JPS59228601A - Optical switch - Google Patents

Abstract

PURPOSE:To reduce the size and cost of an optical switch by providing a transparent liquid layer to a specific interval at which smooth surfaces of two transparent body blocks face each other, and providing an optical system which makes light incident to a driving mechanism for an air bubble in the liquid layer at a specific angle and detects either of reflected light and transmitted light. CONSTITUTION:A transparent body block 6 which has a smooth plane is provide in prallel to and at the interval (l) from the smooth plane of a transparent body block 5, and the transparent air bubble 8 is put in the transparent liquid layer 7 between the planes. When an incident light beam 9 is incident to the liquid layer 7 at an angle theta1, part of it is reflected at the angle theta1 as a reflected light beam 10, and the remainder entering the liquid layer 7 is refracted at an angle theta3 and then refracted partially by the boundary surface between the liquid layer 7 and transparrent body block 6 at an angle theta2 as a transmitted light beam 11. When the air bubble 8 is moved by the air bubble driving mechanism to where the light is reflected and transmitted, the reflection, transmission, and loss vary in extent because the refractive index of the air bubble 8 is considered to be 1.0, so that optical switch operation is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an optical switch used in the fields of optical communication and optical information processing.

(Background Art) A 3×3 switch is an example of a conventional device of this type.
As shown in the figure. Figure 1(a) is a top view of a 3x3 optical switch.
(b) is a cross-sectional view taken along the dashed-dotted line AK.OThis switch includes the input optical fiber lens system 1, fiJJU optical fiber lens systems 2 and 2j, nine pentagonal prisms 3, and nine prism drives. It consists of an electromagnet 4. The light beam emitted from the input optical fiber lens system 1 is incident on the output optical fiber lens system 2' in the off state,
By energizing the prism driving electromagnet 4, the pentagonal prism at the desired optical path position can be inserted into the optical path as shown in FIG. ing.

Such optical switches have the following problems. First of all, it requires a highly precise moving part to insert the prism into the optical path. Second, the electromagnet for driving the prism and the sliding part require a large volume, making it extremely difficult to downsize the prism.

Furthermore, as shown in the conventional example above, if we consider the case of assembling a matrix switch, ``Thirdly, it requires a large number of specially shaped pentagonal prisms that require a high degree of skill to manufacture, and fourthly, during assembly. , a high degree of positioning accuracy is required for each of the large number of prisms, and fifthly, the number of parts is extremely large. Therefore, conventional switches are not suitable for mass production and are extremely expensive.

(Object of the Invention) In order to eliminate these problems, the present invention is characterized by using movable bubbles as a substitute for the conventionally used movable prism. The objective is to realize an inexpensive and compact optical switch, and will be described in detail below with reference to the drawings.

(Structure and operation of the invention) The basic structure of the optical switch of the present invention is shown in Figure 2.

The transparent blocks 6 of the mound 2 having smooth planes are arranged parallel to the plane of the first transparent block 5 having a smooth plane, with an interval 1 between them. The layer 7 is filled. Furthermore, transparent air bubbles 8 are inserted into the liquid layer 7.

In such a structure, consider the case where an incident light beam 9 is incident on the liquid layer 7 from the inside of the first transparent body bronc S at an angle of 01. Here, for convenience of the following explanation, the X axis is parallel to the liquid layer 7, the yz axis is within the incident plane of the incident light beam 90, and the Z
The axis is taken to be perpendicular to the liquid layer 7. Incident light beam 9
A part of the light is reflected at an angle θ and becomes a reflected light beam 10, and the light incident on the liquid layer 7 is refracted at an angle θ3. The transmitted light beam 11 is refracted at an angle θ2 at the interface between the transparent blocks 6 and 2.
becomes.

The reflected light beam 10 and transmitted light beam 110 intensities are:
It is necessary to consider the incident light beam by decomposing it into P waves whose electric vectors are parallel to the plane of incidence and S waves whose electric vectors are perpendicular to the plane of incidence. Here, in the following, all the media are non-magnetic, and the magnetic permeability is 1.
Suppose it is 0. The refractive index of the first transparent block 5 is n
l, the refractive index of the second transparent block 6 is 02, and the liquid layer 7
When the refractive index 7 of is 113, the reflectance of the P-wave component of the reflected light beam 10 is R-, and the S-wave component R8 is. The transmittance of the transmitted light beam 11 is, for the P-wave component, and for the S-wave component 8. Angle θ
0. between θ3 and refractive index n1 s R2t 113, Snell's law nI CO3θ1-113CO5θ3-n2CO8θ2
...(5) holds true, and the incident angle θ
1, the refraction angle θ2. θ3 is obtained,
By substituting these into equations (1) to (4), the reflectance and transmittance are determined. R8 and T8. Or, even if R9 and T8 are added, it does not become 1.0, and the loss for P wave and S wave is, R5 beam, -1,0-R, -T, concave... (6) L
=1゜O-R-T ・River...(Power S S
S, and these are the liquid layer 7 and the second transparent body block 6
This is the reflection that occurs at the interface.

Now, if the bubble 8 is moved to the area where such reflection and transmission occur using an appropriate bubble drive mechanism, the refractive index of the bubble 8 can be regarded as 1.0, so (1) ~ (force formula In this case, the refractive index n3 of the liquid layer 7 becomes 1.0, and the intensity of reflection, transmission, and loss changes, and an optical switch operation is obtained.However, for this purpose, the area occupied by the bubble 8 must be , refraction, and transmission, and therefore it is clear that a relationship between the bubble 80 radius R and the incident light beam radius r needs to be established.

Next, as a special state of the above relationship, when the refractive index 01 of the first transparent body block 5, the refractive index n2 of the second transparent body block 6, and the refractive index n3 of the liquid layer 7 are equal and n think of. When there is no bubble 8 at the incident site to the liquid layer 7, complete transmission with zero loss is obtained from equations (1) to (7).On the other hand, when there is a bubble 8 at the incident site, the incident angle θ is set to θ, (cos −” (1/+1)
...If selected to satisfy mountain (9), formula (1)
~(From the sword, R,, -R5=1.0T, -T3=o and Lp-R5-o, total reflection is realized, and total reflection type complete switching operation is obtained by the movement of the bubble 8. Hereafter The explanation deals only with the case of such switch operation.

Next, the bubble drive mechanism will be described. First, the bubbles are added to the liquid layer 7.
To make it stand still stably inside, do as shown in Figure 3. That is, as shown in FIGS. 3(a) and (b),
First transparent block 5 and second transparent block 6
Two depressions having bottom surfaces parallel to the planes thereof are formed in the cavity, and a constriction connects the two depressions to form a first bubble chamber 12 and a second bubble chamber 12I. Bubble chambers 12 and 1
24'! (The shape is symmetrical with respect to the fin.Then, the bubble 8 is inserted only into the bubble chamber on one side.In this way, the bubble 8 can be inserted into either the first or second bubble chamber.) If an external force is applied to this bubble 8 by an appropriate mechanism, the bubble 8 will pass through the constriction and move to another bubble chamber, as shown in Fig. 3(c). , it comes to rest stably there.

FIGS. 4 and 5 are diagrams showing a bubble drive mechanism that drives the bubbles 8 using electrostatic force. As shown in Figure 4(a),
First transparent block 5 and second transparent block 6
As shown in the cross-sectional views of FIGS. 4(b) and 4(c), at least half of the area of the bubble chamber 12 formed between 0 and 12' far from the constriction and the periphery of the concavity of the bubble chamber Electrodes 13 and 13' are installed. Here, FIG. 4(b) is a cross-sectional view taken along the dashed line B in FIG.
Further, (C) is a sectional view taken along the dashed-dotted line C in FIG. 4(a), and FIG. 5 is a sectional view taken along the dashed-dotted line A in FIG. 4(a). Furthermore, an insulating layer 15 having the same refractive index as the transparent block and the liquid layer 7 is laminated on the electrodes 13 and 13' in order to prevent the liquid layer 7 from being electrolyzed when a voltage is applied to the electrodes. has been done. In such a configuration, as shown in FIG. 5(a), when the first bubble chamber 12 is filled with bubbles 8, the first bubble chamber 1
The incident light beam 9 that enters a region close to the constriction where the electrode 13 of No. 2 is not installed is totally reflected at the interface between the insulating layer 15 and the bubble 8, and becomes a reflected light beam 10. Next, when a voltage is applied between the electrode 13' on the side of the first transparent block and the electrode 13' on the side of the second transparent block, the interface between the bubble and the liquid existing between the electrodes will be F-1ε per unit area in the y-axis direction of the figure. (ε1−ε,) R2・・・・・・(1
0) acts as an electrostatic force F. Here, ε0 is the permittivity in vacuum, ε ε is the relative permittivity of liquids and bubbles, and E is the electric permittivity of 1″
2 field strength. Therefore, the bubble-liquid interface moves in the y-axis direction of the figure, and the bubble 8 therefore moves through the constriction towards the second bubble chamber as shown in Figure 5 (bl).Electrode 1
3 and 13'&'! ,, even if it is not attached to the entire surface of the first bubble chamber, it is sufficient if it is attached to half or more of the area. The reason for this is that once more than half of the bubbles 80 pass through the constriction and enter the second bubble chamber 12', the surface tension of the bubbles themselves will cause the bubbles to move into the second bubble chamber 12' without applying any force to the bubbles 8.
’.

When the bubble 8 has finished moving in this manner, the incident light beam 9 becomes a transmitted light beam 11 and exits toward the second transparent block 6, as shown in FIG. 5(C). Note that the recess for the bubble chamber 12.12' may be formed only in either one of the first and second transparent blocks 5.6.

Next, another bubble driving mechanism will be described with reference to FIGS. 6 and 7. As shown in FIG. 6, circular heaters 16 and 1 are provided on the plane of the first transparent block 5.
A transparent block 5.6, a liquid layer 7, and an insulating layer 15 having a refractive index of PI - are laminated thereon in order to prevent the liquid from coming into contact with a high-temperature metal heater and decomposing. (Figure 7). On the other hand, depressions are formed on the plane of the second transparent block 6 at portions corresponding to the two heaters 12 and 12', and a constriction is provided between the first bubble chamber 12 and the second bubble chamber. 12'. The bubble 8 is inserted into the first bubble chamber 12 . Then, as shown in FIG. 7 (al), the incident light beam 9 is totally reflected and becomes the reflected light beam 1.
It becomes 0. In this state, as shown in Fig. 6(b), the second
The heater 16' of the bubble chamber 12' is energized. Then, the liquid in the second bubble chamber is heated and its density decreases. Therefore, as shown in FIG. 6 (bl), the bubbles 8 receive buoyancy toward the low-density liquid, so they pass through the constriction and move toward the second bubble chamber 12'.Even if the electricity is turned off, the bubbles 8 is the second
The incident light beam 9 remains stably in the bubble chamber, and the incident light beam 9 becomes transmitted light 11, as shown in FIG. 7(b).

Next, an application form of the optical switch principle described above will be described. FIG. 8 is a diagram showing the basic unit of the optical switch of the present invention. The first transparent block 5 is an isosceles triangular prism, and the angle φ between the equilateral sides is φ(2cos (1/n)
--(It) is taken to satisfy. However, n is the first
, a second transparent block, a liquid layer 7, and an insulating layer 15
is the refractive index of Note that the insulating layer 15 and the bubble driving mechanism are omitted from FIG. 8 onwards. A liquid layer 7 including bubbles 8 and a bubble drive mechanism is provided by a spacer 17 between the column surface including the opposite side of the angle φ of such a triangular column and the plane of the second transparent block 6. In such a configuration, the incident light beam 9 that is perpendicularly incident on one side of the isosceles from the input side optical fiber lens system 1 has an incident angle θ1 on the liquid layer 7 of φ/2. Then, θ1 satisfies the total reflection condition of equation (9) from equation (1), and a total reflection type switch operation is obtained by the movement of the bubble 8.

By combining these basic units, the following multi-input, multi-output optical switch can be obtained. However, in the following, all φ
is set to 90'. This angle is a realistically possible value, as will be described later.

FIG. 9 is an example of a two-man power two-output optical spinch that combines two basic units of the same size.

(Figure 81 shows that there is no bubble 8 in the optical path and the incident light beam is traveling straight, and figure (b) shows that the bubble 8 is inserted in the optical path and the incident light beam is totally reflected. It shows.

FIG. 10 is an example of a 1×14 switch. A transparent block 5' with a trapezoidal cross section is a combination of 13 basic units shown in FIG.
and an isosceles triangular prism transparent block 6 with an area 36 times as large.
Seven bubbles are inserted between blocks 5' and 6', and six bubbles are inserted between blocks 5' and 6''.

FIG. 11 is an example of a 3×3 sinch. From the two basic units shown in Figure 8, two transparent blocks with a trapezoidal cross-sectional area three times that of the basic unit, and two transparent blocks with a trapezoidal cross-section and bond five times that of the basic unit. Become. A total of nine bubbles 8 are inserted at the intersections of each optical path and the liquid layer.

FIG. 13 is an example of a 3×3 switch according to another construction method. First, explanation will be given from Figure i12. This is the basic unit of a 3×3 optical switch, and the first transparent block 5 is a transparent block with a trapezoidal cross section. In addition, an isosceles triangular prism similar to the basic unit and having a cross-sectional area nine times larger is used as the second transparent block 6, and a spacer 17 is placed between them as shown in the figure.
A liquid layer 17 is formed by sandwiching the two layers. In such a structure,
Three input-side optical fiber lens systems 1 to 1'' are arranged on a surface forming an angle V2 with the liquid layer 7 of the first transparent block 5.Such a switch is shown in FIG. 13(a). and (b)
As shown in the figure, align the two units, rotate the switch on the right side of the figure 90° counterclockwise, and attach them so that the output optical paths of the left and right basic units match, and connect the optical fiber lens of the right basic unit. Output side light 7 Aiba lens system 2
~2”, a 3×3 optical switch is constructed.The first
3(a) and 3(b) show the connection state of the input side optical fiber lens system 1 and the output side optical fiber lens system 2. In the above-mentioned operation of the Casinch, the operation is exactly the same even if the input side optical fiber lens system is used as the output side and the output side optical fiber lens system is used as the input side.
This is clear from the principle of retrograde rays.

Next, examples will be described. The first transparent block 5 and the second transparent block 6 are made of fused silica (with a refractive index n
= 1.46). In this case, from equation (9),
The incident angle θ1 of the light beam 90 is 46B0 or less.

Therefore, if 01 is set to 45 degrees, the angle φ between the equal sides of the isosceles triangular prism that forms part of the basic structure of this optical switch becomes exactly a right angle, which is an extremely convenient angle for polishing and forming. Bubble chambers 12 and 12' as shown in FIGS. 4 and 5 are formed on a plane including right-angled opposite sides of a polished triangular prism by a photolithography process to a depth of several mm in the X-axis direction. , a hole with a constriction in the center of about 5 mm in the 3' axis direction is formed.

On top of this, thousands of chromium, which is a metal with excellent adhesion to oxide glass such as quartz, is vapor-deposited and patterned using a photolithographic process as shown in Figure 4.
Set it to 4. Furthermore, several thousand layers of fused silica are laminated thereon by high frequency sputtering to form an insulating layer 15. Two pieces of this type are made, and using a plastic sheet several μm thick as a spacer 17, they are pasted together and fixed as shown in FIG.

Liquid is then inserted between the end faces using capillary action. Then, because the distance between the inside and outside of the bubble chambers 12 and 12' is smaller, the gap between the outside of the bubble chamber is smaller due to surface tension. Apply voltage to the electrodes. Then, in FIG. 4(a), the liquid enters the electrodes 13 and 140 part due to the force according to formula 00), so excess bubbles are discharged outside the bubble chamber from the constricted part where the electrodes 13 and 14 are not present, and no bubbles are formed. It becomes a stable bubble.

These unstable bubbles can be moved to the end of the liquid layer 7 in a desired direction by the density gradient generated by applying a temperature gradient to the liquid layer 7, and then disappear. Thereafter, the bubbles remaining in the bubble chamber move toward either the first or second bubble chamber when the applied voltage is cut off. As a liquid, α0)
As is clear from the above, a higher dielectric constant is desirable. Propylene carbonate (relative dielectric constant ε-69, refractive index n = 1.4) is a transparent, photochemically stable liquid with a high dielectric constant.
2) and ethylene carbonate (relative dielectric constant ε-89.6, refractive index n = 1.42), but the refractive index does not match that of fused silica. Therefore, it is sufficient to use a mixed liquid that is compatible with the above two, has a refractive index higher than that of fused silica, and is chemically stable. Monochlorobenzene (relative dielectric constant ε=56, refractive index 1.52) is suitable as such a liquid. The refractive index may be adjusted to that of fused silica using these mixing ratios. In the method using density change due to heating shown in FIGS. 6 and 7, the steps up to the material and liquid insertion steps may be the same as those described above, and the bubbles in the first bubble chamber 12 and the second bubble chamber 12' may be To delete either one of them, do the following. First both electrodes 16.16'
energize at the same time to heat both bubble chambers. The bubble then expands and spills out of the bubble chamber. When ultrasonic waves are applied in this state, the protruding air bubbles are torn off and separated. When a temperature gradient is then applied to the liquid layer 7, the torn air bubbles move to the high temperature side and can be eliminated.

(Effects of the Invention) The optical switch of the present invention as described above has the following advantages over the conventional optical switch described above. That is, firstly, it is possible to downsize without any need for a high-precision electromagnet-equipped moving part that requires a large volume, and secondly, the bubble driving part can be made in a conventional thin film deposition process and photolithography process. It can be made with no special skills and
It is suitable for mass production. Furthermore, when considering the case of trying to create a matrix, thirdly, it is not necessary to individually package a large number of specially shaped prisms as in conventional switches (it requires far fewer transparent blocks, and fourthly, a large number of specially shaped prisms are required. Positioning accuracy is not required for each individual prism, and it is sufficient to ensure the parallelism and angle of the transparent block.Therefore, the switch of the present invention has a structure, manufacturing method, and It is clear that a much cheaper switch can be provided with significant improvements in volume and volume.

[Brief explanation of the drawing]

Figure 1 is a diagram of a conventional optical switch, Figure 2 is a diagram of the principle of the optical switch of the present invention, Figure 3 is a diagram of a bubble chamber, Figure 4 is a diagram of a bubble drive mechanism, and Figure 5 is a diagram of a bubble drive mechanism. A diagram of the operation of the drive mechanism, Figure 6 is a diagram of the bubble drive mechanism, Figure 7 is a diagram of the operation of the bubble drive mechanism, Figure 8 is a diagram of the basic unit of the optical switch of the present invention, and Figure 9 is a diagram of the two-man power switch. Diagram of 2 output source switch, Figure 10 is 1
A diagram of a ×14 optical switch, Figure 11 is a diagram of a 3 × 3 optical switch, Figure 12 is a diagram of the basic unit of a 3 × 3 optical switch, and Figure 13 is a diagram of a 3 × 3 optical switch.
The figure is a diagram of a 3x3 optical switch. 1.1', 1"...input side optical fiber lens system, 2.
2-2"...Output side optical fiber lens system, 3...5
Square prism, 4... Prism driving electromagnet, 5... First transparent block, 6,6', 6''... Second transparent block, 7... Liquid layer, 8... Bubbles, 9...
Incident light beam, 10... Reflected light beam, 11... Transmitted light beam, 12... First bubble chamber, 12'... Second bubble chamber, 13... Electrode, 14...・Electrode, 15・
...Insulating layer, 16...Heater, 17...Spacer. Patent Applicant Nippon Telegraph and Telephone Public Corporation Patent Application Agent Patent Attorney Megumi Yamamoto Figure 1 (0) (b none 2! Figure 5 (θ) (b) (C) 7- Figure 2 (Q) ( b) (C) East 7 concave (Q) Tai ε diagram zq diagram (α) Rod, 70 diagram / book l1 diagram kan>/2 [2] Vermilion 13 concave mini/7 (b) ! l//?

Claims (1)

[Claims] (IJ) The smooth planes of a first transparent block and a second transparent block having smooth planes are held facing each other with a predetermined interval maintained, and the transparent blocks filled in the interval are a liquid layer;
A transparent bubble inserted into the liquid layer, a bubble drive mechanism that moves the bubble to a desired position in the liquid, and a bubble drive mechanism that is irradiated with light at a predetermined angle through the first transparent block. An optical switch comprising: an optical system that allows the incident light to enter the bubble; and an optical system that detects at least one of the incident light reflected by the bubble drive mechanism or the light that is transmitted through the bubble drive mechanism. (2) The first transparent block, the second transparent block, and the liquid layer have the same refractive index, and the refractive index of these is 11, and the incident light enters the liquid layer through the first transparent block. If the angle between the light and the liquid layer is θ, then θ(co
The optical switch according to claim 1, characterized in that the bubble 1 drive mechanism is made of a liquid layer thicker than the surroundings, and The optical switch according to claim 1, characterized in that it has a plurality of bubble chambers divided by a constriction. Claim 1, characterized in that the device comprises electrodes provided on the first transparent block and the second transparent block, which apply an electrostatic force to the interface between the bubble and the liquid by applying a voltage from the outside. or the optical switch according to item 3. (5) The bubble drive mechanism is provided on the plurality of bubble chambers, each bubble chamber and the first transparent block and second transparent block in the vicinity thereof. 4. The optical switch according to claim 1, further comprising an electrode that heats the liquid in and around the bubble chamber by applying a voltage from the outside.