JP4743514B2 - Driving method of magneto-optical spatial light modulator - Google Patents

Description

  The present invention relates to a driving method of a magneto-optical spatial light modulator that individually controls the magnetization direction of each pixel by a combined magnetic field generated by currents supplied to driving lines on the X side and the Y side. When the magnetization direction is changed, a main current is supplied to the X-side drive line and the Y-side drive line along the target pixel, and an auxiliary current is simultaneously supplied to the drive lines adjacent to the outside of the drive line. The present invention relates to a driving method of a magneto-optical spatial light modulator for controlling the magnetization direction of a target pixel.

  A magneto-optical spatial light modulator is a magneto-optical device that spatially modulates the amplitude, phase, and polarization state of light using the Faraday effect of the magnetic film, and can independently control the magnetization direction of the magnetic film. A large number of pixels (pixels) are two-dimensionally arranged in the X and Y directions. Since the spatial light modulator having such a two-dimensional array of pixels can process information in parallel at high speed, an optical information processing system, optical computing, projector TV, moving image hologram recording, optical volume recording, etc. In recent years, research and development has been advanced as a key device to be realized.

  An example of the configuration of the magneto-optic spatial light modulator is shown in FIG. The spatial light modulator 10 is mainly composed of a magnetic film (magneto-optic material) 12, and a large number of pixels 14 whose rotation direction is rotated by the Faraday effect are magnetically separated from each other in the X direction (lateral direction) and the Y direction. In this structure, the drive lines on the X side and the Y side are wired along each pixel 14 in a two-dimensional arrangement in the (vertical direction). The X side drive pulse current is supplied from the X side drive unit 16 to the X side predetermined drive line, and the Y side drive pulse current is supplied from the Y side drive unit 18 to the Y side predetermined drive line. The operations of the X-side drive unit 16 and the Y-side drive unit 18 are controlled by the control unit 20. The magnetic fields generated by the drive pulse currents flowing through the selected X-side drive line and Y-side drive line are combined, and the magnetization direction of each pixel is individually controlled by the combined magnetic field.

FIG. 7 is an explanatory diagram of the basic operation. Only two pixels are drawn to simplify the drawing. Incident light that has passed through the first polarizer 22 and has become linearly polarized light enters each pixel 14 of the spatial light modulator. Incident light passes through the transparent substrate 24 and the magnetic film 12, is reflected by the metal film 28, passes through the magnetic film 12 and the transparent substrate 24 again, and is emitted. At this time, due to the Faraday effect of the magnetic film 12, the polarization direction of the light reflected by each pixel 14 is rotated by a predetermined angle. Here, if a Faraday rotation of + θ _F (for example, +45 degrees) occurs when a positive magnetic field (+ H) is applied to the upper pixel, a negative magnetic field (−H) is applied to the lower pixel. Sometimes a Faraday rotation of -θ _F (eg, -45 degrees) occurs. These reflected lights reach the second polarizer 30. If the polarization transmission plane is set to +45 degrees, the upper stage light rotated by +45 degrees Faraday is transmitted (ON), but is rotated by -45 degrees Faraday. The lower light is blocked (OFF). In this way, by controlling the direction of the magnetic field applied to each pixel, on / off of the reflected light by each pixel can be controlled.

  By the way, each pixel in the spatial light modulator is not an individual element that is completely independent of each other. Actually, a magnetic film is grown on the entire surface of the substrate by the LPE method or the like. This is a state in which the pixel is magnetically partitioned. This is because it is necessary to arrange each pixel very small and accurately. For example, in Patent Document 1, an oxidizable film pattern such as Si is formed in a region corresponding to a pixel on a magnetic garnet material, and the whole is subjected to heat treatment to reduce the magnetic garnet material directly under the Si film and change the quality. In other words, a technique for forming a large number of pixels capable of reversal of magnetization in units of pixels is disclosed. In this way, the polarization direction of light passing through each pixel can be rotated by a predetermined angle due to the Faraday effect, and thus spatially modulated by arbitrarily selecting the direction of magnetization in each pixel. Light can be generated. In addition, there are several pixel isolation structures such as a structure in which a groove is formed between pixels or a structure in which a nonmagnetic material is embedded in the groove.

  In order to control the magnetization direction of each pixel independently, a drive line wired along each pixel is selected and a drive current is supplied, and a resultant magnetic field generated thereby is used. An example of the prior art is shown in FIG. A represents the drive line in a plan view, and B represents a cross section. Here, the X-side drive line 32 and the Y-side drive line 34 are wired linearly along the periphery on each pixel 14. In addition, the triangular figure has shown the terminal. When the timings of the drive pulse currents flowing in the opposite directions through the two selected drive lines on the X side and the Y side coincide with each other, a magnetic field generated by the drive pulse current is synthesized, and the resultant magnetic field generates the magnetization direction of the target pixel. Is controlled.

  By the way, in the control of the magnetization direction of a pixel by supplying a drive current, a malfunction may occur if a large synthetic magnetic field is generated in a pixel region other than the target pixel. In addition, if the distribution of the composite magnetic field appearing in the target pixel is non-uniform, a current required for the magnetization control of the pixel increases, and the magnetization direction splits inside the pixel (so-called multi-domain), There is a risk that it will not work properly. In a driving method in which a linear driving line as shown in FIG. 8 is combined to flow a current through the driving line and the magnetization of the target pixel is reversed, a relatively uniform magnetic field is basically applied to the target pixel. In addition, there is a characteristic that magnetic field leakage to adjacent pixels can be suppressed to be small.

  However, even if such a drive line structure is adopted, in the conventional drive method in which the magnetization of the target pixel is reversed by passing a current only to the drive line (corresponding to the target pixel) immediately above the target pixel, However, the problem of malfunction of the multiple magnetic domains and pixel magnetization control cannot always be solved completely. This is because a magnetic interaction works between adjacent pixels. This magnetic interaction is called demagnetizing field or magnetostatic energy. A small magnet component (magnetic moment) inside the pixel generates a magnetic field around it and has an influence on the magnet component at another position. It comes from that. Thus, an arbitrary pixel always receives a magnetic action (referred to as “pixel leakage magnetic field”) from surrounding pixels.

  In order to reduce the influence of the pixel leakage magnetic field, the distance between the pixels may be increased by utilizing the fact that the pixel leakage magnetic field decreases as the distance increases. However, if the interval between pixels is widened, the information density decreases, which is not appropriate. In addition, by increasing the threshold value for the magnetization reversal of the pixel, it is possible to make the influence of the pixel leakage magnetic field relatively small and prevent a pixel drive error. In this case, it is necessary for the magnetization reversal of the pixel. The current value increases significantly. When the drive current increases, a large amount of heat is generated due to the resistance of the drive line, causing a problem in that each pixel and the drive line are heated to deteriorate the stability of the operation. Smaller pixels and smaller pixel spacing will inevitably reduce the cross-sectional area of the drive line, increase resistance, and further increase the amount of heat generated. Therefore, if the drive current increases, the pixel density cannot be increased. .

In particular, when a pixel that can be driven with a small current is used, instability of driving due to a pixel leakage magnetic field appears remarkably. For example, with the conventional driving method, it has been extremely difficult to realize a high-density pixel configuration with a drive current of 70 mA or less per drive line and a large scale of 10,000 pixels or more and a pixel interval of 20 μm or less. Therefore, in order to manufacture a magneto-optic spatial light modulator with a small driving current and a high information density, it is strongly demanded to solve the problem of the pixel leakage magnetic field caused by adjacent pixels.
US Pat. No. 5,473,466

  The problem to be solved by the present invention is to solve the problem of multi-domain during driving due to the influence of pixel leakage magnetic field and malfunction of pixel magnetization control, which can greatly reduce the drive current, and is small and reliable with many pixels It is possible to realize a high spatial light modulator.

  The present invention has a magnetic film made of a magneto-optical material, and in the magnetic film, a number of pixels that rotate the polarization direction by the Faraday effect are two-dimensionally arranged in the X and Y directions in a state of being separated from each other. A magneto-optic spatial light modulator of a type in which the magnetization direction of each pixel is individually controlled by a combined magnetic field generated by a drive current flowing through the X-side drive line and the Y-side drive line that are arranged and wired along the pixel. In the driving method, when the magnetization direction of the pixel is changed, the main current is supplied to the X-side drive line and the Y-side drive line along the target pixel, and the auxiliary current is simultaneously applied to the drive line adjacent to the target pixel. , And the magnetization direction of the target pixel is individually controlled by a combined magnetic field generated by them.

The X-side drive line and the Y-side drive line extend straight on the periphery of the pixels arranged in the X direction and the pixels arranged in the Y direction, respectively, and each of the two drives on the X side and the Y side Each pixel is wired so as to enclose each pixel in a “well” shape except for its center, and adjacent to the main current of the four drive lines surrounding the target pixel and the outside of the target pixel drive line. that use a combined magnetic and auxiliary current according to one or more drive lines are.

  Here, the current ratio between the main current flowing through the drive line along the target pixel and the auxiliary current flowing through the drive line along the adjacent pixel is controlled within a range of 1: 0.5 to 1: 5. Is good. Typically, the main current flowing in the drive line along the target pixel and the auxiliary current flowing in the drive line along the adjacent pixel are set to the same magnitude.

  In addition, when changing the magnetization direction of the pixel, the main current flows through the X-side drive line and the Y-side drive line along the target pixel, and not only the drive line located outside the target pixel, Further, an auxiliary current may be supplied to the outer drive line.

  In addition, when the magnetization direction of the pixel is changed, the ratio of the auxiliary current to the main current can be changed in accordance with the pixel pattern so that a magnetic field with a flat distribution as a total is applied to the target pixel.

  In the driving method of the magneto-optic spatial light modulator according to the present invention, when the magnetization direction of the pixel is changed, the main current is supplied to the X-side and Y-side driving lines along the target pixel and is adjacent to the outside of the target pixel. Since the auxiliary current is also supplied to the driving line simultaneously and the magnetization direction of the target pixel is individually controlled using the resultant magnetic field, the multi-domain and the pixel at the time of driving due to the influence of the pixel leakage magnetic field are configured. The problem of malfunction of magnetization control can be solved, and the drive current can be greatly reduced, thereby realizing a spatial light modulator with a small size, a large number of pixels, and high reliability.

  Further, according to the present invention, the target pixel can be flattened as a whole by controlling the auxiliary current supplied to the adjacent drive line, using the drive line outside the drive line, or controlling the auxiliary current according to the pixel pattern. A distributed magnetic field can be applied, and the operation reliability of the high-density magneto-optic spatial light modulator can be further improved.

  In order to examine the influence of the pixel leakage magnetic field, first, the strength of the magnetic field generated by the pixel was calculated. The result is shown in FIG. The horizontal axis represents the distance from the center of an arbitrary pixel, and the vertical axis represents the strength of the generated magnetic field. A magnetic field (demagnetizing field) is generated inside the pixel in a direction that hinders its own magnetization direction. A magnetic field is also generated outside the pixel (pixel leakage magnetic field), and the direction of the magnetic field is also the direction of magnetization in the direction opposite to the magnetization direction of the pixel. As a result, the magnitude of the drive current necessary for magnetization reversal changes in adjacent pixels.

  For example, assume that a drive current is supplied to reverse the magnetization direction of a certain arbitrary pixel (target pixel). At this time, assuming that all the surrounding pixels are magnetized in the same direction as the target pixel, a pixel leakage magnetic field is applied from all the surrounding pixels in a direction that assists the magnetization reversal of the target pixel. Since reversal is performed with a magnetic field smaller than the magnetic field necessary for this, magnetization reversal may occur when not intended. Conversely, if all the pixels are magnetized in the direction opposite to the target pixel, a pixel leakage magnetic field is generated in the direction in which the magnetization of the target pixel is retained, and the target pixel may not be reversed. As can be seen from FIG. 9, the strength of the pixel leakage magnetic field varies depending on the distance, and therefore the magnitude of the pixel leakage magnetic field generated inside the pixel varies depending on the position. Due to the non-uniformity of the pixel leakage magnetic field, the magnetic field applied to the inside of the target pixel becomes non-uniform as a result, and the multi-domaining of the pixel occurs. Since the distribution of the pixel leakage magnetic field varies depending on the combination of the magnetization directions of the surrounding pixels, under any constant magnetic field generated from the drive line, any non-uniform distribution of the magnetic field inside the pixel can be obtained. It cannot be solved. In other words, the conventional driving method in which the driving current is supplied only to the driving line immediately above the target pixel cannot eliminate the adverse effect of the pixel leakage magnetic field.

  Therefore, in the present invention, when the magnetization direction of the pixel is changed, the main current is supplied to the X-side drive line and the Y-side drive line along the target pixel, and at the same time, the drive line adjacent to the outside of the target pixel is also assisted. A current is passed, and the magnetization direction of the target pixel is individually controlled by a combined magnetic field generated by them.

  The configuration of the drive line and the drive method in the present invention are shown in FIG. The configuration of the main part of the magneto-optical spatial light modulator may be basically the same as the conventional structure as shown in FIG. That is, it has a magnetic film made of a magneto-optical material, and a number of pixels 14 that rotate the polarization direction by the Faraday effect are two-dimensionally arranged in the X and Y directions in a state of being separated from each other. In this structure, the magnetization direction of each pixel is individually controlled by a combined magnetic field generated by a drive current flowing through the X-side drive line 32 and the Y-side drive line 34 wired along the pixel 14.

  Conventionally, when the magnetization reversal of a target pixel is performed, a current is supplied only to the drive line corresponding to the target pixel immediately above the pixel. In contrast, in the present invention, current is supplied not only to the drive line of the target pixel but also to the outer drive line adjacent thereto. This is a feature of the present invention. FIG. 1B shows an example in which current is supplied to the drive line of the target pixel and the drive line outside the target pixel. In FIG. 1B, illustration of the X-side drive line is omitted, and only the Y-side drive line 34 is drawn. With such a configuration, it is possible to reduce malfunction during driving of the magneto-optical spatial light modulator and to reduce driving current.

Next, the effect of current supply to adjacent drive lines will be described. FIG. 2 shows the distribution of the magnetic field generated from each drive line when a pulse current is supplied. The horizontal axis represents the distance in the drive line cross-sectional direction when the center of the pixel is 0, and the vertical axis represents the magnetization reversal direction component of the magnetic field generated in the upper surface portion of the pixel.
The conditions of the calculation model in FIG. 2 are as follows.
(1) The width of the drive wire is 4.0 μm and the thickness is 1.1 μm.
(2) The pixel size is a square with a side of 14 μm and a thickness of 2 μm.
(3) The distance between the pixel and the drive line is 1.5 μm
(4) The pixel-to-pixel spacing is 2 μm
(5) Resistivity of drive line 1.8 × 10 ⁻⁸ Ω · m
(6) Supply current 50 mA to the drive line
(7) Relative permeability 11.2 of magneto-optical element, saturation magnetization 7.9 × 10 ⁻² T

  As can be seen from FIG. 2, the maximum value of the magnetic field generated from the drive line (referred to as the target pixel line) passing immediately above the target pixel that controls the magnetization reversal appears near the center of the pixel. . On the other hand, the maximum value of the magnetic field generated from the drive line adjacent to the drive line (referred to as the first adjacent line) appears just near the end of the pixel. As shown in FIG. 9, in the distribution of the pixel leakage magnetic field, a strong magnetic field tends to appear toward the edge of the pixel, and the influence of the pixel leakage magnetic field can be canceled by applying the magnetic field from the adjacent line. Further, a magnetic field generated from a drive line adjacent to the outside (referred to as a second adjacent line) has a maximum value of the magnetic field strength appearing inside the adjacent pixel. This produces an effect of canceling the leakage magnetic field generated in the adjacent pixel by the drive line and the first adjacent line.

FIG. 3 shows a magnetic field distribution generated by a driving method in which the magnetization of a pixel is reversed using an adjacent line according to the present invention.
(A) is a case where a magnetic field generated only from a drive line (target pixel line) immediately above a target pixel that controls magnetization reversal is synthesized (that is, a conventional example).
(B) is a combined magnetic field obtained when a current of 25 mA is passed through the target pixel line and the first adjacent line,
(C) is a composite magnetic field that appears when a current of 25 mA flows in the target pixel line and 50 mA in the first adjacent line,
(D) is a combined magnetic field that appears when 10 mA is applied to the target pixel line and 50 mA is applied to the first adjacent line;
(E) is a combined magnetic field that appears when -10 mA is applied to the target pixel line and 50 mA is applied to the first adjacent line;
It is. The boundary lines shown in FIG. 3 correspond to the end portion of the target pixel and the end portion of the adjacent pixel, respectively.

The magnetic field distribution shown in (a) is relatively high in uniformity, but a magnetic field is applied in the opposite direction at the end of the pixel, which causes a multi-domain at the time of driving. On the other hand, in (b), the magnetic field at the pixel end is greatly increased. Therefore, it is difficult for a drive error to occur with respect to increase / decrease of the applied magnetic field at the pixel end due to the pixel leakage magnetic field. Then, by switching on / off the drive current of the adjacent line according to the state of the surrounding pixels, it is possible to further reduce the drive error due to the pixel leakage magnetic field.

  Furthermore, if the ratio of the current flowing through each line is changed, the applied magnetic field distribution inside the target pixel becomes more uniform as shown in FIGS. When the uniformity of the applied magnetic field distribution inside the target pixel is increased, the current required for the magnetization reversal of the target pixel is reduced and the current efficiency is increased. In addition, since a sufficient magnetic field is applied to the end portion of the target pixel, a drive error due to a pixel leakage magnetic field is less likely to occur. (C) is a current ratio adjusted so as to reduce leakage to adjacent pixels, (d) is a current ratio focusing on uniformity inside the pixel, and (e) is a current that is highly effective when the influence of the pixel leakage magnetic field is large. It is a ratio.

FIG. 4 shows a composite magnetic field that appears when only one of the magnetic fields in the first adjacent line is turned off.
(F) is a combined magnetic field obtained when a current of 25 mA is passed through the target pixel line and the first adjacent line,
(G) is a combined magnetic field that appears when 10 mA is applied to the target pixel line and 50 mA is applied to the first adjacent line;
It is.

  The target pixel differs in the magnitude of the magnetic field required for magnetization reversal depending on the magnetization state of the surrounding pixels. For example, when a large number of pixels surrounding one side of the target pixel are reversed and a small number of pixels surrounding the opposite side are in the same magnetization state, magnetization reversal is promoted in the region surrounded by the large number of pixels, and the extra applied magnetic field is On the contrary, on the side surrounded by a small number of pixels, magnetization reversal is prevented and a large magnetic field is required. In such a state, if the first adjacent line magnetic field as shown in (f) is used, the magnetic field can be uniformly applied together with the leakage magnetic field, so that driving with high current efficiency and no occurrence of multi-domains is possible. Note that the improvement in current efficiency here means that operation is possible even with a smaller total current for a pixel having an operating magnetic field of a certain value. Therefore, a drive line with higher current efficiency can drive a pixel having the same operating magnetic field with less power consumption.

  Similarly, when the distribution of the pixel leakage magnetic field is not uniform, for example, based on the condition (e), 20 mA for the right target pixel line, −20 mA for the left target pixel line, and the left first The magnetic field that appears when a current of 70 mA is applied only to the adjacent line is as shown in FIG. 4G, and the non-uniformity of the pixel leakage magnetic field can be canceled almost completely. Therefore, the current efficiency is better than the driving condition shown in (f), and the problem of multi-domain can be solved almost certainly.

FIG. 5 shows an example using the second adjacent line,
(H) is a combined magnetic field that appears when a current of 10 mA is applied to the target pixel line, 50 mA to the first adjacent line, and 20 mA to the second adjacent line.
(I) is a composite magnetic field that appears when a current of 50 mA flows to the target pixel line, 30 mA to the first adjacent line, and further 20 mA to the second adjacent line;
It is. If a current is passed through the second adjacent line further outside the first adjacent line, more precise control of the applied magnetic field becomes possible, and the line leakage magnetic field to the adjacent pixel is reduced while improving the uniformity inside the target pixel. Therefore, it is possible to achieve driving in a more ideal form.

  As can be seen from the above description, the driving method of the magneto-optic spatial light modulator according to the present invention can be driven less affected by the magnetic action exerted by the adjacent pixels than the conventional method, and further supports the state of the magnetic action. Thus, since it is possible to shift to an appropriate driving condition, pixel malfunction during driving can be extremely reduced. In addition, since current efficiency increases and power consumption decreases, temperature rise is suppressed and operation stability is improved.

The magneto-optical spatial light modulator is manufactured, for example, by the following method. The magnetic film is, for example, a Bi-substituted rare earth iron garnet film, and is formed by depositing about 3 μm on the GGG substrate by liquid phase epitaxial growth.
(1) An Al film is formed on the entire surface of the magnetic film by sputtering or vapor deposition. Thereafter, a resist layer is formed only in the pixel formation region.
(2) Next, using the resist layer as a mask, the Al film in the gap region between the pixels is removed by ion milling, and further ion milling is performed to form a groove. Accordingly, the grooves are formed in a lattice shape in the vertical and horizontal directions except for the pixel region. The outer periphery is also ion-milled to form a recess. In the region corresponding to the pixel, the Al film remains and becomes a light reflecting film.
(3) After forming the SiO ₂ insulating film, a Cu film is embedded by sputtering, vapor deposition or plating, and the X-side drive line is wired. The drive line is made of Au, Al, etc. in addition to Cu. May be.
(4) Further, similarly, after forming the SiO ₂ insulating film, a Cu film is buried by sputtering, vapor deposition, plating, or the like, and the Y-side drive line is wired. This drive line may also be made of Au, Al, etc. in addition to Cu.

  In this manner, a magneto-optic spatial light modulator having a total of about 16,000 pixels of 128 horizontal rows × 128 vertical columns was manufactured. When a bias magnetic field was applied to these pixels and the variation of the magnetic field that reversed the magnetization was examined, it was about ± 3200 m / A (40 Oe). The maximum value of the pixel leakage magnetic field, that is, the pixel leakage magnetic field when the pixels around the target pixel are all in the forward direction and in the reverse direction, the difference is ± 2400 m / A (30 Oe). It became about. From this, it can be seen that the main factor of variation in the switching magnetic field of the pixel is the pixel leakage magnetic field.

  In order to prevent multi-domain formation in such a magnetized state, it is indispensable to apply a driving current of 150 mA or more per terminal and a bias magnetic field for increasing the uniformity of the magnetic field. In addition, due to the structure of the magneto-optical spatial light modulator in which a pulse magnetic field about half that of the target pixel is applied to pixels in the same column as the target pixel, an applied magnetic field of about 1.5 times or less of the applied magnetic field variation width is used. Pixels that operate cannot be used. For example, when a pixel whose magnetization is reversed by applying a magnetic field of 8000 m / A (100 Oe) is adopted, a magnetic field of 11200 m / A (140 Oe) must be generated in consideration of variations when the target pixel is reversed. At this time, a magnetic field of 5600 m / A (70 Oe) is applied to the pixels in the same column and row, but there is a pixel in which the operating magnetic field is reduced to 4800 m / A (60 Oe) due to variations. Operation will occur. If a pixel that operates with a smaller driving magnetic field can be employed, the power consumption of the device can be greatly reduced, and further enlargement of the magneto-optic spatial light modulator can be realized.

  Therefore, when the adjacent line was also energized, the multi-domain formation at the time of driving was eliminated, and the device operated normally even when no bias magnetic field was applied. This is because the applied magnetic field at the end of the pixel, which has a strong effect of preventing magnetization reversal, is strengthened by the magnetic field of the adjacent line, thereby enabling magnetization reversal. In addition, since the number of lines to be driven is increased, the same effect as increasing the cross-sectional area of the drive line is obtained, and power consumption during driving can be reduced. Eventually, these effects combined, there was no bias magnetic field, and it was possible to drive at 50 mA per terminal.

  Furthermore, when the current of adjacent lines is switched in accordance with the magnetization state of the surrounding pixels, the current can be cut off at locations where the drive magnetic field is excessively applied due to the pixel leakage magnetic field, further reducing current consumption. I was able to confirm that it was possible.

  On the other hand, in order to simplify the control device for the drive pulse current, the magnitude of the current flowing through the drive line is often fixed. However, if the current flowing through the drive line can be varied, pixel leakage is more efficient. A driving magnetic field distribution capable of canceling the influence of the magnetic field can be realized, and a magneto-optical spatial light modulator can be manufactured that further enhances the stability and low current during driving.

  In addition, it has also been found that there is an effect of further reducing the malfunction of the adjacent pixel during driving by energizing the drive line (second adjacent line) further outside the first adjacent line. This is because the line leakage magnetic field generated in the adjacent pixel can be canceled out by the magnetic field generated from the additional line. When there is no leakage magnetic field in the drive line, there is no variation in the applied magnetic field at the time of driving. Therefore, for the same reason as the variation in the pixel operation magnetic field, the threshold of the pixel operation magnetic field can be lowered to achieve a low drive current.

  As described above, when the driving stability is increased by changing the driving method, it becomes possible to further reduce the current consumption accordingly. In the result of the above experiment, 35 mA per terminal is used for the calculation. The theoretical performance enabled driving at 30 mA per terminal.

  For the above reasons, when the driving method according to the present invention is used, a spatial light modulator that operates well even at a high information density can be obtained.

Explanatory drawing which shows an example of the drive line structure and drive method in this invention. The magnetic field distribution map generated from a target pixel line and an adjacent line. The magnetic field distribution map which generate | occur | produces by the system using the adjacent line in this invention. The magnetic field distribution map which generate | occur | produces when the electric current of the adjacent line of one side is turned off. The magnetic field distribution map which generate | occur | produces when using the line further outside of an adjacent line. FIG. 3 is an explanatory diagram showing an example of the overall configuration of a magneto-optic spatial light modulator. Explanatory drawing of basic operation. Explanatory drawing which shows an example of the drive line and generated magnetic field in a conventional system. The figure which shows distribution of the magnetic field generated from a pixel.

Explanation of symbols

14 pixels 32 X-side drive line 34 Y-side drive line

Claims (5)

A pixel having a magnetic film made of a magneto-optical material, and a plurality of pixels that rotate the polarization direction by the Faraday effect are two-dimensionally arranged in the X direction and the Y direction in a state of being separated from each other. In the method of driving a magneto-optical spatial light modulator in which the magnetization direction of each pixel is individually controlled by a combined magnetic field generated by a drive current flowing through the X-side drive line and the Y-side drive line wired along
The X-side drive line and the Y-side drive line extend straight on the periphery of the pixels arranged in the X direction and the pixels arranged in the Y direction, respectively, and each of the two drives on the X side and the Y side Each pixel is wired by a line so as to enclose each pixel in the shape of a “well” except for its central portion, and when the magnetization direction of the pixel is changed, two X-side drive lines and two Y-sides surrounding the target pixel A main current is supplied to the drive line of the target pixel, and an auxiliary current is supplied to the drive line adjacent to the drive line of the target pixel at the same time, and the magnetization direction of the target pixel is individually controlled by the resultant magnetic field generated by them. A method for driving a magneto-optical spatial light modulator. A main current flowing through the driving line along the target pixel, the current ratio of the auxiliary current flowing through the driving lines along the adjacent pixels, 1: 0.5 to 1: claim 1 Symbol placement is in the range of 5 Driving method of magneto-optical spatial light modulator. 3. The method of driving a magneto-optical spatial light modulator according to claim 2 , wherein the main current flowing through the drive line along the target pixel and the auxiliary current flowing through the drive line along the adjacent pixel have the same magnitude. When the magnetization direction of the pixel is changed, the main current is supplied to the X-side drive line and the Y-side drive line along the target pixel, and not only the drive line located adjacent to the outside of the target pixel, but also the driving method of the magneto-optical spatial light modulator according to any one of claims 1 to 3 on the outside of the drive line and to flow the auxiliary current. When changing the magnetization direction of the pixels, changing the ratio to the main current of the auxiliary current in accordance with the pixel pattern, according to any one of claims 1 to 4 field of flat distribution as a whole to the target pixel is to be applied Driving method of magneto-optical spatial light modulator.

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