9 in which the corner portion at the end of the optical fiber is cut is prepared in advance. Then, a film of a magneto-optical material may be directly formed on the end face 17 of the optical fiber 9 by using the AD method described above.

  FIG. 7 is a diagram schematically showing a method of manufacturing the magnetic probe shown in FIG. 6 by the aerosol deposition method. As shown in FIG. 7, by spraying, for example, an aerosol flow 7 of bismuth-substituted yttrium iron garnet toward the end face 17 of the optical fiber 9 obtained by cutting the corner portion of the end portion, the aspect is formed so as to cover the core region. A garnet film with a small ratio can be formed. Further, in the magnetic probe 10b shown in FIG. 6, a film of a magneto-optical material is formed on the end surface by an AD method using an optical fiber whose end is not specially processed, and then, at the end of the magnetic probe. It can also be manufactured by cutting corner portions.

  FIG. 8 is a diagram schematically showing a cross section near the tip of the magnetic probe used in the third embodiment of the magnetic probe of the present invention. In the magnetic probe 10c, the optical fiber 9 includes a connection part 18b including the end face 17 and a signal transmission part 19b provided following the connection part 18b. The outer diameter of the connection part 18b is the outer diameter of the signal transmission part 19b. The tip of the optical fiber 10c is processed into a convex shape by being formed smaller. Both the connecting portion 18b and the signal transmission portion 19b are part of the optical fiber 9, but for convenience of explanation, the respective portions are described separately.

  More specifically, in the magnetic probe 10c, the magneto-optical material 3 having an aspect ratio larger than 1 and 10 or less is formed at the tip of the optical fiber 9 whose end face 17 is cut into a convex shape. The magneto-optical material 3 is formed so as to cover the end face of the core 2. The shape of the protruding portion 6 at the end of the optical fiber 9 formed as the connecting portion 18b may be a prismatic shape or a cylindrical shape.

  The magnetic probe 10c can be manufactured as follows, for example. That is, the optical fiber 9 is prepared in advance by cutting the shape of the end portion of the optical fiber into a convex shape and forming the connection portion 18b at the tip. Then, a film of a magneto-optical material may be directly formed on the end face 17 of the optical fiber 9 by using the AD method described above. More specifically, after processing so that the width of the end face of the protruding portion 6 (connecting portion 18b) of the end portion of the optical fiber 9 is 40 μm, a bismuth-substituted yttrium iron garnet film having a thickness of 10 μm is formed by the AD method. Form. As a result, a garnet film (magneto-optic material 3) having an aspect ratio of 4 is formed so as to cover the core 2 on the end face 17 of the optical fiber 9, and a highly sensitive magnetic probe 10c can be realized.

  FIG. 9 is a diagram schematically showing a cross section near the tip of the magnetic probe used in the fourth embodiment of the magnetic probe of the present invention. In the magnetic probe 10d, the magneto-optical material 3 includes a tip portion 21b and a substrate portion 21a provided following the tip portion 21b. The substrate portion 21a is formed on the end surface 17, and the width of the tip portion 21b. Is made smaller than the width of the substrate portion 21a, the cross section of the magneto-optical material 3 is processed into a convex shape. Both the tip portion 21b and the substrate portion 21a are part of the magneto-optical material 3, but for convenience of explanation, the respective portions are described separately.

  More specifically, in the magnetic probe 10d, a magneto-optic material is formed as a substrate portion 21a on the end face 17 of the optical fiber 9, and a magneto-optic material having a smaller aspect ratio is formed as a tip portion 21b on the substrate portion 21a. ing. The aspect ratio of the tip 21b of the magneto-optical material 3 is preferably greater than 1 and 10 or less. The tip portion 21b is formed above the core 2 of the optical fiber 9 and may have a rectangular parallelepiped shape or a disc shape.

  The magnetic probe 10d can be manufactured as follows, for example. That is, first, a bismuth-substituted yttrium iron garnet film having a thickness of, for example, 5 μm is formed as the substrate portion 21a on the end face 17 of the optical fiber 9 by the AD method described above. Next, film formation by AD method is performed using the mask 8 as described with reference to FIG. 5, and for example, a disc-shaped bismuth-substituted yttrium iron garnet film having a thickness of 10 μm and a width of 50 μm (aspect ratio of 5) is formed as the tip portion 21b. To do. At that time, the film formation of the tip 21 b is performed so that the tip 21 b is disposed above the core 2. By such a manufacturing process, an optical fiber type magnetic probe 10d having a convex cross section of the magneto-optical material 3 can be manufactured, and a high sensitivity probe can be realized.

  The magnetic probe of the present invention has been described above using specific examples. However, the magnetic probe of the present invention is not limited to the above specific examples, and appropriate design changes and the like are made within the scope of the gist of the present invention. Can do.

  Such a magnetic probe can be used, for example, as a magnetic probe for a mounting electrical design support tool or a circuit failure diagnosis tool. Specifically, magnetic field measurement can be performed on the LSI or in the vicinity of the LSI package using the magnetic probe of the present invention to acquire information for feedback to the electrical design, or circuit operation verification can be performed.

It is the figure which showed typically the cross section of the tip vicinity of a magnetic probe. It is the conceptual diagram which showed the spontaneous magnetization with respect to x, y, z axis. It is the figure which showed typically the cross section of the front-end | tip vicinity of a magnetic probe in case the width | variety of a magneto-optical material is made below into the width | variety of the end surface of an optical fiber. It is the figure which showed typically the cross section of the tip vicinity of the magnetic probe used for the 1st Example of the magnetic probe of this invention. It is a perspective view which shows typically the method of manufacturing the magnetic probe shown in FIG. 4 by the aerosol deposition method. It is the figure which showed typically the cross section of the tip vicinity of the magnetic probe used for the 2nd Example of the magnetic probe of this invention. It is a figure which shows typically the method of manufacturing the magnetic probe shown in FIG. 6 by the aerosol deposition method. It is the figure which showed typically the cross section of the tip vicinity of the magnetic probe used for the 3rd Example of the magnetic probe of this invention. It is the figure which showed typically the cross section of the tip vicinity of the magnetic probe used for the 4th Example of the magnetic probe of this invention. It is typical sectional drawing of the conventional magnetic probe.

Explanation of symbols

1,11 clad 2,12 core 3,13 magneto-optical material 4,14 probe light 5,15 easy magnetization axis (spontaneous magnetization)
6 Protruding portion of optical fiber end portion 7 Aerosol flow 8 Mask 9, 16 Optical fiber 10, 20 Magnetic probe 17 End face 18 Connection portion 19 Signal transmission portion 21a Substrate portion 21b Tip portion

Claims (6)

An optical fiber, comprising: a member made of a magneto-optical material formed on the end face of the optical fiber, the direction of magnetization easy axis of the member, in the traveling direction of the probe light traveling through the core of the optical fiber A magnetic probe formed perpendicular to the
Said member is provided so as to cover the core, the width of the member is formed below the width of said end face, the aspect ratio of the tip width of the member with respect to the thickness of the member is, is 10 or less larger than 1 A magnetic probe characterized by that. 2. The magnetic probe according to claim 1, wherein the optical fiber is formed of a connection portion having a substantially truncated cone shape with the end face as an upper surface, and a signal transmission portion provided subsequent to the connection portion. The optical fiber is composed of a connection portion including the end face and a signal transmission portion provided subsequent to the connection portion, and the outer diameter of the connection portion is smaller than the outer diameter of the signal transmission portion. The magnetic probe according to claim 1, wherein the tip of the optical fiber is processed into a convex shape. An optical fiber and a member made of a magneto-optic material formed on the end face of the optical fiber, and the direction of the easy axis of the member is the traveling direction of the probe light traveling through the core of the optical fiber A magnetic probe formed perpendicular to the
The member is provided so as to cover the core, the width of the member is formed to be equal to or less than the width of the end surface,
The member includes a tip portion and a substrate portion that is provided following the tip portion, the substrate portion is formed on the end surface, and the width of the tip portion is made smaller than the width of the substrate portion. The magnetic probe is characterized in that a cross section of the member is processed into a convex shape. The magnetic probe according to claim 4 , wherein an aspect ratio of a width to a thickness of the tip portion is greater than 1 and 10 or less. It said member is formed by aerosol deposition, a magnetic probe according to any one of claims 1-5.

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