JPS58121024A - Optical switch - Google Patents

Abstract

PURPOSE:To switch a transmission line of an emitted light side with a large extinction ratio against a multi-mode, too, by providing an element plate consisting of an electro-optical substance, on a two-dimensional waveguide inserted into an optical transmission line. CONSTITUTION:A thin film-like optical waveguide 10 is formed by providing a transparent substance whose refractive index is larger than that of a substrate 9, on the surface of the substrate 9 consisting of glass, a semiconductor crystal, a dielectric crystal, etc. As to an element plate 11 of a parallelogram consisting of a thin plate of an electro-optical substance whose refractive index is smaller than that of a substance of the optical waveguide 10, the lower surface of the element plate 11 is made to tightly adhere to the upper surface of the optical waveguide 10 so that one side becomes diagonal to incident light A. On both sides of the upper surface of the element plate 11, strip-like electrodes 12 are provided so that they are parallel to the incident light and are opposed so as to place the incident light between. Accordingly, an equivalent refractive index of the lower part of the element plate 11 of the optical waveguide 10 can be varied by a voltage applied to the electrode, therefore, the emitted light can be switched.

Description

DETAILED DESCRIPTION OF THE INVENTION (&) Technical Field of the Invention The present invention relates to an original switch to which an electro-optic effect is applied.

(b) Background of the technology As the original switch that is inserted into the optical transmission line to switch the optical path, mechanically operated original switches such as optical fiber moving type and moving mirrors, lenses, etc. are widely used. There is. However, the optical switch in this building has a complex structure, requires highly precise mechanical technology, and has a relatively slow switching speed.

Therefore, there is a need for an optical switch with a simple structure, low loss, and high speed.

(C) Prior Art and Problems In response to this demand, a switch that utilizes an electro-optic phenomenon as shown in the perspective view of FIG. 1 is currently being developed.

In the M1 diagram, 1 is an electro-optic material (a material whose refractive index changes depending on the strength of a field applied).
For example, a substrate made of LiNbO3 (lithium oxide) is used. 2 and 3 are each made of a material that has a higher refractive index than the group IIj11 and is transparent to light, such as Ti (titanium) on the substrate.
This is a three-dimensional optical waveguide formed in parallel to the surface of the substrate 1 close to each other (for example, with four gaps) in the form of a thin film with a narrow width. 4. +4. is the optical waveguide 2,
Thin rectangular '+' made of aluminum, for example, formed on the surface of the substrate 1, forming a pair facing each other with 3 in between.
It is tm. 51+51 are electrodes 4.14.51 in the direction of the optical waveguide 2.3. Electrodes 4. are formed on the surface of the substrate 1 in pairs, facing each other with the optical waveguides 2 and 3 in between, at positions at a desired distance. ,4. is the 'wL pole of the same shape.

The original structure configured in this way and transmitted to the multiplication waveguide 2 (or 3) is the electrode 41,4□+51*5! When no voltage is applied to the vehicle, it continues straight ahead. However, for example
+4 and others 4. ,5. Connect electrode 4 to ground. Plus′
- voltage, #IL pole 5, when a negative voltage (for example, several volts) is applied, 1 becomes pole 4□, 4□.

5. 5. The refractive index of the substrate l between them changes. Therefore, for example, the incident light from the optical waveguide 2 passes through the optical waveguide 3.
Then, the light is transmitted to the optical waveguide 3 as emitted light. Further, it is also possible to emit the emitted light transmitted through the optical waveguide ji 63 to the optical transmission line 2.

However, although such an optical switch has good switching performance for single-mode waveguides where the width and thickness of optical waveguides 2 and 3 are small, when the width of the waveguides is increased and the multi-mode If a mode waveguide is used, there are problems such as not only the extinction ratio becomes small and the switching performance deteriorates, but also the voltage required to be applied is several hundred volts.

(d) Purpose of the Invention In view of the above problems, the purpose of the present invention is to provide a high-speed original switch that can be inserted into a multimode transmission line and has a high extinction ratio, a simple structure, and low loss. (e) Structure of the Invention In order to achieve this object, the present invention is directed to a thin film of a transparent material formed on the surface of a substrate such as glass, a semiconductor crystal, or a substrate crystal and having a refractive index higher than that of the substrate. a two-dimensional optical waveguide inserted into an optical transmission line, at least one side of the plate-like shape is obliquely intersecting the incident light, and the lower surface is in close contact with the upper surface of the optical waveguide,
comprising an element plate made of an electro-optical material having a refractive index lower than that of the material of the optical waveguide, and electrodes provided on both sides of the upper surface of the cough element plate parallel to and facing the incident light, By applying a voltage to the cough electrode, the isolateral refractive index of the portion of the optical waveguide below the element plate is changed, thereby switching the optical transmission path for output photometry.

(f) Embodiments of the Invention The present invention will be described in detail below with reference to illustrated embodiments.

FIG. 2 is a perspective view showing an embodiment of the present invention.

In the figure, reference numeral 9 denotes a substrate made of glass, semiconductor crystal, dielectric crystal, etc., and the surface of the substrate 90 is coated with a transparent material (for example, quartz glass) having a higher refractive index than the material of the substrate 9 by known means (for example, sputtering). An optical waveguide 10 is formed in the form of a thin film using a method (method). Reference numeral 6 denotes an optical fiber that is an optical transmission line on the input side and is attached to the end face of the optical waveguide 10, and sL't,s is an optical fiber that is attached to the end face of the optical waveguide 10 on the opposite side from the original fiber 6, facing the optical fiber 6. Nine original fibers are arranged and installed at predetermined positions and serve as optical transmission paths on the output side.

Reference numeral 11 denotes a parallelogram element plate made of a thin plate of an electro-optic material (for example, KDP) that has a lower refractive index than the material of the optical waveguide lO, and its -side is oblique to the incident light (indicated by the chain MA). The lower surface of the element plate 11 is in close contact with the upper surface of the optical waveguide 10 so as to intersect with each other. Reference numeral 12 denotes strip-shaped electrodes that are formed on both sides of the upper surface of the element plate 11, parallel to the incident light, and facing each other so as to sandwich the incident light.

In the portion below the element @11 of the optical waveguide 10 configured in this manner, the equivalent refractive index changes due to the close contact of the element 1fi11. Therefore, former fiber 6)
The incident light C@ is refracted below the element plate 11, and the output light C@
(indicated by it/IB) is input into the optical fiber 7 and transmitted.

Now, when we apply '4 voltage (for example, tens of ports) to the electrode 12, since the element plate 11 is an electro-optic material, the element @1
The refractive index of 1 becomes large. (It will be about 10°3 large).

Therefore, the isolateral refractive index of the portion of the optical waveguide 10 below the element plate 11 also increases, the incident light is greatly refracted, and the output light (indicated by the chain line C) enters the original fiber 8 and is transmitted. Switching of the transmission line with the electrode is done by turning on the voltage applied to the electrode
, is done by OFF, and is extremely fast.
In addition, since there is no mechanical switching mechanism, it is compact and has low coupling loss.

Note that since the refractive index of the element plate 11 changes in proportion to the applied voltage, the extinction ratio can be made sufficiently large.

Furthermore, the present invention is not limited to the illustrated embodiment, and may be used, for example, by making the element plate into a ladder-like prism shape, or by using it in a light guide which is an optical transmission path. It can be modified as appropriate within the range.

(g) Detailed description of the invention As described above, the original switch of the present invention has a simple structure, a high switching speed, and can be inserted into a multimode transmission line with a large extinction ratio and low loss. It has excellent practical effects.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional optical switch, and FIG. 2 is a perspective view showing an embodiment of the present invention. In the figure, 1.9 is the substrate, 2, 3.10 is the waveguide, and 41.4
Snow e 5! +52+ 12 is an electrode, 11 is an element plate,
6.7.8 indicates an optical fiber.

Claims (1)

[Claims] A two-dimensional optical waveguide formed on the surface of an optical substrate such as glass, semiconductor crystal, dielectric crystal, etc., and inserted into a thin film optical transmission path of a transparent material having a large refractive index than that of the substrate; an element plate in which at least one side of a plate shape is oblique to the incident light, a lower surface is in close contact with the upper surface of the optical waveguide, and is made of a pneumatic material having a refractive index lower than that of the material of the optical waveguide; Electrodes are provided on both sides of the upper surface of the element plate in parallel with and facing the incident light, and the light transmission path on the output light side is switched by the voltage applied to the electrode. A former switch that is characterized by the fact that it becomes