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JP2004335502

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DESCRIPTION JP2004335502
A magnetostrictive actuator using a change in deflection of a magnetostrictive element and an
optical switch using the magnetostrictive actuator, which prevents damage and deformation of a
substrate of the magnetostrictive element, and a thin substrate and magnetostrictive element And
a magnetostrictive actuator and an optical switch. In a magnetostrictive actuator according to the
present invention, a magnetic field is applied to a thin film (magnetostrictive thin film) made of a
magnetostrictive material by using a magnetic field application means, whereby the
magnetostrictive thin film expands or contracts to form a magnetostrictive piece. Misalignment
stress occurs between them, causing the magnetostrictive element to bend. The operation of the
magnetostrictive actuator is performed using the deflection of the magnetostrictive piece. In the
magnetostrictive actuator of the present invention, since the amorphous metal material is used as
the substrate, plastic deformation of the substrate can be prevented, and the magnetostrictive
piece can be returned to the original non-flexing state. Thereby, good operation control of the
magnetostrictive actuator can be performed. [Selected figure] Figure 2
Magnetostrictive actuator, method of manufacturing the same, and optical switch
The present invention relates to a magnetostrictive actuator using a piece having a
magnetostrictive film formed on a substrate, a method of manufacturing the same, and an optical
switch utilizing the magnetostrictive actuator. 2. Description of the Related Art In an optical
communication system, an optical switch is required to switch an optical communication line. As
one of the optical switch systems, for example, there is known an optical switch of a system in
which a reflection mirror is disposed on an optical path and the reflection direction of light is
changed by changing the angle. In such an optical switch, as a method of changing the angle of
the reflection mirror, for example, an electrostatic method, a piezoelectric method, a magnetic
force method and the like are known. [0003] As a conventional magnetic force optical switch, an
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optical switch using an attraction between a magnet and an electromagnet is known (see, for
example, Patent Document 1). This optical switch is configured by attaching a mirror to which a
magnetic body is attached to a substrate via a three-dimensionally movable support and
providing an electromagnet in the vicinity of the mirror. In such an optical switch, the
electromagnet is operated to generate a magnetic field from the electromagnet, the magnetic
material attached to the mirror is attracted to the electromagnet by magnetic interaction, and the
laser incident on the mirror is switched in a predetermined direction. . However, in the optical
switch using the attraction between such a magnet and an electromagnet, the number of parts is
increased because it is necessary to attach a magnetic body to the mirror and attach the mirror
to the substrate through a deformable support. As the number increases, the structure becomes
complicated and the manufacturing process also becomes complicated. Therefore, as a magnetic
force type optical switch which can be easily manufactured with a simpler structure, a thin film
(magnetostrictive thin film) made of a magnetostrictive material is formed on a substrate having
bending elasticity and flexibility. There is known an optical switch using a piece (magnetostrictive
piece) (see, for example, Non-Patent Document 1). In this optical switch, light from the optical
fiber for incidence is reflected by a mirror formed on the surface of the magnetostrictive piece.
When no magnetic field is applied to the magnetostrictive element, light is incident on the mirror
at a predetermined angle, and the light reflected by the mirror surface is guided to the first
outgoing optical fiber. On the other hand, in the state where a magnetic field is applied to the
magnetostrictive piece, deflection occurs in the magnetostrictive piece. Thus, the light is incident
on the mirror surface at an angle different from the predetermined angle when no magnetic field
is applied, and the light reflected by the mirror surface is disposed at a position different from
the first emission optical fiber It is led to the second outgoing optical fiber.
Thus, light switching can be performed by switching the value of the applied magnetic field to
control the deflection amount of the magnetostrictive element. [Patent Document 1] JP-A-2000162520 (pages 1-5) [Non-Patent Document 1] S. Moon, S. H. By Lim et al., "Optical Switch Driven
by Giant Magnetostrictive Thin Films" Part of the Symposium on Design, Test, and
Microfabrication of MEMS and MOEMS Paris, France) (March-April, 1999) (Pages 854-862)
However, in the magnetostrictive element used for this optical switch, the thickness of the
substrate is magnetostrictive. If the thickness of the magnetostrictive piece is too large compared
to the thickness of the thin film, the amount of deflection of the magnetostrictive piece becomes
small. In order to increase the deflection of the magnetostrictive piece, it is desirable to make the
thickness of the substrate approximately the same as the thickness of the magnetostrictive thin
film, but when the thickness of the substrate is reduced, the substrate becomes difficult to
handle. For example, in the case of a thin substrate made of a brittle material such as glass or
silicon, the substrate may be cracked when the substrate is placed on a holder of a film forming
apparatus using tweezers or the like. On the other hand, when a metal is used as a thin substrate,
plastic deformation may occur when the substrate is placed in a holder of a film forming
apparatus. In addition, there are limitations on the type of material of the substrate that can be
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placed in a film forming apparatus such as a sputtering apparatus. Therefore, it is an object of
the present invention to prevent damage or deformation of the substrate of a magnetostrictive
element in a magnetostrictive actuator using a change in deflection of the magnetostrictive
element and an optical switch using the magnetostrictive actuator, and A magnetostrictive
actuator and an optical switch comprising a thin substrate and a magnetostrictive piece.
According to a first aspect of the present invention, a substrate formed of an amorphous metal
material, and a thin film formed of a magnetostrictive material on the substrate There is provided
a magnetostrictive actuator comprising: a segment comprising: and magnetic field applying
means for applying a magnetic field to the segment. In the magnetostrictive actuator of the
present invention, by applying a magnetic field to a thin film (magnetostrictive thin film) made of
a magnetostrictive material using a magnetic field application means, the magnetostrictive thin
film expands or contracts to form a magnetostrictive element piece The magnetostrictive element
is bent by the generated displacement stress.
The operation of the magnetostrictive actuator is performed using the deflection of the
magnetostrictive piece. In the magnetostrictive actuator according to the present invention, since
the amorphous metal material is used as the substrate, plastic deformation which easily occurs in
the case of a crystalline metal material can be prevented, and the original magnetostrictive
element is not bent. It can be returned to the state. Thereby, good operation control of the
magnetostrictive actuator can be performed. In the magnetostrictive actuator of the present
invention, the amorphous metal material is preferably an alloy containing a rare earth element
and a transition metal element. The magnetostrictive material is preferably an amorphous alloy
containing a rare earth element and a transition metal element. Similar to the substrate, plastic
deformation of the magnetostrictive thin film can be prevented by using an amorphous alloy as
the magnetostrictive material. In the magnetostrictive actuator of the present invention, it is
desirable that the thermal expansion coefficient of the substrate and the thermal expansion
coefficient of the thin film be substantially the same. This makes it possible to prevent the
occurrence of unintended deflection of the magnetostrictive piece that may occur due to changes
in the environmental temperature of the magnetostrictive actuator. Further, it is desirable that
the thickness of the substrate and the thickness of the thin film be substantially the same.
Thereby, the magnetostrictive piece can be bent most greatly. In this case, the thickness is
desirably 2 to 3 μm. In the present specification, "the thickness of the above-mentioned
substrate and the above-mentioned thin film is substantially the same" means that the thickness
of the substrate with respect to the thickness of the thin film is about 80 to 125%. In the
magnetostrictive actuator of the present invention, an intermediate layer made of an oxide or a
nitride may be formed between the substrate and the thin film. Thereby, when the base and the
thin film are both formed of an alloy containing a rare earth element and a transition metal
element, it is possible to prevent the diffusion of material components generated between the
base material and the thin film material. Moreover, the alloy containing the rare earth element
and the transition metal element may be formed of a magnetostrictive material having a polarity
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opposite to the magnetostriction constant of the magnetostrictive material forming the thin film.
When a magnetic field is applied to such a magnetostrictive element, the substrate shrinks at the
same time as the thin film stretches, or the substrate stretches at the same time as the thin film
shrinks. As a result, the displacement stress between the substrate and the magnetostrictive thin
film is further increased, and the deflection amount of the magnetostrictive piece can be
increased. According to a second aspect of the present invention, there is provided an optical
switch comprising: a magnetostrictive actuator according to the first aspect; a light incidence
portion for causing light to enter the optical switch; and light from the light incidence portion. A
first light emitting portion and a second light emitting portion selectively emitting light from the
switch; a mirror formed on the segment; and a magnetic field applied to the segment from the
light incident portion The light switch is directed to the first light emitting portion, and is
directed to the second light emitting portion through the mirror when no magnetic field is
applied.
In the optical switch according to the present invention, when a magnetic field is applied to the
segment, the magnetostrictive thin film constituting the segment expands or contracts to
generate a displacement stress with the base constituting the segment, The element piece bends
to either the substrate side or the magnetostrictive thin film side. At this time, the light from the
light incident part is irradiated toward the first light emitting part without being blocked by the
segment. On the other hand, when the magnetic field is not applied to the segment, the segment
is not bent. At this time, the light is blocked by the segment, the mirror provided on the segment
is displaced in the optical path of the light from the light incident portion, and the mirror reflects
the light and guides it to the second emission portion. Thereby, switching of an optical switch can
be performed correctly. In the optical switch according to the present invention, it is desirable
that at least one of the light incident part and the light exit part be an optical fiber with a lens.
Further, it is preferable that the magnetic field applying means be constituted by a core partially
including a hard magnetic material, a coil provided around the core, and a power supply.
Furthermore, the hard magnetic body may be made of hard magnetic bodies having different
coercivities. As a result, even when the application of the magnetic field is stopped immediately
after the application of the magnetic field to the core using the magnetic field application means,
the magnetic field continues to be generated in the core, so the bent state of the magnetostrictive
piece is maintained as it is. According to a third aspect of the present invention, there is provided
a method of manufacturing a magnetostrictive actuator according to the first aspect, comprising:
forming a release layer on a support substrate; and forming a substrate on the release layer.
Forming a magnetostrictive layer of a magnetostrictive material on the base, and peeling the
support substrate together with the release layer from the base on which the magnetostrictive
layer is formed; Providing a magnetic field application means for applying a magnetic field to the
magnetic field. A magnetostrictive actuator according to the first aspect of the present invention
can be manufactured using the method of manufacturing a magnetostrictive actuator of the
present invention. In the method of manufacturing the magnetostrictive actuator according to the
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present invention, since the supporting substrate for film formation is used separately from the
substrate of the magnetostrictive element, the handling at the time of manufacturing the
magnetostrictive film is easy. Can be prevented. On the other hand, since the thickness and
strength at the time of manufacture required for the substrate constituting the magnetostrictive
element are relaxed, the range of selection of the substrate material can be expanded. As a result,
it is possible to select a base material and a magnetostrictive thin film material having
substantially the same thermal expansion coefficient so as to improve the thermal stability of the
magnetostrictive piece.
Also, the substrate in the magnetostrictive piece can be made extremely thin. In the method of
manufacturing a magnetostrictive actuator according to the present invention, it is desirable that
the support substrate be formed of glass. Moreover, it is desirable that the said peeling layer is
formed with the resist. In the method of manufacturing a magnetostrictive actuator according to
the present invention, it is desirable to form an underlayer made of an oxide or a nitride between
the release layer and the base. Further, it is desirable to form a protective layer made of oxide or
nitride on the magnetostrictive layer. Furthermore, an intermediate layer of oxide or nitride may
be formed between the substrate and the magnetostrictive layer. This can prevent mutual
diffusion of material components between the base and the magnetostrictive layer, which can
occur when both the base and the magnetostrictive layer are formed of an alloy containing a rare
earth element and a transition metal element. According to a fourth aspect of the present
invention, there is provided a method of manufacturing a magnetostrictive actuator according to
the first aspect, comprising: forming an underlayer made of an oxide or a nitride on a supporting
substrate made of an organic material Forming a substrate on the underlayer; forming a
magnetostrictive layer of magnetostrictive material on the substrate; forming a protective layer
of oxide or nitride on the magnetostrictive layer; Preparing the piece by dissolving and removing
the support substrate from the base layer, the magnetostrictive layer and the protective layer
formed thereon; providing a magnetic field application means for applying a magnetic field to the
piece; A method of manufacturing a magnetostrictive actuator is provided. The magnetostrictive
actuator according to the first aspect of the present invention can be manufactured by using the
method of manufacturing the magnetostrictive actuator of the present invention. BEST MODE
FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described
with reference to the drawings, but the present invention is not limited thereto. Embodiment 1 A
magnetostrictive actuator according to an embodiment of the present invention will be described
with reference to FIGS. 1 (a) and 1 (b) are schematic views of the magnetostrictive actuator 100
of the present invention, and FIG. 1 (a) is a schematic view of a state in which the
magnetostrictive element 10 constituting the magnetostrictive actuator 100 is not bent. Each
shows the state in which the magnetostrictive piece 10 is bent. The details of the operation of the
magnetostrictive actuator 100 according to this embodiment will be described later. [Method of
Producing Magnetostrictive Element] Next, a method of producing a magnetostrictive element
used for the magnetostrictive actuator of the present invention will be described with reference
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to FIGS.
As shown in FIG. 2, the magnetostrictive piece 10 is composed of a base 1, a magnetostrictive
material layer 3, a protective layer 5 and a protective layer 7. The magnetostrictive piece 10 was
produced by the following method. As shown in FIG. 3A, a glass substrate having a diameter of
63 mm and a thickness of 0.6 mm was prepared as a supporting substrate (substrate for film
formation) 12. Next, a resist was formed as a peeling layer 14 on one surface of the support
substrate 12 using a spin coating method so as to have a thickness of 100 μm. Next, SiO 2 was
formed on the release layer 14 to have a thickness of 10 nm as the base layer 15. Next, a
terbium-iron amorphous alloy was formed on the underlayer 15 as a substrate 11 so as to have a
thickness of 3 μm. Next, a samarium-iron amorphous alloy, which is a magnetostrictive material,
was formed as the magnetostrictive material layer 13 on the substrate 11 to a thickness of 3
μm. Furthermore, on the magnetostrictive material layer 13, SiO 2 was formed as a protective
layer 17 so as to have a thickness of 10 nm. The underlayer 15, the substrate 11, the
magnetostrictive material layer 13, and the protective layer 17 were all formed by sputtering.
The thermal expansion coefficient of the samarium-iron amorphous alloy used for the
magnetostrictive material layer 13 was substantially the same as the thermal expansion
coefficient of the terbium-iron amorphous alloy used for the substrate 11. Thereby, the
unintended bending of the magnetostrictive element piece 10 resulting from the change of the
environmental temperature of the magnetostrictive element piece 10 is prevented. Next, the
support substrate 12 on which each layer is formed is diced into a flat plate having a length of
10 mm and a width of 0.8 mm, and then the peeling layer 14 is formed by oxygen plasma in an
ashing apparatus (not shown). Performed the resist ashing. By this ashing, the adhesive force of
the resist bonding the support substrate 12 and the base layer 15 disappears, so the support
substrate 12 is peeled off from the base layer 15 together with the peeling layer 14. Thus, a
magnetostrictive piece 10 as shown in FIG. 3B was obtained. The underlayer 15 formed on the
peeling layer 14 functions as the protective layer 5 of the base 1 in the magnetostrictive element
piece 10. Further, the protective layer 17 functions as the protective layer 7 of the
magnetostrictive material layer 3 in the magnetostrictive element piece 10. In the present
embodiment, the protective layers 5 and 7 are formed using SiO 2, but may be formed of an
oxide or nitride other than SiO 2. [Method of Manufacturing Magnetostrictive Actuator] Next, a
magnetostrictive actuator manufactured using the magnetostrictive piece 10 obtained in this
manner will be described with reference to FIGS. As shown in FIG. 1A, the magnetostrictive
actuator 100 mainly includes a magnetic core 101, a coil 103, a magnetostrictive piece 10, and a
power supply (not shown).
As shown in FIGS. 4 (a) and 4 (b), the magnetic core 101 has a width (length in the Y direction)
d1 = 15 mm, a length (length in the X direction in the drawing) d2 = 10 mm and A through hole
102 having a height (length in the Z direction in the figure) d 3 = 10 mm is formed in the
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magnetic core 101, and a through hole 102 penetrating in the X direction is formed inside the
magnetic core 101. The magnetic core 101 is divided into the top surface portion 101a and the
bottom surface portion 101b in the Z direction by the through holes 102, as shown in FIG. 4 (b).
Furthermore, a gap 108 extending in the X direction is formed at the center in the Y direction on
the top surface 101a of the magnetic core 101, and the gap 108 divides the top surface 101a
into a right top surface 101ar and a left top surface 101al. . The gap 108 is in communication
with the through hole 102. The width of the through hole 102 and the width (gap width) of the
gap 108 are 10 mm and 1.2 mm, respectively. The magnetic core 101 is made of a soft magnetic
material made of ferrite. The soft magnetic material of the magnetic core 101 has a coercive
force of 0.2 [Oe]. The magnetic core 101 was manufactured by pressure molding a soft magnetic
material made of ferrite so as to have a desired shape. As shown in FIG. 1A, on the bottom (100b)
of the magnetic core 101, a coil 103 made of enameled wire having a diameter of 0.3 mm is
circulated about 200 times in the X and Z directions. It is provided. A power supply (not shown)
is connected to both ends of the coil 103 to supply power to the coil 103. The magnetostrictive
element piece 10 extends in the X direction in the gap (108) and is disposed such that the
surface of the magnetostrictive element piece 10 is parallel to the surface of the upper surface
portion (101a) of the magnetic core 101. Here, as shown in FIG. 1A, with one end of the
magnetostrictive piece 10 as a fixed end, the magnetostrictive piece 10 is fixed to the support
piece 105 held at the end of the gap (108) with an adhesive or the like. The free end was not
supported at the other end. The magnetostrictive element piece 10 is disposed in the gap such
that the substrate side of the magnetostrictive element piece 10 faces the coil 103 side. [Driving
Method of Magnetostrictive Actuator] Next, the driving principle of the magnetostrictive actuator
100 will be described with reference to FIG. As shown in FIG. 1B, the magnetic core 101
generates a magnetic field by supplying power to the coil 103 by a power supply (not shown). At
this time, a magnetic field is generated in the width direction (Y direction) of the magnetostrictive
piece 10 in the gap of the magnetic core 101. Thereby, the magnetostrictive material layer made
of samarium-iron alloy having a negative magnetostriction constant in the magnetostrictive piece
10 disposed in the gap is contracted in the direction of the generated magnetic field, and as a
result, in the direction orthogonal to the generated magnetic field It extends in the longitudinal
direction (X direction) of a certain piece.
The expansion of the magnetostrictive material layer causes a displacement stress between the
magnetostrictive material layer of the magnetostrictive element piece 10 and the base, and the
magnetostrictive element piece 10 is indicated by an arrow AR1 with the fixed end fixed by the
support piece 105 as a fulcrum. Thus, the coil 103 bends toward the coil 103 side, that is,
downward. Thereby, the amount of displacement necessary for the operation of the
magnetostrictive actuator is obtained. Next, a specific driving method of the magnetostrictive
actuator in the present embodiment will be described. As shown in FIG. 1A, in the
magnetostrictive actuator 100, the magnetostrictive piece 10 does not bend in a state in which
no current flows through the coil 103, that is, in a state in which no magnetic field is applied to
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the magnetic core 101. On the other hand, a current of 120 mA was passed through the coil 103
to generate a magnetic field H1 = 450 [Oe] in the gap portion of the magnetic core 101. As a
result, as shown in FIG. 1B, the magnetostrictive element piece 10 bends in the direction of the
arrow AR1. The amount of deflection of the magnetostrictive element piece 10 is saturated by
the magnetic field generated in the magnetic core 101. As described above, by repeating ON /
OFF of the power supply to the coil 103, operation of the magnetostrictive actuator becomes
possible. Comparative Example 1 Here, the relationship between the thickness of the substrate of
the magnetostrictive element and the thickness of the magnetostrictive material layer will be
described with reference to FIG. FIG. 11 shows the change in the amount of deflection of the
magnetostrictive piece when the thickness of the magnetostrictive material layer of the
magnetostrictive piece is 4 μm and the thickness of the base is variously changed. As apparent
from FIG. 11, when the thickness of the substrate is 4 μm, which is equal to the thickness of the
magnetostrictive material layer, the maximum amount of deflection of the magnetostrictive piece
can be obtained. In addition, by forming the magnetostrictive piece so that the thickness of the
substrate is 3.2 μm to 5.0 μm, that is, the thickness of the substrate to the thickness of the
magnetostrictive material layer is about 80 to 125%, 650 μm or more Can be obtained.
[Comparative Example 2] FIG. 12 shows the result of comparison of the amount of deflection of
the magnetostrictive piece in the above embodiment and the conventional magnetostrictive piece
in which the magnetostrictive material layer is formed on the glass substrate. The vertical axis of
the graph shown in FIG. 12 represents the amount of deflection of the magnetostrictive element,
and the horizontal axis represents the value of the magnetic field applied to the magnetostrictive
actuator. The conventional magnetostrictive piece used for comparison uses the glass with a
thickness of 15 μm as the substrate, and does not provide the protective layer on the surface of
the substrate opposite to the surface on which the magnetostrictive material layer is formed. The
configuration is the same as the magnetostrictive piece in the example. As apparent from FIG. 12,
in the magnetostrictive actuator according to the present invention, the thickness of the
substrate of the magnetostrictive element can be formed as thin as the magnetostrictive material
layer, and a large amount of deflection can be obtained. As compared with the piece, a
predetermined amount of deflection can be obtained with a smaller applied magnetic field.
Embodiment 2 Another embodiment of the magnetostrictive piece used for the magnetostrictive
actuator of the present invention will be described with reference to FIG. The magnetostrictive
piece in the present invention was configured in the same manner as in Example 1 except that an
intermediate layer 29 was provided between the base 21 and the magnetostrictive material layer
23 as shown in FIG. 5 (a). When the substrate and the magnetostrictive material layer are each
formed of an alloy of a rare earth element and a transition metal element, mutual diffusion of
material components may occur in the vicinity of the interface between the substrate and the
magnetostrictive material layer during sputtering film formation. This is due to the fact that the
materials used for the base and the magnetostrictive material layer are both alloys of a rare earth
element and a transition metal element, and the compositions are similar. In the present
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embodiment, in order to prevent the mutual diffusion of material components in the vicinity of
the interface between the base and the magnetostrictive material layer as described above, the
intermediate layer 29 made of SiO 2 is formed between the base 21 and the magnetostrictive
material layer 23. . Below, the manufacturing method of the magnetostriction piece in a present
Example is demonstrated. As shown in FIG. 5B, the peeling layer 34, the underlayer 35, and the
base 31 made of a terbium-iron amorphous alloy are formed on the supporting substrate 32 by
sputtering in the same manner as in the first embodiment. Then, an intermediate layer 39 made
of SiO 2 was formed on the substrate 31 by sputtering so as to have a thickness of 10 nm. Next, a
magnetostrictive material layer 33 made of a samarium-iron amorphous alloy is formed on the
intermediate layer 39 by sputtering so as to have a thickness of 3 μm, and further on the
magnetostrictive material layer 33 in the same manner as in Example 1. , And the protective
layer 37 was formed. After ashing the support substrate 32 on which each layer is formed, the
support substrate 32 is removed together with the peeling layer 34 to obtain a magnetostrictive
piece 20 as shown in FIG. 5A. A magnetostrictive actuator as shown in FIGS. 1A and 1B can be
configured using the magnetostrictive piece 20 obtained in this manner. In the present
embodiment, although the intermediate layer 39 is formed using SiO 2, it may be formed of an
oxide or nitride other than SiO 2. Third Embodiment Next, an optical switch using a
magnetostrictive actuator according to the present invention will be described with reference to
FIGS. The magnetostrictive actuator used for the optical switch of the present invention is the
same as the magnetostrictive actuator of the first embodiment. 6 (a) and 6 (b) are schematic
views of the optical switch 200 according to the present invention, and FIG. 6 (a) shows that the
magnetostrictive piece 50 constituting the optical switch 200 is not bent and The light emitted
from the lens-mounted optical fiber 202 is a lens serving as a second light emitting portion
disposed at a position different from the optical fiber 204 described later via the mirror 52
formed on the magnetostrictive piece 50. The incident light is shown incident on the attached
optical fiber 206.
On the other hand, in FIG. 6B, the magnetostrictive piece 50 is in a bent state, and the light
emitted from the optical fiber 202 becomes a first light emitting portion disposed at a position
facing the optical fiber 202. The direct incidence on the lensed optical fiber 204 is shown. In the
magnetostrictive element piece 50, as shown in FIG. 7, a mirror 52 is formed in the vicinity of an
end portion on a protective layer 57 formed on the magnetostrictive material layer 53. The
mirror 52 was formed by sputtering using gold so as to have a thickness of 100 nm. In addition,
the surface shape of the mirror 52 was formed to be a square of 0.5 mm × 0.5 mm. In the
present embodiment, as shown in FIG. 6, the magnetostrictive piece 50 is disposed in the gap of
the magnetic core 201 so that the mirror 52 is disposed on the free end side of the
magnetostrictive piece 50. Next, the arrangement of the lensed optical fiber 202 for incidence
and the lensed optical fibers 204 and 206 for emission will be described. The lensed optical fiber
202 for incidence and the lensed optical fibers 204 and 206 for emission are optical fibers each
having a condensing lens installed at its tip, and used a single mode compatible wavelength of
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1.5 μm. . As shown in FIG. 8A, when the magnetostrictive element piece 50 is not bent, the
optical fiber with lens for emission 206 is irradiated from the incident optical fiber 202 and a
mirror formed on the magnetostrictive element piece 50. It is disposed at a position where the
light reflected by the surface 52 is incident. On the other hand, as shown in FIG. 8B, when the
magnetostrictive element piece 50 is bent, the light with lens optical fiber 204 for emission is
directly irradiated with the light irradiated from the optical fiber 202 with lens for incidence, as
shown in FIG. It is disposed at a position where light is incident, that is, at a position facing the
optical fiber 202. A specific switching method of the optical switch in the present invention will
be described with reference to FIG. As shown in FIG. 6A, in the state where no current flows
through the coil 203, that is, in the state where no magnetic field is applied to the magnetic core
201, the magnetostrictive element 50 does not bend and the optical switch 200 does not bend.
The light emitted from the optical fiber 202 is incident on the surface of the mirror 52 on the
magnetostrictive piece 50, is reflected by the mirror 52, and then is incident on the optical fiber
206. On the other hand, by flowing a current of 120 mA through the coil 203 to generate a
magnetic field H1 = 450 [Oe] in the gap portion of the magnetic core 201, as shown in FIG. Bend
in the direction of AR2. As described above, the deflection amount of the magnetostrictive
element piece 50 is in a saturated state.
When the magnetostrictive element piece 50 is bent, the light emitted from the optical fiber 202
for incidence is directly incident on the optical fiber 204 for emission without being blocked by
the magnetostrictive element 50. As described above, by turning on / off the power supply to the
coil 203, it is possible to switch the optical path. Thereby, optical switching is realized.
Embodiment 4 An optical switch using a magnetostrictive actuator according to another
embodiment of the present invention will be described with reference to FIGS. 9 and 10. FIG. FIG.
9 shows an optical switch 300 in the present embodiment, and FIG. 10 shows a magnetic core
301 used for the optical switch 300. In the optical switch according to this embodiment, the
coercive force is set so that the soft magnetic portion is divided at the center in the Y direction of
the bottom portion of the magnetic core, that is, the hard magnetic portion faces the gap. The
configuration was the same as that of Example 3 except that a hard magnetic portion made of
two different types of hard magnetic materials (ferrite) was formed. As shown in FIG. 10A, the
hard magnetic portion of the magnetic core is composed of the first hard magnetic portion 305
and the second hard magnetic portion 307, and the first hard magnetic portion 305 is the second
one. The first hard magnetic material portion 305 is disposed to overlap the hard magnetic
material portion 307, that is, on the gap 308 side of the magnetic core 301. The thickness
(height) of each of the first hard magnetic material portion 305 and the second hard magnetic
material portion 307 was 2.5 mm. The coercivity of the first hard magnetic material part 305 has
80 [Oe], and the coercivity of the second hard magnetic material part 307 has 2500 [Oe]. The
magnetic core 301 was manufactured as follows. The soft magnetic body portion 309, the first
hard magnetic body portion 305, and the second hard magnetic body portion 307 were
respectively pressure-formed into desired shapes in advance. Next, the first hard magnetic
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material portion 305 and the second hard magnetic material portion 307 are fixed with an
adhesive, and the first hard magnetic material portion 305 and the second hard magnetic
material portion 307 fixed are bonded to the soft magnetic material portion 309. It fixed by the
agent. Next, the magnetic properties of the magnetic core 301 will be described with reference to
FIGS. 10 (b) to 10 (d). A current of 150 mA is passed through the coil to generate an external
magnetic field H1 '= 90 [Oe] which is a magnetic field between the coercivity of the first hard
magnetic material part 305 and the coercivity of the second hard magnetic material part 307.
Since the external magnetic field H1 'exceeds the coercivity of the first hard magnetic material
portion 305, the first hard magnetic material portion 305 is magnetized in the direction aligned
with the external magnetic field H1'. The second hard magnetic material portion 307 is assumed
to be magnetized in the direction of the external magnetic field H1 'in advance.
Here, even if the external magnetic field H1 ′ is dissipated, as shown in FIG. 10C, since the first
and second hard magnetic material portions 305, 307 have magnetic hysteresis, the residual
magnetizations AR5a, AR7 remain. (Refer to the residual magnetic field Ms ′ in the hysteresis
curve of the first hard magnetic material portion shown in FIG. 10 (b)). The composite
magnetization AR 3 of these residual magnetizations maintains the state in which the magnetic
field is generated in the gap 308 of the magnetic core 301. On the other hand, when a current of
150 mA is applied in the reverse direction to the above and the magnetic field H2 ′ = − 90 [Oe]
(ie, H2 ′ = − H1 ′) is applied, the magnetic field H2 ′ is the first hard magnetic material
portion 305 The magnetization of the first hard magnetic material portion 305 is reversed as
shown in FIG. On the other hand, since the coercive force of the second hard magnetic material
portion 307 is larger than the external magnetic field H2 ', the direction of magnetization of the
second hard magnetic material portion 307 does not change as shown in FIG. Here, when the
external magnetic field H2 'is dissipated, residual magnetizations AR5b and AR7 remain on the
first and second hard magnetic material portions 305 and 307, respectively. In the first and
second hard magnetic material portions 305 and 307, if the magnitudes of the residual
magnetizations AR5b and AR7 are adjusted in advance so as to be approximately equal to each
other, they are opposite to each other. The overall magnetization is nearly zero. Thereby, the
magnetic field generated in the magnetic core 301 by the hard magnetic material disappears. An
optical switch 300 as shown in FIG. 9 can be manufactured using this magnetic core 301 in the
same manner as in the third embodiment. In the optical switch 300 according to the present
embodiment, even if the coil 303 is supplied with current for a predetermined time (for example,
10 ms) after the current is supplied to the coil 303, the magnetic field continues to be the
magnetic field 301 (308). Condition is maintained. Thereby, as shown in FIG. 9, the bending state
of the magnetostrictive piece 50 disposed in the gap of the magnetic core 301 is also maintained.
On the other hand, the magnetic field generated in the magnetic core 301 disappears by
supplying a current in the opposite direction to the above to the coil 303 for a predetermined
time (for example, 10 ms). As a result, the magnetostrictive element piece 50 returns to the
original state in which it does not bend. As described above, in the optical switch according to the
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present embodiment, the power supply may be performed only when switching the bending state
of the magnetostrictive element 50, that is, only when the light switching is performed. The state
of bending is maintained and it can be said that the state of self-holding is maintained.
Moreover, the optical switch of the present embodiment can switch the state of the optical switch
only by switching the polarity (± H1 ') of the external magnetic field having the same magnitude.
In the present embodiment, the first hard magnetic material portion and the second hard
magnetic material portion are fixed using an adhesive, but the first hard magnetic material
portion is bonded onto the second hard magnetic material portion. The soft magnetic material 51
may be fixed to the side surface thereof with an adhesive without using any agent. Moreover, in
this embodiment, two types of hard magnetic materials having different coercivity are formed to
have the same thickness, but the thickness of the hard magnetic material part having high
coercivity is the thickness of the hard magnetic material part having low coercivity. The first and
second hard magnetic material portions may be shaped so as to be smaller than the other.
Thereby, the applied magnetic field for offsetting the magnetization of the hard magnetic
material portion can be reduced. Furthermore, a hard magnetic material portion is formed of one
kind of hard magnetic material, and a magnetic field is applied to offset the magnetization of the
soft magnetic material of the magnetic core with the magnetization of the hard magnetic material
to make it zero. A magnetic core having a self-holding function similar to that of the above can be
obtained. In the above embodiment, a glass substrate is used as a supporting substrate, and the
peeling layer made of resist provided on the glass substrate is ashed to remove the glass
substrate together with the peeling layer to produce a magnetostrictive piece. Even if the support
substrate is formed using an organic substance such as epoxy resin, and the support substrate on
which each layer is formed is immersed in a solvent such as acetone for a long time to dissolve
and remove the support substrate, a magnetostrictive piece is produced. Good. In the above
embodiment, the substrate of the magnetostrictive piece is formed using the terbium-iron
amorphous alloy, but is formed using the gadolinium-iron amorphous alloy, the neodymium-iron
amorphous alloy, etc. It is also good. In addition, although the magnetostrictive material layer
was formed using a samarium-iron amorphous alloy having a negative magnetostriction constant,
the erbium-iron alloy, thulium-iron alloy, samarium-iron-cobalt alloy, samarium-erbium-iron
alloy, It may be formed using samarium-thulium-iron alloy or the like. Also, terbium-iron alloys,
holmium-iron alloys, terbium-nickel alloys, terbium-cobalt alloys, terbium-iron alloys (for
example, Tb-Co-Fe, Tb-Ni-Fe), terbium having positive magnetostriction constant. The
magnetostrictive material layer can also be formed using a nickel-based alloy (for example, TbCo-Ni), dysprosium-iron alloy, gadolinium-iron alloy, terbium-dysprosium-iron alloy, and the like.
In the case of a magnetostrictive piece using a magnetostrictive material having a positive
magnetostriction constant in the magnetostrictive material layer, the magnetostrictive material
layer of the magnetostrictive piece is the inner side of the magnetic core (coil side) in order to
make the deflection direction of the magnetostrictive piece constant. It is arranged to face.
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In the present invention, when a substrate is formed using a magnetostrictive material, it is
desirable to form the substrate using a magnetostrictive material as described above, which has a
polarity different from that of the magnetostrictive material used for the magnetostrictive
material layer. In addition, it is desirable to select materials that have substantially the same
thermal expansion coefficient for the formation of the substrate and the magnetostrictive
material layer. In the above embodiment, the soft magnetic material portion and the hard
magnetic material portion used for the magnetic core are manufactured using ferrites having
different coercivity. However, iron-boron-silicon amorphous alloy, samarium-cobalt hard alloy are
used. You may produce using a magnetic body etc. In the optical switch in the above
embodiment, the light is directly incident on the optical fiber 204 from the optical fiber 202.
However, in order to make the optical switch compact by changing the position of the optical
fiber 204, the reflecting member is appropriately used The light may be incident on the optical
fiber 204 with the The position of the optical fiber 206 may be similarly changed, and the light
from the optical fiber 202 may be made incident on the optical fiber 206 by interposing a
reflecting member as appropriate. Furthermore, when a magnetic field is applied to the
magnetostrictive element by arranging the magnetostrictive element so that the front and back of
the magnetostrictive element are opposite, or by using a magnetostrictive material having
opposite magnetostrictive constants for the magnetostrictive film of the magnetostrictive
element, The light may be reflected by a mirror on the element piece, and the light path may not
be blocked when the magnetic field is not applied. According to the magnetostrictive actuator of
the present invention, since the substrate can be formed thin while preventing damage and
plastic deformation of the substrate in producing the magnetostrictive piece, the large piece can
be obtained with a small applied magnetic field. The amount of deflection can be obtained.
Thereby, a magnetostrictive actuator with reduced power consumption can be manufactured
with high yield. In addition, it is possible to manufacture an optical switch that efficiently
switches light such as 1 × 2 channel by using this magnetostrictive actuator. BRIEF
DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration view of a magnetostrictive
actuator in Example 1 of the present invention. FIG. 2 is a schematic configuration view of a
magnetostrictive piece in Example 1; 3 is a view showing a method of manufacturing a
magnetostrictive piece in Example 1. FIG. FIG. 4 is a schematic view of a magnetic core used for
the magnetostrictive actuator in Example 1; FIG. 5 is a view showing a method of manufacturing
a magnetostrictive piece in Example 2 of the present invention. FIG. 6 is a schematic view of an
optical switch according to a third embodiment of the present invention. FIG. 7 is a schematic
view of a magnetostrictive element of the optical switch of Example 3;
FIG. 8 is a diagram for explaining how an optical switch is switched in the third embodiment; FIG.
9 is a schematic view of an optical switch according to a fourth embodiment of the present
invention. FIG. 10 is a diagram for explaining a self-holding function in the optical switch of the
fourth embodiment. 11 is a graph showing the relationship between the thickness of the
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magnetostrictive element substrate in Comparative Example 1 and the amount of deflection of
the magnetostrictive element. FIG. 12 is a graph showing a comparison result of the amount of
deflection of the magnetostrictive piece manufactured in Example 1 and the amount of deflection
of the conventional magnetostrictive piece in Comparative Example 2. FIG. [Explanation of the
code] 1, 21, 51 substrate 3, 23, 53 magnetostrictive material layer 5, 7, 25, 27, 55, 57 protective
layer 10, 20, 50 magnetostrictive piece 12, 32 supporting substrate 14, 34 peeling layer 52
Mirror 100 Magnetostrictive actuator 101, 201, 301 Magnetic core 103, 203, 303 Coil 105, 205
Support piece 108 Gap 200, 300 Optical switch 202, 302 Optical fiber with lens for incidence
204, 304, 206, 306 With lens for emission Optical fiber 305 First hard magnetic body portion
307 Second hard magnetic body portion 309 Soft magnetic body portion
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