KR100360082B1 - Spatial light modulation - Google Patents

Abstract

The present invention relates to a spatial light modulator, the conventional magneto-optic spatial light modulator has a large power consumption by applying a relatively large current in order to reverse the magnetization direction of the pixel. The present invention in view of such a problem and a plurality of electrodes to which the current in the set direction is applied; A plurality of soft magnetic bodies that are insulated with an insulating film opposite to each of the plurality of electrodes and determine a direction of magnetization according to a direction of a current applied to the electrodes; A reflection layer disposed on an upper surface of the insulating layer and the plurality of soft magnetic materials to reflect incident light; An intra-pixel magnetic domain wall movement suppressing unit positioned at a position opposite to a central portion of the plurality of soft magnetic bodies on the upper side of the reflective layer; The incident light is determined by determining a vertical magnetization direction in a direction different from each other on the left and right sides of the pixel wall movement suppressing unit facing the front surface of the intra-pixel magnetic domain movement suppressing unit and the soft magnetic material. A pair of magnetic domains rotated along the polarization plane; An intra-pixel magnetic domain wall movement suppressing unit for preventing the magnetic domain wall from moving between the pair of magnetic domains; Inverted magnetic domain is composed of a soft magnetic layer is located in the upper pixel of the magnetic domain movement suppressing unit between the pixel and the upper surface of the magnetic domain and the magnetization direction is determined in a direction to circulate the direction of the magnetization formed on the magnetic domain and the magnetic domain By not forming the nucleus of, it is driven at a relatively small current has the effect of reducing the power consumption.

Description

Spatial Light Modulators {SPATIAL LIGHT MODULATION}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spatial light modulator, and more particularly, to a magneto-optic spatial light modulator having a high switching sensitivity and a high operating speed by converting a magnetization direction of a pixel with a small current.

In general, the spatial light modulator for spatially modulating the incident light is used in the field of optical information processing, optical computing, optical information storage using holography, micro display and the like. In the above fields, it is necessary to process a large amount of information at high speed, so that a spatial light modulator having a high operating speed and a large switching sensitivity of the pixel is required.

Conventional magneto-optic spatial light modulators are made of magneto-optical materials, respectively, as disclosed in US Pat. The Faraday effect, which is a magneto-optical effect on the transmitted light, causes the polarization planes of the light passing through the pixels to rotate by a predetermined angle in opposite directions, depending on the direction of magnetization of each pixel.

Due to this characteristic, it is possible to generate spatially modulated light by arbitrarily setting the magnetization direction of the pixel.

The conventional spatial light modulator generates a magnetic field by passing a current through two electrode lines intersecting in a pixel in a terminal sphere state to invert a magnetization direction of a pixel, thereby generating a magnetic field, and inverted magnetization in a direction opposite to a portion of the pixel. To form the nucleus and magnetic wall.

Then, a current flows through a bias coil provided around the spatial light modulator to generate a magnetic field, thereby moving the formed magnetic wall to the end of the pixel, thereby inverting the magnetization direction of the entire pixel.

At this time, the magnetic wall easily moves even when the size of the magnetic field is small, but a strong magnetic field must be applied to generate a nucleus of the inverted magnetic domain, and a relatively large current must be applied to the electrode line to apply the strong magnetic field.

As described above, the conventional spatial light modulator requires a large current to generate a nucleus of the inverting domain, that is, to invert the magnetization direction of the pixel, thereby causing a large power consumption problem.

It is an object of the present invention to provide a spatial light modulator capable of changing the magnetization direction of a pixel without forming a magnetic domain nucleus.

1 is a cross-sectional view of one embodiment of the spatial light modulator of the present invention.

Figure 2 is a schematic diagram of the operation of the circuit and the spatial light modulator for driving the spatial light modulator of the present invention.

3 is a plan view of an electrode, a soft magnetic body, and a magnetic domain in FIG. 1;

4 is another embodiment of the present invention.

FIG. 5 is a plan view of an electrode, a soft magnetic body, and a magnetic domain in FIG. 4; FIG.

6 is another embodiment of the present invention.

7 is a plan view of an electrode, a soft magnetic body, and a magnetic domain in FIG. 6;

Figure 8 is another embodiment of the present invention.

9 is another embodiment of the present invention.

Figure 10 is another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

14: soft magnetic material 15: electrode

16: reflection layer 17: insulating film

18: inter-pixel magnetic domain movement suppressing unit 19: intra-pixel magnetic domain movement suppressing unit

11: wall 12a, 12b:

20: soft magnetic layer 24: substrate

25: stator magnetization layer

The above object is a plurality of electrodes to which the current in the set direction is applied; A plurality of soft magnetic bodies that are insulated with an insulating film opposite to each of the plurality of electrodes and determine a direction of magnetization according to a direction of a current applied to the electrodes; A reflection layer disposed on an upper surface of the insulating layer and the plurality of soft magnetic materials to reflect incident light; An intra-pixel magnetic domain wall movement suppressing unit positioned at a position opposite to a central portion of the plurality of soft magnetic bodies on the upper side of the reflective layer; The incident light is determined by determining a vertical magnetization direction in a direction different from each other on the left and right sides of the pixel wall movement suppressing unit facing the front surface and the soft magnetic material. A pair of magnetic domains rotated along the polarization plane; An intra-pixel magnetic domain wall movement preventing unit for preventing the magnetic domain wall from moving between the pair of magnetic domains; It is achieved by forming a soft magnetic layer positioned on the inter-pixel magnetic domain movement suppressing unit and the upper surface of the magnetic domain to transmit light, and the direction of magnetization is determined in a direction circulating the direction of the magnetization formed in the soft magnetic domain and the magnetic domain. When described in detail with reference to the accompanying drawings, the present invention as follows.

1 is a cross-sectional view of an embodiment of the spatial light modulator of the present invention, as shown therein; a plurality of electrodes 15 to which current in a set direction is applied; A plurality of soft magnetic bodies 14 which are insulated from the insulating film 17 so as to face each of the plurality of electrodes 15 and determine the direction of magnetization according to the direction of the current applied to the electrodes 15; A reflection layer 16 disposed on the upper surface of the insulating layer 17 and the plurality of soft magnetic bodies 14 to reflect the applied light; An intrapixel pixel wall movement suppressing unit (19) located at a position opposite to a central portion of the plurality of soft magnetic bodies (14) on the upper side of the reflective layer (16); The left and right sides of the in-pixel magnetic domain movement suppressing unit 19 are positioned to face the soft magnetic material 14 so as to be centered on the magnetic wall 11 which is a central upper side of the intra-pixel magnetic domain movement inhibiting unit 19. A plurality of magnetic domains 12a and 12b for determining a vertical magnetization direction in another direction; An intra-pixel magnetic domain movement preventing unit (18) for preventing the magnetic domain from moving between the plurality of magnetic domains (12a, 12b); Located on the upper surface of the inter-pixel magnetic domain movement suppressing unit 18 and the magnetic domains 12a and 12b to transmit light, and to circulate the direction of magnetization formed in the soft magnetic body 14 and the magnetic domains 12a and 12b. It consists of a soft magnetic layer 20 in which the direction of magnetization is determined in the direction. Reference numerals 13a and 13b denote pixels.

Hereinafter, the structure and operation of an embodiment of the present invention configured as described above will be described in more detail.

FIG. 2 is a schematic diagram of a circuit and a spatial light modulator for driving the spatial light modulator of the present invention. As shown in FIG. 2, the driver 30 receiving the control signal according to the modulation information of the controller 40 is connected to a specific electrode 15. Allow negative or positive current to flow.

When a current flows through the electrode 15 in this manner, a magnetization direction in the right or left direction is formed in the soft magnetic body 14 according to the direction of the current. That is, the magnetization direction from the left to the right is formed in the soft magnetic body 14 in the direction in which the current enters, and the magnetization direction from the right to the left is formed in the soft magnetic body 14 in the direction of the current. At this time, the soft magnetic body 14 has uniaxial magnetic anisotropy, and has two axes for magnetization opposite to each other. Therefore, when the direction of the current applied to the electrode 15 changes, the soft magnetic body 14 is applied to the soft magnetic body 14. The polarity also changes.

When the magnetization direction is determined as described above, the leakage magnetic flux generated from the soft magnetic body 14 interacts with the magnetic domains 12a and 12b so that the S pole of the magnetic domain is attracted to the N pole of the soft magnetic body 14. The north pole of the magnetic domain is attracted to the south pole of the magnetic body 14. In this manner, the magnetic domains 12a and 12b are provided with magnetization directions in different directions, respectively. In this case, reference numeral 12a denotes a magnetic domain whose magnetization direction is determined to the upper side, and 12b denotes a magnetic domain whose magnetization direction is determined to the lower side.

The direction of magnetization formed on the magnetic domains 12a and 12b is separated by the intra-pixel magnetic domain wall movement suppressing unit 19 so that the magnetic domain wall does not move, and thus the state can be maintained. In this case, the intra-pixel magnetic domain movement suppressing unit 19 may be formed as a shallow groove in which a part of the pixels 13a and 13b are removed.

According to the positions of the two magnetic domains 12a and 12b, that is, the direction of magnetization formed on the right and left magnetic domains, binary light modulation can be performed by defining the states of the pixels as 1 and 0. A magneto-optical material having an optical effect may be used, but it is particularly preferable to use a magnetic garnet thin film or a one-dimensional magnetic photonic crystal.

Representative examples of the magnetic garnet thin film include a rare earth iron-based garnet thin film, and the manufacturing method thereof is a liquid epitaxial method (LPE method) or sputtering method on top of a gadolinium gallium garnet (Gd ₃ Fe ₅ O ₁₂ , GGG) or a glass substrate. To form a magnetic garnet thin film using.

FIG. 3 is a schematic view showing the plane of the electrode 15, the soft magnetic body 14, and the two magnetic domains 12a and 12b. In FIG. When applied to the soft magnetic body 14, the magnetization direction from the right side to the left side is determined, and the magnetization direction 12b located at the left side of the soft magnetic body 14 is determined by the direction of the magnetization direction outward of the plane. As for the magnetic domain 12a located in the right part, the magnetization direction to the inside of a plane is determined.

At this time, if the direction of the current applied to the electrode 15 changes downward in the plane as shown in Fig. 3 (b), the magnetization direction of the soft magnetic material 14 from left to right is determined, accordingly magnetic domain 12a The magnetization direction of (12b) is also reversed.

Finally, when the magnetization directions of the magnetic domains 12a and 12b are determined, partially different magnetization directions are determined in the soft magnetic layer 20.

In this case, light incident through the soft magnetic layer 20 is applied to the two magnetic domains 12a and 12b after passing through the pixels 13a and 13b. At this time, the polarization plane is rotated according to the magnetization direction of the pair of two magnetic domains 12a and 12b in each pixel due to the Faraday effect, and a Faraday rotation angle is imposed and reflected through the reflective layer 16 to be soft magnetic layer 20 again. Is emitted to outside.

The imposition of the rotation angle by the Faraday effect is that the polarization plane of the light passing through the magnetic domain 12a in the pixel whose magnetization direction is upwards passes through + θ _F and the magnetic domain 12b in the pixel whose magnetization direction is downward. the polarization plane of light is rotated by -θ _F, even when the reflection is also the same as the rotation amount of each light is rotated by the angle of rotation of + 2θ _{F, F} -2θ.

The light incident on the spatial light modulator 1 by the above operation is spatially modulated, and a pixel having a pair of magnetic domains magnetized in the up and down directions from the left with respect to the surfaces of the pixels 13a and 13b is 1. And a pixel having a pair of magnetic domains magnetized in the downward direction and the upward direction from the left side as 0 can be used to perform binary light modulation.

In this way, the magnetization directions of the two magnetic domains 12a and 12b magnetized in the opposite directions in each pixel by the electrode 15 and the soft magnetic material 14 are independently set for each pixel. The polarization plane is rotated according to the magnetization direction of two magnetic domains in each pixel to modulate spatially. The direction of magnetization formed in the soft magnetic material 14 and the magnetic domains 12a and 12b is about several nanoseconds (ns) as fast as time. It is possible to change to a very fast operation speed can be obtained.

In addition, reliability is improved by not using a fluid such as a liquid crystal, and light is prevented from being scattered by not using a transparent electrode, thereby miniaturizing pixels.

4 is a cross-sectional view of another embodiment of the spatial light modulator according to the present invention, in which an electrode 15 is provided to be in contact with the reflective layer 16, and a soft magnetic material 14 is formed on the upper surface of the electrode 15 as an insulating film. It can be positioned so as to be insulated by (17), which has the same operation and effect as the spatial light modulator described in FIG. 1, and the position of the soft magnetic material 14 and the electrode 15 in a plane as shown in FIG. It can be seen that is changed from the position shown in FIG.

FIG. 6 is a cross-sectional view of another embodiment of the spatial light modulator of the present invention. As shown therein, the electrodes 15 shown in FIG. 1 are insulated from each other with an insulating layer interposed therebetween, and intersect each other at the center lower side of the soft magnetic material 14. The dual structure of the transverse electrode 22 and the longitudinal electrode 23 is configured to be converted.

When a current pulse is applied to the electrode 22, the magnetization direction of the soft magnetic material 14 magnetized in the magnetizing axis is directed to the magnetization difficulty axis direction. To go back. At this time, when a current flows through the electrode 23 provided to be perpendicular to the easy axis of magnetization of the soft magnetic material 14, the magnetization of the soft magnetic material 14 can be set in a direction parallel to the axis of easy magnetization according to the polarity of the current. This process is illustrated in FIG.

The advantage of such a structure is that by using the electrodes 22 and 23 on the lattice, it is possible to simplify the electrode pattern, it is possible to simplify the driving circuit for driving it.

FIG. 8 is a cross-sectional view of another embodiment of the present invention. As shown in FIG. 1, a substrate 24 capable of transmitting light is provided on the upper portion of the soft magnetic layer 20 in the configuration of FIG. It further comprises a stator magnetization layer 25 fixed to the upper direction of the magnetization upward.

The stator magnetization layer 25 is formed of the same material as the magnetic domains 12a and 12b. Since the magnetization direction is fixed, a fixed Faraday rotation angle is always given to incident light.

When light is incident through the stator magnetization layer 25, the incident light is applied by rotating the polarization plane by + θ _F , which passes through the substrate 24 and the soft magnetic layer 20, and then generates magnetic domains 12a and 12b. Will rotate again. As described above, the pair of magnetic domain and each of the magnetization directions of the upward and downward direction setting, whereby the + θ _F is rotated by the incident light is again + θ _F as the plane of polarization is rotated, or rotated by -θ _F You will return to the initial state.

As described above, the light whose polarization plane is rotated by + 2θ _F or the light in its original state is reflected by the reflection layer 16 and exits through the magnetic domains 12a and 12b and the stator magnet layer 25 so that the magnetization direction is upward ( The light passing through 12a) is emitted by being rotated by + 4θ _F compared with the incident light, and the light passing through the magnetic domain 12b having the downward magnetization direction is emitted in the same state as the incident light.

If θ _F is set to 22.5 degrees, the emitted light can obtain light rotated at 90 degrees and 0 degrees, and two kinds of light having different polarization directions can be easily obtained at a large extinction ratio.

9 and 10 show the substrate 24 and the magnetization layer 25 as shown in FIG. 8 on the upper side of another embodiment of the present invention shown in FIGS. 4 and 6, respectively, and rotated by + 4θ _F. FIG. The structure is such that the same light as that obtained at the time of incidence is obtained, and the operation thereof is as described above.

As described above, the spatial light modulator of the present invention obtains the magnetic domains in different directions in the same pixel by using an electrode and a soft magnetic material, thereby rotating the light by rotating the polarization plane of the light incident on each pixel. By modulating it, the operation speed is fast and it does not form a nucleus, so it can be driven at low current, thereby reducing power consumption. In addition, it is possible to improve the reliability of the operation by not using the liquid crystal, and to easily obtain two kinds of light having different polarization directions with a large extinction ratio by using the stator magnetization layer.

Claims (6)

A plurality of electrodes to which current in a set direction is applied; A plurality of soft magnetic bodies that are insulated with an insulating film opposite to each of the plurality of electrodes and determine a direction of magnetization according to a direction of a current applied to the electrodes; A reflection layer disposed on an upper surface of the insulating layer and the plurality of soft magnetic materials to reflect incident light; An intra-pixel magnetic domain wall movement suppressing unit positioned at a position opposite to a central portion of the plurality of soft magnetic bodies on the upper side of the reflective layer; The incident light is determined by determining a vertical magnetization direction in a direction different from each other on the left and right sides of the pixel wall movement suppressing unit facing the front surface of the intra-pixel magnetic domain movement suppressing unit and the soft magnetic material. A pair of magnetic domains rotated along the polarization plane; An intra-pixel magnetic domain wall movement preventing unit for preventing the magnetic domain wall from moving between the pair of magnetic domains; It is composed of a soft magnetic layer positioned in the pixel wall movement suppressing unit between the pixel and the upper surface of the magnetic domain and transmits light, and the direction of magnetization is determined in a direction to circulate the direction of the magnetization formed in the soft magnetic body and the magnetic domain. Spatial light modulator characterized by. The semiconductor device of claim 1, further comprising: a substrate positioned on the soft magnetic layer and transmitting light; Spatial light modulator, characterized in that it further located on the substrate, the magnetization layer for rotating the polarization plane of the incident light while maintaining the vertical magnetization direction. A plurality of electrodes to which current in a set direction is applied; A reflection layer positioned on an upper side of the plurality of electrodes to reflect incident light; A plurality of soft magnetic materials positioned at positions insulated with an insulating film so as to face all surfaces except the surface in contact with the reflective layer, and the direction of magnetization is determined according to the direction of the current applied to the electrode; An intra-pixel magnetic domain wall movement suppressing unit positioned at a position opposite to a central portion of the plurality of soft magnetic bodies on the upper side of the reflective layer; The incident light is determined by determining a vertical magnetization direction in a direction different from each other on the left and right sides of the pixel wall movement suppressing unit facing the front surface of the intra-pixel magnetic domain movement suppressing unit and the soft magnetic material. A pair of magnetic domains rotated along the polarization plane; An intra-pixel magnetic domain wall movement preventing unit for preventing the magnetic domain wall from moving between the pair of magnetic domains; It is composed of a soft magnetic layer positioned in the pixel wall movement suppressing unit between the pixel and the upper surface of the magnetic domain and transmits light, and the direction of magnetization is determined in a direction to circulate the direction of the magnetization formed in the soft magnetic body and the magnetic domain. Spatial light modulator characterized by. The semiconductor device of claim 3, further comprising: a substrate positioned on the soft magnetic layer and transmitting light; Spatial light modulator, characterized in that it further located on the substrate, the magnetization layer for rotating the polarization plane of the incident light while maintaining the vertical magnetization direction. A plurality of first electrodes to which current in a set direction is applied; A second electrode insulated from the plurality of first electrodes by an insulating film, the second electrode perpendicularly intersecting the first electrode with the insulating film interposed therebetween at a specific position; The second electrode is insulated with an insulating film and positioned to face the first electrode, and the direction of magnetization perpendicular to the easy axis of magnetization is set according to a current pulse applied to the first electrode, and applied to the second electrode. A plurality of soft magnetic bodies for determining a magnetization direction parallel to the biaxial axis for magnetization according to the current; A reflection layer disposed on an upper surface of the insulating layer and the plurality of soft magnetic materials to reflect incident light; An intra-pixel magnetic domain wall movement suppressing unit positioned at a position opposite to a central portion of the plurality of soft magnetic bodies on the upper side of the reflective layer; The incident light is determined by determining a vertical magnetization direction in a direction different from each other on the left and right sides of the pixel wall movement suppressing unit facing the front surface of the intra-pixel magnetic domain movement suppressing unit and the soft magnetic material. A pair of magnetic domains rotated along the polarization plane; An intra-pixel magnetic domain wall movement suppressing unit for preventing the magnetic domain wall from moving between the pair of magnetic domains; It is composed of a soft magnetic layer positioned in the pixel wall movement suppressing unit between the pixel and the upper surface of the magnetic domain and transmits light, and the direction of magnetization is determined in a direction to circulate the direction of the magnetization formed in the soft magnetic body and the magnetic domain. Spatial light modulator characterized by. The semiconductor device of claim 5, further comprising: a substrate positioned on the soft magnetic layer and transmitting light; Spatial light modulator is positioned on the substrate, and further comprising a pinned magnetization layer for rotating the polarization plane of the incident light while maintaining the magnetization direction in the vertical direction.