JP5538834B2 - Liquid crystal optical modulator - Google Patents

Description

  The present invention relates to a liquid crystal optical modulation element.

  In general, the liquid crystal optical modulation element includes a first electrode substrate having a plurality of pixel electrodes and a second electrode substrate having a counter electrode facing the first electrode substrate, and the first electrode substrate and the second electrode substrate. Are bonded at predetermined positions and intervals through a sealing material, liquid crystal is sealed at the predetermined intervals, a potential difference is applied between the pixel electrode and the counter electrode, and various optical modulations are performed by controlling the alignment of the liquid crystals. To get.

  6A and 6B are diagrams showing a liquid crystal optical modulation element according to the prior art, in which FIG. 6A is a top view and FIG. 6B is a cross-sectional view along line aa. Reference numeral 1 denotes a first electrode substrate 1 having a plurality of pixel electrodes 3, for example, a silicon substrate. Reference numeral 2 denotes a second electrode substrate 2 having a counter electrode 4 (for example, ITO) facing the first electrode substrate 1, and is a glass substrate, for example. The first electrode substrate 1 and the second electrode substrate 2 are bonded to each other with a predetermined position and interval by a sealing material 5 to constitute a liquid crystal optical modulation element in which liquid crystal 8 is sealed at the predetermined interval. Yes.

  The counter electrode 4 used in a general liquid crystal optical modulation element focuses on transmission in the visible light region, and in order to reduce power consumption, the resistance value of the counter electrode 4 is preferably low. . (For example, the resistance value in the case of ITO is used with a film thickness of about 200 to 300 Ω.) The low resistance of the counter electrode 4 means that heat is generated when a voltage is applied to the liquid crystal optical modulation element. Can also be suppressed.

  When the infrared light wavelength region is used, absorption of the infrared light wavelength region is inevitable with the thickness of the counter electrode 4. When the infrared light wavelength region is used, the film thickness is such that the infrared light wavelength region can be transmitted (for example, in the case of ITO, a film thickness with a resistance value of about 1 kΩ is used). . That is, the counter electrode 4 is thinned to reduce absorption in the infrared wavelength region.

  Making the film thickness of the counter electrode 4 transparent to the infrared light wavelength means that the resistance value of the counter electrode 4 becomes high and heat is generated when a voltage is applied to the counter electrode 4. The temperature of the liquid crystal in the modulation element rises, and the temperature characteristics of the liquid crystal optical modulation element change.

  When the liquid crystal optical modulation element is used as a wavelength conversion / selection element for laser light, the temperature change of the liquid crystal is caused by a slight change in the refractive index of the liquid crystal, particularly the difference between ordinary light (no) and extraordinary light (ne). A certain refractive index difference (Δn) changes, and the wavelength to be selected is different from the target wavelength, so that the purpose as a wavelength conversion / selection element for laser light cannot be achieved. Therefore, it is very important to keep the temperature of the liquid crystal uniform.

  Also, since lasers that can easily achieve high output as lasers are infrared lasers, and because infrared rays are already used for optical fiber communications, liquid crystal optical modulation elements are used in optical fiber systems for infrared lasers. Although it is effective, if the infrared transmittance of the counter electrode is low, the liquid crystal optical modulation element causes energy loss, attenuates the light of the laser beam, long distance communication becomes impossible, and an amplifier must be provided Bad effects such as dont occur.

A first electrode substrate having a plurality of pixel electrodes; and a second electrode substrate having a counter electrode made of a transparent conductive film opposite to the first electrode substrate, wherein the first electrode substrate and the second electrode substrate are sealed with a sealing material. In the liquid crystal optical modulation element in which liquid crystal is sealed at the predetermined interval after being bonded at a predetermined position and interval, the entire region where the sealing material is formed is outside the region facing the pixel electrode of the counter electrode. A liquid crystal optical modulation element in which a metal film is formed so as to cover and have an outer peripheral portion extending outside the formation region of the sealing material .

A liquid crystal optical modulation element in which a Peltier element is thermally connected to the outer peripheral portion of the metal film extending to the outside of the sealing material formation region .

  A liquid crystal optical modulation element in which a region facing the pixel electrode of the counter electrode is thinned to a thickness through which an infrared light wavelength region is transmitted.

The metal film is a liquid crystal optical modulation element that is a laminated film of Cr having a thickness of 20 nm or more, Ni having a thickness of 30 nm or more, and Au having a thickness of 50 nm or more .

  According to the present invention, when used in the infrared light wavelength region, the thickness of the counter electrode can be transmitted through the infrared light wavelength region, the resistance of the counter electrode can be increased, and a metal film can be provided around the electrode. As a result, it is possible to control the temperature change of the liquid crystal at the same time, and to greatly reduce the change in the refractive index of the liquid crystal.

  By forming the metal film outside the region facing the pixel electrode of the counter electrode, the heat radiation performance outside the facing region can be improved, and the rise of the liquid crystal temperature due to the heat generation of the counter electrode can be suppressed. In addition, since the temperature control element is connected to the metal film, the temperature of the light modulation unit of the counter electrode can be reliably controlled in a short time through the metal film by controlling the temperature of the temperature control element. It becomes possible to suppress the temperature change. Therefore, it is possible to provide a high-performance liquid crystal optical modulation element that can reduce and stabilize a weak change in the refractive index change of the liquid crystal.

  By reducing the film thickness of the region of the counter electrode facing the pixel electrode to a thickness that allows the infrared light wavelength region to pass through, the use in the infrared light wavelength region becomes possible.

  In general, the metal film and the sealing material have low adhesion strength, and troubles are likely to occur at the seal portion. However, at least a part of the sealing material region of the metal film has a surface shape having an anchor effect, so that the metal film It is possible to maintain the adhesion strength between the sealing material and the liquid crystal optical modulation element with high reliability.

  By utilizing the present invention, it is possible to provide a stable and long-life liquid crystal optical modulation element.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows Example 1 of the liquid crystal optical modulation element by this invention, (A) is a top view, (B) is aa sectional drawing. 8A and 8B are diagrams showing a second embodiment of the liquid crystal optical modulation element according to the present invention, in which FIG. Sectional drawing which shows Example 3 of the liquid crystal optical modulation element by this invention Sectional drawing which showed the film forming process of this invention Sectional drawing which showed another film forming process of this invention 2A and 2B are diagrams showing a liquid crystal optical modulation element according to the prior art, in which FIG.

  A first electrode substrate having a plurality of pixel electrodes and a second electrode substrate having a counter electrode opposite to the first electrode substrate, wherein the first electrode substrate and the second electrode substrate are placed at a predetermined position via a sealing material; In the liquid crystal optical modulation element in which liquid crystal is sealed at the predetermined interval after being bonded at intervals, a liquid crystal optical modulation element in which a metal film is formed outside the region of the counter electrode facing the pixel electrode is used.

  1A and 1B are diagrams showing Embodiment 1 of a liquid crystal optical modulation element according to the present invention. FIG. 1A is a top view and FIG. In addition, the code | symbol shall be the same regarding the overlap part with a prior art. Reference numeral 1 denotes a first electrode substrate having a plurality of pixel electrodes 3, for example, a silicon substrate (hereinafter the same). Reference numeral 2 denotes a second electrode substrate having a counter electrode (for example, ITO) 4 facing the silicon substrate 1, for example, a glass substrate (the same applies hereinafter). 5 is a sealing material, for example, WorldLock 798L manufactured by Kyoritsu Chemical Co., Ltd. 6 is a metal film, for example, Cr-Ni-Au. The silicon substrate 1 and the glass substrate 2 are bonded to each other with a predetermined position and interval by a sealing material 5 to constitute a liquid crystal optical modulation element in which liquid crystal 8 is sealed at the predetermined interval.

  A metal film 6 is formed on the counter electrode 4 outside a region facing the pixel electrode 3. The film thickness of the metal film 6 is 200 nm (nanometer). Cr: 20 nm or more, Ni: 30 nm or more, and Au: 50 nm or more (total of 200 nm) are preferable from the viewpoints of adhesion, low resistance, patternability, and thermal conductivity. The metal film 6 serves to dissipate heat generated when a voltage is applied to the silicon substrate 1 and the counter electrode 4 when the liquid crystal optical modulation element is driven. Since the thickness of the metal film 6 increases the thickness of the liquid crystal layer, the size of the spacer (not shown) inserted into the sealing material 5 is reduced by the thickness of the metal film 6.

2A and 2B are diagrams showing Embodiment 2 of the liquid crystal optical modulation element according to the present invention, in which FIG. 2A is a top view and FIG. 2B is a cross-sectional view along line aa. Reference numeral 7 denotes a temperature control element, for example, a Peltier element.
Heat is generated when a voltage is applied to the counter electrode 4, and the temperature of the liquid crystal 8 in the liquid crystal optical modulation element changes. Therefore, by connecting the metal film 6 and the temperature control element 7, the temperature of the liquid crystal part of the liquid crystal optical element due to heat generation when a driving voltage is applied to the counter electrode 4 is suppressed.

  FIG. 3 is a sectional view showing Embodiment 3 of the liquid crystal optical modulation element according to the present invention. Since the adhesion strength between the sealing material 5 and the metal film 6 is weakened, the surface of the sealing material region having an unevenness having an anchor effect is used to maintain the adhesion strength of the sealing material 5 at least in part. Yes.

FIG. 4 is a cross-sectional view showing the film forming process of the present invention. FIG. 4 (a) shows that an indium tin oxide (ITO) film passes through the counter electrode 4 through infrared rays as much as possible, and the ITO film is removed when the metal film is etched away. In order to make the ITO film 30 nm (nanometer) in order to make the film thickness suitable for lowering the resistance value of ITO by further etching the ITO film uniformly in the film thickness direction without causing deterioration and pinholes. FIG. 4B is a cross-sectional view showing a substrate state formed in a film thickness, and FIG. 5B shows a substrate state in which the metal film 6 is formed by laminating Cr: 40 nm, Ni: 60 nm, and Au: 100 nm in the same vacuum chamber by continuous sputter deposition. In the cross-sectional view, (c) removes all of the metal film 6 in the region facing the pixel electrode 3 of the metal film 6 and increases the ITO film of the counter electrode 4 from the original 30 nm to the remaining 10 nm in order to increase the infrared transmittance. Removed until Sectional view showing a plate state, a cross-sectional view at (d) of bonding the first electrode substrate 1 and the second electrode substrate 2. For convenience of explanation, explanation will be made from (b).
(B) forms a laminated metal film 6 of Cr—Ni—Au with a film thickness of 200 nm (nanometer) on the counter electrode 4 of the glass substrate 2 (c) shows the pixel electrode 3 of the metal film 6 formed in (b). The area opposite to is removed with RIE10NR manufactured by Samco. At this time, the thickness of the counter electrode 4 is reduced to a thickness that allows transmission of the infrared wavelength region.
In (d), the silicon substrate 1 and the glass substrate 2 are bonded together with a seal material 5 at a predetermined position and interval.

FIG. 5 is a cross-sectional view showing another film forming process when the metal film 6 is formed. (A) is when the counter electrode 4 is formed, (b) is when the counter electrode 4 is removed, and (c) is the metal film 6. At the time of formation (d) At the time of removing the metal film 6 in the region facing the pixel electrode 3, (e) is a view at the time of bonding. For convenience of explanation, explanation will be made from (b).
In (b), the thickness of the counter electrode 4 is reduced to a thickness that allows transmission of the infrared wavelength region.
(C) forms a metal film 6 on the counter electrode 4.
(D) removes the area | region which opposes the metal film 6 to the pixel electrode 2 by RIE10NR by Samco.
In (e), the silicon substrate 1 and the glass substrate 2 are bonded together with a sealant 5 at predetermined positions and intervals.
Note that the metal film Cr—Ni—Au is an example, and other examples include Cr—Au and Al. ITO of the counter electrode is an example, and there is a transparent conductive film in which ZnO (zinc oxide), ZrO (zirconia oxide), and TiO (titanium oxide) are added to In ₂ O ₃ (indium oxide). WorldLock 798L manufactured by Kyoritsu Chemical Co., Ltd. is an example, and an equivalent seal material can be used.

DESCRIPTION OF SYMBOLS 1 1st electrode substrate 2 2nd electrode substrate 3 Pixel electrode 4 Counter electrode 5 Seal material 6 Metal film 7 Temperature control element 8 Liquid crystal

Claims (4)

A first electrode substrate having a plurality of pixel electrodes; and a second electrode substrate having a counter electrode made of a transparent conductive film opposite to the first electrode substrate, wherein the first electrode substrate and the second electrode substrate are sealed with a sealing material. In a liquid crystal optical modulation element in which liquid crystal is sealed at the predetermined interval after being bonded at a predetermined position and interval,
A metal film is formed outside the region of the counter electrode facing the pixel electrode so as to cover the entire region where the sealing material is formed and the outer peripheral portion extends outside the region where the sealing material is formed. A liquid crystal optical modulation element characterized by the above. The liquid crystal optical modulation element according to claim 1 , wherein a Peltier element is thermally connected to an outer peripheral portion of the metal film extending to the outside of the sealing material forming region .   3. The liquid crystal optical modulation element according to claim 1, wherein a region facing the pixel electrode of the counter electrode is thinned to a thickness that allows an infrared wavelength region to pass therethrough. The metal film is a laminated film of Cr having a thickness of 20 nm or more, Ni having a thickness of 30 nm or more, and Au having a thickness of 50 nm or more . Liquid crystal optical modulation element.

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