JPH02106717A - Parts for optical modulation - Google Patents

Abstract

PURPOSE:To obtain the parts for optical modulation having an excellent optical modulation characteristic by providing a light transmittable insulating liquid layer on an electrode pattern layer consisting of a pair of light transmittable electrodes provided apart a prescribed spacing from each other on a transparent substrate. CONSTITUTION:The light transmittable comb-shaped electrode pattern layer 3 is provided on the transparent substrate 2 and the light transmittable insulating liquid layer 4 is provided thereon. A nonuniform strong electric field is generated between the two electrodes 3a and 3b of the electrode pattern layer 3 when a voltage is impressed between the electrodes 3a and 3b by a voltage impressing part 5. The dielectric force proportional to the square of the change rate of the electric field is then acted in the insulating liquid (silicone oil) of the insulating liquid layer 4 and the insulating liquid is deformed until this force balances with surface tension. Light is scattered and the modulation of the light is executed when the light is made incident to this deformed region. The original state is restored upon stopping of the voltage impression. The efficient optical modulation characteristic is obtd. in this way with the simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light modulation component that can electrically modulate light.

(Prior Art) Various types of components that modulate light have been known.

Among these parts, the acousto-optic modulator (A10 modulator) generates compression waves in the optical crystal by propagating sound waves of about several tens of MHz through an optical crystal such as TeO2, and This device changes the direction of the reflected light based on the Bragg reflection principle, and is used, for example, to control the light on/off of a laser printer using a gas laser.

In addition, as another example of a conventional light modulation component, on a circuit layer formed by a plurality of charge storage electrodes arranged at intervals,
Some have a structure in which an elastic layer and a light-reflecting conductive layer are laminated. In such a configuration, the electric attraction between the light-reflecting conductive layer and the circuit layer becomes strong in the region of the charge storage electrode where charges are accumulated due to the application of a voltage, which locally deforms the elastic layer. . By utilizing this deformation, the schlieren optical system controls the on/off of light (see Japanese Patent Application Laid-Open No. 60-253383 or Japanese Patent Application Laid-Open No. 6.1-148431).

(Problem to be Solved by the Invention) However, although the former type of light modulation component is suitable for high-speed control of light, optical crystals such as TeO2 are expensive, and a high frequency circuit is required. However, there were problems in that the parts became more expensive and more complex.

In addition, the latter light modulating component has a problem in that it is difficult to form a light-reflecting conductive layer that does not change over time on the elastic layer.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a light modulation component that can be constructed extremely simply and at low cost, and has excellent light modulation characteristics.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an electrode pattern layer consisting of a pair of light-transmitting electrodes spaced apart at a predetermined distance on a transparent substrate. A light-transparent insulating liquid layer was provided.

(Function) According to the present invention, when a voltage is applied between both electrodes of the electrode pattern layer, a strong non-uniform electric field is generated between the two electrodes. As a result, a dielectric force proportional to the square of the rate of change of the electric field acts in the optically transparent insulating liquid, and the optically transparent insulating liquid is deformed to the point where this force and the surface tension are balanced. Light modulation is performed by scattering light in the deformed region of the insulating liquid.

(Example) FIG. 1 is a configuration diagram showing an example of a light modulation component 1 according to the present invention. In the figure, reference numeral 2 denotes a transparent substrate, which is made of glass (for example, Corning 7059) with a thickness of 1 mm. 3 is a light-transmissive comb-shaped electrode pattern layer disposed on the transparent substrate 2, which has a thickness of 1100 mm as shown in FIG.
A pair of electrodes 3a and 3b made of n comb-shaped ITO patterns
The teeth of each comb are arranged so that they mesh with each other at equal intervals. Moreover, the electrode pinch is 2 μm.

4μm, 10μm, 20μm, 40μm, 100μm,
Various values are selected, such as 200 μm. 4 is a light-transmissive insulating liquid layer disposed on the electrode pattern layer 3, with a thickness of 3 μm.
m silicone oil (for example, Toshi Silicone 5H
200-10C/S). Reference numeral 5 denotes a voltage application unit that applies a voltage pulse between each electrode 3a and 3b of the electrode button layer 3.

Next, the operation of the above configuration will be explained.

When a voltage is applied (turned on) by the voltage application unit 5 between the picture electrodes 3a and 3b of the electrode pattern layer 3, the picture electrodes 3a and 3b
A strong, non-uniform electric field is generated between the two.

As a result, a dielectric force proportional to the square of the rate of change of the electric field acts in the insulating liquid (silicon oil) of the insulating liquid layer 4,
The insulating liquid deforms to the point where this force and surface tension are balanced. When light enters the deformed region of this insulating liquid layer 4,
Light is scattered and light modulation occurs.

On the other hand, when the voltage application by the voltage application unit 5 is stopped (turned off), the deformed region described above returns to its original state, and light scattering is suppressed.

FIG. 3 is a block diagram showing a system for measuring light modulation characteristics of a light modulation component according to the present invention. In FIG. 3, 1 is the light modulation component, 5 is the voltage application section, and 6 is the wavelength of 632.8 n.
7 and 8 are mirrors; 9 is an optical detector (e.g., silicon detector, Hamamatsu Photonics 51227-1010BR); 10 is a synchroscope; the light source 6 reflected by the mirror 7;
enters the light modulation component 1, the light modulated by the voltage application state by the voltage application unit 5 is reflected by the mirror 8, this light is detected by the optical detector 9, and observed by the synchroscope 10. This is how it was done.

FIG. 4 is a diagram showing an example of measurement of the light scattering state that changes depending on the voltage application state near the optical detector 9 of the measurement system shown in FIG. 3 (light scattering distribution projected on the screen). Figure 4 (a) shows the light scattering state before applying a voltage to the light modulation component 1 with an electrode pitch of 20 μm, and Figure 4 (b) shows the light scattering state when a voltage of 00 V is applied. , where A is the 0th order light, B is the scattered light corresponding to the electrode pitch,
C is the newly generated scattered light by applying a voltage, D is the scattered light C
This shows the mixed scattered light of B and B.

4 (a) and (b), when no voltage is applied to the light modulation component 1, the 0th order light A is strong in the center, and the electrodes are placed on both sides of this 0th order light A. Scattered light B corresponding to the pitch is weakly observed (it becomes even weaker as the transparency of ITO increases), and when a voltage of 100 V is applied, the 0th-order light A in the center weakens, and the 0th-order light intensity is newly increased. It is observed that strong scattered light C is generated on the side. This scattered light C exists between the scattered lights B corresponding to the electrode pitch, and is scattered light corresponding to the synchronization of twice the electrode pitch.

As a result of observing the light modulation component l during this series of operations using a microscope, it was found that the silicone oil in the optically transparent insulating liquid layer 4 was in a uniform state as shown in FIG. 5(a) before the voltage was applied. However, after applying a voltage of 100 V, the electrodes of the comb-shaped electrode pattern layer 3 move every other comb, forming a deformed region, as shown in FIG. 5(b). I understand. As a result, as shown in FIG. 4(b), scattered light C corresponding to twice the electrode pitch is generated.

FIG. 6 is a graph showing the dependence of the 0th-order light amount on applied voltage when the electrode pitch of the light modulation component 1 is 20 μm and 100 μm. The horizontal axis represents the applied voltage, and the vertical axis represents the light scattering rate. The solid line ■ is the dependence of the light scattering rate of the 0th order light on the applied voltage when the electrode pitch is 20 μm, and the solid line ■ is the dependence of the light scattering rate on the applied voltage when the electrode pitch is 100 μm. It shows the dependence of the light scattering rate of zero-order light on applied voltage.

From Fig. 6, light scattering starts at an applied voltage of around 30 V, and when the electrode pitch is 20 μm, the applied voltage is 10 V.
0V, applied voltage 60V when electrode pitch is 100μm
It can be seen that almost 100% of the light can be scattered. In this way, the light modulation component 1 has an extremely high scattering rate,
In addition, it has a feature that a voltage threshold exists for scattering. Further, the new scattered light generated by applying a voltage is below the measurement limit when no voltage is applied, so it has an extremely high S/N ratio.

FIG. 7 is a waveform chart showing the optical response characteristics when the voltage applied to the optical modulation component with an electrode pitch of 20 μm is turned on and off. Figure 7(a) shows that when the applied voltage is turned on, the 7th
(b) of the figure shows the photoresponse characteristics when the applied voltage is turned off, and in the figure, VOn is the voltage application (on) waveform, Ad
n is a falling waveform of the 0th-order light, Voff is a voltage-off waveform, and Aup is a rising waveform of the 0th-order light. Also,
In FIG. 7, the horizontal axis is time, and the - scale (-frame) is 10 mS% in (a) of the same figure and 5 ms in (b) of the same figure.

From Figure 7, the fall of the 0th order light is about 3ms.

The rise time is about 2 ms, and it can be seen that the optical modulation component according to the present invention has good optical response characteristics on the order of several ms. This means that it can be fully applied, for example, as a light modulation component for a projection display for moving images.

FIG. 8(a) is a diagram showing an example of a configuration in which light modulation components 1 according to the present invention having the above-described configuration and characteristics are arranged in a two-dimensional matrix, and FIG. 8(b) This is an enlarged view of one electrode section indicated by D in (a) of the same figure. In the figure, 20 is the first layer wiring, 21 is the second layer wiring, and 22 is a through hole.
It is connected to the layer wiring 21. In such a configuration, each comb-shaped electrode can be specified (addressed) by arbitrarily selecting the vertical and horizontal electrode portions. Furthermore, by disposing a TFT element on each comb-shaped electrode, the light scattering state at a designated location can be maintained continuously until the next refresh time. Furthermore, by combining it with a Schrillen optical system, it is possible to construct an efficient projection display that can control the light from the light source.

As described above, according to this embodiment, the light modulation component 1 is constructed by disposing the light-transmitting comb-shaped electrode pattern layer 3 and the light-transmitting insulating liquid layer 4 on the transparent substrate 2 in this order. , a voltage is applied from the voltage application unit 5 to the electrode pattern layer 3 to form the insulating liquid layer 4.
By changing the shape of the insulating liquid, we modulated the light.
An excellent optical modulation component with an extremely simple configuration and high S/N ratio has been realized.

In this example, any material that transmits light can be used as the transparent substrate 2, but the heat resistance during electrode production,
Glass is preferred from the viewpoint of stability.

Furthermore, since high temperatures of about 1000° C., which are required when manufacturing silicon devices, are not required, inexpensive glass can be used.

Furthermore, in this example, the light-transmissive comb-shaped electrode pattern layer 3 was constructed using ITO, but it is not limited to this, and any material that can be microfabricated and transmits light can be used. . For example, ``209'' and S n O2 are preferable, but it is also possible to operate with an optical semi-transparent film such as 8Ω or Au.Furthermore, although the electrode pattern is constructed using a comb-shaped one, the present invention is not limited to this. However, as shown in FIG.
Even if the thickness is about 10 nm, it can be operated as long as a current is passed through it, and from the viewpoint of optical transparency, a thinner one is preferable.

In addition, in this example, silicone oil was used as the light-transmitting insulating liquid from the viewpoint of stability, but the invention is not limited to this, and any insulating liquid that allows light to pass through can be used. It is possible. For example, various oils such as paraffin oil (Exxon: Aitsuba type, etc.), aromatic oil such as alkylbenzene] 1 can also be used. Further, as for the viscosity, a lower value is preferable from the viewpoint of responsiveness.

Furthermore, based on the above-mentioned operating principle, it is inferred that similar light scattering ability can be obtained by using a deformable elastomer instead of the insulating liquid. In this case, silicone gel (Dow Corning: Silpot 300A&B, or Toshi Silicone: 5E18) is used as the elastomer material.
80GEL) etc. can be used. As for the thickness, the effect is produced when it is about half the wavelength of the light, but if it is too thick compared to the electrode pitch, the mode of deformation changes and the scattering efficiency may decrease.

(Effects of the Invention) As explained above, according to the present invention, on a transparent substrate,
An electrode pattern layer consisting of a pair of light-transparent electrodes spaced apart at a predetermined distance is provided, and a light-transparent insulating liquid layer is provided on the electrode pattern layer, so that by applying a voltage to the electrode pattern layer, It is possible to modulate light by deforming a light-transmissive insulating liquid, and has the advantage of realizing efficient light modulation characteristics with an extremely simple configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the light modulation component according to the present invention, FIG. 2 is a diagram showing a comb-shaped electrode pattern according to the present invention, and FIG. 3 is a diagram showing the light modulation characteristics of the light modulation component according to the present invention. FIG. 4 is a diagram showing a measurement example of the state of scattering of light that changes depending on the state of voltage application. FIG. 5 is an explanatory diagram of the deformation of the insulating liquid due to the application of voltage in the light modulation component according to the present invention. , 6th
The figure is a graph showing the applied voltage dependence of the light scattering characteristics of the light modulation component according to the present invention, and FIG. 7 is the waveform showing the optical response characteristics when the applied voltage to the light modulation component according to the present invention is turned on and off. 8 are diagrams showing a configuration example in which light modulation components according to the present invention are arranged in a two-dimensional matrix, and FIG. 9 is a diagram showing another example of an electrode pattern according to the present invention. In the figure, 1... light modulation component, 2... transparent substrate, 3...
... Light-transparent electrode pattern layer, 4... Light-transparent insulating liquid layer, 5... Voltage application section. (,,1) (b) Explanatory diagram of the transformation of electric current/i application t''-,,I divisional image Figure 5

Claims (1)

[Scope of Claims] An electrode pattern layer consisting of a pair of light-transmitting electrodes spaced apart at a predetermined distance is provided on a transparent substrate, and a light-transmitting insulating liquid layer is provided on the electrode pattern layer. Components for light modulation.