JPS61270736A - Light deflecting element - Google Patents

Abstract

PURPOSE:To attain a deflection having a large angle by forming perovskite or tungsten bronze type polycrystal as a prism to form an electrode for generating an electric field rectangular to a light transmission direction. CONSTITUTION:The rays of light from a light source 7 are made incident upon a prism-like perovskite type polycrystalline light deflecting element 1, and while changing voltage to be applied, the deflection angle is measured. Consequently, the rays of light can be oscillated by >=1 deg. in case of vertical polarization and an optional deflection angle can be selected because the deflection angle is large.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an optical deflection element, and particularly to an optical deflection element using an electro-optic material.

(Conventional technology) Various types of optical deflectors have been proposed in the past.

Among these, those that utilize changes in refractive index due to electro-optic effects are widely used because the design of the optical deflector is simple. Simply put, when an electric field in a direction perpendicular to the propagation direction of light is applied to an element that has an electro-optic effect, the refractive index changes depending on the magnitude of the electric field, and the deflection angle of the light changes.
The material of the deflection element used in the optical deflector needs to have a large electro-optic coefficient and refractive index, and other aspects such as light transmittance, resistivity, optical uniformity, and optical damage are also taken into consideration.

However, even the best conventional optical deflection materials have 74
Even when measured at a high voltage of 00V, the deflection angle (with respect to vertical deflection) is only about α2 degrees. Therefore, an optical deflection element with a large deflection angle is desired.

[Purpose of the invention]

An object of the present invention is to provide an optical deflection element with a large deflection angle.

[Summary of the invention]

The optical deflection element of the present invention is an optical deflection element characterized in that a prism is formed from a Pedapsky polycrystal or a tungsten bronze polycrystal, and is provided with an electrode that generates an electric field perpendicular to the light propagation direction. , the perebskite liquor polycrystal is PLZT, and the tungsten bronze dust polycrystal is PBLN.

In the optical deflection element according to the present invention, the deflection angle changes greatly depending on the applied electric field, and can be increased from about 2 degrees in the conventional case to 1 degree or more, and the deflection angle can be selected.

[Structure of the invention]

Figure 1 shows a prism-shaped light deflection element of the present invention. 1 in the figure shows a PLZ whose refractive index changes greatly due to the electro-optic effect.
T, and 2 are thin film electrodes formed on the upper and lower surfaces thereof by sputtering or the like. The PLZT light deflection material has an entrance surface 4 and an exit surface 5 that form an angle depending on the purpose. A fixed or variable DC power supply 6 is connected between the electrodes 2.3.

Now, when the light A is incident, the optical deflection material 1 changes its refractive index according to the magnitude of the voltage applied between the electrodes 2 and 3, and changes the propagation direction of the light. The deflection angle differs depending on the polarization.

It has been found that the PLZ deflection material changes the deflection angle by more than 1 degree when the incident light is perpendicular. This is inconceivable with conventional deflection elements. This point will be discussed in detail later.

A polycrystalline material having a perovskite structure represented by: Among these, for the purpose of the present invention, a material having a large change in refractive index due to the electro-optic effect and a high light transmittance is desired.

The present inventor tried variously changing xll in the above chemical formula, and found that La/Zr/Ti (eleven ratio is 7 to 14/3
0-70770-30. More preferably around 9/657
It has been found that these conditions are best satisfied when the PLZT has a diameter of 55%.Since such PLZT has a large refractive index and a large -order or second-order electro-optic coefficient, the change in the deflection angle is also large.

In the case where the refractive index changes due to the primary electro-optic effect, La/Zr/Ti has a value of 8/65755.
8/40/6G, 12/40/
60 sl 4150/70 is typical.

Furthermore, as a case where the refractive index changes due to the secondary electro-optic effect, La/Zr/Ti is 9765155.10
/45155.11/65/15 is typical.

Moreover, as a tungsten bronze type, (pb.

Ba, La) Nb20. , (Pb,K)Nb,04,(
Sr, Ba) Nb20. etc.

Furthermore, %PBLNk is generally expressed as ((Pb+Ba), La2/sY) Nb2O, and the ratio of Pb/La/Ba is 100 to 40/4.
~2010~60 is typical.

Before explaining the present invention below using a specific example of PLZT (9/65/35), the principle of light deflection based on the electro-optic effect will be explained. As shown in FIG.
Suppose that it is refracted at ,. The refracted light enters the exit surface #2 at an incident angle θ12, is refracted, and exits in a direction forming an angle of 0° with respect to the normal to the exit surface #2. When electrodes are attached to the top and bottom surfaces of the prism shown in Figure 1 and a voltage is applied, the refractive index changes due to the lateral electro-optic effect. If this change in refractive index is expressed as Δn, it can be seen that according to Snell's law, the change in deflection angle due to Δn is expressed as Δn. Here, n is the refractive index before applying a voltage.

On the other hand, the change in refractive index Jl['? ,: P L Z T
Due to the (9/65/35) symmetry (m S m ), when a voltage is applied to the upper and lower surfaces, the Kerr effect due to the electric field in the Z direction causes the refractive index ellipsoid to become as shown in FIG. 3. Therefore, Δn
is given by using the second-order electro-optic coefficient R5j.

Δn due to the first-order electro-optic effect is is given by

Therefore, no is large and the coefficient Rss or R1 or r. Or it is necessary that r and s are large.

Next, specific examples of the present invention will be shown.

〔Example〕

An experiment was conducted using the configuration shown in FIG. 1 in the figure is P of the present invention.
The LZT optical deflection material is PLZT (9/45155) in the form of a right-angled isosceles triangle with a thickness of 1 inch and 7 sides of equal sides, and has a gold sputtered electrode structure similar to that in FIG. A He-Ne laser 7 is used as a light source, and light with a wavelength of 6528 is incident on a prism-type PLZT optical deflection element via a linear polarizer 8 (depending on its orientation, it becomes vertically polarized light or horizontally polarized light), and the applied voltage is set to 0 to The deflection angle was measured while changing it within a range of 1000V.

Figure 5 shows the change in deflection angle for vertically polarized light and horizontally polarized light.
It is shown against the voltage applied to the electrode. As can be seen from FIG. 5, Δθo k becomes positive or negative depending on the plane of polarization. Also, as a matter of course, since ' Rss l > I Rls I, it can be seen that the deflection angle is larger in the case of vertically polarized light. As can be seen from the curve curve for vertically polarized light, ■
I was able to make the light sway more than 1 degree at about 900v per hit. Comparing this to the conventional angle of about 12 degrees, it can be seen that this is a significant improvement.

As described above, the prism type optical deflection element of the present invention not only has a large refraction angle, but also has a large deflection angle due to the electric field, from 120 degrees at high voltage (approximately 5000V) in the prior art to 1 degree or more at low voltage (900V). Since it fluctuates to
It can be widely applied to various devices that utilize optical deflection.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the optical deflection element of the present invention, Figure 2 is a diagram showing the relationship between a prism and light, Figure 5 is a diagram showing the electro-optic effect of refractive index, and Figure 4 is a deflection angle measuring device. A conceptual diagram showing
and Figure 5 are graphs showing the relationship between the applied voltage and the deflection angle of horizontal and vertical polarized light.

Claims (3)

[Claims] (1) An optical deflection element characterized in that a perovskite polycrystal or a tungsten bronze polycrystal is formed into a prism and provided with an electrode that generates an electric field perpendicular to the light propagation direction. (2) The light deflection element according to claim 1, wherein the perovskite polycrystal is PLZT. (3) The optical deflection element according to claim 1, wherein the tungsten bronze polycrystal is PBLN.