JP5782334B2 - Spatial light modulator and pixel driving method thereof - Google Patents

Description

  The present invention relates to a spatial light modulator that emits incident light by spatially modulating the phase and amplitude of the light by a magneto-optic effect.

  A spatial light modulator uses an optical element (light modulation element) as a pixel and arranges it two-dimensionally in a matrix to spatially modulate the phase and amplitude of light. Display technology and recording technology Widely used in such fields. Liquid crystal is conventionally used as a spatial light modulator, but in recent years, a magneto-optical spatial light modulator using a magneto-optical material, which is expected to be capable of high-speed processing and pixel miniaturization of 1 μm or less. Development is underway.

  In a magneto-optic spatial light modulator (hereinafter referred to as a spatial light modulator), when light incident on a magnetic material is transmitted or reflected, the direction of polarization is changed (rotation) and emitted (in the case of reflection) Uses the Kerr effect) and uses a magneto-optic material that is particularly effective among magnetic materials. For example, the magnetization direction of the light modulation element in the pixel to be displayed brightly (selected pixel) is different from the magnetization direction of the light modulation element in the other pixel (non-selected pixel), so that the light emitted from the selected pixel is not selected. Only the selected pixel is displayed brightly by causing a difference in the rotation angle (optical rotation angle) of the polarization of the light emitted from the pixel. As a method of changing the magnetization direction of such a light modulation element, in addition to a magnetic field application method in which a magnetic field is applied to the light modulation element, in recent years, a spin injection method in which spin is injected by supplying a current to the light modulation element ( For example, there is Patent Document 1).

  Specifically, the spin injection type light modulation element is a TMR (Tunnel MagnetoResistance) element or a CPP-GMR (Current Perpendicular to the Plane Giant MagnetoResistance) element. A spin-injection magnetization reversal element that is also applied to a magnetic random access memory (MRAM) can be applied. A spin-injection magnetization reversal element is a laminate consisting of at least two magnetic films with a nonmagnetic or insulating intermediate layer sandwiched between them, and a pair of electrodes are connected to the top and bottom to supply current perpendicular to the film surface. As a result, spin is injected and the magnetization direction of a part of the magnetic film (magnetization free layer) changes (inverts). As the element size (area) of the spin-injection magnetization reversal element is smaller, the magnetization is easily reversed with a smaller current, and the light modulation element to which such a spin-injection magnetization reversal element is applied is used to generate a magnetic field. Further miniaturization is possible as compared with a magnetic field application method including electrodes (wirings) along the outer periphery.

  Further, as another aspect of the light modulation element, the present inventors have developed a spatial light modulator that uses a magnetic material (magnetic wire) processed with fine wires as a light modulation element (Patent Document 2). This is because in magnetic thin wires, two or more magnetic domains are easily formed in the thin line direction, and the domain walls that delimit these magnetic domains move by supplying current to the magnetic thin line in the thin line direction. (See Non-Patent Documents 1 and 2). Specifically, as shown in FIG. 17, when one magnetic thin wire 101 is provided for each pixel 104 and current is supplied in the direction of the thin wire by a pair of electrodes 131 and 132 connected to both ends thereof, the direction of the current is opposite. The domain wall moves in the direction, and the magnetization direction in the region sandwiched between the positions before and after the domain wall movement is reversed. Therefore, the reflected light can be extracted with this region as the light incident region (opening region). In FIG. 17, in order to indicate the magnetization direction of the magnetic wire 101, a part of the electrode 132 is notched.

JP 2008-83686 A JP 2010-20114 A

T. Koyama et al., “Control of Domain Wall Position by Electrical Current in Structured Co / Ni Wire with Perpendicular Magnetic Anisotropy”, Appl. Phys. Express 1, 101303 (2008) Xin Jiang et al., “Enhanced stochasticity of domain wall motion in magnetic racetracks due to dynamic pinning”, Nature Communications, 1, pp.1-5 (2010)

  The spin-injection magnetization reversal element described in Patent Document 1 needs to control the film thickness of the magnetic film and the intermediate layer with an accuracy of 1 nm or less in order to obtain desired magnetic characteristics. A complicated structure such as a multilayer film is required, and there are many problems in production. In addition, since the spin injection magnetization reversal element is provided with electrode materials above and below, a transparent electrode material that transmits light must be applied to the light incident / exit side in order to enter and exit the light as the light modulation element. Don't be. Since the transparent electrode material is greatly inferior in conductivity as compared with the metal electrode material, there is a possibility that the operation is delayed in the central portion as the high-definition spatial light modulator has a larger number of light modulation elements arranged in a matrix. In order to operate such a spatial light modulator, it is necessary to supply a large current, and there is room for improvement in terms of power saving. Alternatively, if the cross-sectional area is increased by increasing the thickness of the electrode (wiring), the wiring resistance can be reduced. However, increasing the film thickness relative to the wiring width including the metal electrode material has manufacturing limitations. This is difficult with a finer pixel.

  On the other hand, the light modulation element described in Patent Document 2 has a simple structure composed of one magnetic wire 101 as shown in FIG. 17, but the magnetic wire 101 has a magnetization direction in the opening region with a domain wall interposed therebetween. Magnetic domains having different magnetization directions are formed. Therefore, the light that can be extracted as pixel information in the magnetic thin wire 101 is limited to the reflected light from the region sandwiched between the positions before and after the movement of the magnetic domain wall at the center, and the aperture ratio of the pixel 104 is limited, and there is room for improvement. is there.

  The present invention was devised in view of the above problems, and an object thereof is to provide a spatial light modulator including a pixel having a sufficient aperture ratio with a simple structure that facilitates production by applying a magnetic thin wire. .

  In order to solve the above-mentioned problems, the inventors of the present invention have proposed that the light modulation in one row of the spatial light modulator is performed because the moving speed of the domain wall in the magnetic wire is as high as about several tens m / s to 250 m / s. It was conceived that the element is composed of a single continuous magnetic wire, and the data of all the pixels in the row is rewritten one by one in order.

  The spatial light modulator according to the present invention includes a pixel array in which pixels are arranged in a matrix, and each of the pixels in the pixel array in any of two different magnetization directions based on binary data input to the pixel. And a pixel driving means. The pixel array includes a plurality of pixels arranged in a line, and is formed by arranging a plurality of magnetic thin wires made of a magnetic material formed in a thin line shape along the arrangement direction. The pixel area including the plurality of pixels and the writing area are provided at predetermined positions so as to be separated in a thin line direction. On the other hand, the pixel driving means connects the magnetic thin line to a predetermined magnetization direction in the writing region, and connects the magnetic thin line to both ends of the magnetic thin line so that the magnetic domain formed on the magnetic thin line Current supply means for supplying a pulse current that moves intermittently together with the partitioning domain wall, and a magnetization direction based on data of a predetermined pixel in the writing region when the current in the pulse current supplied to the magnetic wire is stopped Control means for controlling the writing means to control the current supply means so that the magnetic domain formed in the writing area reaches the predetermined pixel.

  With such a configuration, the spatial light modulator may be configured by configuring a pixel array arranged in a matrix with one magnetic thin line for each row and supplying a current at both ends thereof, and setting each magnetic thin line. Since it is sufficient that the written area has a magnetization direction based on the data, a simple structure can be obtained. In addition, since it is not necessary to directly connect the electrode for each pixel, and therefore there is no wiring for connecting from the outside to the region of the pixel array, the entire region of the magnetic thin wire becomes a light incident region in one pixel, and the aperture ratio Becomes higher.

  In the spatial light modulator according to the present invention, the writing means may apply a magnetic field to the magnetic wire. With such a configuration, the spatial light modulator can have a simple structure including the writing area, and a well-known writing method similar to that of a magnetic head such as a magnetic disk can be applied to write the magnetic thin line writing area. Can be in the desired magnetization direction.

  Alternatively, in the spatial light modulator according to the present invention, the magnetic thin wire has a spin-injection magnetization reversal element structure in a writing region, and the writing means is perpendicular to the film surface to the spin-injection magnetization reversal element structure of the magnetic thin wire. A current may be supplied in the direction. With such a configuration, even if the spatial light modulator is a fine pixel, the writing region can be set to a desired magnetization direction by high-speed spin injection magnetization reversal in parallel with respect to the plurality of magnetic thin wires.

  In the spatial light modulator according to the present invention, the pixel driving unit initializes at least one of the two magnetization directions from the at least the writing region of the magnetic wire to the end opposite to the side where the pixel region is provided. The writing means may be configured so that the magnetic wire is only the other of the two magnetization directions in the writing region. With this configuration, the writing unit only needs to be able to make the magnetization in one direction, so that the driving circuit can have a simple structure.

  Furthermore, in the spatial light modulator according to the present invention, it is preferable that the magnetic thin line is formed in a shape that is bound at one or more points on a boundary dividing the pixel in the thin line direction. Alternatively, it is preferable that the magnetic thin line is formed in a thin line shape bent at one or more points on the boundary dividing the pixel in the thin line direction.

  With this configuration, when the current in the pulse current is stopped, the magnetic wall reaches the constricted or bent portion of the magnetic thin wire and stops, so that the magnetic domain formed in the writing region reaches the set pixel in the magnetic thin wire. Thus, it is easy to move, and accurate display is possible.

  Furthermore, in the spatial light modulator according to the present invention, it is preferable that the pixel array includes a magnetic transfer film in contact with the magnetic thin line, and the light is incident on the magnetic thin line through the magnetic transfer film.

  With this configuration, the spatial light modulator includes a magnetic transfer film having a large Faraday effect in contact with the light incident side of the magnetic thin wire, so that the light incident on the pixel is incident upon passing through the magnetic transfer film. Light is emitted with a large rotation.

  Further, the pixel driving method of the spatial light modulator according to the present invention includes a plurality of pixels arranged in a line, and a plurality of magnetic thin wires made of a magnetic material formed in a thin line shape along the arrangement direction. In the spatial light modulator having a pixel array in which pixels are arranged in a matrix, each pixel of the pixel array is placed in one of two different magnetization directions based on binary data input to the pixel. It is a method to do. The method includes: a pixel selection step of selecting one pixel in the order in which the plurality of pixels provided in the magnetic thin line are arranged; and the magnetic thin line is partitioned from the region including the plurality of pixels in a thin line direction. In the writing area provided in advance, the writing process for setting the magnetization direction based on the data of the selected one pixel, and the magnetic domains formed in the magnetic thin line are connected to the plurality of pixels from the writing area. A magnetic domain moving step of moving a distance of one pixel length in the direction of the thin line toward the area to be provided, and sequentially magnetizing all the pixels provided in the magnetic thin line based on the data It is to make. Therefore, for each of the plurality of magnetic wires arranged in parallel, a pulse current in which the magnetic domains formed on the magnetic wires move intermittently together with the domain walls that delimit the magnetic domains is supplied to the magnetic wires in the direction of the thin wires. Thus, the pixel selection step and the writing step are performed when the current in the pulse current is stopped, and the magnetic domain movement step is performed when the current in the pulse current is supplied.

  With such a procedure, for a spatial light modulator in which a pixel array arranged in a matrix is composed of one magnetic thin line for each row, a pulse current is supplied to the magnetic thin line, and pixels are set one by one in the set writing area. By sequentially setting the magnetization direction based on the data, it is possible to make all the pixels have a desired magnetization direction without connecting wiring for each pixel.

  Further, in the pixel driving method of the spatial light modulator according to the present invention, before performing the writing step on the first of the arranged pixels, at least the side of the magnetic thin line opposite to the side where the pixel area is provided is provided. When an initialization process is performed to make one of the two magnetization directions up to the end of the side, and in each of the writing processes, the magnetization direction based on the data of one selected pixel is the same as the one magnetization direction May not change the magnetization direction of the magnetic wire.

  With this procedure, the initialization process is performed once, so that the write area of the magnetic thin wire only needs to be the other of the two magnetization directions in the writing process. The magnetic thin line pixel can be set to the magnetization direction based on the data without requiring much time.

  Furthermore, in the pixel driving method of the spatial light modulator according to the present invention, it is preferable that a common pulse current is supplied to two or more magnetic thin wires and each of the steps is performed in parallel.

  With this procedure, it is possible to reduce the time required for making all the pixels of the pixel array have a desired magnetization direction.

  The spatial light modulator according to the present invention can be a spatial light modulator that has a high aperture ratio of pixels and can be easily manufactured. Further, according to the pixel driving method of the spatial light modulator according to the present invention, a desired image can be displayed on the spatial light modulator.

It is a perspective view of the magnetic fine wire explaining the composition of the spatial light modulator concerning the present invention. It is a top view of the light modulation part of the spatial light modulator which concerns on 1st Embodiment. It is a schematic diagram explaining the structure of the display apparatus using the spatial light modulator which concerns on this invention, and is a figure corresponding to sectional drawing along the horizontal direction of FIG. It is sectional drawing in the thin wire | line direction of the magnetic fine wire for demonstrating the structure of the light modulation part of the spatial light modulator which concerns on 1st Embodiment, (a) is a schematic diagram at the time of the writing to an upward magnetization direction, ( b) is a schematic diagram during movement of a magnetic domain, and (c) is a schematic diagram during writing in a downward magnetization direction. It is a block diagram which shows the structure of the spatial light modulator which concerns on 1st Embodiment. In the spatial light modulator which concerns on this invention, it is a figure explaining the operation | movement which displays an image based on image data, (a) is an image, (b) is image data, (c) is pixel row data, (d ) Is a pixel array. 4 is a flowchart for explaining a pixel driving method in the spatial light modulator according to the first embodiment. 6 is a timing chart illustrating a pixel driving method in the spatial light modulator according to the first embodiment. It is a top view of the light modulation part of the spatial light modulator which concerns on the modification of 1st Embodiment. It is a block diagram which shows the structure of the spatial light modulator which concerns on 2nd Embodiment. It is a flowchart explaining the pixel drive method in the spatial light modulator which concerns on 2nd Embodiment. It is sectional drawing in the thin wire | line direction of the magnetic fine wire for demonstrating another structure of the light modulation part of the spatial light modulator which concerns on the modification of 2nd Embodiment, (a) is at the time of the writing to an upward magnetization direction FIG. 4B is a schematic diagram at the time of writing in the downward magnetization direction. It is sectional drawing in the fine wire direction of the magnetic fine wire for demonstrating the structure of the light modulation part of the spatial light modulator which concerns on 3rd Embodiment. It is sectional drawing in the fine wire direction of the magnetic fine wire for demonstrating the structure of the light modulation part of the spatial light modulator which concerns on 4th Embodiment, (a) is a schematic diagram at the time of initialization, (b) is upward magnetization. Schematic diagram at the time of writing in the direction, (c) shows a schematic diagram at the time of movement of the magnetic domain. It is a flowchart explaining the pixel drive method in the spatial light modulator which concerns on 4th Embodiment. It is a magnetic force microscope image photograph of the sample of the light modulation part of an Example, The width | variety of a magnetic fine wire is 150 nm, (b) is 250 nm, (c) is 500 nm. It is a plane schematic diagram which shows the structure of the spatial light modulator which applied the conventional magnetic thin wire | line to the pixel.

  Hereinafter, embodiments for realizing a spatial light modulator according to the present invention will be described with reference to the drawings. In the description with reference to the drawings in this specification, horizontal (horizontal) and vertical (vertical) refer to directions in a plan view.

[First Embodiment]
As shown in FIG. 1, the spatial light modulator 10 according to the first embodiment includes a stripe-shaped magnetic wire 1 extending in the horizontal direction and both ends of each magnetic wire 1 connected to the magnetic wire 1. A scanning current supply unit (current supply means) 80 (see FIG. 5) for supplying a pulse current to the scanning current source 8 and a limited region (writing region 1w) of the magnetic thin wire 1 for each magnetic thin wire 1 And a data writing unit (writing means) 50 that changes the magnetization direction of the magnetic field to upward or downward (two directions different from a predetermined one direction and the opposite direction). As shown in FIG. 5, the spatial light modulator 10 further includes a control unit 90 that controls operations of the scanning current supply unit 80 and the data writing unit 50.

  As shown in FIG. 2, the spatial light modulator 10 according to the present embodiment includes eight magnetic thin wires 1 arranged in parallel on the substrate 2 as the light modulator 20. The magnetic thin line 1 includes eight pixels 4 arranged in a row (one row) continuously in the thin line direction, with a region divided by a predetermined unit length Lb in the thin line direction as one pixel 4. Every 4 indicates one of the magnetization directions. That is, the magnetic wire 1 is formed by dividing the magnetic domain in the direction of the wire. In the magnetic wire 1, a region where all (eight in this embodiment) pixels 4 are provided is referred to as a pixel region 1 px. Since the optical modulation unit 20 includes the eight magnetic thin wires 1, the light modulation unit 20 includes the pixels 4 (pixel array 40) arranged in a matrix of 64 columns of 8 columns × 8 rows. In this specification, the light modulation unit 20 (pixel array 40) uses the row direction (lateral direction) as the thin line direction of the magnetic thin line 1. However, the row and column may be interchanged. Note that a pixel array of a general spatial light modulator has, for example, about 2.70 million pixels in a horizontal (horizontal) direction 1920 × vertical (vertical) direction 1080 in full high-definition, for the sake of simplification and description in this specification. Is composed of 8 columns × 8 rows.

  Here, the pixel 4 is a region including a gap (insulating layer 6) between the magnetic thin wires 1 and 1, as indicated by a broken line frame in FIG. 2, but is appropriately divided by the unit length Lb of the magnetic thin wire 1. Points to the designated area. In general, a pixel is the smallest unit that can display color tone and gradation. For example, in order to display full color (RGB 3 colors × 256 gradations), each pixel has a lot of information of 24 bits. However, the pixel in this specification refers to a means for presenting light / dark binary (1 bit) as information in the minimum unit of display by the spatial light modulator.

(Light modulation operation of spatial light modulator)
The light modulation operation of the spatial light modulator according to the present invention will be described with reference to FIG. 3 using a display device using this spatial light modulator. The display device may have the same configuration as that using the conventional spatial light modulator 100 shown in FIG. 17 or using a spin-injection magnetization switching element as the light modulation element. Since the spatial light modulator 10 according to the present embodiment is a reflection type, and the magnetic wire 1 serving as the light modulation unit is made of a perpendicular magnetic anisotropic material and the magnetization direction is upward or downward, the display device is as follows. It is preferable to adopt the configuration. Immediately above the pixel array 40 of the spatial light modulator 10, an optical system OPS having a light source or the like that irradiates light (laser light) toward the pixel array 40, and the light emitted from the optical system OPS is applied to the pixel array 40. A polarizer PFi that converts light of one polarization component (polarized light in one direction, hereinafter referred to as “polarized light” as appropriate) and incident polarized light (incident polarized light) incident on the pixel array 40 from above is transmitted and the pixel is incident. A half mirror HM that reflects the light reflected and emitted from the array 40 to the side is disposed. Further, on the side of the half mirror HM above the pixel array 40, a polarizer PFo that shields light of a specific polarization component from light that is reflected by the half mirror HM and light that has passed through the polarizer PFo. And a detector PD for detecting.

  The optical system OPS includes, for example, a laser light source, a beam expander that is optically connected to the laser light source and expands the entire surface of the pixel array 40 with laser light, and a lens that converts the expanded laser light into parallel light. (Not shown). Since the light (laser light) emitted from the optical system OPS includes various polarization components, this light is transmitted through the polarizer PFi in front of the pixel array 40 to be one polarization component light (polarized light). To do. The polarizers PFi and Pfo are polarizing plates, respectively, and the detector PD is an image display means such as a screen.

  The optical system OPS irradiates the parallel laser light so as to enter the pixel array 40 perpendicularly to the film surface (at an incident angle of 0 °). The laser light passes through the polarizer PFi to become polarized light (incident polarized light), passes through the half mirror HM, and enters from the upper side of the pixel array 40 toward all the pixels 4, that is, the magnetic thin wires 1. Incident polarized light is reflected by the magnetic wire 1 and is emitted from the pixel array 40 as outgoing polarized light. Since the incident angle is 0 °, the outgoing polarized light has the same optical path as the incident polarized light. Therefore, a half mirror HM inclined by 45 ° with respect to the pixel array 40 is disposed between the polarizer PFi and the pixel array 40, and the outgoing polarization is reflected to the side, so that only the outgoing polarization is converted to the polarizer Pfo. To reach. The polarizer PFo shields specific polarized light out of all outgoing polarized light, and light transmitted through the polarizer PFo enters the detector PD. In addition, it is good also as a structure which does not arrange | position the half mirror HM so that incident polarized light may be inclined and may enter into the pixel array 40 (incident angle> 0 °), and the emitted polarized light may not overlap with the optical path. However, since the magneto-optical effect is higher as the incident direction is closer to the magnetization direction, the incident angle is preferably within about 30 °.

  When the light is reflected or transmitted by the magnetic wire 1, the direction of polarization is one direction and the opposite direction corresponding to the magnetization direction in the region where the light of the magnetic wire 1 is incident due to the magneto-optic effect. Rotate at the same angle. In FIG. 3, the light is rotated at an angle θk by the Kerr effect when reflected by the magnetic wire 1, the light reflected in the region showing the upward magnetization direction is + θk, and the light reflected in the region showing the downward magnetization direction is -Θk rotation. The polarizer PFo shields light that has been rotated by -θk with respect to incident polarized light. Therefore, the outgoing polarized light reflected by the region (magnetic domain) in the downward magnetization direction is shielded by the polarizer PFo, whereas the outgoing polarized light reflected by the magnetic domain in the upward magnetization direction passes through the polarizer PFo and is detected by the detector PD. Is irradiated. Therefore, the light emitted from one magnetic wire 1 is displayed on the detection unit PD in a pattern that is divided into bright and dark (black and white) for each magnetic domain formed in the magnetic wire 1. Therefore, in one magnetic thin wire 1, a magnetic domain is formed as a desired magnetization direction, either upward or downward, for each pixel 4 partitioned in the thin line direction, so that each pixel is bright / dark (white / black). ) Can be displayed.

  In the conventional spatial light modulator 100 (see FIG. 17) or the like, a magnetic body (light modulation element) that performs a light modulation operation is provided separately for each pixel. Therefore, by providing the electrodes 131 and 132 as horizontal and vertical grid-like wirings of the pixel array 140 so that all the light modulation elements (magnetic thin wires 101) are connected to a pair of electrodes of different combinations, the pixel 104 The desired magnetization direction can be set every time. On the other hand, in the spatial light modulator 10 according to the present invention, as shown in FIG. 2, the magnetic material (magnetic thin wire 1) is in the form of a thin wire continuous in the horizontal direction (row direction) and includes a plurality of pixels 4. And separated one pixel at a time in the vertical direction (column direction). Accordingly, a common current is supplied to both ends of one magnetic wire 1 between the pixels 4 in the same row. Hereinafter, the spatial light modulator 10 which is a pixel composed of a magnetic body that is continuous in the row direction and can have a desired magnetization direction for each pixel without wiring between the pixels. This will be described in detail.

(Magnetic wire)
The magnetic wire 1 is formed by forming a magnetic body into a thin wire shape that is sufficiently long with respect to the thickness and width. As shown in FIG. 2, in the light modulation unit 20, the magnetic fine wires 1, 1,... Are formed on the substrate 2 in parallel with each other with the insulating layer 6 interposed therebetween in plan view. As described above, the magnetic thin line 1 includes a region to be the pixel 4, and the pixel region 1px in which a predetermined number (eight) pixels 4 are continuously provided in the thin line direction is a portion that performs light modulation. The pixel region 1px is an incident region of light in the magnetic thin wire 1, and when light incident on the pixel region 1px is transmitted through or reflected from the magnetic thin wire 1 and is emitted, the pixel region 1px differs depending on the magnetization direction in the pixel 4. It is modulated into light rotated at one of two angles. Further, the magnetic thin line 1 is provided with a writing region 1w in a region partitioned in the thin line direction outside the pixel region 1px (left side of the pixel region 1px in FIG. 2). The write region 1w is a region that is changed by the data writing unit 50 in the same magnetization direction as one of the pixels 4 provided on the magnetic thin wire 1. The magnetic thin line 1 has a magnetic domain having the same magnetization direction as the upward or downward magnetization direction of a certain pixel 4 formed in the writing region 1w, and this magnetic domain is moved in the thin line direction to reach the pixel 4 in the pixel region 1px. Thus, the pixel 4 has a desired magnetization direction. In the present embodiment, such an operation (pixel driving) is executed in parallel for each magnetic wire 1 as shown in FIG.

  The magnetic wire 1 is made of a magneto-optical material having perpendicular magnetic anisotropy. As such a material, a known ferromagnetic material can be applied. Specifically, a multilayer film such as a Co / Pd multilayer film in which transition metals such as Co and Pd, Pt, and Cu are repeatedly laminated, and Tb- An alloy (RE-TM alloy) of a rare earth metal such as Fe—Co, Gd—Fe and a transition metal can be used. These materials are formed into a film by a known method such as a sputtering method, and are formed into the following fine wire shape by photolithography and etching or lift-off to form the magnetic wire 1. In the present embodiment, since the magnetic wire 1 is a perpendicular magnetic anisotropic material, the two different magnetization directions indicate either upward or downward as shown in FIGS. 1 and 3.

If the magnetic thin wire 1 has a thickness (film thickness) of 70 nm or less and a width of 300 nm or less, it is preferable because the magnetic domains are easily divided in the thin wire direction during formation (manufacturing). Further, the movement of the magnetic domains described above is performed by supplying a current to the magnetic wire 1 in the direction of the wire, and the moving speed is increased in proportion to the current density per cross-sectional area, so that the thickness and width ( The smaller the cross-sectional area, the faster the magnetic domain can be moved with a smaller current (see below). In addition, when the thickness and width are larger than the above range, the magnetic fine wire may be formed by dividing the magnetic domain in the width direction or the like, but by applying an external magnetic field in advance, only the fine wire direction can be obtained. The magnetic domain can be divided into two. However, since the incident light is easily transmitted when the magnetic wire 1 is thin, in the reflective spatial light modulator 10, it is preferable that the magnetic wire 1 has a thickness of about 30 nm or more although it depends on the material. Alternatively, a reflective layer made of a non-magnetic metal such as Al, Ta, or Ag is provided on the substrate 2, and the magnetic thin wire 1 is passed through an insulating layer such as SiO ₂ having a thickness of about 300 nm or less so as to transmit light. It may be formed (not shown). In this case, the light transmitted through the magnetic wire 1 is further transmitted through the insulating layer, reflected by the reflecting layer, and then transmitted through the insulating layer and the magnetic wire 1 again to be emitted. Therefore, in order to increase the optical rotation angle, it is preferable that the magnetic wire 1 is as thick as possible so that light can be transmitted. On the other hand, as will be described later, in order to reverse the spin injection magnetization of the magnetic wire 1 in the writing region 1w, the thickness is preferably 5 to 30 nm. Further, although depending on the wavelength of incident light (laser light shown in FIG. 3), the magnetic thin wires 1 and 1 (pixel pitch) are preferably about 200 nm or more, and the width of the magnetic thin wires 1 is about 100 nm or more. It is preferable.

  The length in the fine line direction (unit length Lb) of the pixel 4 in the magnetic fine line 1 is set according to the wavelength of the incident light similarly to the magnetic fine lines 1 and 1, and is preferably about 200 nm or more. On the other hand, when the unit length Lb becomes longer, the distance for moving the magnetic domain becomes longer and the time (response time) required for displaying the image of the pixel array 40 becomes longer. Since the magnetic domain reaching the pixel 4 is formed in the writing area 1w, the unit length Lb is equal to or less than the length of the writing area 1w described later in the thin line direction. From the above, the length of the magnetic wire 1 in the direction of the wire is equal to the number of pixels 4 (8 in this embodiment), that is, the pixel region 1px, the write region 1w, and the electrodes 31 and 32 at both ends. Region, at least.

  The writing area 1w is an area partitioned in the thin line direction set to limit the magnetic thin line 1 to this area and change it in the same magnetization direction as each pixel 4 provided in the magnetic thin line 1. Therefore, at least in this region, the magnetic wire 1 has a structure corresponding to the writing method in order to be able to change the direction of magnetization upward or downward (to be written appropriately). . The length in the thin line direction of the writing area 1w may be equal to or longer than the unit length Lb, and may correspond to the writing method, processing accuracy, and the like. Further, the position of the writing area 1w in the magnetic thin wire 1 may be outside the pixel area 1px and behind the moving direction of the magnetic domain (and domain wall) described later. What is necessary is just not to prevent the light entering and exiting the pixel region 1px.

  In this embodiment, spin injection magnetization reversal is applied as a writing method. By forming the spin injection magnetization reversal element structure in the write region 1w, the magnetic wire 1 can be changed to a desired magnetization direction by spin injection magnetization reversal. Specifically, as shown in FIG. 4A, the magnetic thin wire 1 is laminated on the magnetization fixed layer 51 via the intermediate layer 52 in the write region 1w to form a magnetization free layer of the spin injection magnetization reversal element. A pair of electrodes 34 and 33 for flowing a current in the direction perpendicular to the film surface to the injection magnetization reversal element structure are connected vertically. In the present embodiment, the magnetization fixed layer 51, the intermediate layer 52, and the magnetic wire 1 (magnetization free layer) are stacked in this order. The spin transfer magnetization reversal element structure is a known element such as a CPP-GMR element or a TMR element. The magnetization fixed layer 51 is made of a ferromagnetic perpendicular magnetic anisotropy material like the magnetic wire 1 and is made of a material or a thickness that is larger than the coercive force in the writing region 1 w of the magnetic wire 1, and its magnetization direction Is fixed to one of upward or downward (downward magnetization direction in FIG. 4). The intermediate layer 52 is made of a nonmagnetic conductor such as Cu or an insulator such as MgO. The lower electrode 33 and the upper electrode 34 can be made of the same metal electrode material as the positive electrode 31 and the negative electrode 32 described later. Further, as described above, the length in the thin line direction of the writing region 1w is preferably not less than about 200 nm in order to be not less than the unit length Lb. On the other hand, the spin-injection magnetization reversal element structure preferably has a square whose side is about 300 nm or less in a plan view or an area corresponding to this in order to enable the spin-injection magnetization reversal. Therefore, the length of the write region 1w in the fine line direction is preferably 300 nm or less, although it depends on the width of the magnetic fine line 1.

  By configuring the write region 1w with such a configuration, when the current is supplied upward or downward, the magnetic wire 1 is magnetized in the same direction as or opposite to the magnetization direction of the magnetization fixed layer 51 in the write region 1w. Can be in the direction. For example, in FIG. 4A, as a result of supplying an electric current upward from the lower electrode 33 to the upper electrode 34, the magnetic fine wire in which the magnetization direction indicates a downward direction (hereinafter referred to as an initial state) before the electric current is supplied. 1 is inverted upward in the writing area 1w.

  As shown in FIGS. 1 and 4, in this embodiment, the magnetic thin wire 1 is formed with recesses 1c0, 1c1,... (Appropriately collectively referred to as the recess 1c) so as to be locally thin on the upper surface in the pixel region 1px. Has been. Since a domain wall is likely to be generated at a location where such a cross-sectional area (cross-section perpendicular to the fine wire direction) is locally small, the magnetic fine wire 1 is in a state in which a magnetic domain is formed so as to be separated at the location where the recess 1c is formed. easy. Further, since the domain wall is easily locked (trapped) when the supply of current to the magnetic wire 1 is stopped, the domain wall that has reached the vicinity when the pulse current is stopped (base period) moves to the recess 1c. Then stop. Therefore, since the concave portion 1c is formed at the boundary that separates the pixels 4 of the magnetic thin wire 1, the magnetic domains formed in the writing region 1w can easily reach each pixel 4 accurately as described later. In order to lock the magnetic domain wall in the magnetic thin wire 1, the cross-sectional area only needs to be locally small, that is, it is formed in a constricted shape. A constriction with a recessed side surface may be formed (not shown). In the magnetic thin wire 1, the constricted portion such as the concave portion 1c is narrow so that the width or thickness thereof is 98% or less in cross-sectional area with respect to other portions in order to suitably lock the domain wall. Or it is preferable to make it thin. However, if the cross-sectional area at the constricted portion is reduced, the resistance when supplying the pulse current to the magnetic thin wire 1 is increased.

  In addition, the recess 1c may be formed at one or two locations such as the end of the pixel region 1px (the recesses 1c0 and 1c8 in FIG. 4C), but the same data is used between the adjacent pixels 4 and 4. Since the domain wall is not generated in the meantime, it is preferably formed at every predetermined number of pixels 4, and most preferably at the boundary of all the pixels 4. Moreover, it is preferable that the shape of the constriction (recess 1c) is the same in order to align the effect of locking the domain wall. In addition, a concave portion is formed between the pixel region 1px and the writing region 1w. For example, the domain wall generated when the magnetic domain is formed in the writing region 1w shifts the distance of the unit length Lb. You may make it latch on the position which moves and arrives (the stationary position of the domain wall DW1 in FIG.4 (b)). As described above, the moving speed of the domain wall is proportional to the current density in the cross section perpendicular to the thin wire direction, but the narrow cross-sectional area due to the recess 1c is slightly smaller than the entire magnetic thin wire 1 and supplies a constant current. It can be considered that the moving speed of the domain wall in the magnetic wire 1 is constant.

(electrode)
The positive electrode 31 and the negative electrode 32 are terminals for supplying a current to the magnetic wire 1 in one direction as a pair of electrodes, and are connected to both ends of the magnetic wire 1 as shown in FIGS. Is done. In the present embodiment, as shown in FIG. 4, the electrodes 31 and 32 are both connected to the upper surface of the magnetic wire 1, but the connection surface of the magnetic wire 1 is not limited to this, and may be connected to the lower surface, for example. Further, as shown in FIG. 2, in this embodiment, a pair of electrodes 31 and 32 are connected to each of the magnetic thin wires 1, but for example, all eight magnetic thin wires 1 are connected in parallel. It is good also as the electrodes 31 and 32 extended in the vertical direction in 2 (not shown). The electrodes 31 and 32 are made of a general metal electrode material such as a metal such as Cu, Al, Ta, Cr, W, Ag, Au, or Pt, or an alloy thereof, and is formed by sputtering or the like, or formed by photolithography or the like. Molded into stripes. In addition, the thickness, width, and length in the thin line direction of the electrodes 31 and 32 are set according to the magnetic thin line 1, 1 pitch (pixel pitch), the material, the supplied voltage / current, and the like.

(substrate)
The substrate 2 is a base of the light modulation unit 20 for forming the magnetic wire 1 and the like in a desired shape and position, and a known substrate such as a Si substrate whose surface is thermally oxidized can be applied. Alternatively, when light is incident from below the light modulation unit 20, the substrate 2 is made of a transparent material, and examples thereof include known transparent substrate materials such as SiO ₂ , magnesium oxide (MgO), and glass.

(Insulating layer)
The insulating layer 6 is disposed between the magnetic fine wires 1 and 1, between the positive electrodes 31 and 31 and between the negative electrodes 32 and 32, between the substrate 2 and the magnetic fine wire 1, and on the magnetic fine wire 1. The The insulating layer 6 is made of a known insulating material such as SiO ₂ , Si ₃ N ₄ , or Al ₂ O ₃ , and the same material may not be applied to the entire light modulation unit 20.

(Scanning current supply unit)
As shown in FIG. 4B, the scanning current supply unit 80 includes a scanning current source 8 connected to both ends of each magnetic wire 1 of the optical modulation unit 20 via electrodes 31 and 32 as a pulse current source, and is connected to a direct current. A current (referred to as scanning current Isc) is supplied as a pulse current to the magnetic thin wire 1 from the positive electrode 31 to the negative electrode 32, that is, in one direction in the thin wire direction. When the scanning current Isc is supplied to the magnetic wire 1 from the positive electrode 31 side to the negative electrode 32 side, the domain wall passes through the magnetic wire 1 due to electrons e ⁻ flowing in the magnetic wire 1 in the opposite direction. It moves along the thin line direction from the negative electrode 32 side to the positive electrode 31 side, and the magnetic domains partitioned by the domain wall also move together (see FIG. 4B). Therefore, the magnetic domain formed in the writing region 1w of the magnetic fine wire 1 moves to the pixel region 1px along the fine wire direction. Furthermore, since the magnetic domain moves intermittently in the magnetic wire 1 by supplying the scanning current Isc as a pulse current, it moves in units of one pixel 4 as will be described later, and a predetermined pixel in the pixel region 1px 4 can be reached.

As shown in FIGS. 1 and 5, the scanning current supply unit 80 connects all eight magnetic wires 1 of the optical modulation unit 20 to the scanning current source 8 in parallel at both ends, and generates a common pulse current. Supply at the same time. In the spatial light modulator 10 according to the present embodiment, it is only necessary to supply a common pulse current to all the magnetic wires 1, and the scanning current supply unit 80 may include a scanning current source 8 for each magnetic wire 1 ( (Not shown). The scanning current Isc (peak current) in the DC pulse current is preferably adjusted so that the magnetic domain moves at a desired speed as described later in the range of current density: 10 ⁸ to 10 ¹³ A / m ² . Also, the DC pulse current, pulse width (peak time) t _H: 1ps~10μs, stop time (base time) t _L: is preferably adjusted in a range of 10Ps～10myuesu, the pulse width t _H is magnetic domain movement speed Therefore, the stop time t _L is set to be longer than the write time t _W by the data writing unit 50 described later.

(Data writing part)
As shown in FIGS. 1 and 5, the data writing unit 50 is provided for each magnetic wire 1 of the light modulation unit 20, and makes the magnetic wire 1 have a desired magnetization direction in the writing region 1w. As shown in FIG. 4, the data writing unit 50 includes a write current source 5 connected to the electrodes 33 and 34 provided in the write region 1 w of the magnetic wire 1. The write current source 5 can supply a direct current Iw to the spin injection magnetization reversal element structure in the write region 1w as a write current + Iw, -Iw by reversing the positive and negative currents Iw. By being controlled by 90, the current Iw is supplied in any desired direction. That is, the write current source 5 shows three outputs of + Iw, 0, and −Iw when the supply stop (OFF) state is included. Such an operation of the data writing unit 50 is similar to a current supplied to a coil of a magnetic head used for recording on a current magnetic disk, and a driving circuit (for example, a switching circuit configured by a plurality of transistors). , See FIG. 2 of Japanese Patent Laid-Open No. 2007-234136). In the present embodiment, the magnitudes (absolute values) of the write currents + Iw and −Iw are set to be equal to or greater than the current (spin injection magnetization reversal current) for reversing the spin injection magnetization in the write region 1w.

In the data writing unit 50, terminals connected to the electrodes 33 and 34 are formed in accordance with the pitch of the magnetic thin wires 1 arranged in the light modulation unit 20, and the write current source 5 is electrically connected by wiring. Even if the fine magnetic wires 1 have a narrow pitch, writing can be performed simultaneously on the write regions 1w of all the fine magnetic wires 1. Further, since the spin transfer magnetization reversal is extremely fast, the write time t _W (the current supply time of the write current source 5) may be about several tens ps or more. The write current may be supplied as a pulse current having a write time t _W as a pulse width.

(Control part)
As shown in FIG. 5, the control unit 90 divides image data (see FIG. 6B) input from the outside into data for one row, and generates pixel column data (see FIG. 6C). .., And a pixel column control unit 9 that causes the data writing unit 50 to write pixel column data to the magnetic thin wire 1. Accordingly, the pixel column control unit 9 is provided with eight as many as the number of rows of the pixel array 40, that is, the number of the magnetic thin wires 1, and each controls the data writing unit 50 that writes to the specific magnetic thin wire 1. Further, the control unit 90 further includes a counter TCNT, so that the pixel column control unit 9 controls the data writing unit 50 so as to be synchronized with the pulse current supplied from the scanning current supply unit 80 to the magnetic thin wire 1 ( Details will be described later).

(Manufacturing method of light modulator)
The light modulation unit 20 of the spatial light modulator 10 can be manufactured by forming the magnetic wire 1 by a lift-off method or a damascene method. An example of a manufacturing method of the light modulation unit 20 shown in FIG. First, the lower electrode 33 is formed of a metal electrode material on the substrate 2 at a position where the writing region 1w is provided, and the respective materials of the magnetization fixed layer 51 and the intermediate layer 52 are continuously formed thereon, Mold into a desired shape. Next, an insulating film such as SiO ₂ or Al ₂ O ₃ is formed on the substrate 2 by a known method such as sputtering, and is buried up to the height of the upper surface of the intermediate layer 52. Next, a resist mask pattern is formed on the insulating film (insulating layer 6) and the intermediate layer 52, a magnetic material is formed by sputtering or the like, the resist is removed, and the striped magnetic thin wires 1, 1, ... are formed. And the recessed part 1c is formed in the surface of each magnetic fine wire 1. FIG. Or it is set as the magnetic fine wire 1 of the planar view shape provided with the narrow constriction part by the resist mask pattern. Next, the electrodes 31, 32 and the upper electrode 34 are formed of metal electrode material in the vicinity of both ends of the magnetic wire 1 on the magnetic wire 1 and in the writing region 1w. Finally, except for the electrodes 31, 32 and 34, the surface is covered with an insulating film (insulating layer 6), and the substrate 2 is removed from the back surface in the writing region 1w to expose the lower electrode 33.

  When forming the magnetic wire 1 by the damascene method, when forming an insulating film on the substrate 2, the film is formed up to the height of the upper surface of the magnetic wire 1, and electron beam lithography, ion milling and reactivity are formed on the insulating film. Grooves in the shape of magnetic fine wires 1, 1,... Are formed by etching such as ion etching (RIE) to form the insulating layer 6. A magnetic material is deposited on the insulating layer 6 in a groove by a film forming method such as a sputtering method, and then the magnetic material other than the groove is removed by CMP (Chemical Mechanical Polishing) or the like on the surface. Magnetic wires 1, 1,...

[Pixel driving method]
Next, a method (pixel driving method) for setting each pixel 4 of the pixel array 40 to a desired magnetization direction based on image data before operating (light modulating) the spatial light modulator according to the present invention is shown in FIG. Explanation will be made with reference to FIGS. As shown in FIG. 1, the pixel driving method in the spatial light modulator 10 according to the first embodiment supplies a pulse current to the magnetic wires 1, 1,. Are written in the writing area 1w of each magnetic wire 1 by the data writing section 50 while being shifted and shifted intermittently.

(image data)
The pixel driving method in the spatial light modulator 10 according to the first embodiment is such that, for example, image data for each screen (frame) is controlled as shown in FIG. 5 for moving image data stored in an external database DB. This is a procedure from input to the unit 90 until an image is displayed by the pixel array 40. As shown in FIG. 6B, the image data F1 includes eight pieces of data (pixel data) in which the pixels to be displayed in black are represented by “1” and the pixels to be displayed in white are represented by “0” in the horizontal direction (column direction). 8 lines of 12-digit data with a row address consisting of 4-digit data are arranged. For example, such image data F1 is obtained by converting an original image (not shown) into horizontal Nh columns × vertical Nv rows (8 columns × 8 rows) in accordance with the configuration of the pixel array 40 of the spatial light modulator 10. ) Of the bitmap data (see FIG. 6A), black is converted to “1”, and white is converted to “0”. Such an image data generation function may be built in the spatial light modulator 10.

(Image data input, pixel column data generation)
As shown in FIG. 5, the control unit 90 transmits an image data output command to an external database DB, and the database DB that receives this command outputs a signal of the image data F1, whereby the image data F1 is controlled. (Steps in FIG. 7 (hereinafter omitted) S10, S20). Then, in the control unit 90, the pixel column data generation unit 99 divides the image data F1 into one row at a time, and generates Nv (= 8) pixel column data composed of Nh (= 8) data (S31). ). The pixel column data is distributed and output one by one to the pixel column control unit 9 based on the row address (S32). Next, the control unit 90 sends a command to the scanning current supply unit 80 to start supplying the pulse current to the magnetic wire 1, and the scanning current supply unit 80 turns on the scanning current source 8 to perform the pulse. Supply of current is started (S50). The scanning current supply unit 80 further outputs a pulse signal having the same timing as the pulse current to the control unit 90. Then, the control unit 90 starts the pixel column data writing step S60 to the pixel 4 (magnetic thin line 1).

(Pixel column data writing)
The pixel column control unit 9 is input with individual pixel column data (S61), while the counter TCNT starts counting from 1 with the transmission of a pulse current supply start command to the scanning current supply unit 80 (S62). . Then, the pixel column control unit 9 outputs the first data that is the same as the count value i in the pixel column data to the data writing unit 50. When the binary data “0” or “1” is input, the data writing unit 50 writes the magnetic thin wire 1 in the writing area 1w (S63). Next, the magnetic domain formed in the magnetic wire 1 is shifted by the distance of the unit length Lb by the first current supply of the pulse width t _H in the pulse current (S64). In the present embodiment, the current supply time (movement time) t _SC required for shifting by the distance of the unit length Lb is defined as the pulse width t _H. Next, the count value i is determined (S65), and the data writing (S63) and the magnetic domain shift movement (S64) are repeated while incrementing the count by 1 until reaching Nh (= 8) (S66).

  Here, data writing to the magnetic wire 1 (S63) and magnetic domain shift movement (S64) will be described in detail with reference to FIG. 4 and FIG. In FIG. 4, only the substrate 2 and the insulating layer 6 are shown in FIG. 4 (a), and although not shown in FIGS. 4 (b) and 4 (c), all show the light modulator 20 having the same structure. ing. Here, a method for writing to the magnetic thin wire 1 (11) based on the pixel column data (see FIG. 6C) at the row address (0) will be described.

The pixel column controller 9 (91) receives the pixel column data and temporarily stores it in a memory (not shown) (S61), receives the start of counting (S62: i = 1), and stores the pixel The first data “0” of the column data is output to the data writing unit 50. When data “0” is input, the data writing unit 50 supplies a write current + Iw from the built-in write current source 5 for a predetermined write time t _W. As shown in FIG. 4A, the write current source 5 is connected to the spin-injection magnetization reversal element structure provided in the write region 1w of the magnetic thin wire 1 by the electrodes 33, 34. Current Iw flows upward in the write region 1w, that is, in the direction perpendicular to the film surface from the magnetization fixed layer 51 side. Due to this current Iw, the magnetic thin wire 1 undergoes spin injection magnetization reversal in the write region 1w so as to be antiparallel to the magnetization direction of the magnetization fixed layer 51. Therefore, a magnetic domain having an upward magnetization direction (referred to as a magnetic domain D0; see FIG. 4B) is formed in the write area 1w, and domain walls DW1 and DW2 are generated so as to separate both sides of the magnetic domain D0 (S63). In general, the length (thickness) of the domain wall depends on the shape and size (width, thickness, thin wire length) of the magnetic wire, but is about 5 to 100 nm and the length of the magnetic domain (unit length). Although it is extremely short (narrow) with respect to the length Lb), the domain wall is schematically enlarged in FIG.

After the supply of the write current + Iw from the write current source 5 is stopped (OFF), the scanning current Isc is pulsed to the magnetic thin wire 1 as the first current supply (one pulse) in the pulse current from the scanning current supply unit 80. It is supplied for a time of width t _H. In the present embodiment, a waiting time t _hld is provided as shown in FIG. 8 so that the first current supply in the pulse current is executed after the writing of the first data. . Note that writing may be performed after the first current supply in the pulse current. As shown in FIG. 4B, the scanning current Isc is supplied to the magnetic wire 1 for the time t _SC (= pulse width t _H ) during which the domain walls DW1 and DW2 move by the distance of the unit length Lb. The magnetic domain D0 sandwiched between DW1 and DW2 also moves equidistantly, that is, shifts. Therefore, at least a part (the length of the unit length Lb) of the magnetic domain D0 leaves the write area 1w (S64).

In synchronization with the current stop in the pulse current (falling of the pulse signal), the count value i is determined and incremented by 1 (S65: No, S66: i = 2), and the second data “1” is written. (S63). Specifically, the data write unit 50 receives data “1” from the pixel column control unit 9 and supplies the write current −Iw from the write current source 5 as shown in FIG. A current Iw flows downward in the write region 1w of the magnetic wire 1, that is, in the direction perpendicular to the film surface toward the magnetization fixed layer 51. Due to this current Iw, the magnetic wire 1 has a magnetic domain D0 indicating an antiparallel magnetization direction limited to the write region 1w so as to be parallel to the magnetization direction of the magnetization fixed layer 51 in the write region 1w. Invert. As a result, the domain wall DW2 existing in the write area 1w disappears and a domain wall DW3 is generated. Therefore, the magnetic domain D0 formed by writing the first data “0” Is the moving distance Lb by one pulse (supply of the pulse width t _H of the scanning current Isc). After the supply of the write current -Iw is stopped, the scanning current Isc is again supplied from the scanning current source 8 to the magnetic wire 1 as the next pulse in the pulse current, and the domain walls DW1 and DW3 have the unit length Lb. (S64).

In this manner, in synchronization with the pulse current (scanning current) supplied by the scanning current supply unit 80 (scanning current source 8), the pixel column control unit 9 starts from the pixel column data in the order of 1 at the stop (base period). The data is output to the data writing unit 50 one by one, and the data writing unit 50 supplies the write currents + Iw and −Iw from the write current source 5 based on the binary data “0” and “1”. Therefore, every time writing based on one piece of data is executed on the magnetic thin wire 1, all the formed magnetic domains D0 and the like are shifted by a distance of the unit length Lb. Therefore, even if the adjacent pixels 4 and 4 have the same data and no domain wall is generated between them, all the written regions move from the writing region 1w toward the pixel region 1px. . The data writing unit 50 supplies the write current only during the stop time (base period) of the pulse current from the scan current source 8 so that the magnetic thin wire 1 is connected to the scan current source 8 and the write current source. 5, the control unit 90 controls the data writing unit 50 so that no current is supplied from both of them simultaneously. Therefore, as described above, the current stop time t _L in the pulse current is set to be longer than the time (current supply time) t _W required for writing (spin injection magnetization reversal) of the magnetic wire 1 by the write current source 5.

  Then, after the writing based on the last, that is, the Nh (= 8) th data “0” of the pixel column data (S63) in the magnetic thin wire 1, the next count value i of the shift shift (S64) of the magnetic domain In the determination, the process skips S63 to S66 in the pixel column data writing step S60 (S65: Yes). At this time, in the magnetic wire 1, the area written based on the last data has left the writing area 1 w but has not reached the pixel area 1 px. Therefore, the magnetic domain shift is further performed by supplying a pulse current until this region reaches the pixel region 1px (S70). In the present embodiment, since the space between the writing area 1w and the pixel area 1px is twice the unit length Lb, the pulse current is supplied twice as shown in FIG. Finally, a command is sent to the scanning current supply unit 80 to stop the supply of the pulse current, and the scanning current supply unit 80 turns off the scanning current source 8 and stops the supply of the pulse current (S80). As a result, as shown in FIG. 3, in the magnetic thin wire 1, all the data of the pixel column data is continuously written in the area of the unit length Lb, and all the areas where the writing is further performed are performed. Since the pixel area 1px is reached, a black or white pattern is displayed for each pixel 4 (see FIG. 6D).

Magnetic wire 1, since the moving speed of the domain wall if the magnitude of the current supplied constant is constant, the peak current Isc and the pulse width t _H is a constant pulse current, intermittent each distance unit length Lb The magnetic domain can be moved. However, when the movement distance of one time is slightly shifted due to errors such as the magnitude of the current and the pulse width, and this minute shift is accumulated, writing of all data of the pixel column data is completed (S65: Yes). Further, when the magnetic domain shift movement (S70) is completed, there is a possibility that the magnetic domain formed by writing is largely deviated from the position of the pixel 4 corresponding to the data and cannot be displayed accurately. In order to prevent such positional deviation of the magnetic domains, the magnetic thin wire 1 is formed with a constriction like a concave portion 1c at the boundary separating the pixels 4 as described above. Each time the current in the pulse current is stopped, the domain wall that has reached the vicinity of one of the recesses 1c is locked by the recess 1c, and the magnetic domain delimited by the domain wall is shifted accordingly. The error is corrected. When the position of the magnetic domain in the magnetic wire 1 can be sufficiently controlled by adjusting the pulse current or the positional accuracy of the required magnetic domain with respect to the pixel is rough, the magnetic wire 1 is constricted like the recess 1c. It does not have to be formed.

  In the magnetic wire 1, after fixing the position of the domain wall by these operations, the magnetization is held by the coercive force of the magnetic wire 1 in each of the two magnetic domains sandwiching each domain wall. Therefore, the magnetic domain does not move or change in size (length in the direction of the thin line) or disappear until a new current is supplied to the magnetic thin line 1 or an external magnetic field is applied. The stationary state is maintained at the position of the pixel 4. In FIG. 4, writing is performed on the magnetic thin wire 1 in the initial state, which shows the downward magnetization direction as a whole, but new image data is written on the magnetic thin wire 1 on which image data (pixel column data) has already been written. The same applies to writing. In this writing, the magnetic domain based on the previous image data disappears when it reaches the end of the magnetic wire 1 (end on the positive electrode 31 side) by the shift of the magnetic domain.

  In the present embodiment, data writing (S63) is simultaneously executed in all the pixel column controllers 9 by the counter TCNT. Therefore, a pulse current can be supplied in parallel to all the magnetic wires 1 from one DC pulse current source (not shown) of the scanning current supply unit 80, and the magnetic domains can be shifted simultaneously. Further, since the concave portion 1c is formed in each magnetic thin wire 1, it is possible to prevent a positional shift in the movement of the magnetic domain even if a common pulse current is supplied. Therefore, the timing chart is as shown in FIG. As described above, the time required to display one image data on the pixel array 40 by simultaneously writing data and moving the magnetic domains in parallel for all the magnetic thin wires 1 is the above-described one. This is the same as the time required for writing the pixel column data in the pixel region 1px of the magnetic wire 1 and the display can be switched in a short time. In particular, when the display change time or non-display time, that is, the response time (see FIG. 8) becomes longer in order to make it possible to display one new image data on the pixel array 40, an afterimage is visually recognized in the moving image display. Therefore, the spatial light modulator is required to further reduce the response time.

  After the image by the image data F1 can be displayed on the pixel array 40, the database DB is requested to output the image data of the next frame (S10), and the display by the pixel array 40 is enabled again. This image data output command transmission (S10) can be set to be performed, for example, every 1/60 seconds by an external signal, an oscillator built in the control unit 90, or the like. If no image data is input (S20: No), the work may be set to end. With such a configuration, the spatial light modulator 10 can display a high-definition image at high speed even if the light modulation unit 20 has a simple structure.

  In the present embodiment, the control unit 90 is controlled to synchronize with the pulse signal having the same timing as the pulse current with reference to the pulse current supplied by the scanning current supply unit 80. 90 may incorporate an oscillator to output a pulse signal, and the scanning current supply unit 80 may supply a pulse current synchronized with the pulse signal.

In FIG. 8, for the pulse current, the pulse width t _H and the stop time t _L are shown as the same time, that is, the duty ratio is 50%. However, the present invention is not limited to this, and the range (pulse width t _H : 1 ps to 10 μs, stop) The time t _L can be adjusted at 10 ps to 10 μs). For example, by increasing the pulse width t _H per cycle (t _H + t _L ) (duty ratio over 50%), the cycle of the pulse current for moving the magnetic domain by the unit length Lb is shortened. As a result, the response Time can be shortened. In this embodiment, the movement time t _{SC is set} to the pulse width t _H , and the magnetic domain is moved once by the current supply of the pulse current, that is, the distance of the unit length Lb in one cycle. It may be moved intermittently by supplying the current twice or more times. In this case, control is performed so that the write current source 5 supplies a current during one stop time per the predetermined number of cycles of the pulse current.

  The spatial light modulator 10 according to this embodiment is a reflective spatial light modulator that reflects and emits light incident from above on the surface of the magnetic wire 1, but may be a transmissive spatial light modulator. . In this case, a transparent substrate material is applied to the substrate 2 and the thin magnetic wire 1 is formed thin to facilitate light transmission, or is formed of a material having high transmittance such as magnetic garnet. In the display device, the optical system OPS and the polarizer PFi are disposed immediately above the pixel array 40, the polarizer PFo and the detector PD are disposed immediately below, and the half mirror HM is not necessary (not shown).

  Further, an in-plane magnetic anisotropic material may be applied to the magnetic wire 1. In-plane magnetic anisotropy materials include transition metals selected from Ni, Fe, and Co, transition metal alloys such as Ni—Fe, Ni—Fe—Mo, and Co—Cr, or Pd and Pt such as Co—Pt. , Cu alloy, and easier to form than a multilayer film of perpendicular magnetic anisotropic material. When the magnetic wire 1 is made of an in-plane magnetic anisotropic material, the magnetization direction of the magnetic wire 1 is oriented along the direction of the thin wire (see FIG. 17). It is preferable that light is incident along. However, if the incident direction is too close to being parallel to the thin wire direction of the magnetic thin wire 1, it becomes difficult for light to enter each pixel 4. Therefore, the thin wire of the magnetic thin wire 1 is set so that the incident angle is within about 80 °. It is preferable that the direction is an angle of about 10 ° to 60 ° with respect to the direction. Therefore, in the spatial light modulator in which the magnetic wire 1 is made of an in-plane magnetic anisotropic material, the incident polarization direction and the emission direction are inclined so that the incident polarization direction is inclined so that the incident angle is in the range of about 30 ° to 80 °. An optical system OPS, polarizers PFi, PFo, and the like are arranged in accordance with the respective optical paths of polarized light (not shown).

(Modification)
A spatial light modulator according to a modification of the first embodiment will be described with reference to FIG. In the spatial light modulator according to the modification of the first embodiment, elements other than the light modulation unit 20A are the same as those of the spatial light modulator 10 (see FIGS. 1 and 5), and thus illustration and description thereof are omitted. Furthermore, in the light modulation unit 20A, since elements other than the magnetic wire 1A are the same as those in the light modulation unit 20 (see FIG. 2), these elements are denoted by the same reference numerals and description thereof is omitted. The cross-sectional structure of the light modulation unit 20A is the same as that of the light modulation unit 20 shown in FIG. 4 except that the magnetic wire 1A is not formed with the recess 1c and has a constant thickness. Therefore, the spatial light modulator according to this modification can be applied to a display device with the same configuration as the spatial light modulator 10 according to the first embodiment shown in FIG.

  As shown in FIG. 9, in the light modulation section 20A, the magnetic thin wire 1A is formed in a zigzag shape in plan view. Specifically, the magnetic wire 1A is formed to bend at a certain angle at the boundary between the pixels 4 and 4. The material and size (thickness, width, length in the direction of the thin wire) of the magnetic wire 1A are the same as those of the magnetic wire 1 of the first embodiment. In the magnetic thin wire 1A, the bent portion is easy to lock the domain wall when the current is stopped in the pulse current (base period) as in the case of the constriction (recess 1c, see FIG. 4). can do. Further, unlike the magnetic wire 1 in which the magnetic wire 1A is formed with a constriction, the magnetic wire 1A has a constant thickness and width, so that the resistance does not increase. The angle of bending of the magnetic wire 1A is preferably in the range of 15 ° to 135 ° in order to suitably lock the domain wall, and is preferably set to the same angle in order to achieve the same effect of locking the domain wall. . Further, the bent portion may be one or two places such as an end portion of the pixel region 1px as in the case of the narrowing. Note that, as shown in FIG. 9, the magnetic thin wire 1A bent at all the boundaries delimiting the pixels 4 is formed of a perpendicular magnetic anisotropic material because the thin wire directions are not parallel between the adjacent pixels 4 and 4. It is preferred that Further, the pixel driving method in the spatial light modulator according to the present modification is the same as that in the first embodiment. However, in the light modulation unit 20A shown in FIG. .

  As described above, according to the spatial light modulator according to the first embodiment and the modification thereof, the light incident component has a simple structure, facilitates pixel miniaturization, and has a high aperture ratio. It becomes a vessel.

[Second Embodiment]
In the spatial light modulator 10 according to the first embodiment, writing or the like is performed simultaneously on all the magnetic thin wires 1 in pixel driving. However, the present invention is not limited to this. For example, two or more predetermined numbers (nv) of the magnetic thin wires 1 are provided. It is also possible to select one from each set in order and write in parallel by limiting to the number (Nv / nv) of the magnetic thin wires 1 as a set. Similar to the spatial light modulator 10, the spatial light modulator 10A according to the second embodiment includes a light modulation unit 20 including eight magnetic thin wires 1, and a set of four adjacent magnetic thin wires 1 as a set. Drive. This set of four magnetic wires 1 is referred to as a magnetic wire group. Such a spatial light modulator control unit and its peripheral configuration, and a pixel driving method will be described with reference to FIGS. 10 and 11. FIG. 10 and 11, the same elements and steps as those in FIGS. 5 and 7 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 10, in the present embodiment, the control unit 90A, like the control unit 90 of the first embodiment, has eight pixel column control units 91, 92,. Hereinafter, the pixel column control unit 9) is provided as appropriate. Each pixel column control unit 9 outputs data to the data writing unit 50 provided for each magnetic wire 1 as in the first embodiment shown in FIG. However, the two pixel column controllers 9 designated in parallel output data. Further, the counter TCNTA provided in the control unit 90A performs another count operation described later in addition to the count operation (S62 and S66 in FIG. 7) performed by the counter TCNT in the first embodiment. In addition to the terminals connected to the scanning current source 8 and the electrodes 31 and 32 of the magnetic wire 1, for example, the scanning current supply unit 80 </ b> A supplies the pulse current only to the selected magnetic wire 1. And a switch for each terminal (not shown).

(Pixel driving method)
A pixel driving method will be described with reference to a flowchart shown in FIG. The control unit 90A receives the image data F1 (see FIG. 6B) and generates and distributes the pixel column data (see FIG. 6C) as described with reference to FIG. (S10, S20, S31, S32A).

  Along with the distribution of pixel column data (S32A), the counter TCNTA starts counting from 1 (S41), and the control unit 90A selects the first magnetic wire 1 that is the same as the count value j from each group of magnetic wires. (S42). Then, the scanning current supply unit 80A starts the supply of the pulse current limited to the selected two magnetic thin wires 1 (11, 15) (S50A). On the other hand, the control unit 90A operates the pixel column control unit 9 (91, 95) that stores the pixel column data corresponding to the two selected magnetic thin lines 1, and thereby the pixel column to the two magnetic thin lines 1 is operated. Data is written (S60). Then, the magnetic domain formed by writing is made to reach the pixel region 1px (S70), and the supply of the pulse current is stopped (S80A). The steps S50A, S60, S70, and S80A are the same as S50, S60, S70, and S80 (see FIG. 7) of the first embodiment except that the steps are limited to the selected magnetic thin wires 11 and 15. It is.

  Next, the count value j is determined (S43), the count is incremented by 1 until it reaches nv (= 4) (S44), and the next magnetic thin wire 1 is switched (S42) to write the pixel column data and the magnetic domain A series of steps (S50A, S60, S70, S80A) for performing the shift movement are repeated. Then, the determination of the count value j after the writing of the pixel column data to all the magnetic wires 1 of the magnetic wire group (S43: Yes) completes the writing of all the image data.

  According to the pixel driving method according to the present embodiment, writing of pixel column data and the like is repeated for the number (four) of the magnetic thin wires 1 in the set of magnetic thin wire groups. A response time four times that of the driving method is required. However, since the number of magnetic thin wires 1 that simultaneously supply the pulse current (scanning current) and the write current is small, it is possible to save power. Therefore, the pixel driving method according to the present embodiment is suitable when the number of pixels in the pixel array 40 is small or when high-speed response is not necessary. In addition, although a set of magnetic thin wire groups is set as adjacent magnetic thin wires 1, 1, 1, 1, and two magnetic thin wires 1, 1 to be simultaneously written are arranged every three (magnetic thin wires 11, 15, etc.). For example, a combination in which writing is performed simultaneously on two adjacent magnetic thin wires 1 and 1 may be employed. Further, it is possible to write pixel column data in order one by one to the magnetic thin wire 1 by setting nv = Nv (= 8).

(Modification)
In the second embodiment, as in the first embodiment, the specification is such that writing is performed by the data writing unit 50 provided for each magnetic wire 1. However, the data writing unit 50 that operates simultaneously has four specifications. One for each magnetic wire 1 (magnetic wire group). Therefore, the spatial light modulator 10A that drives such pixels may include one data writing unit 50A in a set of magnetic thin wire groups. Specifically, one data writing unit 50A includes a terminal connected to each of the write current source 5, the electrodes 33 and 34 of the four magnetic thin wires 1, and a switch for each terminal. Write currents + Iw and -Iw are supplied only to the selected magnetic wire 1 (not shown). In addition, since it is only necessary to provide the data writing section 50A for each predetermined number of magnetic wire groups, a writing method using writing means larger than the pitch of the magnetic wires 1 and 1 can be applied.

As such a writing method, the data writing unit 50A may include the magnetic head 55 and apply an external magnetic field, as in the current writing (recording) to the magnetic disk. In this case, as shown in FIG. 12A, the data writing unit 50A further includes a magnetic head 55 facing the optical modulation unit 20B in the writing region 1w, and the write current source 5 is a coil of the magnetic head 55. Connected to. Write currents + Iw and -Iw supplied by the write current source 5 are direct currents for generating a magnetic field from the magnetic head 55 for magnetizing the magnetic wire 1 in a predetermined direction in the write region 1w. The direction of the magnetic field is reversed depending on the direction of the current Iw supplied to. Similar to the spin injection magnetization reversal shown in FIGS. 4A and 4C, the data writing unit 50A converts the write currents + Iw and −Iw into the write currents based on the binary data “0” and “1”. By supplying from the source 5, magnetic fields of different directions are generated from the magnetic head 55 and applied to the magnetic wire 1. In such a writing method in which a magnetic field is applied, the writing time t _W may be about several hundred ps or more.

  On the other hand, the optical modulation unit 20B includes a soft magnetic layer 53 stacked under a magnetic thin wire 1 (opposite the side facing the main magnetic pole of the magnetic head 55) via a nonmagnetic layer 54, like a magnetic disk. . The soft magnetic layer 53 forms a magnetic path for the external magnetic field from the magnetic head 55 to form a perpendicular write magnetic flux with the magnetic wire 1. With such a configuration, for example, in FIG. 12A, the magnetic thin wire 1 whose initial magnetization direction is downward is shown, and the magnetic head 55 (only the main magnetic pole is shown) has an upward magnetic field in the writing region 1w. This is applied to reverse the magnetization upward. Similarly, in FIG. 12B (the substrate 2 and the insulating layer 6 are not shown), the magnetic head 55 applies a downward magnetic field to reverse the magnetization downward. The magnetic fine wire 1 made of an in-plane magnetic anisotropic material only needs to be applied with a magnetic field oriented in the direction of the fine wire, so that it is not necessary to provide the soft magnetic layer 53 and the nonmagnetic layer 54, and light modulation is performed. The part 20B can have a simpler structure.

  In addition, the magnetic head 55 has a structure in which writing is performed collectively in the writing area 1w of all the magnetic wires 1 in the magnetic wire group. This is because, in the spatial light modulator 10A according to the present invention, it is difficult to move the magnetic head 55 with respect to the light modulation unit 20B at a high speed, unlike the recording device that rotationally drives the magnetic disk. Even if these magnetic wires 1 have the same magnetization direction in the write region 1w, the magnetic wires 1 that have not been selected are not shifted in the magnetic domain, and therefore the pixel 4 of the magnetic wire 1 has the magnetization direction. Magnetic domains never reach.

  As described above, according to the spatial light modulator according to the second embodiment, it is possible to display an image without writing data in parallel with all the magnetic thin wires, and it can be driven with power saving. It can be a spatial light modulator. Furthermore, according to the spatial light modulator according to the modification of the second embodiment, a spatial light modulator having a simpler structure can be obtained.

[Third Embodiment]
A spatial light modulator according to the third embodiment will be described with reference to FIG. The spatial light modulator according to the third embodiment and its modification is the same as the spatial light modulator 10 (see FIGS. 1 to 5) according to the first embodiment or the second embodiment except for the light modulation units 20C and 20D. The configuration is the same as that of the spatial light modulator (see FIGS. 10 and 12), and the same elements are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 13A, the light modulating unit 20C has a structure in which the magnetic transfer film 3 is provided in contact with the upper surface of the magnetic wire 1 in the pixel region 1px in the light modulating unit 20 shown in FIG. . In such a spatial light modulator, light passes through the magnetic transfer film 3 from above, is reflected on the upper surface of the magnetic wire 1, and passes through the magnetic transfer film 3 again to be emitted. Therefore, the display device to which the spatial light modulator according to this embodiment is applied can have the same configuration as that of the spatial light modulator 10 according to the first embodiment shown in FIG. In addition, the spatial light modulator according to the present embodiment can be used as a transmissive spatial light modulator by making the magnetic wire 1 highly transmissive and the substrate 2 a transparent substrate, as in the first embodiment. Good.

(Magnetic transfer film)
The magnetic transfer film 3 is easily magnetized with an external magnetism, and is particularly strongly influenced by the magnetism of the magnetic material in contact therewith. Therefore, as shown in FIG. 13A, the magnetic transfer film 3 has the same magnetization in the region immediately above the magnetic domain formed in the magnetic wire 1 in the region where the magnetic wire 1 is in contact with the lower surface. A magnetic domain indicating a direction is formed, and a domain wall that divides the magnetic domain is generated. Therefore, if the magnetization direction in a certain region of the magnetic wire 1 changes due to writing or magnetic domain shift movement by applying a magnetic field or the like in the magnetic wire 1, the magnetization direction of the magnetic transfer film 3 immediately above the region correspondingly changes. Changes quickly. Therefore, when a pulse current is supplied to the magnetic wire 1, the magnetic domain apparently shifts in the magnetic transfer film 3 together with the magnetic wire 1. In this embodiment, the magnetic wire 1 is made of a perpendicular magnetic anisotropic material, but the magnetization direction of the magnetic wire 1 is similarly transferred to the magnetic transfer film 3 even if it is an in-plane magnetic anisotropic material. By laminating the magnetic wire 1 on the magnetic transfer film 3 having a large Faraday effect, the light reflected by the magnetic wire 1 is transmitted through the magnetic transfer film 3 and emitted, so that the optical rotation angle is increased and the difference in magnetization direction is caused. The difference in the direction of polarization of the outgoing light can be enlarged to improve the magnetic detection accuracy.

The magnetic transfer film 3 is made of an insulating magnetic material having a low coercive force and a large magneto-optical effect (a large Faraday rotation angle), and a material having a high transmittance is preferable. Specific examples of such a material include a magnetic garnet film such as yttrium iron garnet (Y ₃ Fe ₅ O ₁₂ : YIG), and in particular, a bismuth-substituted magnetic garnet (Y _{3 -X} Bi _x Fe ₅ O ₁₂ : Bi-YIG) is preferable because the Faraday rotation angle is as large as about 5 ° / μm (wavelength: 532 nm). The magnetic garnet film can be manufactured by, for example, forming a film on a Gd ₃ Ga ₅ O ₁₂ (gadolinium gallium garnet: GGG) single crystal substrate by a liquid phase epitaxy (LPE) method. Alternatively, the magnetic transfer film 3 is applied to a glass substrate or the like by a metal organic decomposition (MOD) method or a metal organic chemical vapor deposition (MODV) method, which is a kind of spin coating sintering method. Can also be formed. The film thickness of the magnetic transfer film 3 is not particularly limited, and the Faraday rotation angle can be proportionally increased as the thickness is increased. On the other hand, the light is absorbed and the emitted light is attenuated. About 1 to 2 μm is preferable. Since the substrate 2A for forming the magnetic transfer film 3 is a transparent substrate material, the formed magnetic transfer film 3 is cut out in accordance with the planar view shape of the pixel array 40 together with the substrate 2A, and the substrate 2A is turned up. Then, it may be attached on the magnetic thin wire 1 of the light modulator 20C. Specifically, in the manufacture of the light modulation unit 20C, the space between the magnetic thin wires 1 and 1 is filled with the insulating layer 6, and then the magnetic transfer film 3 is laminated thereon so as to be stuck thereon.

  The magnetic transfer film 3 may be formed at least in the region of the pixel region 1px (pixel array 40), or may be formed on the entire surface of the light modulation unit 20D as in the modification shown in FIG. As an example, the substrate 2A is replaced with the substrate 2A in the shape of the light modulation unit 20D, the magnetic transfer film 3 is formed on the entire surface, and the magnetic thin wires 1, 1,... Are formed on the magnetic transfer film 3. Alternatively, the magnetic transfer film 3 may be processed into the same planar view shape when the magnetic wire 1 is formed. In such a spatial light modulator, light is transmitted through the substrate 2A from below the light modulator 20D and is incident thereon. The light further passes through the magnetic transfer film 3, is reflected by the lower surface of the magnetic wire 1, passes through the magnetic transfer film 3 again, and is emitted. In addition, when the concave portion 1c is formed on the upper surface of the magnetic fine wire 1, light is reflected on the smooth lower surface of the magnetic fine wire 1, and therefore, irregular reflection is suppressed, which is preferable. Although the soft magnetic layer 53 and the like in the writing region 1w are formed on the magnetic thin wire 1, for example, the formed magnetic transfer film 3 is removed in the writing region 1w and the soft magnetic layer 1 is formed before the magnetic thin wire 1 is formed. 53 and the nonmagnetic layer 54, or the lower electrode 33, the magnetization fixed layer 51, and the intermediate layer 52 (see FIG. 13A) may be laminated. Further, the magnetic transfer film 3 may be provided in the light modulation unit 20A (see FIG. 9) of the spatial light modulator according to the modification of the first embodiment.

  As described above, according to the spatial light modulator according to the third embodiment and the modification thereof, the difference in the optical rotation angle due to the difference in the magnetization direction in the pixel becomes large. The spatial light modulator has excellent selectivity.

[Fourth Embodiment]
Writing to the magnetic fine wire 1 in pixel driving for the spatial light modulators 10, 10A and the like according to the first and second embodiments and the modifications thereof is performed in two magnetization directions based on each of binary data. However, the present invention is not limited to this, and the magnetic fine wire 1 may be set in one magnetization direction in advance so that only the other magnetization direction is used in writing. The configuration of such a spatial light modulator and the pixel driving method will be described with reference to FIGS.

  The spatial light modulator according to the fourth embodiment is the same as that of the spatial light modulator 10 (see FIGS. 1 and 5) except for the light modulation unit 20E and the data writing unit 50B (not shown). In the light modulation unit 20E, the same components as those in the light modulation unit 20 shown in FIG. Furthermore, as shown in FIG. 14A, the spatial light modulator according to this embodiment includes an initialization unit (initialization unit) 70 including an electromagnet 71 and the like opposed to the light modulation unit 20E.

  The light modulation unit 20E of the spatial light modulator according to this embodiment is formed on a transparent substrate 2A in the same manner as the light modulation unit 20D of the spatial light modulator according to the modification of the third embodiment shown in FIG. The magnetic fine wire 1 is formed on the surface, and light is incident from below. Further, the optical modulation unit 20E includes the magnetic thin wire 1 having a spin injection magnetization switching element structure formed in the writing region 1w, similar to the optical modulation unit 20 of the spatial light modulator 10 according to the first embodiment. The length of the writing area 1w in the thin line direction is formed so as to substantially coincide with the unit length Lb. Further, the light modulation unit 20E has the stacking order of the spin-injection magnetization reversal element structure in the writing region 1w opposite to that in the first embodiment, and the electrodes 31 and 32 are also connected to the lower surface of the magnetic wire 1, The same stacking order as in the first embodiment may be used. Furthermore, the light modulation unit 20E is a magnetic thin wire 1A having a bent shape in plan view, like the light modulation unit 20A (see FIG. 9) of the spatial light modulator according to the modification of the first embodiment, or the third embodiment. The magnetic transfer film 3 may be provided in the same manner as the light modulators 20C and 20D (see FIG. 13) of the spatial light modulator according to the embodiment.

(Initialization part)
The initialization unit 70 is controlled by the control unit 90 (see FIG. 5), and makes all the magnetic wires 1 of the light modulation unit 20E one of the two magnetization directions. This is called initialization of the magnetic wire 1, and in this embodiment, the magnetic wire 1 is set to a downward magnetization direction. The region of the magnetic wire 1 to be initialized is preferably the entire magnetic wire 1 as will be described later in the present embodiment. Further, the initialization of the magnetic wires 1 may be performed for one or a predetermined number of magnetic wires 1, but in particular, in the case where writing is performed simultaneously on all the magnetic wires 1 as in the first embodiment. Is preferably collectively applied to all of these magnetic wires 1. As described above, it is preferable to apply a magnetic field in order to simultaneously set the entire magnetic thin line 1 of the light modulation unit 20E to the same magnetization direction at the same time. In the present embodiment, the initialization unit 70 includes a magnetic field applying unit. As an electromagnet 71 provided to face the light modulator 20E, and an initialization current source 7 connected to the coil of the electromagnet 71.

  The electromagnet 71 is supplied with the initialization current Iinit from the initialization current source 7 and generates a magnetic field toward the light modulation unit 20E. When this magnetic field is applied, all the magnetic wires 1 of the light modulation unit 20E are directed downward. It becomes the magnetization direction. A known electromagnet can be applied to the electromagnet 71, and a magnetic field having a predetermined direction and strength is uniformly applied to each of the predetermined magnetic wires 1 (all magnetic wires 1 in the present embodiment) in the light modulation unit 20E. It is comprised so that it may apply to. In FIG. 14A, the electromagnet 71 is shown by showing only one magnetic wire 1 and is opposed to the magnetic wire 1. However, in the spatial light modulator according to the present embodiment, the light modulation unit One that is opposed to the entire 20E (the entire upper surface) is provided. However, the present invention is not limited to this, and the electromagnet 71 may be provided for each one or a predetermined number of the magnetic wires 1 depending on the specification, the size of the light modulation unit 20E (width and pitch of the magnetic wires 1), and the like. Good. The magnetic field applied by the electromagnet 71 only needs to be strong enough to exceed the coercive force of the magnetic wire 1 and to have a downward magnetization direction, and spin-injection magnetization reversal in the writing region 1w as in this embodiment. When the magnetization fixed layer 51 having an element structure is provided and writing is performed by spin injection magnetization reversal, it is preferable that the magnetization direction is the same (parallel) downward as the magnetization fixed layer 51. When the magnetic wire 1 is set to have a magnetization direction opposite (antiparallel) to the magnetization fixed layer 51, the magnetic field applied by the electromagnet 71 is made weaker than the coercivity of the magnetization fixed layer 51.

  The initialization of the magnetic wire 1 may be performed at least in the region from the one end on the connected side of the negative electrode 32 to at least the writing region 1w. However, as described above, in particular, the recess 1c (1c0) as in the present embodiment. In the magnetic thin wire 1 in which the magnetic thin wire 1 is formed, it is preferable that the entire magnetic thin wire 1 is used. The domain walls between the magnetic domains divided by random lengths remaining in the pixel area 1px and the like by being not initialized, or the domain walls generated between the areas that were not initialized and the areas that were not initialized are driving pixels. When the magnetic domain is shifted, there is a possibility that the moving distance may be shifted due to being locked by the recess 1c. Therefore, the entire magnetic thin wire 1 is made uniform in the magnetization direction so as not to generate a domain wall. Therefore, the electromagnet 71 is provided so as to face the entire light modulation unit 20E. In such a case, particularly in such a case, the light incident / exit side is not interfered with the light incident / exiting on the pixel region 1px. On the opposite side, it is provided above the light modulator 20E in this embodiment. In this embodiment, in FIG. 14A, the electromagnet 71 is an area from one end (left end) of the optical modulation unit 20E on the side where the negative electrode 32 is connected to the vicinity of the writing area 1w. Although the magnetic field is applied only in this region, the entire magnetic wire 1 is initialized.

(Data writing part)
The data writing unit 50B has the same configuration as the data writing unit 50 of the first embodiment except that it includes a write current source 5B instead of the write current source 5, and is controlled by the control unit 90. (See FIG. 5). The write current source 5B is connected to the write region 1w via the electrodes 33 and 34 in the same manner as the write current source 5, but supplies only one-value write current + Iw, that is, including the OFF state. Two outputs of + Iw, 0 are shown. Therefore, unlike the data writing unit 50 of the spatial light modulator 10 according to the first embodiment, the data writing unit 50B can be driven by a simple circuit that is only switched ON / OFF. In the present embodiment, the write current + Iw causes the magnetization direction of the magnetic wire 1 turned downward by the initialization unit 70 (electromagnet 71) to be turned upward by reversing the spin injection magnetization in the writing region 1w (antiparallel). To do).

(Pixel driving method)
A pixel driving method in the spatial light modulator according to the present embodiment will be described with reference to a flowchart shown in FIG. In FIG. 15, the same steps as those in the first embodiment shown in FIG.

  The controller 90 receives image data F1 (see FIG. 6B), generates and distributes pixel column data (see FIG. 6C), and in parallel with the steps (S20, S31, S32), The initialization unit 70 performs an initialization step S90 in which the magnetization direction of all the magnetic wires 1 is directed downward, that is, data “1” is written. At this time, the initialization current source 7 of the initialization unit 70 supplies the initialization current Iinit only for the time required for the magnetization direction of the magnetic wire 1 to be aligned downward, and thereafter stops the supply and initializes step S90. To complete. Although depending on the strength of the magnetic field applied by the electromagnet 71 and the size of the region, such as the coercive force and the number of the magnetic thin wires 1, the time for applying the magnetic field by supplying the initialization current Iinit, that is, the initialization time is several hundreds ps. It may be more than about. The initialization step S90 may be performed before the supply of the pulse current is started (S50) or until the first data determination (S67: i = 1) in the pixel column data writing step S60B. It may be simultaneous with the output command transmission (S10).

  The pixel column data writing step S60B is substantially the same as the pixel column data writing step S60 of the first embodiment described with reference to FIG. 7, but instead of data writing to the magnetic thin wire 1 (S63). Only when the data input to the data writing unit 50B is “0” (S67: Yes), the data “0” is written to the magnetic wire 1 (S63B), and the magnetic domain is shifted. (S64). On the other hand, when the data input to the data writing unit 50B is “1” (S67: No), only the magnetic domain shift movement (S64) is performed without performing any writing on the magnetic wire 1. In the pixel column data writing step S60B, a step S67 is added as compared with the first embodiment. However, in the data writing in the first embodiment (S63), the data writing unit 50 has a binary value. Depending on whether data “0” or “1” is input, different writing is performed based on the data, so that the process and processing time do not substantially increase.

  Here, data writing to the magnetic wire 1 (S63B) and magnetic domain shift movement (S64) will be described in detail with reference to FIG. In FIG. 14, only the substrate 2A and the insulating layer 6 are shown in FIG. 14 (a), and are omitted in FIGS. 14 (b) and 14 (c), but all show the light modulation section 20E having the same structure. The electromagnet 71 is opposed to the light modulation unit 20E. Here, as in the description of the first embodiment, a method of writing to the magnetic thin wire 1 (11) based on the pixel column data (see FIG. 6C) at the row address (0) will be described.

  As in the first embodiment, when the first data “0” of the pixel column data is input from the pixel column control unit 9 (91), the data writing unit 50B writes data from the built-in write current source 5B. Supply current + Iw. Therefore, as shown in FIG. 14B, a current Iw flows downward in the write region 1w of the magnetic wire 1, that is, in the direction perpendicular to the film surface from the magnetization fixed layer 51 side. In the region 1w, the spin injection magnetization is reversed to be antiparallel to the magnetization direction of the magnetization fixed layer 51. As a result, a magnetic domain having an upward magnetization direction (referred to as a magnetic domain D0; see FIG. 14C) is formed in the write area 1w, and domain walls DW1 and DW2 are generated so as to separate both sides of the magnetic domain D0 (S63B). At the same time, on the opposite side of the writing region 1w of the magnetic thin wire 1 from the pixel region 1px, a magnetic domain D1 is formed which is separated from the magnetic domain D0 by the domain wall DW2 and the magnetization direction remains downward at the time of initialization.

After the supply of the write current + Iw from the write current source 5B is stopped (OFF), the magnetic current 1 is pulsed with the scanning current Isc as the first current supply (one pulse) in the pulse current from the scanning current supply unit 80. is supplied by a time width t _H, as shown in FIG. 14 (c), the unit only shifts the moving distance of the length Lb with domain walls DW1, DW2 magnetic domain D0 sandwich it. As described above, since the length of the write area 1w in the thin line direction substantially coincides with the unit length Lb, the entire magnetic domain D0 comes to rest when it has left the write area 1w (S64). That is, the magnetic domain D1 reaches the write area 1w.

Here, in the magnetic wire 1, electrons having an upward spin opposite to the magnetic domain D 1 are discriminated by the outermost magnetic domain D 1 on the negative electrode 32 side into which electrons e ⁻ are injected. Only electrons with downward spin are injected. By injecting electrons having this downward spin, the magnetic domain D1 extends in the direction of the thin line as the domain wall DW2 shifts while maintaining the downward magnetization direction. Therefore, even if the magnetic domain shift movement (S64) is repeated by supplying the scanning current Isc in the magnetic thin wire 1, one downward magnetization is always provided from the end on the negative electrode 32 side of the magnetic thin wire 1 to the writing region 1w. That is, when the data is determined (S67), the write area 1w always exhibits downward magnetization.

  For the second data “1”, the write area 1w already shows downward magnetization, so there is no need to write, and when the data write unit 50B receives the data “1”, The write current source 5B is kept in the OFF state even during the current stop in the pulse current. When the scanning current Isc is again supplied from the scanning current source 8 as the next pulse in the pulse current to the magnetic wire 1, the domain walls DW1 and DW2 and the magnetic domain D0 sandwiched between them move the distance of the unit length Lb. (S64), and accordingly, the magnetic domain D1 extends by the same distance. This extended portion of the magnetic domain D1 becomes the corresponding pixel 4 at the stage where the shift movement (S70) of the magnetic domain is completed.

In this way, first, by writing the data “1” with the magnetization direction of the magnetic wire 1 downward, the actual writing is performed only when the data is “0” in the writing of each data. do it. However, since data “1” is not written, unlike the first embodiment (see FIGS. 4B and 4C), the data “1” is formed by writing data “0” to the write area 1w. The magnetic domain reaches the pixel region 1px (pixel 4) while maintaining the length of the writing region 1w in the fine line direction regardless of the unit length Lb (pulse width t _H ). Accordingly, it is most preferable that the writing area 1w has the length in the thin line direction coincident with the unit length Lb as described above, and is designed in a range corresponding to the required position accuracy with respect to the pixel of the magnetic domain.

  Compared with the first embodiment, the pixel driving method of the spatial light modulator according to the present embodiment has a processing time corresponding to one initialization step S90 each time an image of one frame is displayed on the pixel array 40. Except for addition before the start of supply of the pulse current (S50), it is the same as the timing chart shown in FIG. 8, and the increase in response time is very small. When the output of the write current source 5 in the timing chart shown in FIG. 8 is “−Iw”, the output of the write current source 5B is “0” in the present embodiment. Further, in the present embodiment, the initialization is performed for each frame. However, the present invention is not limited to this. For example, the setting for initialization is performed every predetermined number of frames in displaying a moving image, or only once when the spatial light modulator is activated. Also good.

(Modification)
The initialization unit 70 may be provided in the spatial light modulator 10A (see FIG. 10) according to the second embodiment in which writing is limited to a predetermined number of magnetic thin wires 1 in pixel driving. In pixel driving of such a spatial light modulator (see FIG. 11), the controller 90A selects all the magnetic wires 1 before selecting the first magnetic wire 1 in the magnetic wire group (S42: j = 1). Is initialized. Alternatively, when the region of the magnetic wire 1 to which the electromagnet 71 applies a magnetic field is limited and the magnetization direction in the pixel region 1px is not changed, the magnetic wire 1 is limited to the magnetic wire 1 every time the process is selected (step S42). It may be initialized.

  Furthermore, the initialization unit 70 may be provided in a spatial light modulator (see FIG. 12) according to a modification of the second embodiment to which magnetic field application is applied as a writing method. In this case, the write current source 5B is connected to the coil of the magnetic head 55, and the magnetic field applied to the magnetic wire 1 by the magnetic head 55 is only upward as shown in FIG. Here, as described above, the magnetic head 55 may be provided for each group of magnetic thin wires, and writing may be performed by applying a magnetic field to all the write regions 1w of all the magnetic thin wires 1 at a unit length. The magnetic field is applied only to the writing region 1w whose length in the fine line direction substantially matches Lb. In addition, since the data writing unit 50A writes to the writing area 1w of all the magnetic thin wires 1 for each magnetic thin wire group by the magnetic head 55, the pixel line is written for each magnetic thin wire 1 in the magnetic thin wire group. Prior to the determination of the first data in the data writing step S60B (see FIG. 15) (S67: i = 1), the magnetic domain is shifted by at least the unit length Lb, and the magnetic domain D1 reaches the writing area 1w. (See FIG. 14C).

  As described above, according to the spatial light modulator according to the fourth embodiment, it is not necessary to apply a complicated drive circuit for outputting a current that can be positively and negatively inverted to the writing unit, and thus the pixels are further miniaturized. However, it is possible to easily provide the writing means for each of the fine magnetic wires having a narrow pitch. In particular, when spin-injection magnetization reversal is applied as a writing method, the magnitude (absolute value) of each spin-injection magnetization reversal current that is parallel and anti-parallel differs for the spin-injection magnetization reversal structure in the writing region. However, it is not necessary to apply a more complicated driving circuit to the writing means, and it is not necessary to provide a spin injection magnetization reversal structure in which the magnitudes of the spin injection magnetization reversal currents are uniform.

In order to confirm the effect of the present invention, a sample simulating the light modulation unit (see FIGS. 2 and 3) of the spatial light modulator according to the first embodiment was produced, and the formed magnetic domains were observed. A Si substrate whose surface was thermally oxidized was used as a substrate 2 and an insulating layer 6 (thermal oxide film: SiO ₂ ), and a magnetic wire 1 was formed by a damascene method. That is, a linear groove having a length of 10 μm is formed in the thermal oxide film at a constant interval by the RIE method, and a perpendicular magnetic anisotropic material [Co (0.3 nm) / Pd (1.2 nm) is formed thereon. ] × 30 multilayer film (total thickness 45 nm) was formed, and the Co / Pd multilayer film other than in the groove was removed by CMP to form the magnetic thin wire 1 as a sample. By changing the width of the groove, three types of magnetic wires having a width of 150 nm (1 μm pitch), a width of 250 nm (1.5 μm pitch), and a width of 500 nm (1.5 μm pitch) were formed.

  As an initialization, a magnetic field of 10 kG was applied upward (from the substrate 2 side toward the magnetic wire 1) to saturate the entire magnetization of all the magnetic wires (with a uniform magnetization direction). After that, a downward magnetic field of 0.6 kG, which is slightly smaller than the coercive force of the magnetic wire (Co / Pd multilayer film), was applied to form a plurality of magnetic domains in each magnetic wire. The surface of this sample was imaged and observed with a magnetic force microscope (MFM). In the MFM image photograph shown in FIG. 16, the magnetic thin line shows white / black contrast for each magnetic domain depending on whether the magnetization direction is upward or downward. As shown in FIGS. 16 (a) and 16 (b), it is confirmed that the magnetic domains of 150 nm and 250 nm in width are divided only in the direction of the thin line, and a plurality of magnetic domains are formed along the direction of the thin line. It was done. In particular, in the case of a magnetic thin wire having a width of 150 nm, a boundary line (domain wall) separating magnetic domains is generated almost perpendicularly to the thin wire direction, the magnetic domain has a rectangular shape in plan view, and a minute magnetic domain having a minimum length of about 30 nm is formed. It was done. From this, it can be said that the magnetic thin wire 1 having a sufficiently narrow width can easily show a uniform magnetization direction stably in one pixel 4. On the other hand, as shown in FIG. 16C, in the magnetic thin wire having a width of 500 nm, the magnetic domain may be divided in the width direction only by applying a magnetic field from the outside.

  In order to confirm the effect of the present invention, the spatial light modulator according to the first embodiment (see FIG. 2, FIG. 3, FIG. 7, FIG. 8) has a full high-definition pixel count, and a simulation using a computer is performed. The response time was obtained. That is, the number of pixels of the spatial light modulator in the present embodiment is horizontal 1920 × vertical 1080, and the fine wire direction of the magnetic fine wire 1 is the horizontal direction. The pixel size was 250 nm on a side. Therefore, the number of magnetic thin wires 1 provided in the spatial light modulator is 1080 and the pitch is 250 nm. In one magnetic thin wire 1, the number of pixels 4 is 1920 and the unit length Lb is 250 nm. Therefore, the length of the pixel region 1px is 250 nm × 1920 = 480 μm. The interval between the writing area 1w and the pixel area 1px is 2 μm, that is, the length corresponding to 80 pixels 4 is set. The width and thickness of the magnetic wire 1 are the same as one of the samples of Example 1, and are 150 nm wide and 45 nm thick. That is, the pixel 4 has an aperture ratio of 0.6.

It is assumed that a pulse current of 9.45 mA DC current is supplied to such a magnetic wire 1. The current density is 1.4 × 10 ¹² A / m ² , and the moving speed of the magnetic wall of the magnetic wire 1 by this pulse current is 40 m / s (see Non-Patent Document 1).

The moving time t _SC of the domain length Lb by the current supply of the pulse current of the magnetic wire 1 is 6.25 ns, and the domain wall and the magnetic domain are moved by the distance of the unit length Lb by one current supply in the pulse current. Therefore, the pulse width t _H is set to 6.25 ns. Further, assuming that the stop time t _{L is} 6.25 ns (duty ratio: 50%), the pulse period is 12.5 ns. Accordingly, the response time of the spatial light modulator according to the present embodiment is 12.5 ns × (1920 + 80) = 25 μs. Since the response time of the spatial light modulator using the current liquid crystal is 20 to 30 ms, the speed can be greatly increased. Since the spatial light modulator according to the present embodiment has a sufficiently short response time for 1/60 second (≈16.7 ms) of one frame in full high vision, it is sufficient for displaying such a moving image. It can be said that it has performance.

  As mentioned above, although the form for implementing this invention was described, this invention is not limited to these embodiment, A various change is possible in the range shown to the claim.

10, 10A Spatial light modulator 1, 1A, 11-18 Magnetic thin wire 1c, 1c0-1c8 Recessed part 1px Pixel area 1w Write area 20, 20A, 20B, 20C, 20D, 20E Light modulator 2, 2A Substrate 3 Magnetic transfer Membrane 31 Positive electrode 32 Negative electrode 40 Pixel array 4 Pixel 50, 50A Data writing unit (writing means)
5,5B Write current source 55 Magnetic head 70 Initialization unit (initialization means)
71 Electromagnet 7 Initialization Current Source 8 Scanning Current Source 90, 90A Control Unit D0, D1 Magnetic Domain DW1, DW2, DW3 Domain Wall Lb Unit Length

Claims (10)

A pixel array in which pixels are arranged in a matrix, and pixel driving means for causing each of the pixels in the pixel array to have one of two different magnetization directions based on binary data input to the pixel. A spatial light modulator,
The pixel array is formed by arranging a plurality of magnetic fine wires made of a magnetic material formed in a thin line shape along the arrangement direction with a plurality of pixels arranged in a line,
The magnetic thin line is provided at a position designated in advance so as to divide a pixel region including the plurality of pixels and a writing region in a thin line direction,
The pixel driving means includes a writing means for causing the magnetic thin wire to have a predetermined magnetization direction in the writing region;
A current supply means for supplying a pulse current that is connected to both ends of the magnetic wire and intermittently moves a magnetic domain formed in the magnetic wire together with a domain wall that delimits the magnetic domain;
When the current in the pulse current supplied to the magnetic wire is stopped, the writing means is controlled to form the magnetic wire in a magnetization direction based on data of a predetermined pixel in the writing region. A spatial light modulator comprising: control means for controlling the current supply means so as to cause the magnetic domain to reach the predetermined pixel.   2. The spatial light modulator according to claim 1, wherein the writing unit applies a magnetic field to the writing region of the magnetic wire to make a predetermined magnetization direction. 3. The magnetic thin wire has a spin-injection magnetization reversal element structure in the writing region,
2. The space according to claim 1, wherein the writing means supplies the current in a direction perpendicular to the film surface to the spin-injection magnetization switching element structure so that the magnetic thin wire has a predetermined magnetization direction. Light modulator. The pixel driving unit includes an initialization unit that makes at least one of the two magnetization directions from the writing region of the magnetic thin wire to an end opposite to the side where the pixel region is provided,
4. The spatial light modulator according to claim 1, wherein the writing unit sets the magnetic thin wire only to the other of the two magnetization directions in the writing region. 5. .   5. The spatial light modulator according to claim 1, wherein the magnetic thin line is formed in a shape confined at one or more points on a boundary dividing the pixel in the thin line direction. 6. .   5. The spatial light modulation according to claim 1, wherein the magnetic thin line is formed in a thin line shape that is bent at one or more positions on a boundary that divides the pixel in the thin line direction. vessel. The pixel array includes a magnetic transfer film in contact with the magnetic thin wire,
The spatial light modulator according to claim 1, wherein light is incident on the magnetic wire through the magnetic transfer film. Spatial light comprising a plurality of pixels arranged in a line and a pixel array in which a plurality of magnetic thin wires made of a magnetic material formed in a thin line shape along the arrangement direction are arranged in parallel to form pixels. In the modulator, the pixel driving method of the spatial light modulator, wherein each pixel of the pixel array is set to one of two different magnetization directions based on binary data input to the pixel,
A pixel selection step of selecting one pixel in the order in which the plurality of pixels provided in the magnetic thin line are arranged;
A writing step in which the magnetic thin line is made a magnetization direction based on data of the selected one pixel in a writing area provided in advance by dividing the magnetic thin line from the region including the plurality of pixels;
A magnetic domain moving step of moving a magnetic domain formed in the magnetic thin line from the writing region to a region including the plurality of pixels in a thin line direction by a distance corresponding to the length of one of the pixels. Repeat in order to make all the pixels provided in the magnetic wire a magnetization direction based on data,
For each of the plurality of magnetic thin wires arranged side by side, by supplying a pulse current in which the magnetic domains formed in the magnetic thin wires move intermittently with the domain walls that delimit the magnetic domains in the direction of the thin wires, A pixel driving method of a spatial light modulator, wherein the pixel selecting step and the writing step are performed when the current in the pulse current is stopped, and the magnetic domain moving step is performed when a current is supplied in the pulse current. Before performing the writing step on the first of the arranged pixels, at least one of the two magnetization directions extends from the writing region to the end opposite to the side where the pixel region is provided. Perform the initialization process to
9. In each of the writing steps, when the magnetization direction based on the data of the selected one pixel is the same as the one magnetization direction, the magnetization direction of the magnetic wire is not changed. A pixel driving method of the spatial light modulator described in 1.   The spatial light modulator pixel driving method according to claim 8, wherein each of the steps is performed in parallel by supplying a common pulse current to the two or more magnetic thin wires. .