JPH05289122A - Optical switch - Google Patents

Abstract

PURPOSE:To obtain an optical switch which can control a position to which light reaches through a two dimensional waveguide path and does not require to form so many waveguide paths. CONSTITUTION:This switch is provided with a waveguide layer 1 which can guide flux of light and on surface of which plural liquid crystal filling grooves 11-14 are formed in the same direction as a grating, liquid crystal which is filled in the liquid crystal filling grooves 11-14 of this waveguide layer 1 and a refraction index of which is varied by applying voltage, the first and the second clad layers 2, 3 which are arranged respectively so as to sandwich the waveguide layer 1 and has plural electrodes 31, 34 which are arranged in the different direction from the arranging direction of grooves 11-14 of the waveguide layer 1 on the surface, and the power supply which applies voltage to at least a pair of electrode of the first and the second clad layers 2, 3 and makes the refraction index of liquid crystal between electrodes the prescribed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch used in, for example, an optical integrated circuit and capable of switching by a two-dimensional waveguide.

[0002]

2. Description of the Related Art In recent years, optical communication has made remarkable progress in the field of information communication. Along with this, demands for commercialization of various optical elements are increasing.

[0003]

Conventionally, various types of optical switches, such as an embedded Y-branch waveguide, have been proposed as optical switches among various optical elements, but all of them have the same number as the number of branches. The waveguide must be formed. Therefore, an object of the present invention is to provide an optical switch that does not need to form a large number of waveguides.

[0004]

In order to achieve the above object, the invention according to claim 1 is capable of guiding a light beam, and a waveguide having a plurality of liquid crystal filling grooves formed in the same direction on the surface thereof. Layer and liquid crystal filling grooves of the waveguide layer, the liquid crystal of which refractive index changes by the application of a voltage, and the liquid crystal filling groove are respectively disposed so as to sandwich the waveguide layer, and the groove of the waveguide layer is formed on the surface. First and second clad layers having a plurality of electrodes arranged in a direction different from the arrangement direction, and the first and second clad layers.
And a power supply for applying a voltage between at least one pair of electrodes of the clad layer to make the refractive index of the liquid crystal between the pair of electrodes a predetermined value.

[0005]

According to the invention corresponding to claim 1, since the principle that the refractive index is changed by applying a voltage to the waveguide layer in which the liquid crystal filling groove is filled with the liquid crystal is utilized, the two-dimensional guiding The position where the light beam reaches can be controlled by the waveguide, and a large number of waveguides need not be formed.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view for explaining an outline of an optical switch of the present invention, which includes a waveguide layer 1, and a lower clad layer 2 and an upper clad 3 which are disposed in contact with the upper and lower surfaces of the waveguide layer 1. And a first grating 4 and a second grating 5 formed on the waveguide layer 1.

In FIG. 1, when a light ray L from any light source enters from the end face of the waveguide layer 1, the light ray L is diffracted by the grating 4 and this diffracted light becomes a light ray A. When the grating 4 is not provided, the light ray L is diffracted by the grating 5 and the diffracted light becomes the light ray B. In this way, if the position of the grating formed on the waveguide layer 1 can be changed to the position of the grating 4 at one time and the position of the grating 5 at another time, the positions of the diffracted lights A and B can be controlled. can do.

FIG. 2 is a schematic view showing a part of an embodiment of the present invention, and the grating is constructed as shown in FIG. FIG. 3 is an exploded perspective view of the grating taken along the line A-A in FIG. The grating is the waveguide layer 1
It is formed by cutting the grooves 11 to 14. The lower clad layer 2 includes, for example, a plurality of (four in this case) strip-shaped electrodes 21 on one surface (outer side) of a SiO ₂ glass plate.
-24 are formed spaced apart from each other. Similar to the lower clad layer 2, the upper clad layer 3 is made of, for example, SiO.
₂ Plural (4 in this case) on one side (outside) of the glass plate
Strip electrodes 31 to 34 are formed at intervals. The electrodes 21 to 24 of the lower clad layer 2 and the electrodes 31 to 34 of the upper clad layer 3 are one-to-one above and below each other.
Is formed to correspond to.

The waveguide layer 1 has a plurality of liquid crystal filling grooves 11 to 14 each having a rectangular cross section on one plate surface of a plate glass (for example, 7059 glass manufactured by Corning Co., Ltd. (actually, the number of grooves is set so as to function as a grating). More) are spaced apart from one another. These liquid crystal filling grooves 11 to 14
Is the direction of the electrodes 21-24 and 31-34 formed of the lower clad layer 2 and the upper clad layer 3,
It is a right angle, and the liquid crystal filling grooves 11 to 14 are formed at equal intervals.

Then, the liquid crystal filling grooves 11 to 14 of the waveguide layer 1 are formed.
Is filled with a liquid crystal (for example, PCH1132 nematic liquid crystal from Merck). In this case, the refractive index of the nematic liquid crystal is 1.48 to 1.6, and the nematic liquid crystal is preliminarily subjected to parallel alignment processing such as rubbing method for aligning liquid crystal molecules in the direction of the propagation light L shown in FIG. Keep it.

Further, as shown in FIG. 3, between the electrodes 21 and 31, between the electrodes 22 and 32, and between the electrodes 23 and 33.
Between the electrodes 24 and 34, the switch 7,
The common power source 6 is connected via 8, 9, and 10.

In such a structure, when an appropriate voltage is applied to one of the electrode pairs, the liquid crystal between the electrodes has a refractive index of 1.6 with respect to the incident TM mode light. For example, switch 7 is closed and electrodes 21 and 31
Voltage is applied between the electrodes to adjust the refractive index to TM mode light incident on the liquid crystal to be 1.6, and between the remaining electrodes 22 and 32, between electrodes 23 and 33, between electrodes 24 and 34. It is adjusted so that the refractive index of the TM mode light incident on is equal to that of the waveguide layer 1. With such adjustment, the grating operates as if it were between the electrodes 21 and 31 with respect to the incident light.

Similarly, the switch 10 is closed, a voltage is applied between the electrodes 24 and 34, the refractive index is adjusted to 1.6 with respect to the incident TM mode light, and the remaining electrodes are adjusted. The refractive index is adjusted to be equal to that of the waveguide layer 1 with respect to the TM mode light incident between the electrode 21 and the electrode 31, between the teaching electrodes 22 and 32 and between the electrodes 23 and 33. With such adjustment, the grating operates as if it were between the electrodes 24 and 34 with respect to the incident light. From the above description, the position of the apparent grating can be controlled by freely changing the position applied between the pair of electrodes with the switches 7 to 10.

In FIG. 2, a voltage is applied between the pair of electrodes 24 and 34 so that the crystal has a refractive index of 1.6 between the pair of electrodes 24 and 34 so that the grating is located at the position of the electrode 34, and between the remaining electrodes. When a voltage is applied so that the refractive index of the liquid crystal during that time becomes equal to that of the waveguide layer, the incident light L is diffracted by the grating existing between the electrode pairs 24 and 34, and the position of S as diffracted light A is obtained. Proceed to. Also,
A voltage is applied between the electrode pairs 21 and 31 so that the refractive index of the liquid crystal between them becomes 1.6, and the refractive index of the liquid crystal therebetween is between the electrode pairs 21 and 31 so that the refractive index of the liquid crystal is 1.6. When a voltage is applied so as to be equal to that of the waveguide layer, the incident light L is diffracted by the grating existing between the electrode pairs 21 and 31, and advances to the position S1 as diffracted light B. Further, between the electrode pair 22 and 32, 2
The same can be considered for between 3 and 33, and four gratings can be controlled by the method of applying a voltage, whereby a 1 × 4 optical switch can be configured. Although the description has been given when there are several pairs of electrodes (specifically, four pairs), in reality, it is possible to increase the number of electrodes as much as possible and control the number of gratings commensurate with that. You can do it.

The grating length can be made variable by adjusting the number of electrodes to which a voltage is applied. For example, between electrodes 21 and 31 and electrodes 22 and 3
A voltage is simultaneously applied between the two electrodes so that the refractive index becomes 1.6, and a voltage is applied between the remaining electrodes so that the S-polarized light incident on the waveguide layer 1 becomes equal to the refractive index of the waveguide layer. If so, the grating length is apparently 2 of that in the above-described embodiment.
Double. According to the first embodiment described above, the position where the light beam reaches can be controlled by the two-dimensional waveguide, and it is not necessary to form many waveguides.

FIG. 4 is a perspective view for explaining the second embodiment of the present invention, in which the incident light L1 and the outgoing light A,
B, C are obtained, and the outgoing light A,
B and C are obtained. This is obtained when there are four pairs of electrodes. By doing so, a 2 × 3 optical switch can be obtained. As is apparent from this, an n × m optical switch can also be configured by selecting the number of electrode pairs.

In the above-described embodiment, the liquid crystal filling grooves 11 to 1 are used.
Although nematic liquid crystal is used as the liquid crystal to be filled in 4, the liquid crystal is not limited to this, and any other liquid crystal may be used as long as the same function can be obtained.

[0018]

According to the present invention, since the principle that the refractive index is changed by applying a voltage to the waveguide layer in which the liquid crystal filling groove is filled with the liquid crystal is utilized, the light beam is guided by the two-dimensional waveguide. It is possible to provide an optical switch in which the position reached by the optical path can be controlled and in which a large number of waveguides need not be formed.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining the principle of an optical switch according to the present invention.

FIG. 2 is a perspective view for explaining the first embodiment of the optical switch according to the present invention.

FIG. 3 is an exploded perspective view showing the configuration of the grating shown in FIG.

FIG. 4 is a perspective view for explaining a second embodiment of the optical switch according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Waveguide layer, 2 ... Lower cladding layer, 3 ... Upper cladding layer, 4,5 ... Grating, 11-14 ... Liquid crystal filling groove, 21-24, 31-34 ... Electrode, 6 ... Power supply, 7-1
0 ... switch.

Claims (1)

[Claims] 1. A waveguide layer capable of guiding a light beam, having a plurality of liquid crystal filling grooves formed on the surface in the same direction, and a liquid crystal filling groove of each of the waveguide layers filled with a voltage. A liquid crystal having a different refractive index, and a first and a first electrode having a plurality of electrodes which are respectively disposed so as to sandwich the waveguide layer and which are disposed on the surface in a direction different from the direction in which the grooves of the waveguide layer are arranged. A power supply for applying a voltage between the second clad layer and at least one pair of electrodes of the first and second clad layers to make the refractive index of the liquid crystal between the pair of electrodes a predetermined value. And an optical switch equipped with.