Optical processing device

Abstract

In order to provide a spatial light phase modulator that can be miniaturized and that is operable at high speed, each microcell (C) of this spatial light phase modulator (13) is composed of a magnetization free layer (C11) and a control unit (electrode C12) that controls the magnetization direction (arrow M11) of the magnetization free layer (C11). The magnetization free layer (C11) and the control unit (electrode C12) are configured to control the magnetization direction (arrow M11) so as to be parallel or substantially parallel the direction (arrows kf, kr) of a normal to the first optical effective surface and the second optical effective surface (bottom surfaces C111, C112).

Description

[Technical Field]

[0001] The present invention relates to a spatial light phase modulator and an optical processing device including a plurality of spatial light phase modulators. [Background technology]

[0002] A spatial light modulator is obtained by arranging a plurality of light modulators in a matrix. Known spatial light modulators include LCOS (Liquid Crystal On Silicon, see, for example, Patent Document 1) and DMD (Digital Mirror Device, see, for example, Patent Document 2). These spatial light modulators are used in, for example, projectors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-198949 [Patent Document 2] Japanese Patent Publication No. 2007-510174 Summary of the Invention [Problem to be solved by the invention]

[0004] A problem with these spatial light modulators is that it is difficult to reduce the pixel size.

[0005] Another issue with LCOS and DMD is that it is difficult to operate them at high speeds, since LCOS uses liquid crystals and DMD uses mechanically moved mirrors.

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a spatial light phase modulator that can be miniaturized and can operate at high speed, and also to provide an optical computing device that includes a plurality of such spatial light phase modulators. [Means for solving the problem]

[0007] To solve the above problems, a spatial optical phase modulator according to a first aspect of the present invention is a spatial optical phase modulator including a plurality of microcells. In this spatial optical phase modulator, each microcell is configured by an optical phase modulator including a magnetization free layer having a first optical effective surface and a second optical effective surface facing each other, and a control unit that controls the magnetization direction of the magnetization free layer, and each magnetization free layer and each control unit are configured to control the magnetization direction so that it is parallel or approximately parallel to the normal direction of each of the first optical effective surface and the second optical effective surface. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to provide a spatial light phase modulator that can be miniaturized and can operate at high speed, and an optical computing device that includes a plurality of such spatial light phase modulators. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a configuration of an optical arithmetic device according to an embodiment of the present invention. [Figure 2] 2(a) is a plan view showing a specific example of a spatial light phase modulator included in the optical processing device shown in Fig. 1, and FIG. 2(b) is a cross-sectional view of a microcell included in the spatial light phase modulator. [Figure 3] FIG. 3 is a cross-sectional view of a first modified example of the microcell shown in FIG. 2(b). [Figure 4] FIG. 3 is a cross-sectional view of a second modified example of the microcell shown in FIG. 2(b). [Figure 5] 2(a) is a perspective view of a third modified example of the microcell shown in FIG. 2(b), and FIG. 2(b) is a plan view of the third modified example. [Figure 6] 2(a) is a perspective view of a fourth modified example of the microcell shown in FIG. 2(b), and FIG. 2(b) is a plan view of the fourth modified example. [Figure 7]FIG. 10 is a schematic diagram showing the configuration of a modified example of an optical arithmetic device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] An optical arithmetic device 1 according to one embodiment of the present invention will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a schematic diagram showing the configuration of the optical arithmetic device 1. Fig. 2(a) is a plan view showing a specific example of a spatial light phase modulator 13 included in the optical arithmetic device 1. Fig. 2(b) is a cross-sectional view of a microcell C included in the spatial light phase modulator 13.

[0011] [Configuration of Optical Computing Device] As shown in FIG. 1, the optical processing device 1 includes a polarizing beam splitter 11, a quarter-wave plate 12, a spatial light phase modulator 13, and a mirror .

[0012] <Polarizing beam splitter> The polarizing beam splitter 11 is a polarization separation element that can split incident light into p-polarized and s-polarized components. In this embodiment, a polarization separation element in which a polarization separation film is sandwiched between two right-angle glass prisms is used as the polarizing beam splitter 11. However, the type of polarization separation element used as the polarizing beam splitter 11 is not limited to this, and for example, a flat-plate type may also be used.

[0013] In this embodiment, the polarization splitting film included in the polarizing beam splitter 11 transmits p-polarized light L1, which is the p-polarized component of the incident light Li, and reflects s-polarized light L2, which is the s-polarized component. In the state shown in FIG. 1, signal light Li enters the polarizing beam splitter 11 from its right side. The polarizing beam splitter 11 splits the signal light Li into p-polarized light L1 and s-polarized light L2, transmits the p-polarized light L1 to the left side of the polarizing beam splitter 11, and reflects the s-polarized light L2 to the upper side of the polarizing beam splitter 11. The signal light Li has a two-dimensional intensity distribution.

[0014] As will be described later, s-polarized light L7 enters the polarizing beam splitter 11 from its left side. The polarizing beam splitter 11 reflects the s-polarized light L7 downward, thereby outputting the signal light Lo to the outside of the polarizing beam splitter 11.

[0015] In addition, in Figure 1, the polarization directions of p-polarized light L1 and s-polarized light L2, as well as right-handed circularly polarized light L3, right-handed circularly polarized light L4, left-handed circularly polarized light L5, and left-handed circularly polarized light L6, which will be described later, are schematically shown with arrows. These arrows indicating the polarization directions indicate the polarization direction when each polarized light is viewed from behind the propagation direction. When comparing right-handed circularly polarized light L3 and right-handed circularly polarized light L4 with left-handed circularly polarized light L5 and left-handed circularly polarized light L6, they appear to rotate in the same direction (clockwise in the state shown in Figure 1). However, because the propagation directions of right-handed circularly polarized light L3 and right-handed circularly polarized light L4 and left-handed circularly polarized light L5 and left-handed circularly polarized light L6 are opposite to each other, their polarization directions are also opposite.

[0016] <Quarter-wave plate> The quarter-wave plate 12 is an optical element having a fast axis and a slow axis that are orthogonal to each other, and which generates a phase difference of a quarter wavelength between linearly polarized light transmitted through the fast axis and linearly polarized light transmitted through the slow axis.

[0017] The quarter-wave plate 12 is disposed so that one of its principal surfaces (the principal surface located on the right side in the state shown in FIG. 1) faces and is parallel to one side surface (the side surface located on the left side in the state shown in FIG. 1) of the polarization beam splitter 11. That is, the quarter-wave plate 12 is provided on the side of the magnetization free layer C11 of each microcell C. The quarter-wave plate 12 is also provided so that its principal surface is parallel or approximately parallel to the bottom surface C111 of each microcell C, which will be described later.

[0018] Furthermore, the quarter-wave plate 12 is disposed so that its slow axis forms a 45-degree angle with the polarization direction of the p-polarized light L1. With this configuration, the quarter-wave plate 12 can convert linearly polarized light to circularly polarized light and vice versa. Therefore, the quarter-wave plate 12 converts the p-polarized light L1 into right-handed circularly polarized light L3 and left-handed circularly polarized light L6 into s-polarized light L7.

[0019] <Half-wave plate> Although not shown in the optical processing device 1 shown in FIG. 1 , a half-wave plate may be provided between the polarizing beam splitter 11 and the quarter-wave plate 12 on the optical paths of the p-polarized light L1 and the s-polarized light L7. In this case, the half-wave plate is arranged so that (1) one of its main surfaces faces and is parallel to one side of the polarizing beam splitter 11, and (2) the other main surface faces and is parallel to one of the main surfaces of the quarter-wave plate 12. This configuration is widely used as a configuration for a wideband circular polarizer. One example of a wideband circular polarizer is a configuration in which the half-wave plate is arranged so that its slow axis forms an angle of 15 degrees with the polarization direction of the p-polarized light L1, and the quarter-wave plate 12 is arranged so that its slow axis forms an angle of 75 degrees with the polarization direction of the p-polarized light L1.

[0020] In this way, by applying the configuration of a wideband circular polarizer to the optical computing device 1, it is possible to widen the wavelength band of light that can be converted between linearly polarized light and circularly polarized light.

[0021] <Spatial light phase modulator> The spatial light phase modulator 13 includes a substrate 131 and a plurality of microcells C arranged two-dimensionally (i.e., arranged in a matrix) on one main surface of the substrate 131. Each microcell C is configured so that the phase modulation amount can be set independently of each other. A specific example of the spatial light phase modulator 13 including each microcell C will be described later with reference to FIG. 2.

[0022] The spatial light phase modulator 13 is disposed so that the other principal surface of the substrate 131 faces and is parallel to the other principal surface of the quarter-wave plate 12 (the principal surface located on the left side in the state shown in FIG. 1). Therefore, the right-handed circularly polarized light L3 converted by the quarter-wave plate 12 is converted into right-handed circularly polarized light L4 by passing through the spatial light phase modulator 13, and the right-handed circularly polarized light L4 is irradiated onto a reflecting surface 141 of a mirror 14, which will be described later. Furthermore, the right-handed circularly polarized light L4 is reflected by the reflecting surface 141, and the left-handed circularly polarized light L5 is converted into left-handed circularly polarized light L6 by passing through the spatial light phase modulator 13, and the left-handed circularly polarized light L6 is irradiated onto the other principal surface of the quarter-wave plate 12.

[0023] As will be described in detail later with reference to FIG. 2, when converting right-handed circularly polarized light L3 into right-handed circularly polarized light L4, the spatial light phase modulator 13 can phase-modulate the right-handed circularly polarized light L3 according to a phase modulation amount predetermined for each microcell C. Furthermore, when converting left-handed circularly polarized light L5 into left-handed circularly polarized light L6, the spatial light phase modulator 13 can phase-modulate left-handed circularly polarized light L5 according to a phase modulation amount predetermined for each microcell C. In the spatial light phase modulator 13, the magnetization-free layer of the microcell C is configured so that the magnetization direction of the magnetization-free layer is parallel or approximately parallel to the propagation direction of light propagating inside the microcell C. Therefore, the phase modulation amount for the right-handed circularly polarized light L3 and the phase modulation amount for the left-handed circularly polarized light L5 are added together. Therefore, in the optical processing device 1 using the spatial light phase modulator 13 as a reflective type, it is possible to obtain twice the phase modulation amount compared to when the spatial light phase modulator 13 is used as a transmissive type.

[0024] The phase modulation amount of each microcell C of the spatial light phase modulator 13 is determined in advance so as to perform a desired optical calculation. The setting of the phase modulation amount of each microcell C can be realized, for example, by using machine learning. In this machine learning, for example, a model can be used in which the two-dimensional intensity distribution of right-handed circularly polarized light L3 incident on the other main surface of the substrate 131 is used as an input, and the two-dimensional intensity distribution of left-handed circularly polarized light L6 reflected by the reflective surface of the mirror 14 (described later) and emitted from the other main surface of the substrate 131 is used as an output, and the model includes the phase modulation amount of each microcell C as a parameter.

[0025] (Example) A specific example of the spatial light phase modulator 13 will be described with reference to Fig. 2. Fig. 2(a) is a plan view of the spatial light phase modulator 13 according to this example. Fig. 2(b) is a cross-sectional view of a microcell C that constitutes the spatial light phase modulator 13 according to this example.

[0026] 2(a), the spatial light phase modulator 13 is composed of a plurality of microcells C, each having a phase modulation amount set independently of the other. When signal light (in this embodiment, right-handed circularly polarized light L3 or left-handed circularly polarized light L5) enters the spatial light phase modulator 13, the signal light phase-modulated by each microcell C interferes with each other, causing a predetermined optical calculation to be performed. The phase modulation amount of each microcell C may be variable or fixed, but is variable in this specific example.

[0027] In this specification, the term "microcell" refers to a cell having a cell size of less than 10 μm, for example. The term "cell size" refers to the square root of the area of ​​the cell. For example, if the shape of the microcell C in plan view is a square, the cell size of the microcell C is the length of one side of the microcell C. The lower limit of the cell size of the microcell C is, for example, 1 nm.

[0028] The spatial light phase modulator 13 shown in Fig. 2(a) is composed of 200 x 200 microcells C arranged in a matrix. The planar shape of each microcell C is a 500 nm x 500 nm square, and the planar shape of the spatial light phase modulator 13 is a 100 μm x 100 μm square.

[0029] Each microcell C constituting the spatial light phase modulator 13 includes a magnetization free layer C11 and an electrode C12, as shown in FIG. 2(b), for example.

[0030] The magnetization free layer C11 is a rectangular parallelepiped columnar member formed to stand on one main surface of the substrate 131. In this embodiment, a pair of bottom surfaces C111 and C112 facing each other among the six surfaces constituting the magnetization free layer C11 are squares of 500 nm × 500 nm as described above. Note that the bottom surfaces C111 and C112 of the magnetization free layer C11 refer to the surfaces parallel to the main surface of the substrate 131 among the six surfaces constituting the magnetization free layer C11.

[0031] Each of the bottom surfaces C111 and C112 is a surface in the magnetization free layer C11 that transmits light and is an example of an optically effective surface. In this specific example, right-handed circularly polarized light L3, which is the outgoing signal light, is incident on the bottom surface C111, and left-handed circularly polarized light L5, which is the returning signal light, is incident on the bottom surface C112. Therefore, the optically effective surface onto which the signal light first enters the magnetization free layer C11 is the bottom surface C111. Therefore, the bottom surface C111 is an example of a first optically effective surface, and the bottom surface C112 is an example of a second optically effective surface.

[0032] In Figure 2(b), the propagation direction of right-handed circularly polarized light L3, which is the outgoing signal light, is indicated by arrow kf, and the propagation direction of left-handed circularly polarized light L5, which is the return signal light, is indicated by arrow kr. Arrow kf is the direction from bottom surface C111 to bottom surface C112, i.e., the direction from the right to the left of the magnetization free layer C11 in the state shown in Figure 2(b). Arrow kr is the direction from bottom surface C112 to bottom surface C111, i.e., the direction from the left to the right of the magnetization free layer C11 in the state shown in Figure 2(b).

[0033] The magnetization free layer C11 is made of a soft magnetic material (e.g., CoFeB) that is conductive and transparent. However, the soft magnetic material that makes up the magnetization free layer C11 is not limited to CoFeB. Other examples of soft magnetic materials that make up the magnetization free layer C11 include YIG (yttrium iron garnet), which is a magnetic garnet, and substituted magnetic garnets in which part of the yttrium in YIG is replaced with Bi, Ce, or the like, as in the case of a spin orbit torque (SOT) MRAM.

[0034] The electrode C12 is a conductive film formed on one of the four side surfaces, excluding the pair of bottom surfaces, among the six surfaces constituting the magnetization free layer C11. That is, the electrode C12 is formed in direct contact with one side surface of the magnetization free layer C11. In the state shown in FIG. 2(b), the electrode C12 is formed on the side surface located below the magnetization free layer C11. In this specific example, the electrode C12 is a single electrode.

[0035] In one aspect of the present invention, the control unit may be formed so as to be in direct contact with the magnetization free layer, for example, as electrode C12 (see FIG. 2(b)), or may be formed indirectly with respect to the magnetization free layer via another material, for example, as electrode Cb12 (see FIG. 4) described later. However, even in the latter case, the control unit is configured so as to be able to inject a current or a spin current into the magnetization free layer or to be able to apply an external magnetic field to the magnetization free layer in order to control the magnetization direction of the magnetization free layer.

[0036] The conductor constituting the electrode C12 preferably contains a heavy metal. Examples of heavy metals include palladium (Pd), platinum (Pt), tantalum (Ta), and tungsten (W). The electrode C12 may be composed of any one of these heavy metals, or may be composed of an alloy of multiple heavy metals. The electrode C12 may also be composed of an alloy of at least one of these heavy metals with a transition metal. Examples of transition metals include iron (Fe), cobalt (Co), and copper (Cu). The electrode C12 may also be composed of a multilayer film including a layer made of at least one of the above heavy metals and a layer made of at least one of the above transition metals.

[0037] The optical computing device 1 also includes a power supply PS connected to the electrode C12 of each microcell C (see FIG. 2(b)). The power supply PS is configured to generate a pulse voltage or a pulse current. In this embodiment, the power supply PS is configured to supply a pulse voltage. Here, the pulse voltage means a voltage having a waveform in which the voltage exceeds a predetermined voltage for only a very short time when the horizontal axis represents time and the vertical axis represents voltage. The pulse current means a voltage having a waveform in which the horizontal axis represents time and the vertical axis represents voltage. current When the current is at a specified value for a very short time, current The pulse voltage or pulse current generated by the power supply PS connected to the electrode C12 may be a continuous pulse or a single pulse.

[0038] When a pulse voltage or pulse current is applied to the electrode C12, a spin current, which is a flow of spin-polarized electrons, is injected from the electrode C12 into the magnetization free layer C11, as in the case of an SOT-type MRAM. In this way, the electrode C12 is an electrode that injects a spin current into the magnetization free layer C11. In this specific example, the polarization direction of the spin current injected into the magnetization free layer C11 is parallel or approximately parallel to the normal direction of the bottom surfaces C111 and C112, of spin current The direction is from the bottom surface C111 to the bottom surface C112.

[0039] The magnetization free layer C11 is magnetized so as to be aligned with the polarization direction of the injected spin current. In (b) of Figure 2, the direction of magnetization of the magnetization free layer C11 is indicated by an arrow M11.

[0040] As described above, in this specific example, the magnetization free layer C11 is configured so that the direction of magnetization generated when a spin current is injected from the electrode C12 is parallel or approximately parallel to the normal directions of the bottom surface C111 and the bottom surface C112. Specifically, the propagation direction (see arrow kf) of the right-handed circularly polarized light L3, which is the outgoing signal light, is parallel or approximately parallel to and in the same direction as the magnetization direction (see arrow M11) of the magnetization free layer C11. Furthermore, the propagation direction (see arrow kr) of the left-handed circularly polarized light L5, which is the return signal light, is parallel or approximately parallel to and in the opposite direction to the magnetization direction (see arrow M11) of the magnetization free layer C11. As described above, the electrode C12 is one aspect of a control unit that controls the magnetization direction of the magnetization free layer C11 by injecting a spin current into the magnetization free layer C11.

[0041] Therefore, when right-handed circularly polarized light L3 is selected as the signal light propagating through the microcell C in the direction of arrow kf, the phase of the right-handed circularly polarized light L3 changes in either a delay or an advance direction depending on the magnitude of the magnetization of the magnetic free layer C11. In this specific example, the phase of the right-handed circularly polarized light L3 is assumed to be delayed. Furthermore, when left-handed circularly polarized light L5 is selected as the signal light propagating through the microcell C in the direction of arrow kr, the phase of the left-handed circularly polarized light L5 changes in either a delay or an advance direction depending on the magnitude of the magnetization of the magnetic free layer C11. In this specific example, the phase of the left-handed circularly polarized light L5 is assumed to be delayed. In this way, in this specific example, the phase modulation amount can be controlled for both right-handed circularly polarized light L3 and left-handed circularly polarized light L5 depending on the magnitude of the magnetization of the magnetic free layer C11.

[0042] Furthermore, the magnitude of the magnetization of the magnetization free layer C11 is determined according to the magnitude of the spin current injected into the magnetization free layer C11. Furthermore, the magnitude of the spin current injected into the magnetization free layer C11 is determined according to the magnitude of the pulse voltage or pulse current supplied from the power supply PS to the electrode C12. Therefore, the phase modulation amount of the microcell C can be controlled by controlling the magnitude of the pulse voltage or pulse current supplied from the power supply PS to the electrode C12. As described above, each microcell C of the spatial optical phase modulator 13 of this specific example is composed of a spin injection type optical phase modulator.

[0043] In the signal light propagating through the magnetization-free layer, the refractive index differs between right-handed and left-handed circularly polarized light, and therefore a phase difference occurs between the right-handed and left-handed circularly polarized light due to the magnetization of the magnetization-free layer. This phase difference between the right-handed and left-handed circularly polarized light is known as the Faraday effect.

[0044] Furthermore, each microcell C in this example does not use liquid crystals like LCOS, nor does it use mechanically moving mirrors like DMD. LCOS and DMD operate based on bulk physical properties, so a certain size is necessary for smooth operation. As the structure becomes smaller, especially at the nanoscale level, the influence of intermolecular forces from the wall surfaces becomes stronger, and the original operability is lost.

[0045] On the other hand, each microcell C in this example employs an optical phase modulator configured similarly to SOT-type MRAM to inject spin current into the magnetization-free layer. The magnetization of the magnetization-free layer due to spin injection is a phenomenon that occurs in a nano-sized space. Therefore, devices that utilize magnetization due to spin injection, such as this example, tend to achieve higher speeds by reducing the size of the microcell. Therefore, this example, like MRAM, can be miniaturized and can operate at high speeds.

[0046] Therefore, this example can provide an optical phase modulator that can be miniaturized and can operate at high speed.

[0047] In addition to the Faraday effect used in the spatial light phase modulator 13, other magneto-optical effects that can be used to modulate the phase of the signal light include, for example, the Cotton-Mouton effect. However, when the thickness (length along the propagation direction of the signal light) and magnitude of magnetization of the magnetization-free layer C11 are uniform, the amount of phase modulation caused by the Faraday effect exceeds the amount of phase modulation caused by the Cotton-Mouton effect. Therefore, when the thickness and magnitude of magnetization of the magnetization-free layer C11 are uniform, the spatial light phase modulator 13 can increase the maximum amount of phase modulation that can be given to the signal light compared to a spatial light phase modulator that uses the Cotton-Mouton effect. Also, a spatial light phase modulator that uses the Cotton-Mouton effect and When the same amount of phase modulation needs to be applied to the signal light, the thickness of the magnetic free layer C11 can be made thinner than that of a spatial light phase modulator using the Cotton-Mouton effect. Reducing the thickness of the magnetic free layer C11 has the following effects: it makes it easier to form each microcell C, it makes the distribution of magnetization in the magnetic free layer C11 more uniform, and it is possible to suppress absorption of the signal light in the magnetic free layer C11.

[0048] Note that, for example, a matrix structure employed to drive pixels in a liquid crystal display or an organic EL display can be used as a structure for applying a pulse voltage or pulse current to each microcell C. Here, the matrix structure used in the spatial light phase modulator 13 may be a simple matrix structure or an active matrix structure.

[0049] The simple matrix structure includes a first signal line group in which each signal line extends along a first direction and a second signal line group in which each signal line extends along a second direction to apply a pulse voltage or pulse current to each microcell C. The first and second directions intersect. In the plan view of the spatial light phase modulator 13 shown in FIG. 2(a), if the direction along the top and bottom of the paper is the first direction, the direction along the left and right of the paper is the second direction. Both the first signal line group and the second signal line group may be provided on one main surface of the substrate 131, or one of them (e.g., the first signal line group) may be provided on one main surface of the substrate 131 and the other (e.g., the second signal line group) may be provided on one main surface of a substrate other than the substrate 131. An example of one main surface of a substrate other than the substrate 131 is the reflective surface 141 of the mirror 14, which will be described later.

[0050] The active matrix structure includes a first signal line group in which each signal line extends along a first direction, a second signal line group in which each signal line extends along a second direction, active elements (also called switching elements), and a common electrode to apply a pulse voltage or pulse current to each microcell C. As in the simple matrix structure, the first and second directions also intersect in the active matrix structure. In the active matrix structure, both the first and second signal line groups are provided on one main surface of the substrate 131. The common electrode is provided on one main surface of a substrate other than the substrate 131 (e.g., the reflective surface 141 of the mirror 14) so ​​as to face the first and second signal line groups. Active elements are connected to the intersections of the signal lines constituting the first signal line group and the second signal line group, and cell groups C are interposed between the active elements and the common electrode.

[0051] <Mirror> The mirror 14 has a reflecting surface 141 that specularly reflects incident light. In this embodiment, a glass plate-shaped member is used as the base material, and a metal film is formed on one main surface of the plate-shaped member to obtain the reflecting surface 141. However, the configuration of the mirror 14 is not limited to this and can be selected as appropriate.

[0052] The mirror 14 is disposed so that the reflecting surface 141 faces the bottom surface C112 of each microcell C of the spatial light phase modulator 13 and is parallel or approximately parallel to the bottom surface C112.

[0053] When the right-handed circularly polarized light L4 is reflected by the reflecting surface 141, the rotation direction of the circularly polarized light is maintained, while the propagation direction of the light is reversed. Therefore, the mirror 14 reflects the right-handed circularly polarized light L4 at the reflecting surface 141 to produce left-handed circularly polarized light L5. to Convert.

[0054] 1 and 2(b), in this embodiment, each microcell C of the spatial light phase modulator 13 is spaced apart from the reflecting surface 141 of the mirror 14. However, each microcell C and the reflecting surface 141 may be in close contact with each other.

[0055] [First Modification of Microcell] A microcell Ca, which is a first modified example of the microcell C (see FIG. 2(b)), will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view of the microcell Ca.

[0056] As shown in FIG. 3, the microcell Ca includes a magnetization free layer Ca11 and an electrode Ca12.

[0057] The magnetization free layer Ca11 is configured in the same manner as the magnetization free layer C11 of the microcell C. However, the magnetization free layer Ca11 differs from the magnetization free layer C11 in that the magnetization free layer Ca11 is not formed so as to stand directly on one main surface of the substrate 131, but is formed so as to stand on the surface of the electrode Ca12 laminated on one main surface of the substrate 131.

[0058] The electrode Ca12 is a single electrode made of a conductive film, similar to the electrode C12 of the microcell C. However, the electrode Ca12 differs from the electrode C12 in that the electrode Ca12 is formed on the bottom surface Ca112, rather than on one of the four side surfaces excluding the bottom surfaces Ca111 and Ca112, among the six surfaces constituting the magnetization free layer Ca11. In other words, the electrode Ca12 is formed so as to be interposed between the bottom surface Ca112 of the magnetization free layer Ca11 and one major surface of the substrate 131. That is, the electrode Ca12 is formed in direct contact with the bottom surface Ca112, which is one of the bottom surfaces of the magnetization free layer Ca11.

[0059] In this way, in the microcell Ca, the bottom surface Ca112 of the magnetization free layer Ca11 is covered with the electrode Ca12, so that the bottom surface Ca112 reflects light. That is, the bottom surface Ca112 reflects light. Therefore, in the microcell Ca, the bottom surface Ca111 forming the tip surface thereof is used as the first optically effective surface, and right-handed circularly polarized light L3, which is the outgoing signal light, is incident thereon.

[0060] As in the case of the microcell C, the right-handed circularly polarized light L3 incident on the magnetization free layer Ca11 propagates within the magnetization free layer Ca11 in the direction of the arrow kf (from right to left in the state shown in Figure 3).

[0061] The right-handed circularly polarized light L3 that has propagated to the bottom surface Ca112 is reflected by the surface of the electrode Ca12 and converted into left-handed circularly polarized light L6, which is the return signal light. Therefore, the surface of the electrode Ca12 functions as a reflective surface. In other words, the electrode Ca12 functions as the mirror 14 in the microcell C in addition to its function as an electrode.

[0062] The left-handed circularly polarized light L6 reflected by the electrode Ca12 propagates inside the magnetization free layer Ca11 in the direction of the arrow kr (from left to right in the state shown in Figure 3), as in the case of the microcell C, and is emitted to the outside of the microcell Ca from the bottom surface Ca111.

[0063] Although not shown in FIG. 3, the electrode Ca12 is connected to a power source PS that generates a pulse voltage or a pulse current, similar to the case of the electrode C12.

[0064] In the microcell Ca, when a pulse voltage or pulse current is applied to the electrode Ca12, a spin current, which is a flow of spin-polarized electrons, flows through the electrode C12, just as in the case of the SOT-type MRAM. a 12 to the magnetic free layer C a The polarization direction of the spin current injected into the magnetization free layer Ca11 is parallel or approximately parallel to the normal direction of the bottom surfaces Ca111 and Ca112, of spin current The direction is from the bottom surface Ca111 to the bottom surface Ca112.

[0065] As described above in the section on microcell C, the magnetization free layer C11 is magnetized to align with the polarization direction of the injected spin current. Therefore, in the case of microcell Ca, the magnetization free layer Ca11 is magnetized to be parallel or approximately parallel to the normal directions of the bottom surfaces Ca111 and Ca112, as in the case of the magnetization free layer C11 of microcell C (see arrow M11 shown in FIG. 3). Therefore, like microcell C, microcell Ca functions as a spin injection optical phase modulator. Furthermore, microcell Ca employs a configuration similar to that of a SOT-type MRAM in order to inject a spin current into the magnetization free layer Ca11. In microcell Ca, electrode Ca12 is one aspect of a control unit that controls the magnetization direction of the magnetization free layer Ca11.

[0066] [Second Modification of Microcell] A microcell Cb, which is a second modified example of the microcell C (see FIG. 2(b)), will be described with reference to FIG. 4. FIG. 4 is a cross-sectional view of the microcell Cb.

[0067] As shown in FIG. 4, the microcell Cb includes a magnetization free layer Cb11, an electrode Cb12, an electrode Cb13, a magnetization fixed layer Cb14, and an insulating layer Cb15.

[0068] The magnetization free layer Cb11 is configured in the same manner as the magnetization free layer C11 of the microcell C. However, the magnetization free layer Cb11 differs from the magnetization free layer C11 in that the magnetization free layer Cb11 is not formed so as to stand directly on one main surface of the substrate 131, but is stacked so as to stand on the electrode Cb12, the magnetization fixed layer Cb14, and the insulating layer Cb15 that are stacked on one main surface of the substrate 131.

[0069] In the magnetization free layer Cb11, the bottom surface Cb111 functions as a first optically effective surface, and the bottom surface Cb112 functions as a second optically effective surface.

[0070] The electrode Cb12 is an electrode made of a conductor film, similar to the electrode C12 of the microcell C. However, the electrode Cb12 is an electrode made of a conductor film, similar to the electrode C12 of the microcell C. b The electrode Cb12 differs from the electrode C12 in that it is not formed on one of the four side surfaces excluding the pair of bottom surfaces Cb111 and Cb112 out of the six surfaces constituting the microcell Ca11, but is indirectly formed on the bottom surface Cb112 via an insulating layer Cb15 and a magnetization fixed layer Cb14. In other words, the electrode Cb12 is configured similarly to the electrode Ca12 of the microcell Ca (see FIG. 3). Furthermore, the electrode Cb12 is preferably made of a metal with high conductivity such as aluminum (Al) or copper (Cu). The electrode Cb12 is an example of a second electrode provided on the magnetization fixed layer Cb14, which will be described later.

[0071] In the microcell Cb, not only the electrode Cb12 but also a magnetization fixed layer Cb14, an insulating layer Cb15, a magnetization free layer Cb11, and an electrode Cb13 are stacked on one main surface of the substrate 131 in this order.

[0072] The magnetization fixed layer Cb14 is made of, for example, a conductive hard magnetic material (e.g., Permalloy). The magnetization fixed layer Cb14 is configured so that its magnetization direction (see arrow M14 in FIG. 4) is parallel or approximately parallel to the normal direction of each of the bottom surface Cb111, which is the first optically effective surface, and the bottom surface Cb112, which is the second optically effective surface. In FIG. 4, the surface of the electrode Cb12 (the interface between the electrode Cb12 and the magnetization fixed layer Cb14) is illustrated as functioning as a reflective surface for right-handed circularly polarized light L3. However, the material constituting the magnetization fixed layer Cb14 exhibits a certain reflectivity for right-handed circularly polarized light L3 having a predetermined wavelength. Therefore, depending on the wavelength of the right-handed circularly polarized light L3 and the reflectivity of the magnetization pinned layer Cb14 for that wavelength, the right-handed circularly polarized light L3 is reflected not only by the surface of the electrode Cb12, but also inside the magnetization pinned layer Cb14 or by the surface of the magnetization pinned layer Cb14 (the interface between the magnetization pinned layer Cb14 and the insulating layer Cb15).The position at which the right-handed circularly polarized light L3 is reflected can be changed by appropriately selecting the material that constitutes the magnetization pinned layer Cb14 and the thickness of the magnetization pinned layer Cb14.

[0073] The insulating layer Cb15 is an insulating layer that forms a tunnel junction together with the magnetization fixed layer Cb14 and the magnetization free layer Cb11.

[0074] The electrode Cb13 is an electrode made of a conductor film, similar to the electrode Cb12. However, the electrode Cb13 faces the electrode Cb12 and is formed to cover the bottom surface Cb111 so as to sandwich the magnetization fixed layer Cb14, the insulating layer Cb15, and the magnetization free layer Cb11 together with the electrode Cb12. That is, the electrode Cb13 is formed in direct contact with the bottom surface Cb111, which is one of the bottom surfaces of the magnetization free layer Cb11. The electrode Cb13 is made of a transparent electrode material that transmits right-handed circularly polarized light L3 and left-handed circularly polarized light L6. Suitable transparent electrode materials include ITO, IGZO, ZnO, GZO (gallium-doped zinc oxide), silver nanowires, and carbon nanotube thin films. The electrode Cb13 is an example of a first electrode provided on the magnetization free layer Cb11.

[0075] A power supply PS is connected to the pair of electrodes Cb12 and Cb13 (see FIG. 4). When a potential difference is applied between the electrodes Cb12 and Cb13 using a voltage generated by the power supply PS, a spin current is injected from the magnetization fixed layer Cb14 to the magnetization free layer Cb11 through the insulating layer Cb15 due to the tunnel effect, and magnetization occurs in the magnetization free layer Cb11 (see arrow M11 in FIG. 4). Here, the magnetization generated in the magnetization free layer Cb11 is parallel to the magnetization of the magnetization fixed layer Cb14 (see arrow M14 in FIG. 4). In other words, the magnetization free layer Cb11 is magnetized so as to be parallel or approximately parallel to the normal directions of the bottom surfaces Cb111 and Cb112 of the magnetization free layer Cb11. Therefore, the microcell Cb functions as a spin injection optical phase modulator, similar to the microcell C. Furthermore, the microcell Cb employs a configuration similar to that of an STT-type MRAM in order to inject a spin current into the magnetization free layer Cb11. In the microcell Cb, the electrodes Cb12 and Cb13 are one aspect of a control unit that controls the magnetization direction of the magnetization free layer Ca11. Note that in one aspect of the present invention, like the electrodes Cb12 and Cb13, one of the two control units (electrode Cb13) may be formed so as to be in direct contact with the magnetization free layer, and the other (electrode Cb12) may be formed indirectly with respect to the magnetization free layer via another material.

[0076] [Third Modification of Microcell] A microcell Cc, which is a third modified example of the microcell C (see (b) of FIG. 2), will be described with reference to FIG. 5. (a) of FIG. 5 is a perspective view of the microcell Cc. (b) of FIG. 5 is a plan view of the microcell Cc. Note that the plan view shown in (b) of FIG. 5 shows the bottom surface Cc111 of the magnetization free layer Cc11 constituting the microcell Cc, as viewed from the normal direction of the bottom surface Cc111 (to the right in (a) of FIG. 5).

[0077] As shown in (a) and (b) of FIG. 5, the microcell Cc includes a magnetization free layer Cc11 and a conductor pattern Cc16.

[0078] The magnetization free layer Cc11 is configured in the same manner as the magnetization free layer C11 of the microcell C. That is, the magnetization free layer Cc11 is formed so as to stand directly on one of the main surfaces of the substrate 131.

[0079] The conductor pattern Cc16 is a conductor film formed over three of the four side surfaces of the magnetization free layer Cc11, which is a rectangular parallelepiped columnar member. That is, the conductor pattern Cc16 is formed in direct contact with the three side surfaces of the magnetization free layer Cc11. In the conductor pattern Cc16 shown in FIG. 5(b), the region formed on the lower side surface of the three side surfaces is referred to as the first region Cc161, the region formed on the left side surface is referred to as the second region Cc162, and the region formed on the upper side surface is referred to as the third region Cc163. The conductor pattern Cc16 is one aspect of a control unit that controls the magnetization direction of the magnetization free layer Cc11.

[0080] The conductor constituting the conductive pattern Cc16 is preferably a metal, more preferably a metal with good conductivity, such as gold, copper, and aluminum.

[0081] This modification shows a part of a matrix structure formed on one main surface of the substrate 131. The matrix structure used in this modification is a simple matrix structure. However, in this modification, an active matrix structure can also be used instead of the simple matrix structure.

[0082] 5(a) and 5(b) illustrate a first signal line LS1 extending in a first direction (the up-down direction in FIG. 5(b)), and a second signal line LS2 extending in a second direction (the left-right direction in FIG. 5(b)). The first signal line LS1 and the second signal line LS2 are formed in different layers, and an insulating layer is interposed between the layer on which the first signal line LS1 is formed and the layer on which the second signal line LS2 is formed. Therefore, although the first signal line LS1 and the second signal line LS2 intersect in the plan view of FIG. 5(b), the first signal line LS1 and the second signal line LS2 are insulated from each other at the intersection.

[0083] In the conductor pattern Cc16, the first region Cc161 is electrically connected to the first signal line LS1 via the first electrode pattern EL1, and the third region Cc 163 is electrically connected to the second signal line LS2 via the second electrode pattern EL2. Therefore, when a current I flows from the first signal line LS1 to the second signal line LS2, the current I flows qualitatively as shown by the arrows in FIGS. 5(a) and 5(b). As a result, an external magnetic field caused by the current I flowing through the conductor pattern Cc16 is applied to the magnetization free layer Cc11, and the magnetization free layer Cc11 is magnetized. In FIGS. 5(a) and 5(b), the direction of magnetization of the magnetization free layer Cc11 is indicated by the arrow M11. The magnitude of the magnetization of the magnetization free layer Cc11 can be controlled by the direction and magnitude of the current flowing through the conductor pattern Cc16.

[0084] In this manner, in this modification, the magnetization free layer Cc11 is configured so that the direction of magnetization generated when a current I flows through the conductor pattern Cc16 is parallel or approximately parallel to the normal direction of each of the pair of bottom surfaces (the bottom surface Cc111 and the bottom surface opposite to the bottom surface Cc111). Therefore, similar to the microcell C shown in FIG. 2(b), the microcell Cc can control the amount of phase modulation of the circularly polarized light according to the magnitude of the magnetization of the magnetization free layer Cc11.

[0085] As described above, in one aspect of the present invention, the microcell Cc includes a magnetization free layer Cc11 having a pair of first and second optically effective surfaces (bottom surface Cc111 and a bottom surface opposite to bottom surface Cc111) that face each other, and an electrode (conductor pattern Cc16) that controls the magnetization direction of the magnetization free layer Cc11. In the microcell Cc, each magnetization free layer Cc11 and each control unit (conductor pattern Cc16) are configured to control the magnetization direction of the magnetization free layer Cc11 so that it is parallel or approximately parallel to the normal directions of the first and second optically effective surfaces (bottom surface Cc111 and a bottom surface opposite to bottom surface Cc111).

[0086] In this modification, the conductor pattern Cc16 is formed continuously over three of the four side surfaces constituting the magnetization free layer Cc11. However, the number of side surfaces on which the conductor pattern Cc16 is formed is not limited to three and may be two or four. When the number of side surfaces on which the conductor pattern Cc16 is formed is two, the two side surfaces may be adjacent to each other or may be opposing each other. When the conductor pattern Cc16 is formed on two opposing side surfaces, the first signal line and the second signal line may be connected to each conductor pattern. When the number of side surfaces on which the conductor pattern Cc16 is formed is four, one end of the conductor pattern Cc16 (the end connected to the first electrode pattern EL1) and the other end (the end connected to the second electrode pattern EL2) may be spaced apart so that the conductor pattern Cc16 does not form a closed loop around the magnetization free layer Cc11.

[0087] [Fourth Modification of Microcell] A microcell Cd, which is a fourth modified example of the microcell C (see (b) of FIG. 2), will be described with reference to FIG. 6. (a) of FIG. 6 is a perspective view of the microcell Cd. (b) of FIG. 6 is a plan view of the microcell Cd. In the plan view shown in (b) of FIG. 6, the bottom surface Cd111 of the magnetization free layer Cd11 constituting the microcell Cd is d Normal direction of 111 (Fig. 61 shows the state as seen from the right side of (a).

[0088] The microcell Cd can be considered a modified example of the microcell Cc. In this modified example, the configuration of the microcell Cd will be described based on the microcell Cc. As shown in (a) and (b) of Figure 6, the microcell Cd includes a magnetization free layer Cd11, a conductor pattern Cd16, and a gap filler FG.

[0089] The magnetization free layer Cd11 has the same configuration as the magnetization free layer Cc11 of the microcell Cc. The bottom surface Cd111 corresponds to the bottom surface Cc111 of the magnetization free layer Cc11. Therefore, in this modification, a description of the magnetization free layer Cd11 will be omitted.

[0090] The conductor pattern Cd16 corresponds to the conductor pattern Cc16 of the microcell Cc and is one aspect of a control unit that controls the magnetization direction of the magnetization free layer Cd11. As shown in FIG. 6(a), the conductor pattern Cd16 is obtained by forming a strip-shaped conductor film in a spiral shape on the four side surfaces of the magnetization free layer Cd11. That is, the conductor pattern Cd16 is formed in direct contact with the four side surfaces of the magnetization free layer Cd11. The conductor pattern Cd16 can also be considered a kind of solenoid coil.

[0091] In this modification, one end of the conductor pattern Cd16 is located on the base side of the magnetization free layer Cd11 (on the left side in the state shown in FIG. 6(a)), and the other end of the conductor pattern Cd16 is located on the tip side of the magnetization free layer Cd11 (on the right side in the state shown in FIG. 6(a)). Therefore, in the conductor pattern Cd16, a gap is formed between one end and the other end at the height of the magnetization free layer Cd11 (the gap between the bottom surface Cd111 and the bottom surface opposite to the bottom surface Cd111). equivalent There is a gap.

[0092] Therefore, in this modified example, of the first and second signal line groups that constitute the matrix structure, the first signal line group (the first signal line LS1 in (a) of Figure 6) is formed on one main surface of the substrate 131, and then a gap filler FG having the same thickness as the height of the magnetization free layer Cd11 is formed on one main surface of the substrate 131, and the second signal line group (the second signal line LS2 in (a) of Figure 6) is formed on the surface of the gap filler FG.

[0093] The material of the gap filler FG is not limited and can be appropriately selected from existing materials. Examples of the material of the gap filler FG include SOG (Spin-On-Glare) and SOG (Spin-On-Glare). Glass ) and polymers.

[0094] In the microcell Cd, the conductor pattern Cd16 functions as a solenoid coil. Therefore, by passing a current I from the first signal line LS1 to the second signal line LS2, an external magnetic field caused by the current I flowing through the conductor pattern Cd16 can be applied to the magnetization free layer Cd11, as shown in Figures 6(a) and 6(b). Therefore, like the microcell C shown in Figure 2(b), the microcell Cd can control the amount of phase modulation of circularly polarized light depending on the magnitude of magnetization of the magnetization free layer Cd11.

[0095] [Modification of Optical Computing Device] An optical arithmetic device 1A, which is a modified example of the optical arithmetic device 1, will be described with reference to Fig. 7. Fig. 7 is a schematic diagram showing the configuration of the optical arithmetic device 1A.

[0096] The optical arithmetic device 1A has the same configuration as the optical arithmetic device 1. However, while the optical arithmetic device 1 includes a single spatial light phase modulator 13, the optical arithmetic device 1A includes a spatial light phase modulator group 13A consisting of three spatial light phase modulators 13a, 13b, and 13c. Therefore, in this modification, only the spatial light phase modulator group 13A will be described, and descriptions of the other components will be omitted.

[0097] Each of the spatial light phase modulators 13a, 13b, and 13c has the same configuration as the spatial light phase modulator 13 in the optical processing device 1. Each of the spatial light phase modulators 13a, 13b, and 13c is disposed between the quarter-wave plate 12 and the mirror 14 and on the optical path of the signal light in a stacked state in order.

[0098] According to the above configuration, the spatial light phase modulators 13a, 13b, and 13c act in the order of the spatial light phase modulators 13a, 13b, and 13c on the signal light traveling from the quarter-wave plate 12 to the mirror 14. Furthermore, the spatial light phase modulators 13a, 13b, and 13c act in the order of the spatial light phase modulators 13c, 13b, and 13a on the signal light reflected by the mirror 14 and traveling back from the mirror 14 to the quarter-wave plate 12.

[0099] Each of the spatial light phase modulators 13a, 13b, and 13c configured in this manner can perform a multi-stage optical operation on the signal light Li input to the optical operation device 1.

[0100] In this modification, adjacent spatial light phase modulators 13a, 13b, and 13c are in contact with each other. Therefore, the distance between adjacent magnetization-free layers C11 (for example, the distance between the bottom surface C112 of the spatial light phase modulator 13a and the bottom surface C111 of the spatial light phase modulator 13b) is determined by the thickness of the substrate 131. The thickness of the substrate 131 that determines the distance between the magnetization-free layers C11 is not particularly limited and can be determined appropriately. Furthermore, adjacent spatial light phase modulators 13a, 13b, and 13c may be spaced apart by a predetermined distance. In this way, in the optical processing device 1A, the distance between the magnetization-free layers C11 and the distance between the spatial light phase modulators 13 can be adjusted depending on the design of the optical processing device 1A, the tasks performed by the optical processing device 1A, and the like.

[0101] 〔summary〕 A spatial light phase modulator according to a first aspect of the present invention is a spatial light phase modulator including a plurality of microcells, wherein each microcell is configured by an optical phase modulator including a magnetization free layer having a first optically effective surface and a second optically effective surface facing each other, and a control unit that controls the magnetization direction of the magnetization free layer, and each magnetization free layer and each control unit are configured to control the magnetization direction so that it is parallel or approximately parallel to the normal direction of each of the first optically effective surface and the second optically effective surface.

[0102] According to the above configuration, it is possible to provide a spatial light phase modulator that can be miniaturized and can operate at high speed.

[0103] Furthermore, in a spatial light phase modulator according to a second aspect of the present invention, in addition to the configuration of the spatial light phase modulator according to the first aspect described above, the control unit is an electrode that injects a spin current into the magnetization free layer, and the magnetization free layer is configured so that the direction of magnetization generated when the spin current is injected from the electrode is parallel or approximately parallel to the normal direction of each of the first optically effective surface and the second optically effective surface.

[0104] The spatial optical phase modulator according to the second aspect of the present invention can also be expressed as follows: That is, the spatial optical phase modulator according to the second aspect of the present invention is a spatial optical phase modulator including a plurality of microcells arranged two-dimensionally, each microcell being configured as a spin injection type optical phase modulator including a magnetization free layer and an electrode that injects a spin current into the magnetization free layer, each magnetization free layer having a first optical effective surface and a second optical effective surface facing each other, and configured so that the direction of magnetization generated when the spin current is injected from the electrode is parallel or approximately parallel to the normal direction of each of the first optical effective surface and the second optical effective surface.

[0105] Each microcell of this spatial optical phase modulator employs an optical phase modulator configured similarly to a spin transfer torque (STT) magnetoresistive random access memory (MRAM) or a spin orbit torque (SOT) MRAM to inject spin current into the magnetization free layer. The magnetization of the magnetization free layer due to spin injection is a phenomenon that occurs in nanoscale spaces. For this reason, devices that utilize magnetization due to spin injection tend to achieve higher speeds by reducing the size of the microcell. Therefore, this spatial optical phase modulator, like MRAM, can be miniaturized and operate at high speeds.

[0106] Furthermore, the magnetization free layer is magnetized so as to be parallel or approximately parallel to the normal direction of each of the first optically effective surface and the second optically effective surface due to the spin current, which is a flow of spin-polarized electrons. In each microcell, the signal light propagates in the magnetization free layer along the normal direction of each of the first optically effective surface and the second optically effective surface. Therefore, in each microcell, the propagation direction of the signal light and the magnetization direction in the magnetization free layer are parallel or approximately parallel. Therefore, in each microcell, magnetization The amount of phase modulation in each microcell can be controlled by using the magnitude of the spin current injected into the free layer.

[0107] Therefore, the present spatial optical phase modulator configured as described above can be miniaturized, and an optical phase modulator capable of operating at high speed can be provided.

[0108] Furthermore, in a spatial light phase modulator according to a third aspect of the present invention, in addition to the configuration of the spatial light phase modulator according to the second aspect described above, magnetization The optically effective surface on which the signal light is first incident on the free layer is defined as the first optically effective surface, and magnetizationThe configuration further includes a mirror provided on the side of the free layer facing the second optically effective surface, and the reflective surface of the mirror is parallel or approximately parallel to the second optically effective surface.

[0109] According to the above configuration, each optical phase modulator of the spatial optical phase modulator is a reflective optical phase modulator in which signal light incident on a first effective optical surface is reflected by a mirror and the reflected signal light exits from the first effective optical surface. A reflective optical phase modulator can double the optical path of the signal light compared to a transmissive optical phase modulator. Therefore, a reflective optical phase modulator can widen the range of controllable phase modulation amounts compared to a transmissive optical phase modulator. Note that a transmissive optical phase modulator refers to an optical phase modulator that does not include a mirror and in which signal light incident on a first effective optical surface exits from a second effective optical surface.

[0110] Furthermore, in a spatial light phase modulator according to a fourth aspect of the present invention, in addition to the configuration of the spatial light phase modulator according to the third aspect described above, a configuration is adopted in which the spatial light phase modulator further comprises a quarter-wave plate provided on the side of the first optically effective surface of each of the magnetization free layers and whose main surface is parallel or approximately parallel to the first optically effective surface.

[0111] According to the above configuration, the quarter-wave plate converts linearly polarized light into either right-handed circularly polarized light or left-handed circularly polarized light, so that linearly polarized light can be used as the signal light to be incident on the spatial light phase modulator.

[0112] Furthermore, in a spatial light phase modulator according to a fifth aspect of the present invention, in addition to the configuration of the spatial light phase modulator according to any one of the second to fourth aspects described above, a configuration is adopted in which, in each of the microcells, the electrode is a single electrode made of a material containing a heavy metal.

[0113] According to the above configuration, in each microcell of the spatial light phase modulator, a configuration similar to that of an SOT-type MRAM is adopted as a configuration for injecting a spin current into the magnetization free layer. Therefore, compared to a spatial light phase modulator that adopts a configuration similar to that of an STT-type MRAM as a configuration for injecting a spin current into the magnetization free layer, the spatial light phase modulator can operate at a higher speed. Furthermore, according to the above configuration, the conversion efficiency of converting a current into a spin current polarized in one direction can be improved.

[0114] Furthermore, in a spatial light phase modulator according to a sixth aspect of the present invention, in addition to the configuration of the spatial light phase modulator according to the fifth aspect described above, a configuration is adopted in which the spatial light phase modulator further comprises a power supply connected to the electrodes and generating a pulse voltage or a pulse current.

[0115] According to the above configuration, the conversion efficiency can be further improved.

[0116] Furthermore, in a spatial light phase modulator according to a seventh aspect of the present invention, in addition to the configuration of the spatial light phase modulator according to any one of the second to fourth aspects described above, each microcell further comprises a magnetization fixed layer, and in each microcell, the electrode consists of a first electrode provided on the magnetization free layer and a second electrode provided on the magnetization fixed layer.

[0117] According to the above configuration, each microcell of this spatial light phase modulator employs a configuration similar to that of an STT-type MRAM for injecting a spin current into the magnetization-free layer. Compared to a spatial light phase modulator that employs a configuration similar to that of an SOT-type MRAM for injecting a spin current into the magnetization-free layer, each microcell of this spatial light phase modulator has a wider range of materials available for use as electrode materials. Therefore, this spatial light phase modulator allows for greater freedom in electrode design.

[0118] An optical computing device according to an eighth aspect of the present invention includes a plurality of spatial light phase modulators according to any one of the first to seventh aspects described above. In this optical computing device, the spatial light phase modulators are arranged to act on the signal light in sequence.

[0119] According to the above configuration, each spatial light phase modulator can be made smaller and its operation can be made faster, so that an optical arithmetic device that can be made smaller and operate at high speed can be provided. [Explanation of symbols]

[0120] 1,1A optical processing device 11 Polarizing beam splitter 12 Quarter-wave plate 13, 13a, 13b, 13c Spatial light phase modulator 131 Circuit Board 13A Spatial light phase modulator group C, Ca, Cb, Cc, Cd microcells C11,Ca11,Cb11,Cc11,Cd11 Magnetization free layer C111,Ca111,Cb111,Cc111,Cd111 Bottom C112,Ca112,Cb112 Bottom C12, Ca12, Cb12 electrodes (control section) Cb13 electrode Cb14 magnetization fixed layer Cb15 insulating layer Cc16, Cd16 conductor pattern (control section) 14. Mirror

Claims

1. An optical computing device including, in order of incidence of light, a polarization separation element, a quarter-wave plate, a spatial light phase modulator, and a mirror, the polarization separation element transmits only one of the orthogonal polarization components of incident light, the quarter-wave plate has a fast axis and a slow axis that are orthogonal to each other; the spatial light phase modulator comprises a plurality of microcells; each microcell includes a magnetization free layer having a first optically effective surface and a second optically effective surface facing each other, and a control unit that controls the magnetization direction of the magnetization free layer; each magnetization free layer and each control unit is configured to control the orientation of the magnetization so that the orientation of the magnetization becomes parallel or approximately parallel to a normal direction of each of the first optically effective surface and the second optically effective surface; an optically effective surface onto which the signal light is first incident on the magnetization free layer is defined as a first optically effective surface, and the quarter-wave plate is provided on the side of the first optically effective surface of each of the magnetization free layers, and is disposed such that a principal surface is parallel or substantially parallel to the first optically effective surface and the slow axis forms an angle of 45 degrees with one of the polarization components; the mirror is provided on the side of the second optically effective surface of each of the magnetization free layers, and a reflecting surface is parallel or approximately parallel to the second optically effective surface; An optical computing device characterized by:

2. the control unit is an electrode that injects a spin current into the magnetization free layer, the magnetization free layer is configured so that the direction of magnetization generated when the spin current is injected from the electrode is parallel or approximately parallel to the normal direction of each of the first optically effective surface and the second optically effective surface.

2. The optical computing device according to claim 1.

3. In each of the microcells, the electrode is a single electrode made of a material containing a heavy metal.

3. The optical computing device according to claim 2.

4. Further comprising a power supply connected to the electrodes and generating a pulsed voltage or pulsed current.

4. The optical computing device according to claim 3.

5. Each of the microcells further includes a magnetization fixed layer; In each of the microcells, the electrodes include a first electrode provided on the magnetization free layer and a second electrode provided on the magnetization fixed layer.

3. The optical computing device according to claim 2.

6. A plurality of the spatial light phase modulators are provided, Each spatial light phase modulator is arranged to act on the signal light in sequence.

6. The optical computing device according to claim 1, wherein the optical computing device comprises: a first optical fiber;

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