JP2011237598A - Light modulation element, spatial light modulator, image generation device, image display device, and optical switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light modulation element having a large rotation angle of a polarization plane and capable of downsizing.SOLUTION: A grid member 304 has five linear members made of Al that are disposed along an X axis direction with a pitch of equal to or less than half of a wavelength of an incident light, and linear polarized light having an electric field vector oscillates along a direction parallel to the X axis direction is incident on the linear members. When current is supplied to a line-shaped electrode in the X direction and a line-shaped electrode in the Y direction, a magnetic field is applied onto the grid member and the incident light is emitted from the grid member while the polarization direction thereof performs Faraday rotation of +θor Faraday rotation of -θ. An analyzer 309 makes the light that has performed Faraday rotation of +θtransmit and the light that has performed Faraday rotation of -θshade.

Description

  The present invention relates to a light modulation element, a spatial light modulator, an image generation apparatus, an image display apparatus, and an optical switch. More specifically, the present invention relates to a light modulation element using a magneto-optic effect, and a spatial light modulation having a plurality of the light modulation elements. The present invention relates to a display device, an image display device having the spatial light modulator, and an optical switch having the light modulation element.

  In products that involve optical information processing such as cameras and projectors, a spatial light modulator (SLM) that controls the phase and amplitude of propagating light is a key device that displays an image. Currently, liquid crystal type and MEMS (Micro Electro Mechanical System) type SLMs are in practical use.

  In recent years, a further increase in response speed has been required for SLMs. However, in the liquid crystal type that controls the orientation of molecules and the MEMS type that changes the angle of the mirror, the response speed remains at the microsecond level, and in order to achieve a further increase in the response speed, these are different in principle. It was necessary to develop a spatial light modulator.

  By the way, in principle, there is a magneto-optical method as a method having a response speed of nanoseconds to sub-nanoseconds. The effect of rotating the polarization plane of linearly polarized light when a magnetic field is applied to a substance is called a magneto-optic effect. In particular, when it affects transmitted light, it is called the Faraday effect, and when it affects reflected light, it is called the magnetic Kerr effect. For example, high-speed switching is enabled by utilizing the fact that the magnetization reversal speed of the magnetic moment of the magnetic thin film is from nanoseconds to subnanoseconds.

  Spatial light modulators utilizing the magneto-optic effect are disclosed in Non-Patent Document 1, Patent Documents 1-8, and the like.

  Patent Document 8 discloses a display device, a holography device, and a hologram recording device using an optical modulator.

  Further, Patent Document 9 discloses a hologram data recording / reproducing apparatus using an optical modulator.

  By the way, Patent Document 10 discloses a substrate having a first surface and a refractive index, a region on the first surface of the substrate, a region having a refractive index smaller than the refractive index of the substrate, and the region. A broadband wire grid polarizer is disclosed comprising an array of parallel elongated elements disposed on top of each other.

  Further, in Patent Document 11, a magneto-optical crystal is embedded in a recess formed at each pixel location on the surface of a non-magnetic substrate, and the magneto-optical crystal is magnetized by a partition wall integral with the non-magnetic substrate at the inter-pixel gap position. A magneto-optic device is disclosed that is isolated in the form of a planar surface.

  Further, in Patent Document 12, a surface layer whose crystallinity is deteriorated by heat treatment is partially formed on a substrate having good crystallinity, and a magnetic film is epitaxially grown on the surface layer. A method of manufacturing a magneto-optical device is disclosed in which the crystal structure of the magnetic film is two-dimensionally different between the part and the other part.

  Patent Document 13 discloses a magneto-optical body including a composite magnetic thin film formed by combining metal nanoparticles inside a translucent magnetic thin film.

  Further, Patent Document 14 has a fine particle arrangement layer containing at least regularly arranged metal magnetic fine particles on a non-magnetic support, and generates a magnetization by applying a magnetic field from the outside to the metal magnetic fine particles. In addition, there is disclosed a magneto-optical element that receives linearly polarized light and increases the magneto-optical effect by the interaction between the incident light on the metal magnetic fine particles and the surface plasmon vibration of the metal.

  Patent Document 15 discloses an optical switch including at least a magnetic head layer, a layer having a magneto-optical effect, and a polarizer layer as constituent layers.

  However, the spatial light modulators disclosed in Patent Documents 1 to 8 have the inconvenience that the rotation angle of the polarization plane is small and further downsizing is difficult.

  The present invention has been made under such circumstances, and a first object of the present invention is to provide a light modulation element that has a large rotation angle of a polarization plane and can be miniaturized.

  A second object of the present invention is to provide a spatial light modulator capable of high-density light modulation with a large rotation angle of the polarization plane.

  A third object of the present invention is to provide an image generation apparatus capable of generating a high-definition image.

  A fourth object of the present invention is to provide an image display device capable of displaying a high-definition image.

  A fifth object of the present invention is to provide an optical switch having a small size and excellent response characteristics.

  From a first viewpoint, the present invention is a light modulation element that modulates incident light, and linearly polarized light whose polarization direction is the first direction is incident, and any one of gold, silver, copper, platinum, and aluminum is used. A plurality of linear members arranged in a longitudinal direction along a second direction perpendicular to the first direction and arranged at intervals of half or less of the wavelength of the incident light along the first direction; A magnetic field applying mechanism for applying a magnetic field to the linear member; an analyzer which is disposed on an optical path of light via the plurality of linear members and selectively transmits or blocks light when the magnetic field is applied And a light modulation element.

  According to this, the rotation angle of the polarization plane is large, and downsizing can be achieved.

  From a second viewpoint, the present invention is a spatial light modulator in which a plurality of light modulation elements of the present invention are two-dimensionally arranged.

  According to this, the rotation angle of the polarization plane is large, and high-density light modulation can be performed.

  From a third aspect, the present invention is an image generation device that generates an image according to image information, the light source; and the spatial light modulation of the present invention disposed on the optical path of a light beam emitted from the light source. And a control device that individually controls a plurality of magnetic field application mechanisms of the spatial light modulator according to the image information.

  According to this, since the spatial light modulator of the present invention is provided, a high-definition image can be generated.

  According to a fourth aspect of the present invention, there is provided an image comprising: an image generating device of the present invention that generates an image according to image information; and a projection optical system that projects a light beam from the image generating device onto a projection surface. It is a display device.

  According to this, since the image generation apparatus of the present invention is provided, as a result, a high-definition image can be displayed.

  According to a fifth aspect of the present invention, there is provided an optical switch for turning on / off light transmission, the optical modulation element of the present invention; and a control for controlling a magnetic field application mechanism of the light modulation element according to the on / off information And an optical switch.

  According to this, a small and excellent response characteristic can be obtained.

It is a block diagram for demonstrating schematic structure of the projector system which concerns on one Embodiment of this invention. It is a figure for demonstrating the structure of the projector apparatus in FIG. It is a figure for demonstrating the structure of the image generation apparatus in FIG. It is a figure for demonstrating the spatial light modulator contained in the image forming panel in FIG. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a figure for demonstrating the light which injects into a spatial light modulator. FIG. 8A is a diagram for explaining a grid member of the spatial light modulator, and FIG. 8B is a cross-sectional view taken along line AA of FIG. 8A. It is a figure for demonstrating the selected pixel. FIGS. 10A and 10B are diagrams for explaining the relationship between the current supplied to each line-shaped electrode and the magnetic field applied to the grid member. 11A and 11B are diagrams for explaining the relationship between the magnetic field applied to the grid member and the Faraday rotation, respectively. FIG. 12A and FIG. 12B are diagrams for explaining the operation of the analyzer. It is a figure for demonstrating the light which permeate | transmits a spatial light modulator, and the light shielded with a spatial light modulator. It is a figure for demonstrating the relationship between the magnetic field applied to a grid member, and a rotation angle. It is a figure for demonstrating the relationship between the magnetic field applied to a grid member, and ellipticity. It is a figure for demonstrating a light modulation element. It is a figure for demonstrating the modification 1 of a grid member. It is a figure for demonstrating the modification 2 of a grid member. It is a figure for demonstrating the modification of an image generation apparatus. FIG. 20 is a diagram for describing a spatial light modulator included in the image forming panel in FIG. 19. FIG. 20 is a diagram (No. 1) for describing an operation of an analyzer in the spatial light modulator of FIG. 19; FIG. 20 is a diagram (No. 2) for explaining the operation of the analyzer in the spatial light modulator of FIG. 19; It is a figure for demonstrating the modification 3 of a grid member. It is a figure for demonstrating an optical switch.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a projector system 10 as an image display system according to an embodiment.

  The projector system 10 includes a projector device 1000 as an image display device and a host device 2000.

  The host device 2000 is an image information management device that sends information about an image to the projector device 1000, and a personal computer can be used as an example. The host device 2000 can send information related to the image sent via the network and information related to the image acquired (downloaded) via the network to the projector device 1000.

  The projector device 1000 is a front projection type projector device that displays an enlarged image on a screen 1100 as a projection surface based on information about an image sent from the host device 2000.

  As shown in FIG. 2 as an example, the projector apparatus 1000 includes an image generation apparatus 100, a projection optical system 200, and the like. In this specification, in the XYZ three-dimensional orthogonal coordinate system, the plane on which the projector apparatus 1000 is placed is the XZ plane, and the direction of the light beam emitted from the image generation apparatus 100 toward the projection optical system 200 is the Z-axis direction. Will be described.

  Projection light traveling from the projection optical system 200 toward the screen 1100 is emitted through an opening provided in the housing.

  As shown in FIG. 3 as an example, the image generating apparatus 100 includes a light source 101, a reflector 102, a color wheel 103, a wheel driving device 104, a rod integrator 105, an illumination optical system 106, an image forming panel 107, a microlens array 108, A communication interface 131, a main control device 132, and the like are included.

  The communication interface 131 controls communication between the main control device 132 and the host device 2000.

  The main control device 132 controls the light source 101, the wheel driving device 104, and the image forming panel 107 in accordance with the information regarding the image received via the communication interface 131.

  As the light source 101, a lamp light source such as a xenon lamp, a halogen lamp, a metal halide lamp, or an ultrahigh pressure mercury lamp can be used. A solid light source such as an LED, LD, or semiconductor laser may be used. Here, as an example, the wavelength of light emitted from the light source 101 is 690 nm.

  The light source 101 is turned on according to an instruction from the main controller 132.

  The reflector 102 condenses the light beam emitted from the light source 101.

  The color wheel 103 is a disk-shaped member having red, blue, and green filters, and is disposed in the vicinity of the condensing position of the light beam from the reflector 102.

  The wheel driving device 104 is a device for rotating the color wheel 103. The wheel driving device 104 rotates the color wheel 103 according to the color information of the image from the main control device 132 so that the light flux from the reflector 102 passes through the filter corresponding to the color information.

  The rod integrator 105 makes the light quantity distribution of the light beam that has passed through the color wheel 103 uniform.

  The illumination optical system 106 efficiently guides the optical path of the light beam via the rod integrator 105 to the image forming panel 107.

  The light beam from the illumination optical system 106 illuminates the image forming panel 107 via the microlens array 108. This illumination light is modulated by the image forming panel 107 in accordance with the image information.

  The light beam transmitted through the image forming panel 107 is emitted to the projection optical system 200.

  The projection optical system 200 displays an enlarged image of the image on the image forming panel 107 on the screen 1100.

  Next, the image forming panel 107 will be described.

  The image forming panel 107 includes a spatial light modulator 300 shown in FIGS. 4 to 6 as an example.

  The spatial light modulator 300 includes a glass substrate 301, a resin layer 302, a polarizer 303, a plurality of grid members 304, a plurality of Y-direction line electrodes 305, an insulating layer 306, a glass substrate 307, a resin layer 308, and an analyzer 309. , A glass substrate 310, a plurality of X-direction line electrodes 311 and the like. 4 is a plan view of the spatial light modulator 300, FIG. 5 is a cross-sectional view taken along the line AA in FIG. 4, and FIG. 6 is a cross-sectional view taken along the line BB in FIG.

  Here, a quartz substrate having a thickness of about 0.5 mm to 1 mm is used as each glass substrate. Moreover, the photocurable resin is used for the resin material of each resin layer.

  A resin layer 302 is provided on the + Z side of the glass substrate 301, and a polarizer 303 is provided on the + Z side of the resin layer 302.

An insulating layer 306 is provided on the + Z side of the polarizer 303, and a glass substrate 307 is provided on the + Z side of the insulating layer 306. Insulating layer 306 is a layer formed of SiO _2. Note that the thickness of the insulating layer 306 is about 1 μm.

  A resin layer 308 is provided on the + Z side of the glass substrate 307, an analyzer 309 is provided on the + Z side of the resin layer 308, and a glass substrate 310 is provided on the + Z side of the analyzer 309.

  And it arrange | positions so that light may inject from the -Z side of the glass substrate 301 (refer FIG. 7).

  The polarizer 303 converts incident light that has passed through the glass substrate 301 and the resin layer 302 into linearly polarized light whose electric field vector oscillation direction is parallel to the X-axis direction.

  The plurality of X-direction line electrodes 311 are formed on the surface of the glass substrate 307 on the + Z side. The plurality of Y-direction line electrodes 305 are formed in the insulating layer 306. Therefore, the X-direction line-shaped electrode 311 and the Y-direction line-shaped electrode 305 are not in contact with each other. Each line-like electrode is made of indium tin oxide (ITO), and its line width is about 80 nm.

  Each grid member 304 is a region surrounded by the X-direction line-shaped electrode 311 and the Y-direction line-shaped electrode 305 in a plan view, and is formed on the surface on the −Z side of the glass substrate 307. Here, 124 × 124 grid members 304 are formed in a matrix with the X-axis direction and the Y-axis direction as the arrangement direction. One grid member 304 corresponds to one pixel in the image. That is, here, one image is composed of 15376 pixels.

  As shown in FIG. 8A as an example, each grid member 304 has five Al (aluminum) linear members extending in the Y-axis direction and arranged at equal intervals in the X-axis direction. Yes. Between the linear members, silicon oxide (SiOx) is filled.

  FIG. 8B is a cross-sectional view taken along the line AA in FIG. Here, the symbol L1 (width) in FIG. 8B is about 70 nm, the symbol L2 (thickness) is about 150 nm, and the symbol L3 (arrangement pitch) is about 150 nm. The arrangement pitch L3 is smaller than half of the wavelength of incident light (here, 690 nm). Such a lattice structure of fine metal wires is called a wire-grid structure.

  As an example, as shown in FIG. 9, a pixel can be specified by selecting an X-direction line-shaped electrode 311 and a Y-direction line-shaped electrode 305. When a current is passed through each selected line-shaped electrode, a magnetic field is applied to the grid member 304 included in the specified pixel. In addition, the code | symbol L5 in FIG. 9 is about 1 micrometer.

  At this time, as shown in FIG. 10A and FIG. 10B as an example, the direction of the magnetic field applied to the grid member 304 can be defined by the direction of the current flowing through each line electrode.

When the magnetic field is applied to the linearly polarized light transmitted through the grid member 304, the plane of polarization is rotated (Faraday rotation). Here, Faraday rotation of + θ _F occurs when a magnetic field in the positive direction is applied (see FIG. 11A), and Faraday rotation of −θ _F occurs when a magnetic field in the negative direction is applied (FIG. 11). (See (B)).

Analyzer 309 transmits the light that the Faraday rotation of + theta _F, is set so as to shield the light Faraday rotation of - [theta] _F.

  Therefore, when a positive magnetic field is applied to the grid member 304, the light incident on the grid member 304 is transmitted through the analyzer 309 as shown in FIG. On the other hand, when a negative magnetic field is applied to the grid member 304, the light incident on the grid member 304 is blocked by the analyzer 309 as shown in FIG.

  Therefore, when a current is supplied to the X-direction line electrode 311 and the Y-direction line electrode 305 so that a positive magnetic field is applied to the grid member 304, the light incident on the grid member 304 is directly subjected to the spatial light modulator 300. Is injected from. On the other hand, when current is supplied to the X-direction line electrode 311 and the Y-direction line electrode 305 so that a negative magnetic field is applied to the grid member 304, the light incident on the grid member 304 is transmitted from the spatial light modulator 300. Not fired.

  Therefore, light can be transmitted only by a designated pixel among the plurality of pixels (see FIG. 13).

  Therefore, the main control device 132 determines the grid member 304 to apply a positive magnetic field and the grid member 304 to apply a negative magnetic field according to image information, and determines the determination result for 15376 grid members 304. Based on this, a current is supplied to each line electrode.

  Thereby, the light modulated according to the image information is emitted from the image generation apparatus 100 toward the projection optical system 200.

  The projection optical system 200 includes a plurality of lenses, mirrors, diaphragms, and the like, and enlarges the light from the image generation apparatus 100 at a specified magnification and projects the light onto the screen 1100.

  FIG. 14 shows the relationship between the magnetic field applied to the grid member 304 and the rotation angle of the polarization plane. There is a linear relationship between the applied magnetic field and the rotation angle of the polarization plane. The slope of the straight line representing the linearity is -0.34 [deg. / KOe].

  For example, if the positive magnetic field is 10 kOe and the negative magnetic field is −10 kOe, the difference in rotation angle is about 7 °.

  FIG. 15 shows the relationship between the magnetic field applied to the grid member 304 and the ellipticity. There is a linear relationship between the applied magnetic field and the ellipticity. The slope of the straight line representing the linearity is -0.52 [deg. / KOe]. For example, if the applied magnetic field is 10 kOe, the ellipticity is −5.2 °. The ellipticity can be a rotation angle if a λ / 4 plate is used.

  The relationship between the applied magnetic field, the rotation angle of the polarization plane, and the ellipticity varies depending on the L1 (width), the L2 (thickness), and the L3 (arrangement pitch). Therefore, it is possible to design according to the application.

  Here, the supply current to each line electrode suitable for applying the positive electric field and the negative electric field to the designated grid member 304 was obtained by simulation using a computer. In FIGS. 11A and 11B, for easy understanding, Faraday rotation on a glass substrate is not considered, but a material having relatively large Faraday rotation such as quartz is used as the substrate. In some cases, it is necessary to consider Faraday rotation on the glass substrate.

  That is, the magnitude of the current flowing through the line-shaped electrode is obtained by simulation so that a magnetic field is generated around it, and is synchronized with one grid member 304 in the XY directions so that the generated magnetic field in the horizontal direction is obtained. Controlled.

  Here, the grid member 304 is made of aluminum having a major axis and a minor axis, and has a magnetic field dependency of modulation characteristics (rotation angle, ellipticity). And since the grid member 304 is a wire grid structure, the magnetic field dependence of a modulation characteristic (rotation angle, ellipticity) is strong. That is, the inclination in FIGS. 14 and 15 is large.

  In addition, since the arrangement pitch of the plurality of linear members is about several tens to several hundreds of nanometers and is half or less of the wavelength of incident light, the size of one pixel can be reduced. Therefore, the image generation apparatus 100 can generate a high-definition image.

  Next, a method for manufacturing the spatial light modulator 300 will be described.

  First, a quartz substrate subjected to surface polishing was prepared. This serves as a support for the grid member. And ITO and the grid member were formed on the quartz substrate using the vapor deposition apparatus. Next, after forming the mask, a pattern was produced using a reactive etching apparatus. In principle, a focused ion beam that scrapes the sample by repelling atoms on the sample surface with a Ga ion beam can also be produced. Thereafter, the space between the microstructures was filled with silicon oxide, and processing and film formation were repeated again to produce each line electrode. Thereafter, the polarizer and the analyzer were fixed using a photocurable resin.

  As is clear from the above description, in the spatial light modulator 300 according to this embodiment, the light modulation element of the present invention is configured by a portion corresponding to one pixel (see FIG. 16). A plurality of linear members are configured by the grid member 304, and a magnetic field application mechanism is configured by the X-direction line-shaped electrode 311 and the Y-direction line-shaped electrode 305. The main control device 132 constitutes a control device in the image generation device of the present invention.

  That is, in the spatial light modulator 300, a plurality of light modulation elements are two-dimensionally arranged.

  As described above, according to the spatial light modulator 300 according to the present embodiment, the glass substrate 301, the resin layer 302, the polarizer 303, the plurality of grid members 304, the plurality of Y-direction line electrodes 305, the insulating layer 306, A glass substrate 307, a resin layer 308, an analyzer 309, a glass substrate 310, a plurality of X-direction line electrodes 311 and the like are included.

  The polarizer 303 converts incident light into linearly polarized light whose electric field vector oscillation direction is parallel to the X-axis direction.

  Each grid member 304 has five linear members made of Al (aluminum) that receive light through the polarizer 303 and extend in the Y-axis direction. The five linear members are arranged along the X-axis direction at a pitch equal to or less than half the wavelength of incident light.

When a current is supplied to the X-direction line electrode 311 and the Y-direction line electrode 305, a positive magnetic field or a negative magnetic field is applied to the grid member 304. Thus, light incident on the grid member 304 has its polarization direction, + theta with Faraday rotation of the Faraday rotation or - [theta] _F of _F, transmitted through the grid member 304.

The analyzer 309 is set to transmit + _F Faraday-rotated light and block -θ _F Faraday-rotated light.

  Therefore, by supplying current to the X-direction line electrode 311 and the Y-direction line electrode 305 so that a positive magnetic field is applied to the grid member 304, the light incident on the grid member 304 is converted into a spatial light modulator. 300 can be injected. On the other hand, by supplying a current to the X-direction line electrode 311 and the Y-direction line electrode 305 so that a negative magnetic field is applied to the grid member 304, the light incident on the grid member 304 is converted into a spatial light modulator. It is possible to prevent injection from 300.

  In this case, the rotation angle of the polarization plane can be made larger than before, and incident light can be reliably modulated. Also, light modulation can be performed at high speed. Furthermore, the size of one pixel, that is, the size of the light modulation element can be reduced.

  In the spatial light modulator 300, since a plurality of light modulation elements are two-dimensionally arranged, the rotation angle of the polarization plane is large and high-density light modulation is possible.

  Moreover, since the linear member of the grid member 304 is made of Al (aluminum), light absorption by the grid member 304 can be suppressed. That is, the optical loss in the spatial light modulator 300 can be minimized.

  Moreover, since it does not contain an organic material, it is excellent in durability.

  Moreover, it was excellent in mass productivity and a high production yield could be obtained.

  Here, when a magnetic field in a direction perpendicular to the glass substrate is applied to the wire grid structure, the modulation characteristics (rotation angle, ellipticity) of incident light change according to the applied magnetic field. ing. At this time, even if the linear member is not a magnetic material, the modulation characteristics (rotation angle, ellipticity) of incident light change linearly with respect to the applied magnetic field. In particular, the change is large in the light transmitted through the wire grid structure.

  In the conventional spatial light modulator, the rotation angle of the polarization plane is small, and as a result, the modulation accuracy (S / N ratio) is low. However, in the spatial light modulator 300, a higher modulation accuracy (S / N ratio) than before can be obtained.

  The image generation apparatus 100 according to the present embodiment includes the spatial light modulator 300, so that a high-definition image can be generated.

  Further, according to the projector apparatus 1000 according to the present embodiment, since the image generating apparatus 100 is provided, as a result, a high-definition image can be displayed on the screen.

  In the above embodiment, the case where each grid member 304 includes five linear members has been described, but the present invention is not limited to this (see FIG. 17).

  For example, if the number of linear members included in one grid member is reduced without changing the dimensions of the linear members, the number of pixels can be increased as compared to the above embodiment. That is, the image generation device can generate a higher definition image.

  Conversely, if the number of linear members included in one grid member is increased without changing the dimensions of the linear members, the size of one pixel increases and the light intensity per pixel can be increased. .

  Therefore, the number of linear members included in one grid member may be set according to the required resolution and the light intensity per pixel.

  Further, in the above-described embodiment, each linear member of the grid member 304 may have a discontinuous shape that is broken in the middle of the Y-axis direction as illustrated in FIG. 18 as an example. However, the continuous shape has a larger slope in the relationship between the modulation characteristics (rotation angle, ellipticity) and the applied magnetic field.

  Moreover, although the said embodiment demonstrated each linear member of the grid member 304 made from Al (aluminum), it is not limited to this, The product made from Al alloy may be sufficient. Moreover, the raw material of each linear member may be gold, silver, copper, platinum, or any of these alloys. Al (aluminum) is most preferable. Further, Ag has a drawback that it is slightly unstable chemically, but its characteristics do not change greatly with time.

In the above-described embodiment, the case where the analyzer 309 is set to transmit + _F Faraday rotated light and to block −θ _F Faraday rotated light is described. However, the present invention is not limited thereto. It is not something. The analyzer 309 may be set so as to transmit light that has undergone Faraday rotation of −θ _F and to block light that has undergone Faraday rotation of + θ _F. However, in this case, the main controller 132 applies a negative magnetic field to the grid member 304 of the pixel that is desired to transmit light, and applies a positive magnetic field to the grid member 304 of the pixel that is desired to be shielded from light.

  In the above embodiment, the main control device 132 may apply a positive magnetic field to the grid member 304 of the pixel that is desired to transmit light, and may not apply a magnetic field to the grid member 304 of the pixel that is desired to be shielded from light.

Further, in the above embodiment, when the analyzer 309 is set to transmit the light having the Faraday rotation of −θ _F , the main controller 132 applies a negative voltage to the grid member 304 of the pixel that is desired to transmit the light. It is good also as not applying a magnetic field to the grid member 304 of the pixel which wants to shield light.

  In the above embodiment, instead of the image generation apparatus 100, an image generation apparatus 100 'shown in FIG. 19 may be used as an example. The image generating apparatus 100 ′ is characterized in that a spatial light modulator is different from the image generating apparatus 100. Accordingly, the following description will focus on differences from the image generation apparatus 100, and the same or equivalent components as those of the image generation apparatus 100 described above will be denoted by the same reference numerals, and the description thereof will be simplified or omitted. Shall.

  The image generation device 100 ′ includes a light source 101, a reflector 102, a color wheel 103, a wheel driving device 104, a rod integrator 105, an illumination optical system 106 ′, an image forming panel 107 ′, a total reflection prism 109, a communication interface 131, and a main control device. 132 or the like.

  The illumination optical system 106 ′ efficiently guides the optical path of the light beam via the rod integrator 105 to the total reflection prism 109.

  The total reflection prism 109 is composed of two triangular prisms and has a minute air layer between them.

  The light beam from the illumination optical system 106 ′ incident on the total reflection prism 109 illuminates the image forming panel 107 ′. This illumination light is modulated in accordance with the image information by the image forming panel 107 '.

  The light beam reflected by the image forming panel 107 ′ and incident on the total reflection prism 109 passes through the total reflection prism 109 and is emitted to the projection optical system 200.

  Next, the image forming panel 107 'will be described. The image forming panel 107 ′ includes a spatial light modulator 300 ′ shown in FIG. 20 as an example. Here, the description will focus on differences from the spatial light modulator 300, and the same or equivalent components as those of the spatial light modulator 300 described above will be denoted by the same reference numerals, and the description thereof will be simplified or Shall be omitted.

  The spatial light modulator 300 ′ includes a glass substrate 301, a polarizer 303, a plurality of grid members 304, a plurality of Y-direction line electrodes 305, an insulating layer 306, a glass substrate 307, an analyzer 309, and a plurality of X-direction line shapes. An electrode 311 (not shown) and the like are included. Note that FIG. 20 is a cross-sectional view of the grid member 304 of the spatial light modulator 300 ′.

  Here, the analyzer 309 is disposed on the optical path of the light reflected by the grid member 304. Further, the microlens array 108 is disposed between the polarizer 303 and the analyzer 309 and the plurality of grid members 304.

When the magnetic field is applied, the linearly polarized light reflected by the grid member 304 receives the magnetic Kerr effect, and the plane of polarization rotates (Kerr rotation). Here, when a positive magnetic field is applied, + θ _K Kerr rotation occurs (see FIG. 21), and when a negative magnetic field is applied, −θ _K Kerr rotation occurs (see FIG. 22). To do.

The analyzer 309 is configured to transmit + θ _K Kerr-rotated light and block −θ _K Kerr-rotated light.

  Therefore, when a positive magnetic field is applied to the grid member 304, the light reflected by the grid member 304 passes through the analyzer 309 as shown in FIG. On the other hand, when a negative magnetic field is applied to the grid member 304, the light reflected by the grid member 304 is shielded by the analyzer 309 as shown in FIG.

  Therefore, when a current is supplied to the corresponding X-direction line electrode 311 and Y-direction line electrode 305 so that a positive magnetic field is applied to the grid member 304, the light incident on the grid member 304 is reflected as reflected light. The light is emitted from the light modulator 300 ′. On the other hand, when a current is supplied to the corresponding X-direction line electrode 311 and Y-direction line electrode 305 so that a negative magnetic field is applied to the grid member 304, the light incident on the grid member 304 is converted into a spatial light modulator. No injection from 300 '.

  Therefore, the spatial light modulator 300 ′ can reflect light only with a designated pixel among the plurality of pixels.

  Therefore, the main control device 132 determines the grid member 304 to apply a positive magnetic field and the grid member 304 to apply a negative magnetic field according to image information, and determines the determination result for 15376 grid members 304. Based on this, a current is supplied to the corresponding line electrode.

  Thereby, the light modulated according to the image information is emitted from the image generation apparatus 100 ′ toward the projection optical system 200.

  In the spatial light modulator 300 ′, the main controller 132 may apply a positive magnetic field to the grid member 304 of the pixel whose light is to be reflected, and may not apply a magnetic field to the grid member 304 of the pixel that is desired to be shielded from light. .

Further, in the spatial light modulator 300 ', the analyzer 309 transmits light that the Kerr rotation of - [theta] _K, may be set so as to shield the light Kerr rotation of + theta _K. However, in this case, the main controller 132 applies a negative magnetic field to the grid member 304 of the pixel whose light is to be reflected by the spatial light modulator 300 ′, and applies a positive magnetic field to the grid member 304 of the pixel whose light is to be shielded. Will be.

Further, in the spatial light modulator 300 ′, when the analyzer 309 is set so as to transmit the Kerr-rotated light of −θ _K , the main controller 132 causes the grid member of the pixel to reflect light. It is possible to apply a negative magnetic field to 304 and not apply a magnetic field to the grid member 304 of the pixel to be shielded from light.

  By the way, as a method of applying a magnetic field to the grid member, use of a magnetic head (TMR or GMR) used in a hard disk device, a method of making a micro magnetic head composed of a coil shape and a magnetic core in the vicinity of the grid member, There is also a method of bringing permanent magnets close together.

  In the above embodiment, the grid member 304 may have a magnetic material layer on the + Z side or the −Z side.

  In this case, the magnetic material layer has a multilayer structure of any one of iron (Fe) / platinum (Pt), cobalt (Co) / platinum (Pt), and cobalt (Co) / palladium (Pd), and is perpendicular. What has magnetic anisotropy can be used.

  For example, the thickness of the linear member may be 100 nm, and a Co / Pt multilayer film may be provided on the + Z side of the linear member (see FIG. 23). As this Co / Pt multilayer film, an artificial lattice structure comprising a Co layer having a thickness of 1 nm and a layer in which five layers of Co having a thickness of 0.5 nm and Pt having a thickness of 1 nm are stacked. Can be used. This artificial lattice structure has perpendicular magnetic anisotropy.

  When a magnetic material is used, a curve indicating the relationship between the rotation angle and the applied magnetic field and the relationship between the ellipticity and the applied magnetic field has a square hysteresis. In this case, the state (rotation angle, ellipticity) can be maintained even when the magnetic field is no longer applied.

  Note that the number of layers composed of Co having a thickness of 0.5 nm and Pt having a thickness of 1 nm is not limited to five. However, about 5-7 layers are preferable from the relationship of light reflectivity and saturation magnetization.

  Thus, the rotation angle and ellipticity can be further increased by using an artificial perpendicular magnetization film.

  Further, as the magnetic material layer, a layer containing at least cobalt Co and having a granular structure in which a nonmagnetic substance is segregated between crystal grains grown in a columnar shape can be used.

For example, a granular structure made of CoCrPt—SiO ₂ (thickness 5 nm) may be used. This CoCrPt—SiO 2 has perpendicular magnetic anisotropy.

  By the way, “granular” means “granular” and means a material having a structure in which nanometer-scale particles are dispersed in a matrix of another material.

Here, Co forms a crystal having an hcp structure (hexagonal close-packed lattice), and Cr (chromium) and SiO ₂ segregate to form a grain boundary. By using CoCrPt—SiO ₂ , SiO ₂ is segregated around Co, which is a ferromagnetic material, so that it is easy to form physically isolated (dispersed) fine Co particles.

  In addition, a layer containing a half metal can be used as the magnetic material layer. Note that half metal refers to a substance in which one electron spin has a metallic band structure and the other electron spin has an insulating band structure.

  For example, PtMnSb can be used. In PtMnSb, by adjusting the composition ratio of platinum (Pt), manganese (Mn), and antimony (Sb), it was possible to form a state having spin in only one direction (theoretical spin polarization 100%). Note that Ti (titanium) having a thickness of 2 nm was used as the underlayer. A micro magnetic head was used as the magnetic field applying means.

The half metal material is preferably a Heusler alloy or a half metal ferromagnetic film (for example, a Co ₂ MnSi film) in which all electrons are spin-polarized in a predetermined direction when an external magnetic field is applied. However, it may be formed of another ferromagnetic film similar to the Heusler alloy or the half metal ferromagnetic film.

The half metal includes conductive ferromagnetic oxides such as (La, Sr) MnO ₃ , Fe ₃ O ₄ , and CrO ₂ , half-Heusler alloys such as NiMnSb, Co ₂ MnSi, Co ₂ MnAl, Co ₂ MnGe, and Co _2. Full Heusler alloys such as CrGa and zinc blende type CrAs are known.

Further, as the magnetic material layer, a layer containing any one of materials obtained by replacing yttrium iron garnet (YIG, Y ₃ Fe ₅ O ₁₂ ) and a part thereof with another element can be used.

  For example, bismuth-substituted yttrium iron garnet (BiYIG) (for example, see Japanese Patent Application Laid-Open No. 2001-194639) in which part of yttrium iron garnet is substituted with bismuth (Bi) may be used. Since BiYIG has a relatively high transmittance, there is an advantage that the light intensity of the transmitted light is large.

  As a method of forming BiYIG, there is a method of using not only a sputtering method but also a solution (MOD (Metal Organic Decomposition) coating material) in which an organic compound of BiYIG is dissolved in an organic solvent. For example, the process of applying a solution to a quartz substrate and drying it is repeated 5 times, and then a heat treatment step of 100 ° C. for 30 minutes, 500 ° C. for 15 minutes, and 700 ° C. for 180 minutes is added, and BiYIG is fired. This is a method of improving crystallinity.

  Instead of yttrium, any of rare earth elements Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu may be used.

  Further, instead of Bi, any one of Ce, Pb, Ca, and Pt may be used.

  Further, a part of Fe may be substituted with any of Al, Ga, Cr, Mn, Sc, In, Ru, Rh, Co, Cu, Ni, Zn, Li, Si, Ge, Zr, and Ti. .

  The spatial light modulator 300 and the spatial light modulator 300 'can be used for an optical switch. FIG. 24 shows a schematic configuration of the optical switch 3000. The optical switch 3000 includes a spatial light modulator 3010, a control device 3020, and the like.

  The spatial light modulator 3010 has the same structure as the spatial light modulator 300 and is provided in the middle of the plurality of optical fibers.

  The control device 3020 controls the magnetic field applied to the grid member 304 of the spatial light modulator 3010 according to the on / off signal corresponding to each optical fiber. That is, the incident light is transmitted when it is on, and the incident light is shielded when it is off. One optical fiber may be used. At this time, it is only necessary to have one light modulation element.

  In the spatial light modulator 3010, the polarization state can be changed in a few nanoseconds. Therefore, ultrafast optical switching is possible. In a conventional spatial light modulator using a liquid crystal film, switching takes several microseconds.

  The spatial light modulator 300 is an example of a spatial light modulator capable of turning on and off transmitted light using the Faraday effect, and is not limited thereto.

  The spatial light modulator 300 ′ is an example of a spatial light modulator that can turn on and off reflected light using the magnetic Kerr effect, and is not limited thereto.

  In the step of forming a linear member on a glass substrate, a method using a magnetic material / polymer composite material, a method using a sol-gel method, a method using a MOD (Metal Organic Decomposition) coating type material, a method using sputtering, vanadium chromium hexacyano Any one of a method using a molecular magnetic material such as a complex, a method using a nanosheet lamination, and an aerosol deposition method (ADM) using a normal temperature impact solidification phenomenon can be used.

  The sol-gel material is a material in which a colloidal material obtained by hydrolyzing and polymerizing an alkoxide or the like is dispersed in a solution, and has excellent low-temperature film-forming properties.

  The MOD coating type material is a solution in which a metal organic compound is dissolved in an organic solvent, and the oxide thin film can be easily formed by coating the solution on a glass substrate and applying heat treatment after drying. It is a liquid material. Ferromagnetic semiconductor materials such as (Ga, Mn) As and GeFe may be used.

  The spatial light modulator 300 and the spatial light modulator 300 'can be applied to a holography device and a hologram recording device.

  The spatial light modulator 300 and the spatial light modulator 300 ′ can also be used for a magnetic sensor.

  The light modulation element can also be used in a laser processing machine. In this case, only a necessary portion can be irradiated with the laser light while scanning the laser light at high speed.

  Further, in a laser processing machine, when a plurality of the light modulation elements are two-dimensionally arranged, a plurality of places can be processed simultaneously.

  As described above, according to the light modulation element of the present invention, the rotation angle of the polarization plane is large, which is suitable for downsizing. Further, the spatial light modulator of the present invention is suitable for performing high-density light modulation with a large rotation angle of the polarization plane. Further, the image generation apparatus of the present invention is suitable for generating a high-definition image. The image display device of the present invention is suitable for displaying a high-definition image. Moreover, the optical switch of the present invention is suitable for performing switching with a small size and excellent response characteristics.

  DESCRIPTION OF SYMBOLS 10 ... Projector system, 100 ... Image generation apparatus, 101 ... Light source, 107 ... Image forming panel, 108 ... Micro lens array, 132 ... Main control apparatus (control apparatus), 200 ... Projection optical system, 300 ... Spatial light modulator, 300 '... spatial light modulator, 301 ... glass substrate, 302 ... resin layer, 303 ... polarizer, 304 ... grid member (a plurality of linear members), 305 ... Y-direction linear electrode (part of magnetic field application mechanism) 306: insulating layer, 307 ... glass substrate, 308 ... resin layer, 309 ... analyzer, 310 ... glass substrate, 311 ... X-direction linear electrode (part of magnetic field application mechanism), 1000 ... projector device, 3000 ... light Switch, 3010 ... Spatial light modulator, 3020 ... Control device.

JP 2007-310177 A JP 2007-192926 A JP 2007-171450 A JP 2006-154727 A JP 2006-119337 A JP 2004-354441 A JP 2008-145748 A JP 2008-83686 A JP 2006-164480 A Special table 2003-502708 gazette JP 2006-259074 A JP 2006-84871 A JP 2008-268862 A JP 2007-214304 A JP 2004-309700 A

Jk. Cho, et al., “Design, fabrication, switching, and optical characteristics of new magneto-optical spatial light modulator” Appl. Phys. , Vol. 76, p1910-1919 (1994)

Claims (17)

A light modulation element for modulating incident light,
Linearly polarized light whose polarization direction is the first direction is incident, and includes any one of gold, silver, copper, platinum, and aluminum, and a second direction orthogonal to the first direction is a longitudinal direction, and the first direction A plurality of linear members arranged at intervals of half or less of the wavelength of the incident light along the direction;
A magnetic field application mechanism for applying a magnetic field to the plurality of linear members;
And an analyzer that is disposed on an optical path of light via the plurality of linear members and selectively transmits or blocks light when the magnetic field is applied. The magnetic field application mechanism applies a different first magnetic field and second magnetic field to the plurality of linear members,
The light modulator according to claim 1, wherein the analyzer transmits light when the first magnetic field is applied, and blocks light when the second magnetic field is applied. . A polarizer for converting the incident light into linearly polarized light whose polarization direction is the first direction;
The light modulation element according to claim 1, wherein linearly polarized light from the polarizer is incident on the plurality of linear members.   4. The light modulation element according to claim 1, wherein the light incident on the analyzer is light that has passed through the plurality of linear members. 5.   The light modulation element according to any one of claims 1 to 3, wherein the light incident on the analyzer is light reflected by the plurality of linear members.   The light modulation element according to claim 1, wherein the magnetic field application mechanism includes a plurality of line-shaped electrodes surrounding the plurality of linear members.   The light modulation element according to claim 1, wherein the plurality of linear members are members having a wire grid structure.   The light modulation element according to claim 1, wherein each linear member in the plurality of linear members is a discontinuous linear member in a longitudinal direction. Each of the plurality of linear members further includes a magnetic material layer,
The magnetic material layer is provided on one side of each linear member with respect to a third direction orthogonal to both the first direction and the second direction. The light modulation element according to any one of the above.   The optical modulation according to claim 9, wherein the magnetic material layer has a multilayer structure of any one of iron / platinum, cobalt / platinum, and cobalt / palladium, and has perpendicular magnetic anisotropy. element.   The light modulation element according to claim 9, wherein the magnetic material layer has a granular structure in which a nonmagnetic substance is segregated between crystal grains containing at least cobalt and growing in a columnar shape.   10. The magnetic material layer is a layer including a half metal in which one electron spin has a metallic band structure and the other electron spin has an insulating band structure. Light modulation element.   The light modulation element according to claim 9, wherein the magnetic material layer is a layer including one of yttrium iron garnet and a material obtained by substituting a part thereof with another element.   A spatial light modulator in which the light modulation elements according to claim 1 are two-dimensionally arranged. An image generation device that generates an image according to image information,
With a light source;
The spatial light modulator according to claim 14, which is disposed on an optical path of a light beam emitted from the light source;
And a control device that individually controls a plurality of magnetic field application mechanisms of the spatial light modulator according to the image information. The image generation device according to claim 15, which generates an image according to image information;
A projection optical system that projects a light beam from the image generation device onto a projection surface. An optical switch for turning on / off optical transmission,
A light modulation element according to any one of claims 1 to 13;
And a control device that controls a magnetic field application mechanism of the light modulation element according to the on / off information.

Images