JPS6213057Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an optical gate element that is used as a basic element of various optical information processing devices and controls an optical signal on/off or continuously.

FIG. 1 is a configuration explanatory diagram showing a conventional example of such an optical gate element. In the same figure, 1
is the incident light consisting of a non-polarized light beam, etc., and 2 is, for example,
A substrate made of a plate-shaped electro-optic material having an electro-optic effect such as the Kerr effect (for example, a PLZT substrate),
Reference numerals 3a and 3b indicate metal electrodes provided on the surface of the substrate 2 and formed in the shape of comb teeth that extend into each other;
a, 4b are lead wires, 5 is a power source connected to the electrodes 3a, 3b via the lead wires 4a, 4b, 6
7 is a first polarizing element that receives the incident light 1 and generates linearly polarized light at an angle of 45 degrees with respect to the direction of the electric field generated between the electrodes 3a and 3b; 7 is a polarized light that is orthogonal to the polarization plane of the first polarizing element 6; A second polarizing element 8 which has a surface and which receives the light source transmitted through the substrate 2 and generates linearly polarized light having an angle of 45 degrees with respect to the direction of the electric field generated between the electrodes 3a and 3b, is transmitted through the second polarizing element 7. The output light is linearly polarized light.

In the conventional embodiment having the above configuration, when no voltage is applied to the electrodes 3a and 3b, there is no change in the polarization plane of the light transmitted through the substrate 2, and the polarization planes of the first polarizing element 6 and the second polarizing element 7 are unchanged. Coupled with the fact that they are orthogonal to each other, the light beam that has passed through the substrate 2 cannot pass through the second polarizing element 7. Moreover, the electrode 3a,
When a predetermined voltage is applied to 3b, an electric field is generated between the electrodes 3a and 3b on the substrate 2, and due to the electric field, the electric field is horizontal to the electric field of the light beam incident on the substrate 2.
A phase difference is given to the vertical component, and a component that passes through the second polarizing element 7 is generated from the light beam. Then,
By intermittent application of a predetermined voltage from the power source 5 to the electrodes 3a and 3b via the lead wires 4a and 4b, it is possible to intermittent extracting a part of the incident light 1 as the output light 8. Also, the second
The figure illustrates the relationship between the transmittance λ of the light beam passing through the light gate element and the applied voltage V when a predetermined voltage is applied to the electrodes 3a and 3b. In FIG. 2, curves 9b and 9c are characteristic curves showing changes in curve 9a due to changes in ambient temperature, etc. The above-mentioned light gate element is easily affected by changes in ambient temperature, etc., and even when the applied voltage is constant, the transmittance is indicates that it is uncertain.

By the way, in the above conventional example, the electrodes 3a,
The voltage applied to 3b is usually as high as 100 to 200 V, and the voltage-light transmittance characteristics described above are also susceptible to changes in ambient temperature, etc., making it inconvenient to use the optical gate element as an optical switch. It was hot.

The present invention has been made in view of these drawbacks, and its purpose is to provide an optical gate element that has a low driving voltage when used as an optical switch and is less susceptible to changes in ambient temperature.

A feature of the present invention is that, in an optical gate element that performs continuous control of an optical signal by a voltage applied to a light modulation element made of an electro-optic material having an electro-optic effect, the above-mentioned light modulation element, a polarizing prism, A total reflection prism and a stopper are combined to transmit a part of the light beam incident on the light modulation element, reflect the remaining light multiple times in the vertical direction, and transmit the remaining part one by one to output the light beam.

Hereinafter, the present invention will be explained in detail using figures. FIG. 3 is a perspective view of the configuration of an embodiment of the present invention. In the figure, numeral 10 is an electro-optic material having an electro-optic effect such as the Kerr effect. 11a to 11c are total reflection prisms that receive linearly polarized light and totally reflect it in the vertical direction; 12 is a total reflection prism that receives linearly polarized light and reflects a part of the light in the direction of the vertical direction; Polarizing prism that transmits other light, 1
3a and 13b are a light modulation element 10 and a polarizing prism 1
2 and between the light modulation element 10 and the total reflection prism 1
A refractive index matching agent 14, which is sandwiched between 1a and integrally coupled, is bonded to the total reflection prism 11a and sandwiched between the light modulation element 10 and a second buffer member 15b, which will be described later. Stoppers 15a and 15b are provided between the polarizing prism 12 and the total reflection prism 11b, and between the total reflection prism 11b and the total reflection prism 11c.
16 is a convex lens that is bonded to the polarizing prism 12 and condenses the light emitted from the polarizing prism to one point. . Note that the position of the stopper 14 is not limited to the position illustrated in FIG. It may be positioned horizontally at the right end of the buffer member 15a in the figure.

FIG. 4 is an explanatory diagram of the principle of the embodiment of the present invention using the longitudinal cross-sectional view of FIG. 3. In the figure, the same symbols as in FIG. . Further, reference numeral 17 indicates incident light that is linearly polarized light having a plane of polarization perpendicular to the paper surface, and reference numerals 18a to 19g indicate outgoing light that is focused to a single point by the convex lens 16 after passing through the polarizing prism. In Fig. 4, the incident light 1
7 is a light modulation element 10 and a refractive index matching agent 13a
The light passes through the polarizing prism 12 and enters the polarizing prism 12, and some of the light rays are reflected in the vertical direction, but the remaining light rays pass through the polarizing prism 12 as they are and are refracted by the convex lens 16 to become output light 18a. Further, some of the light rays are reflected in the vertical direction and then transmitted through the buffer member 15a and enter the total reflection prism 11b. The light beam is totally reflected in the vertical direction by the total reflection prism 11b, and then exits, passes through the buffer member 15b, enters the total reflection prism 11c, is totally reflected in the vertical direction again, and then exits from the total reflection prism. 11a. The light beam is totally reflected in the vertical direction by the total reflection prism 11a and exits, and is then emitted by the refractive index matching agent 13b, the light modulation element 10,
After passing through the refractive index matching agent 13a, the light enters the polarizing prism 12. The light beam passes through a polarizing prism 12
A part of the light beam is reflected in the vertical direction, but the remaining light beam passes through the polarizing prism 12 as it is and is refracted by the convex lens 16 to become an output light beam 18b. Further, some of the light rays reflected in the vertical direction by the polarizing prism 12 pass through an optical path almost similar to that in the above case, and are sequentially outputted as output lights 18c to 18g while being condensed by the convex lens 16. The last of the rays totally reflected in the vertical direction by the total reflection prism 11a is the stopper 1.
It is stopped by 4. In addition, the refractive index matching agent 13
a, 13b and the buffer members 15a, 15b are not limited to these, and may be replaced with members having similar functions, or may be completely removed. Alternatively, the convex lens 16 may also be removed to extract the emitted light beams 18a to 18g as parallel light beams.

Further, FIG. 5 is an applied voltage-transmittance characteristic curve diagram showing the relationship between the applied voltage V and the transmittance λ of the light beam transmitted through the light modulator 10 when a predetermined voltage is applied to the light modulator 10. . Moreover, the axis of applied voltage has the same scale as in FIG. In FIG. 5, characteristic curves 19b and 19c are the characteristic curve 19a changed due to changes in ambient temperature, etc., and are relatively less affected by changes in ambient temperature, etc., and compared to FIG. 2,
This shows that high light transmittance can be obtained with a small applied voltage.

According to the embodiment of the present invention as described in detail above, in order to exhibit the applied voltage-light transmittance characteristics as shown in FIG. It has the advantage of being difficult to receive.
Furthermore, as is clear from a comparison between FIG. 2 and FIG. 5, the embodiment of the present invention can easily achieve nearly 100% light transmittance with less applied voltage than the conventional example. It also has the advantage of being suitable for intermittent (on/off) optical signals. Furthermore, the convex lens 16 is removed from the embodiment of the present invention shown in FIGS. 3 and 4, and the output lights 18a to 18 are
By connecting individual optical fibers (for example, 18a'' to 18f'') to each output light (for example, 18a' to 18f') of the polarizing prism 12 corresponding to f, the voltage applied to the light modulation element 10 can be changed to half a wavelength. Another advantage is that when the voltage is gradually lowered, an optical demultiplexer can be used in which the output lights 18a' to 18f' are demultiplexed and emitted in accordance with the voltage.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing a conventional example of a light gate element, FIG. 2 is a diagram showing an applied voltage-light transmittance characteristic curve in the conventional example, and FIG. 3 is a perspective view of the configuration of an embodiment of the present invention. Figure 4 is a diagram explaining the principle of the embodiment of the present invention;
FIG. 5 is an applied voltage-light transmittance characteristic curve diagram in an embodiment of the present invention. 1, 17...Incoming light, 2...Substrate, 3a, 3b
...Electrode, 6,7...Polarizing element, 8,18a-1
8g... Outgoing light, 9a to 9c, 19a to 19c...
...Characteristic curve, 10...Light modulation element, 11a-11
c... Total reflection prism, 12... Polarizing prism,
13a, 13b... Refractive index matching agent, 14... Stopper, 15a, 15b... Buffer member, 16...
convex lens.

Claims (1)

[Scope of utility model registration request] A light modulation element made of an electro-optic material having an electro-optic effect, a polarizing prism that receives the light that has passed through the light modulation element, reflects a part of the light in the vertical direction, and transmits the rest, and the polarizing prism reflects the light in the vertical direction. a first total reflection prism that receives a ray of light transmitted through the first total reflection prism and totally reflects it in the vertical direction;
a total reflection prism, a second total reflection prism that receives the light beam that has passed through the first total reflection prism and totally reflects it in the vertical direction, and a second total reflection prism that receives the light beam that has been totally reflected in the vertical direction by the total reflection prism. and a third total reflection prism for total reflection in the vertical direction, and the light beam totally reflected in the vertical direction by the third total reflection prism enters the light modulation element again and then enters the polarization prism etc. The light modulation element and the first to third total reflection prisms are arranged so that transmission or reflection is repeated sequentially, and the voltage applied to the light modulation element is used to turn on/off the optical signal, continuously control it, or control the light output. An optical gate element configured to perform demultiplexing, etc.