JPH06308401A - Waveguide type optical switch - Google Patents

Abstract

PURPOSE:To provide a small-sized waveguide type optical switch with high performance and sure operation. CONSTITUTION:In the waveguide type optical switch provided with a branching part in an optical waveguide, a slit 4 in the central part of the branching part so as to intersect with the optical waveguide, and changing an optical refractive index of a medium in the slit 4 by moving a liquid 5 into the slit 4 and a switching means switching an incident beam from the incident side optical waveguide 1 to any one of two branching side optical waveguides of an outgoing side by transmitting or reflecting, a receiver part 10 communicating with the slit 4 interrupted from the outside and housing a prescribed amount of liquid, a driving solid 11 arranged in the receiver part 10 loadably/unloadably, the switching means 13 switching the branching waveguides 2, 3 by loading/ unloading the driving solid 11 into the liquid 5 and loading/unloading the liquid 5 in the receiver part 10 into the slit 4 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type optical switch, and more particularly to a waveguide type optical switch for changing over an optical path by changing a refractive index of a medium at a waveguide branching portion.

[0002]

2. Description of the Related Art With the development of optical communication technology, the development of optical components has become more active and more frequently used. There is a waveguide type optical switch as one of the optical components, and various methods have been proposed for an optical switch using an optical waveguide.

FIG. 3 is a schematic view of a conventional waveguide type optical switch.

As shown in the figure, the waveguide type optical switch utilizes a slit 4 formed at a branch portion between an incident side optical waveguide 1 and a branch side optical waveguides 2 and 3 to branch light into the branch side optical waveguide 2.
The optical path is switched by transmitting the light to the side or reflecting it to the branch side optical waveguide 3.

As a means for switching between straight traveling and reflection of light, there is a method of putting a reflective film (not shown) such as a metal film in and out of the slit 4 (Japanese Patent Laid-Open No. 4-52616), and refraction in the slit 4. There is a method (Japanese Patent Application No. 2-269489) of putting in and out a medium having a high rate. Among them, the method of using a medium having a high refractive index allows the light to travel substantially straight by making the refractive index of the medium close to the refractive index of the optical waveguide itself, and the refractive index of the slit without the medium to the waveguide. Total reflection at the interface can be caused by making the refractive index sufficiently smaller than the refractive index of itself. As a result, the optical paths can be switched, so that a waveguide type optical switch with little optical loss can be realized.

By the way, the waveguide type optical switch is shown in FIG.
As shown in (a), when the refractive index of the medium of the slit 4 is close to the refractive index of the optical waveguide itself like the liquid medium 5,
Although the light from the incident side optical waveguide 1 may be slightly refracted due to the difference in refractive index, it can be guided to the branch side optical waveguide 2 by an arrangement in consideration of the refraction. In addition, FIG.
(B) is an explanatory view for explaining the operation of a general waveguide type optical switch.

On the other hand, as shown in FIG. 4 (b), the refractive index of the medium of the slit 4 is the same as that of the gas medium (including a dilute or substantially vacuum state) 6, and the refractive index of the optical waveguides 1, 2, 3 itself. If it is sufficiently smaller than that, the light from the incident side optical waveguide 1 is totally reflected at the interface between the end of the incident side optical waveguide 1 and the gas medium 6. Therefore, it is possible to guide the light to the branch side optical waveguide 3 by an arrangement in consideration of this total reflection. That is, the slit 4
The optical path can be switched to the branch side optical waveguide 2 or the branch side optical waveguide 3 depending on the presence or absence of the liquid medium 5 in.

Therefore, in this optical switch, an important technique is how to move the liquid medium 5 having an appropriate high refractive index into and out of the space of the slit 4 (including the optical path connecting the waveguides). Although not shown in FIGS. 3 and 4, in an actual waveguide, in order to efficiently perform optical transmission, the circumference of the optical waveguide is covered with a clad layer having a refractive index lower than that of the waveguide, and Since the cladding layer is coated to protect it from external force and dirt, the slit 4 and the medium are arranged inside the coating layer.

As a method of inputting and outputting the liquid medium to and from the slit 4, there is a method of injecting or ejecting the medium from the outside of the coating layer. In addition, there is a method in which a liquid medium is heated to be vaporized and discharged. This method is simple, but there are problems that the slit 4 is connected to the outside and may be damaged, that it takes time to input and output the medium, and it takes time to switch the switch. Therefore, it is desirable to cut the slit 4 from the outside and move the medium inside the coating layer.

That is, when a space is provided in the slit which is shielded from the outside, a liquid medium having a high refractive index and a gaseous medium are made to coexist in the slit, and the switch is provided on one side of the waveguide, When the liquid medium is moved to the optical path part in the slit and the switch is on the other side of the waveguide, if it is possible to move the liquid medium from the optical path part to the space, it is possible to switch in a short time, It is possible to realize a highly reliable waveguide type optical switch. 5 is a schematic sectional view of the slit of the waveguide type optical switch shown in FIG.

In FIG. 1A, when the liquid medium 5 is located in the liquid retaining portion 8 separated from the optical path portions 7 of the incident side optical waveguide 1 and the branch side optical waveguide 3, the vicinity of the optical path portion 7 has a low refractive index. It is occupied by a gaseous medium, and light is reflected at the interface between the incident side optical waveguide 1, the branch side optical waveguide 3 and the slit 4 as described above. That is, the light incident on the optical waveguide 1 propagates to the branch optical waveguide 3 side.

On the other hand, when the liquid distillation section 8 is heated by a heater (not shown) or the like, a part of the liquid medium 5 is vaporized to form bubbles, and the expansion force of the pressure increase of the bubbles accompanying the heating causes the liquid medium 5 to expand. Moves to the side of the optical path section 7 where the pressure is lower. Due to this movement, the vicinity of the optical path portion 7 is occupied by the liquid medium 5 having a high refractive index, so that the light incident on the incident side optical waveguide 1 travels substantially straight and propagates to the branch side optical waveguide 2 (FIG. 2B).

On the contrary, when the vicinity of the optical path portion 7 is heated, the liquid medium 5 moves due to vaporization and liquefaction of the liquid medium 5.
That is, in the case shown in FIG. 7A, when the liquid distillation section 8 is heated, the liquid medium 5 is vaporized, and the optical path section 7 occupied by the gas.
The pressure in the vicinity increases, and due to this increase in pressure and the temperature in the vicinity of the optical path portion 7 being lower than that of the liquid retaining portion 8, the liquid is liquefied in the vicinity of the optical path portion 7. The movement of the liquid medium 5 occurs even if bubbles are generated, vaporized, and liquefied at the same time. Since this method operates by moving the amount of minute liquid in the minute slit that is shielded from the outside, it is possible to switch the optical path in a short time and realize a highly reliable optical switch.

[0014]

However, in order to keep the optical path stable in a steady state where the operation of switching the optical path is not required, it is necessary to keep the place where the liquid medium exists and the place where the gas medium exists. Therefore, it is necessary to continue to provide a holding force sufficient to prevent movement due to external vibration or surface tension of the liquid and energy for controlling vaporization or liquefaction due to temperature change. For this reason, the liquid medium or gas medium that meets the conditions is limited. Further, it is necessary to continue supplying heating energy and cooling energy for keeping the liquid distillation section and the optical path section within a predetermined temperature range.

Further, the performance, size and cost of the optical switch depend on the type of high refractive index medium, the method of moving to the slit, the operating environment and the like.

On the other hand, the optical switch is required to have various performances, dimensions and costs depending on the purpose of use. For example, the method of moving the high-refractive index medium from the slit is simple and reliable, but it takes time as well as requiring a manual operation or a separate entrance / exit device for the movement, and it is necessary to switch the switch in a short time. Is difficult to deal with. In addition, when the medium is taken in and out from the slit, there is a risk that the medium may be polluted or deteriorated. For this reason, it is conceivable that a small-sized and short-operating time optical switch with a small structure that cuts off the outside from the outside and moves the high-refractive-index medium into and out of the optical path part inside the slit while having high reliability is provided. .

However, there is no method for surely moving the high-refractive-index medium into or out of the predetermined optical path within the small slit.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the above problems and provide a compact waveguide type optical switch with high performance and reliable operation.

[0019]

In order to achieve the above object, the present invention provides a branch portion in an optical waveguide, a slit is provided in the center of the branch portion so as to intersect the optical waveguide, and a liquid is provided in the slit. The optical refractive index of the medium in the slit is changed by moving the slit, and the switching means is provided to switch the light incident from the incident side optical waveguide to either one of the two branch side optical waveguides on the emitting side. In a waveguide type optical switch, a liquid retention part that communicates with a slit that is shielded from the outside and stores a predetermined amount of liquid, a drive solid that is provided in the liquid retention part so that it can be freely taken in and out, and a drive solid is taken in and out of the liquid. And a switching means for switching the branch side optical waveguide by moving the liquid in the liquid reservoir into and out of the slit.

[0020]

According to the above construction, when the driving solid enters the liquid in the liquid reservoir, the liquid in the liquid reservoir moves into the slit and the slit is filled with the liquid. As a result, the incident-side optical waveguide and the branch-side optical waveguide are connected to each other, and the light incident on the incident-side optical waveguide passes through the slit and is emitted from one of the branch-side optical waveguides. When the driving solid comes out of the liquid in the liquid distillation section,
The liquid filling the slit exits from the slit and returns to the liquid retention part, the incident side optical waveguide and the branch side optical waveguide are cut off, and the light incident on the incident side optical waveguide is reflected by the slit and the other branch side. It is emitted from the optical waveguide.

[0021]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side sectional view of an embodiment of the waveguide type optical switch of the present invention. In addition, the same code | symbol was used for the member common to the above-mentioned conventional example.

In FIG. 1A, reference numeral 4 is a slit, which is provided at the center of the branch portion of the incident side optical waveguide 1 and the branch side optical waveguides 2 and 3 so as to intersect the optical waveguides 1, 2 and 3. (See FIG. 4). End faces (optical path portions) of the incident side optical waveguide 1 and the branch side optical waveguide 3 are exposed on the side wall of the slit 4. Although not shown in the drawing, the optical path portion of the branch side optical waveguide 2 is also exposed on the side surface of the slit 4 so as to substantially face the optical path portion 7.

Reference numeral 10 designates a liquid distilling portion, which has a cylindrical shape centered on the Z axis. The central portion of the side surface (left side in the figure) of the liquid reservoir 10 communicates with the side surface of the slit 4.
A drive solid 11 composed of, for example, a permanent magnet is provided in the liquid distillation section 10.
Is housed so as to be movable in the Z-axis direction (vertical direction),
Moreover, the slit 4 and the liquid reservoir 10 are shielded from the outside.

A switching magnet 13 as a switching means is located on the driving solid 11 and a magnetic force acts on the outside (the upper side in the figure) of the coating layer 12 in which the slit 4 and the liquid retaining portion 10 are formed. It is provided to fit. The polarity of the switching magnet 13 can be switched.

A predetermined amount of the liquid medium 5 having a high refractive index is accommodated in the bottom of the liquid retaining portion 10, and when the driving solid 11 is attracted to the switching magnet 13, the position of the liquid surface is The position is substantially the same as the position of the bottom of the slit 4. A gas medium (dry air and liquid evaporation gas) 6 having a low refractive index is filled in the liquid distillation section 10 and the slit 4.

Next, the operation of the embodiment will be described.

As shown in FIG. 1A, the switching magnet 13
When the lower polarity (N pole in the figure) and the upper polarity (S pole in the figure) of the driving solid 11 are different from each other, the driving solid 11 is attracted to the switching magnet 13 and the liquid retention part 10
The liquid medium 5 in the liquid distilling portion 10 remains stored in the bottom portion of the liquid distilling portion 10 and is retained in the slit 4 because the liquid medium 5 in the liquid distilling portion 10 is held in a state of being discharged from the liquid medium 5 in the liquid distilling portion 10. Is filled with a gas medium 6. Therefore, the incident side optical waveguide 1
The light incident on is reflected by the slit 4 and is emitted from the branch side optical waveguide 3 (see FIG. 3B).

On the other hand, when the lower polarity of the switching magnet 13 (S pole in the figure) and the upper polarity of the driving solid 11 (S pole in the drawing) are equal, the driving solid 11 and the switching magnet are the same. 13 repels each other, and the driving solid 11 moves to the liquid retention section 1
Since it moves below 0 and enters the liquid medium 5,
The liquid medium 5 in 0 is discharged (pushed up) and moves into the slit 4, and the slit 4 is filled with the liquid medium 5. Therefore, the incident side optical waveguide 1 and the branch side optical waveguide 2
And the liquid medium 5 are connected to each other, the light incident on the incident side optical waveguide 1 passes through the slit 4 and is emitted from the branch side optical waveguide 2.

Therefore, by reversing the polarity of the switching magnet 13, the optical path of the light incident on the incident side optical waveguide 1 is switched. Moreover, the switching magnet 13 does not replenish the energy from the outside and reflects the optical path.
The transparent state can be maintained.

Next, specific numerical values will be described, but the present invention is not limited to these numerical values.

As shown in FIG. 1, the length of the slit 4 in the direction perpendicular to the paper surface (slit width) is about 5 μm, the diameter of the liquid reservoir 10 is about 50 μm, and the diameter of the driving solid 11 is about 46 μm.
Volume of approximately 20,000 ³ of the liquid medium 5 (hereinafter volume unit [mu] m ^3), the volume of driving the solid-state 11 of about 50,000
Is about 1% of the liquid medium 5 discharged by moving the driving solid 11 below the liquid distillation section 10.
000 moves into the slit 4. At this time, the incident side optical waveguide 1 and the branch side optical waveguide 2 are optically coupled. The remaining about 10,000 is around the driving solid 11 and the liquid reservoir 1.
The space between the inner wall of 0 and the space above it is 9,000.

By reversing the polarity of the switching magnet 13 and moving the driving solid 11 upward, the liquid medium 5 flows down and returns to the liquid retaining section 10, and the inside of the slit 4 is occupied by the gas medium 6. . At this time, the incident side optical waveguide 1 and the branch side optical waveguide 3 are optically coupled.

In the above embodiment, the switching magnet 13 is used.
The driving solid 11 is moved by reversing the polarity of the switching magnet 13. However, the present invention is not limited to this, and the switching magnet 13 is moved toward and away from the driving solid 11 side, and the switching magnet 13 and the driving solid are moved. Alternatively, the gravitational fall of the driving solid body 11 due to the shielding of the magnetic field between the driving solid body 11 and the like may be used. Alternatively, a magnetic material may be used instead of the switching magnet 13 and the magnetic force of the driving solid 11 may be used for attraction. Alternatively, the driving solid 11 may be a magnetic body, and the switching magnet 13 may be moved in the vertical direction by approaching or separating and switching off the magnetic field. Further, although the switching magnet is provided on the upper side of the liquid retaining section 10 in the present embodiment, the present invention is not limited to this, and it may be provided on the lower side or both upper and lower sides of the liquid retaining section 10. Further, the switching magnet 13 or the drive solid 11
The polarity may be reversed, moved, or the like by interrupting the current (of the electromagnet), switching the direction of the current, mechanically rotating, moving, or the like.

Further, in FIG. 1, the depth 10 of the liquid retaining portion 10 is
Assuming that μm is 5 μm, even if the driving solid 11 is moved into the liquid medium 5, the liquid level is about 1 out of 20 μm of the slit.
The optical path section 7 rises only up to 0 μm and the liquid medium 5
Since it cannot be made to sink below, the operation of switching the optical path becomes uncertain. Similarly, when the volume of the driving solid 11 is small, the position of the liquid surface of the liquid medium 5 does not change sufficiently. Therefore, in the slit 4, it is necessary to set the volumes of the liquid retention part 10 and the slit 4 and the volume of the driving solid 11 within a predetermined range so that the optical path part 7 is surely submerged in the liquid medium 5 or excluded. . For example, in FIG. 1, the slit 4 and the liquid reservoir 10
And the space above which the driving solid 11 moves and the cross-sectional areas of the driving solid 11 are Ss, Sl, Sk, and the depth of the liquid retaining portion 10 with liquid is dl, the liquid level required for stable switch switching. It is necessary to set the variation amount H of the above so as to satisfy the expression 1.

[0036]

## EQU00001 ## H <dl.Sk/ (Ss + Sl-Sk) By the way, when the waveguide type optical switch shown in FIG. 1 was prototyped and the operation characteristics were verified, the function was sufficiently exhibited depending on the presence or absence of a magnetic force from the outside. However, a shorter switching time may be required depending on the purpose of use of the optical switch. In order to shorten the operation time of the optical switch, the magnetic force acting on the driving solid 11 is strengthened, the driving force is strengthened to increase the moving speed thereof, and at the same time, the liquid medium 5 is moved between the liquid retaining portion 10 and the slit 4. It is necessary to make the above smooth and switch the presence or absence of the liquid medium 5 in the slit 4 in a short time.

FIG. 2A is a plan view of a slit and a liquid retaining portion of a waveguide type optical switch according to another embodiment of the present invention, and FIG. 2B is a sectional view taken along the line AA. The drive solid and the switching magnet are omitted for the sake of simplicity.

As shown in FIG. 2 (a), the slit width Ws is continuously increased from the slit 4a toward the liquid storage portion 10a at the communicating portion between the liquid storage portion 10a and the slit 4a. Therefore, the liquid medium 5 can be moved between the slit 4a and the liquid reservoir 10a in a short time.

Further, as shown in FIG. 2B, the slit 4
Since the length Hs of a in the depth direction is continuously widened, the liquid medium 5 is formed below the slit 4a.
Becomes easier to move, and the gas medium 6 above the slit 4a becomes easier to move as the liquid medium 5 moves, and the gas medium 6 remains in the liquid medium 5 above the slit 4a (generation of bubbles). Is prevented.

In this embodiment, the case where the driving solid is completely above the liquid surface and the case where the driving solid is completely submerged in the liquid have been exemplified. However, the present invention is not limited to this, and one The optical switch may function by moving parts in and out of the liquid medium. Alternatively, it may function regardless of the size of the specific gravity of the driving solid with respect to the liquid medium or the gas medium, and further, in order to prevent damage due to collision with the upper part or the bottom of the liquid retention part when the driving solid moves, the upper part of the driving solid or It goes without saying that a shock absorbing material may be provided in the lower part.

Further, by selecting an equivalent specific gravity of the driving solid so that a part of the driving solid projects and floats from the liquid surface, the driving solid is moved to the three-state position of the upward force, downward force and no magnetic force. Since it is possible to move and hold the light, it is possible to divide and propagate the light from the waveguide by approximately ½ to the waveguide by changing the liquid level in three steps, or another one different from the optical waveguide. Switching of the optical waveguides in the set can be performed.

[0042]

In summary, according to the present invention, the following excellent effects are exhibited.

Since the liquid in the liquid collecting part is moved into the slit or is discharged from the slit by moving the driven solid into and out of the liquid collecting part by the magnetic force which does not require energy supply, the small size and high performance and operation can be achieved. It is possible to realize a reliable waveguide type optical switch.

[Brief description of drawings]

FIG. 1 is a side sectional view of an embodiment of a waveguide type optical switch of the present invention.

FIG. 2A is a plan view of a slit and a liquid retention portion of a waveguide type optical switch according to another embodiment of the present invention, and FIG. 2B is a sectional view taken along the line AA.

FIG. 3 is a schematic view of a conventional waveguide type optical switch.

FIG. 4 is an explanatory diagram for explaining an operation of a general waveguide type optical switch.

5 is a schematic cross-sectional view of slits of the waveguide type optical switch shown in FIG.

[Explanation of symbols]

 1 Input Side Optical Waveguide 2, 3 Branch Side Optical Waveguide 4 Slit 5 Liquid (Liquid Medium) 10 Liquid Distillation Section 11 Drive Solid 13 Switching Means (Switching Magnet)

Claims (4)

[Claims] 1. An optical waveguide is provided with a branch portion, and a slit is provided in a central portion of the branch portion so as to intersect with the optical waveguide,
By moving the liquid in the slit, the optical refractive index of the medium in the slit is changed, and the light incident from the incident side optical waveguide is transmitted or reflected, and either one of the two branch side optical waveguides on the exit side is provided. In the waveguide type optical switch provided with a switching means for switching to, a liquid retention part that stores a predetermined amount of liquid in communication with a slit that is shielded from the outside, and a drive solid that is provided in the liquid retention part so as to be freely inserted and removed, A waveguide type optical switch, comprising: switching means for switching the branch side optical waveguide by moving the driven solid into and out of the liquid and moving the liquid in the liquid reservoir into and out of the slit. 2. The driving solid is at least partly composed of a magnetic material, and the driving solid is driven by a magnetic force from the outside to hold the liquid put in and out of the slit. 1. The waveguide type optical switch described in 1. 3. A liquid retention part and a drive part so that the amount of the liquid that moves into the slit by moving the driven solid into and out of the liquid becomes an amount that blocks the optical path of the light from the incident side waveguide in the slit. The volume of the solid is made larger than the volume of the slit.
The waveguide type optical switch described in. 4. The cross-sectional area of the communicating portion extending from the slit to the liquid retaining portion is smoothly expanded in the slit or the communicating portion between the slit and the liquid retaining portion so that the liquid can be easily moved. The waveguide type optical switch according to claim 1 or 2.