JPS5855914A - Optical switch - Google Patents

Abstract

PURPOSE:To obtain a optical switch which operates with natural light as well, is simple in construction, permits easy arraying to a large size and can be operated with low electric power by providing a heating means to a part of an optical transmission medium of which the refractive index changes with temp. CONSTITUTION:A slender heating electrode 3 consisting of an Ni-Cr alloy is vapor-deposited on a part of the surface of an optical transmission medium 2 of a rectangular prism shape of which the refractive index changes with temp., for example, crystal such as LiNbO3, molten quartz, glass or the like. The light beam 1 incident through the incident port 5 of an incident mask 4 on the side surface of the medium 2 advances straight and is shut off by an exit mask 6 on the other side surface. However, if suitable electric current is run to the electrode 3, the surface of the medium 2 in contact with the electrode 3 is heated, by which a temp. distribution is generated toward the inside of the medium 2, then the beam 1 is deflected upward in the medium 2 and emits through the exit port 7 of the mask 6. Therefore the optical switch which operates with natural light as well, is simple in construction, permits easy arraying to a large size and can be operated with low electric power is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical switch that utilizes the property of a crystal material that its refractive index changes depending on the temperature.

In the field of optical information processing such as optical fiber communications, optical memory devices, and optical printers, devices that fully control the direction of light and turn on and off the passage of light are essential. Optical switches used as devices of this type are required to have low crosstalk, be able to easily switch with low power, have high switching speed, and be low cost. By the way, some conventional optical switches utilize an acousto-optic effect or an electro-optic effect. FIG. 7 is a schematic perspective view of an optical switch that fully utilizes the electro-optic effect. This light switch is
LiNb01.

On the surface of the optical transmission medium 200 made of a crystal material such as LiTa01 or Te01, comb-shaped electrodes 21 and 22 are formed by vapor deposition or the like so that the tooth portions of the electrodes are alternately arranged. Then, the parallel direction tY-axis of the teeth of the comb-shaped 02 poles 21 and 22, the thickness direction t-X axis of the optical transmission medium 0, and these! As shown in FIG. 1, light is incident in the t-Y axis direction whose polarization plane is the X-axis direction, and the electrode 21
When an appropriate high-frequency voltage is applied between .degree.

2”/A - (2 to/λ) (1* -1111)
--(1) However, A: comb-shaped electrode 21, 220m part O part Ine: Optical transmission medium 200 Refraction multiplex of extraordinary light (light whose electric field direction is parallel to the X axis) of the crystal ・: Ordinary light of the crystal The refractive index is interposed in the optical path of the emitted light in the X-axis direction, and the polarization plane of the emitted light is in the X-axis direction. Therefore, the electrode 21.2
When no voltage is applied to the optical transmission medium 20, even if similar light is incident on the optical transmission medium 20, it is emitted as it is without undergoing conversion of the plane of polarization.

Then, the output light passes through the polarizing plate 23'i, and the plane of polarization is converted into biaxial directions, but the output light after polarization undergoes extremely large absorption by the polarizing plate 23IC, so its intensity is weakened. It is being

In this way, the on/off state of the voltage between the electrodes 21 and 22 corresponds to the intensity of the light passing through the polarizing plate 23t, thereby forming an optical switch.

However, when constructing an optical switch using the electro-optic effect as described above, the electrode structure is complicated because it is necessary to form the electrodes in a periodic structure such as a comb-like O electrode, and the formation process is difficult. is not easy, and it is difficult to create a large array. It was. The incident light is polarized in a specific direction.
It has the disadvantage that it does not work with white light, and it also requires a polarizer, so the polarizer reduces the light intensity. Again. Since single crystals are usually used as optical transmission media, Ohara AK of optical switches
There are restrictions, and it is necessary to use a high-quality 121-volt electric power source. Furthermore [19, because the electro-optical effect varies with temperature.

The temperature sms at which it can operate as an optical switch is extremely narrow.

On the other hand, in optical switches that utilize the acousto-optic effect,
Use crystal material tubes such as PbMoO4 and T@01.

It is extremely expensive because it uses a transducer that converts electrical signals into ultrasonic waves. Sara K.

Since a high-frequency, large-power tube is required to drive the optical switch, there is a problem in that it is difficult to use.

The present invention was made in view of the above points, and is free from restrictions such as the polarization state and wavelength of the light used, can operate even with white light, and does not require a polarizer or analyzer. ,
To provide an optical switch which has a simple electrode structure, can be easily converted into a power switch, has a low attack stalk, and can be operated with low power. The present invention departs from the conventional concept of an optical switch that uses the electro-optic effect or the acousto-optic effect of crystalline materials, and is based on a novel idea that utilizes the temperature dependence of the refractive index of crystalline materials. This is what was done.

An optical switch according to the present invention includes: an optical transmission medium made of a material whose refractive index changes depending on temperature; an optical beam input means for inputting a light beam in a first direction into the optical transmission medium; comprising temperature control means for forming a temperature gradient tube in at least a part of the optical transmission medium portion through which the optical transmission medium passes;
The present invention is characterized in that the light beam is deflected in a direction different from the direction 11 by operating the temperature control means t1jh. In this case, it is preferable that the temperature control means has a heating hand IRt for heating a part of the optical transmission medium. Another aspect of the present invention is an optical transmission medium made of a material whose i-refractive index changes depending on temperature.

An input means for causing only light in a specific incident direction along the surface of the optical transmission medium to be incident on the optical transmission medium, provided on the surface of the optical transmission medium, at least -1! #It has a resistance heating electrode located directly above the direction of incidence of the light, and an output mask provided on the output surface side of the optical transmission medium and having an output opening outside the extension line of the direction of incidence of the light. The present invention provides an optical switch with a t-% characteristic.

Crystal materials such as LiNb0K# LITaO, T·0 snow, and quartz have a property that their refractive index is temperature dependent, and the higher the temperature, the higher the refractive index. and.

When light crosses the boundary between materials with different refractive indexes, it passes through the boundary between materials with different refractive indexes.

A refraction phenomenon occurs as the angle of refraction (the angle between the direction perpendicular to the boundary and the light beam) becomes smaller in a substance with a high refractive index.

Therefore, if a neutralizing temperature gradient or temperature change exists in the optical transmission medium made of the above-mentioned 0jIo crystal material, the light traveling through the optical transmission medium will be deflected toward the high temperature region. The present invention has been made based on this knowledge.

That is, an electrode is formed on the surface of an optical transmission medium using a resistance heating element,
When this electrode 9 is energized to heat the surface of the optical transmission medium 0, a temperature gradient is generated in the region i directly below the electrode in the thickness direction from the surface of the optical transmission medium.

When a light beam is made incident on an optical transmission medium, the light beam becomes hot in the optical transmission medium where a temperature gradient exists
When the light beam is deflected toward , and emitted from the optical transmission medium, the emitting position deviates from the extension line of the incident direction, and the light beam is emitted at a position close to the electrode forming surface. Then, by providing an exit mask with an exit opening at this exit position,
! When the electrode is not energized, there is no temperature gradient in the optical transmission medium and the light beam travels straight; therefore, when the electrode is energized and
An optical switch is configured that turns the emitted light on and off in response to the off state.

EMBODIMENT OF THE INVENTION Below, one specific embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic vertical sectional view of a first embodiment of the present invention.

The optical transmission medium 2 made of the crystalline material has a widthwise dimension of L.
+t (D) It has a rectangular, rod-like shape, and on its surface there is a heating electrode 3t in the form of a narrow layer extending in the width direction of the optical transmission medium 2.
, is formed over an appropriate dimension from one end side of the optical transmission medium 2. The heating electrode 3 is formed of Ni--Cr alloy or the like, for example, by sporadically deposited #. A light beam (l) whose incident direction is parallel to the longitudinal direction of the heating electrode 3 is placed on the side surface of the one end of the optical transmission medium 2 in the vicinity of the area immediately below the heating electrode 3 on the optical transmission medium 2. To let it happen.

An entrance mask 4 with an entrance opening 5 is provided.

Note that it is preferable that the light beam l input into the optical transmission medium 2 be a parallel beam O that is as narrow as possible in order to reduce crosstalk as an optical switch. On the opposite side of the optical transmission medium 2 to the entrance mask 4, there is provided an output mask 6 with an output lower. The lower exit of the exit mask 60 is located at a distance Kd above from a position on the extension line of the incident direction of the light beam 10 (indicated by a dot laK in the figure).

When an appropriate O current is applied to the heating electrode 3, the heating 1
The pole 3 generates resistance heat and is the optical transmission medium 2 in contact with the heating electrode 3.
0! ! The surface is heated, and a temperature distribution is generated from this surface toward the interior of the optical transmission medium 2. Along with this, the refractive index nli of the optical transmission medium 2, the second f! IJ K jj,
It exhibits a refractive index distribution such that the refractive index is highest on the surface on the high MO heating electrode 3 side and gradually decreases in the thickness direction of the optical transmission medium 2. When the light beam 1 whose direction and beam diameter are regulated by the entrance mask 4 enters the optical transmission medium 2, its traveling direction is deflected upward by the refractive index distribution within the optical transmission medium 2, and the light beam l is the area directly below the heating electrode 3''
The light travels along an upwardly curved optical path. Next, when the light beam 1 travels a distance L from the incident mask 4 and leaves the region immediately below the heating electrode 3, it enters a region (length t>4C) which is not heated and has the lowest refractive index.

At this boundary, the light beam 1 is refracted further upward, and there is little change in the refractive index in this region.

The light beam lFi travels approximately linearly in this region and is emitted to the outside from the output lower. In this manner, when the heating electrode 3 is energized, the light beam l that has entered through the entrance mask 4 is emitted from the exit mask 6.

On the other hand, when the heating electrode 3 is not energized, the temperature distribution within the optical transmission medium 2 is uniform and the refractive index is uniform, so the light beam l travels straight through the optical transmission medium 2 in the direction of incidence, As described above, the on/off of energization to the heating electrode 3 corresponds to the on/off of the light beam 10 emitted from the emission mask 6, and an optical switch is configured. Ru.

By the way, the deflection distance d, the electrode length L and the non-electrode length t
There is a relationship between them as shown in (2) 2 below.

d: tLΔn/D -----
------- (2) However, ΔB: Change in refractive index due to temperature of crystal material D = Diffusion depth of change in refractive index due to heating Usually 0.5 to 1. Qgm) Furthermore, when the crystal material of the optical transmission medium 2 is quartz, the ratio of refractive index change Δn/ΔT to the temperature change ΔTK is approximately 10-''. Therefore, the temperature rise 47 due to electrical heating of the heating electrode 3 -s100℃.

Also, assuming that the diffusion depth of quartz is D ti' 0.5 mm, (according to the force equation, υd becomes d -2X 10-'LL.

L = 10mm, t = 5 as+ if d
-0,1 arm.

For a light beam emitted from a surface spaced apart by a distance t (=51u11) from , it is sufficient to provide an output mask 6 having an output lower at a position 0.1+w+m above the extension line of the incident direction. In other words, for an optical switch with such a dimensional relationship, the temperature rise ΔT
All current conditions for the heating electrode 3 may be set so that the temperature is approximately 100°C.

By arranging a plurality of heating electrodes of the optical switch in the width direction, it is possible to construct an optical switch that has the function of turning on and off all of a plurality of light beams, and the optical switch can be used for displays, printers, etc. By applying it, it becomes possible. Figure tA3 is a schematic diagram showing a second embodiment of the present invention. On the surface of the optical transmission medium 2, there are heating electrodes 3a, 3b, 3e, 3d in the form of an M-knit layer extending in the width direction.
.

3e, 3f... are arranged in parallel at appropriate intervals in the width direction. Like the heating electrode 3, the heating electrode 3a and the like are made of a Ni-Cr alloy or the like, and are formed by vapor deposition or the like. The light incident side end of the heating pole 3a fathom is connected by a common electrode 8.

The light emitting side end of the heating electrode 3 & etc. has a lead-out current of 119 m.

9ba, 9c, 9de, 9., 9f, . . . are individually led out, and a voltage can be individually applied between these extraction electrodes 9&, etc. and the common electrode 8. An entrance mask 4 is provided on the side surface of the optical transmission medium 20 on the light incidence side, and a heating electrode 31L, 3 ha 3 c e3d, 3 is provided at a position slightly below the upper end of the entrance mask 4.
. , 3f . . . , and 3f .

5b, 5e, 5d, 5., 51... are provided, and optical beams A la, lb, which are belt-shaped parallel lights, are provided.
lc, ld, l@, If, . An output mask 6 is provided near the side surface of the optical transmission medium 20 on the light output side, and the light beams IL lb, is, ld in the output mask 6 are
, 1.

KFX output lower m, 7b, 7c, 7 at an appropriate dimension above the position on the extension line of the incident direction of 1f...
d, 7@.

7F... has been opened. In this embodiment, the binary transmission medium 2 and the emission mask 6 are separated by a certain distance, and the optical transmission medium 2 is also separated from the light beam la.
etc. are refracted as they exit into the air, so the opening position of the exit lower 1, etc. is slightly above the exit lower in the first embodiment.

Also in this case, when electrode 3 & equal voltage is energized.

A temperature distribution that changes in the thickness direction of the optical transmission medium 2 occurs in the area immediately below the electrodes 3 & etc. in the optical transmission medium 2, and a refractive index distribution occurs correspondingly. As a result, the light beam 1
While traveling through the optical transmission medium 2, the beams a and the like are deflected toward the upper part where the temperature and therefore the refractive index are high, and after exiting the optical transmission medium 2, they pass through the output lower part 1 of the output mask 6, etc. .

On the other hand, if the heating electrode 3a etc. are not energized.

Since the light beams l&, etc. corresponding to the heating electrodes 31, etc. travel straight through the optical transmission medium 2, they are blocked by the emission mask 6 and are not emitted to the outside K11i. By applying pressure in this manner, a plurality of light beams can be turned on and off simultaneously and individually,
Therefore, the optical switch can be applied to displays, printers, etc.

FIGS. 4 and 5 are a dramatic view and a plan view, respectively, showing a third embodiment of the present invention. In this embodiment, the entrance mask 4 provided on the light incidence 80911 surface of the optical transmission medium 2 is
i, entrance ports 5x and 5γ are opened at positions slightly below the upper end, and a narrow @0
The parallel light beams lx and ly are approximately directly incident on the entrance mask 4 at I&. Heating electrodes 3X and ay are formed on the surface of the optical transmission medium 2. Heating electrode 3
For x, etc., the half of the light input side path s is located directly above the direction of incidence of the light beam lx, etc., without a straight line t, and the half of the light output side path is flat with respect to the traveling direction of the light beam lx, etc. It has a curved shape that curves to the right when viewed. The light incident side ends of the heating electrodes 3x and 3y are connected to each other by a common electrode 8, and the light output side ends are individually led out to a power source shown in the drawing through extraction electrodes 9x and 9yK, respectively. An output mask 6 is provided near the side surface of the optical transmission medium 2 on the light output side.
The emission mask 6 has an emission lower x*7)' in the tangential direction of the light emission side end s of the heating electrodes 3x and 3y, respectively.
K has just been opened.

Also in the optical switch of this embodiment, the extraction electrodes 9x, 9y
and the common electrode 8 to heat the heating electrodes 3x, 3.
When electricity is applied to y, the heating electrode 3x.

A temperature distribution that changes in the thickness direction occurs inside the optical transmission medium 2 in the area immediately below the heating electrodes 3y, and this temperature distribution Fi causes the incidence of the light beams lx and ly to change along the curved direction of the heating electrodes 3x and 3y. It is deflected from the direction and exists in a curved state to the right in the direction of travel when viewed from above. The refractive index changes in accordance with such temperature distribution, and due to the nature of the light beam that it is deflected toward the portion where the refractive index It is high, the light beam that enters the optical transmission medium 2 from the entrance mask 4 The original beams lx, 1yti travel along heating electric currents 4, 3x, 3y, curved to the right in the traveling direction in plan view, and simultaneously travel through the Wako transmission medium 2.
The light is emitted from the optical transmission medium 2 while being deflected upward toward the surface side of the light, and passes through the emission lower part x, 7yt of the emission mask 60.

On the other hand, if 37 is not energized to the heating electrode 3,
Since the light beams 5la and lb travel straight through the optical transmission medium 2, they are leaked by the exit mask 6 and are not emitted to the outside.

In this way, an optical switch is constructed in which the heating electrodes 3x, 3y are turned on and off and the light beams 1x, 1y are turned on and off.

In the optical switch according to the present invention as described above, regardless of #i or each of the above embodiments, the crosstalk is extremely low and the switching speed f is high. For example, optical transmission medium 2
If is quartz.

Its temperature transfer coefficient α is 6-75 x 10-'Cal"
/Glue EC, and since the speed of increase in temperature of the optical transmission medium 20@degree is proportional to the temperature transfer coefficient α and the square of the width of the heating electrode 3, etc., it is easy to ensure a switching speed of about 1 m5-C. It is. By the way, by setting the shape and dimensions of the heating electrode appropriately, the optical switch has a heat sink function.
By providing this, the switching speed can be further improved. Figure N46 is a schematic vertical cross-sectional view showing one embodiment thereof. Optical transmission medium 2. Heating electrode 3
(or 31 etc.), incidence mass 4. The structure of the emission mask 6 is the same as that of the first embodiment (see FIG. 1) and the second embodiment (see FIG. 1).
(see figure).

In the embodiment shown in FIG. 6, an insulating layer 10'' made of 8102 or the like is provided on the surface of the optical transmission medium 20 including the upper surface of the heating electrode 3, etc.
A heat dissipation mill, which is a thin metal layer having a high heat dissipation effect, is formed on the insulating layer 10. The insulating layer IO is formed to prevent electrical conduction between the heating electrodes 3a and the like due to the metal heat dissipation layer 11 when a plurality of heating electrodes 3a and the like are arranged in parallel as in the second embodiment. . A heat dissipation plate 12 made of a material such as metal or ceramic having a high heat dissipation effect is adhered to the lower surface of the optical transmission medium 2. By providing the heaton/return function in this way, when the heating electrode 3, etc. is turned off, the optical transmission medium 2t in the area immediately below the heating electrode 3, etc. can be rapidly cooled, and therefore, It is possible to further increase the switching speed as an optical switch.

As explained in detail above, the optical switch Fi according to the present invention is used because it deflects a light beam by utilizing the gradient or change in the refractive index formed in the optical transmission medium by energizing the heating electrode. The light beam is not subject to restrictions such as polarization state and wavelength.

White light, which was previously inoperable, can also be used.

In addition, it goes without saying that a polarizer or analyzer is unnecessary, and the electrode shape can be extremely simple in the form of a plate.As shown in the second embodiment, a large array of optical switches (many optical ) can also be easily realized. In addition, instead of weakening the intensity of the light beam with a polarizer as in the past, the O light beam is reliably turned into KII light with an exit mask when the power is not energized, so the crosstalk is extremely low. Since it is 040 simply to cause the heating electrode to generate heat through resistance, a DC power source may be used as in the example shown in FIG. Note that the present invention is based on the above O.
The present invention is not limited to specific embodiments, and various modifications can be made within the technical scope of the present invention. For example, the heating electrodes 3, 3a, etc. of the first embodiment (see IEI diagram) and the second embodiment (see FIG. 3) may be combined in the width direction of the optical transmission medium 20 as in the third embodiment (see FIG. 4). Of course, it may be formed over the entire length. In addition, heating electrodes 3 and 31
It goes without saying that it is not necessarily necessary to form the plate into a narrow O-long plate shape. Furthermore, when the entire optical transmission medium 2 is in a uniform high temperature state, it is also possible to provide a cooling means in place of the heating means to form a temperature gradient at a predetermined location.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention. Fig. 2 is a schematic diagram showing the distribution of the refractive index n, Fig. 3 is a perspective view showing the second embodiment of the invention, Fig. 4 is a perspective view showing the third embodiment of the invention, and Fig. 5 is a perspective view showing the third embodiment of the invention. Similarly, FIG. 6 is a plan view, FIG. 6 is a vertical sectional view showing a fourth embodiment of the present invention, and FIG. 7 is an explanatory diagram of a conventional optical switch. (Parent of symbols) 1, la, 1~-; Light beam 2: Optical transmission medium 3, 3 &, 3...; Heating electrode 4: Incident! Suffix 5, 5a, Sbl...; Inlet port 6; Output mask 7.71.7bt...; Output port ll; Heat dissipation layer patent applicant Rico Co., Ltd. 2 Chain 114 Figure 2 n 0 Procedural amendment 1981 January 22nd 11゛ Commissioner of the License Office Shima 1) Haruki-dono 1 Indication of the matter 1982 Patent Application No. 153930 2 Title of the invention Optical switch 3 Relationship to the case of the person making the amendment Name of patent applicant (Name b・> (674) Ricoh Co., Ltd. -4
, Agent 6 Detailed explanation of invention increased by supplement 1
1al Remarks 1, Title of the invention Optical switch 2, Claim 1, Optical transmission medium made of a material whose refractive index changes with temperature, Light beam incidence for making a light beam enter the optical transmission medium in a first direction means, comprising temperature control means for forming a temperature gradient in at least a portion of the optical transmission medium through which the light beam passes, and operating the temperature control means to direct the light beam in a direction different from the first direction. A light switch that deflects the mold in the opposite direction. 2. In the above item 1, the ff1 degree control means has heating means for heating a part of the optical transmission medium.
*Slight light switch. 3. An optical transmission medium made of a material whose refractive index changes depending on the degree of rotation, an input means for allowing only light in a specific incident direction along the surface of the optical transmission medium to enter the optical transmission medium, and a surface of the optical transmission medium rr
a resistive heating electrode provided at i and at least a part of which is located directly above the direction of incidence of the light; and an exit port provided on the output surface side of the optical transmission medium and located outside the extension line of the direction of incidence of the light. An optical switch having a perforated emission mask and a t% characteristic. 3. Detailed Description of the Invention The present invention relates to an optical switch that utilizes the property of a transparent dielectric material that its refractive index changes depending on the temperature. In the field of optical information processing such as optical fiber communications, optical memory devices, and optical printers, devices that control the direction of light and turn on and off the passage of light are essential. An optical switch used as a device is required to have low crosstalk, easy switching with low power, high speed, and low cost. Conventional optical switches include those that utilize the acousto-optic effect and those that utilize the electro-optic effect. FIG. 7 is a schematic perspective view of an optical switch that utilizes the electro-optic effect. , L
On the surface of the optical transmission medium 2o made of a crystalline material such as 1NbO3°LsT, comb-shaped electrodes 21 and 22 are formed by island deposition or the like so that the teeth are alternately arranged. The parallel direction of the tooth portions of the comb-shaped electrodes 21 and 22 is the kY axis, the thickness direction of the optical transmission medium 2o is 1k, the The light k is incident on the electrode 21.
When an appropriate high frequency voltage is applied between the optical transmission medium 22 and the wavelength λ of the incident light satisfies the following equation (1), the plane of polarization of the light emitted from the optical transmission medium 20 is converted into biaxial directions. 2/4=C2/λ) (n, -rso) ・-(
1) However, A: Pitch of the teeth of the comb-shaped electrodes 21 and 22 -ne: Extraordinary light of the crystal of the optical transmission medium 20 (when the electric field direction is
The refractive index of light parallel to the axis n0: the ordinary refractive index of the crystal.
3t, the plane of polarization of the emitted light that has passed through the polarizing plate 23' is in the X-axis direction. Therefore, the electrodes 21 and 22
When no voltage is applied to the optical transmission medium 20, even if similar light is incident on the optical transmission medium 20, the polarization plane is not converted and is emitted as is. Then, the output light passes through the polarizing plate 23, and the 19 plane of polarization is converted into biaxial directions.However, the output light after polarization is subjected to extremely large absorption by the polarizing plate 23, so its intensity is weakened. ing. In this way, the on/off state of the voltage between the electrodes 21 and 22 corresponds to the intensity of the light passing through the polarizing plate 23, thereby forming an optical switch. However, when constructing an optical switch using the electro-optic effect as described above, the ninth electrode structure, which requires forming electrodes in a periodic structure such as the 411III-shaped electrode, is complicated, and its formation is difficult. It is not easy, and it is difficult to create a large array. In addition, it is necessary to use incident light that is polarized in a specific direction, and it has the disadvantage that it does not work well with natural light. Attenuation occurs, and further increases.
Since a single crystal is usually used as the optical transmission medium, there are restrictions on increasing the size of the optical switch, and it is necessary to use a high-frequency electric power fAt as the power source. Historically, the electro-optic effect varies with temperature, so the temperature range in which it can operate as an optical switch is extremely narrow. On the other hand, in optical switches that utilize the acousto-optic effect,
Crystalline materials such as PbMoO4 and Te R'k12! Use. Also, those that use transducers to convert electrical signals into ultrasound waves are extremely expensive. I! Second, since it requires a large amount of high-frequency power after driving the optical switch, there are restrictions on how it can be used. The present invention was made in view of the above points, and is not subject to restrictions on the polarization state and wavelength of the light used, can operate even with natural light or white light, and does not require the provision of a polarizer or analyzer. The overall purpose of the present invention is to provide an optical switch that has a simple electrode structure, can be easily formed into a large array, has low crosstalk, and can operate with low current. This device departs from the conventional optical switch concept of utilizing optical effects and is based on a novel idea of utilizing the temperature dependence of the refractive index of transparent materials. That is, the optical switch according to the present invention comprises: an optical transmission medium made of a material whose elliptical refractive index gently changes; a light beam incidence means for causing a light beam to enter the optical transmission medium in a first direction; A temperature control means IRk is provided for forming a temperature gradient in at least a portion of the optical transmission medium portion through which the optical transmission medium passes, and the light beam is deflected in a direction different from the first direction by operating the temperature control means. It is characterized by the fact that In this case, it is preferable that the temperature control means includes a heating means for partially heating the optical transmission medium. a central incidence means for causing only light in a specific incident direction along the surface of the transmission medium to enter;
A resistive heating electrode provided on the surface of the optical transmission medium, at least a part of which is located directly above the direction of incidence of the light; and a resistance heating electrode provided on the exit surface IIK of the optical transmission medium and located outside the extension line of the direction of incidence of the light. The present invention provides a 1kIW optical switch having an output mask with an output location drilled therein. Transparent optical materials such as Os, PLZT-ThO□, fused silica, and glass exhibit temperature dependence in their refractive index, and the higher the temperature, the higher the refractive index. and,
When light passes over a boundary between materials with different refractive indexes, a refraction phenomenon occurs such that the refraction angle (the f angle between the direction of aS and the light beam at the boundary) becomes smaller in the material with a higher refractive index. In an optical transmission medium made of the above-mentioned transparent optical material, if there is a temperature gradient or change in degrees, the light traveling in the optical transmission medium will be deflected toward a higher temperature area. This was done based on extensive knowledge. In other words, when an electrode is formed on the surface of an optical transmission medium using a resistive heating element and electricity is applied to the electrode to heat the surface of the optical transmission medium, a temperature gradient is created in the thickness direction from the surface of the optical transmission medium in the area immediately below the electrode. Occur. Therefore, when a light beam is incident on an optical transmission medium along the solid electrode, that is, along the surface, the light beam is directed toward the high temperature side (high refractive index side) within the optical transmission medium where a temperature gradient exists. When IIc is deflected and emitted from the optical transmission medium, its emission position deviates from the extension line of the incident direction, and the light beam is emitted at a position closer to the electrode formation surface.Then, an output tube is bored at this emission position. By providing an output mask, the light beam travels straight when the electrode is not energized because there is no temperature gradient in the optical transmission medium, so the output light turns on and off in response to the electrode energization. An optical switch is constructed. Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 2 is a schematic vertical cross-sectional view of an example. The width direction dimension of the optical transmission medium zrt made of the optical material is L
It has a rectangular parallelepiped shape, and on its surface, a narrow layered heating electrode 3 extending in the width direction of the optical transmission medium 2 is formed over an appropriate dimension LK from one end side of the optical transmission medium 2. It is. The heating electrode 3 is made of Ni-Cr alloy, etc., for example #f
It is formed by vapor deposition or the like. On the side surface of the one end side of the optical transmission medium 2, in order to cause the light beam l' whose incident direction is parallel to the longitudinal direction of the heating electrode 3 to be incident on the area directly below the heating electrode 3 in the optical transmission medium 2, An entrance mask 4 with an entrance opening 5 is provided. Note that the light beam l incident on the optical transmission medium 2 is preferably a parallel beam as narrow as possible in order to reduce crosstalk as an optical switch. I/c#'i is provided with an output mask 6 having an output lower hole. The emission lower part of the emission mask 6 is located at a distance d upward from a position on the extension line of the incident direction of the light beam l (indicated by the broken line a!J). When an appropriate current is applied to the heating electrode 3, heat is generated through the resistance of the heating electrode 3tj, the surface of the optical transmission medium 20 in contact with the heating electrode 3 is heated, and the temperature is increased from this surface toward the inside of the optical transmission medium 2. A distribution occurs. Along with this, the refractive index nri of the optical transmission medium 2 has a refractive index distribution such that, as shown in FIG. VC as shown. When the light beam l whose direction and beam diameter are regulated by the entrance mask 4 enters the optical transmission medium 2, its traveling direction is deflected upward by the refractive index distribution within the optical transmission medium 2, and the light beam The light beam l curves upward in the area directly below the heating electrode 3 and travels along the optical path.Next, when the light beam l travels a distance L from the incident mask 4 and leaves the area directly below the heating electrode 3, it is heated. region where the refractive index is uniform (
At this boundary, the light beam Ir1
The light beam l is further refracted upward, and since there is little change in the refractive index in this region, the light beam l travels approximately linearly in this region and is emitted from the output lower to the outside. In this way, when the heating electrode 3 is energized, the light beam incident from the entrance mask 4
is emitted from Sufu 6. On the other hand, if the heating electrode 3 is not energized, is it an optical transmission medium?・
Since the temperature distribution within the medium is uniform and the refractive index is uniform, the light beam l travels straight through the optical transmission medium 2 in the direction of incidence, and is blocked by the exit mask 6 and does not exit, as described above.
The turning off of the current supply to the heating electrode 3 corresponds to the turning on and off of the light beam l emitted from the emission mask 6, and an optical switch is set up. By the way, the deflection distance d, the electrode length L and the non-electrode part length l
The relationship shown in (2) 2 below exists between them. Discharge = jLΔn/D ・・・・・・・・・
(2) However, Δn 2. Refraction main change due to temperature on the surface of the optical material D: Diffusion depth of refractive index change due to heating, usually 1.0 mm) In addition, the optical transmission medium 20 optical material is quartz, the ratio of the refraction book change Its to the temperature change ΔT is Δn/
/r is approximately 10-''. Therefore, assuming that the temperature rise n due to the heating electric current and the electrical heating of &3 is 100°C, and the diffusion depth D of quartz is approximately 0.5 mm, dF
id=2XlG-”7L. Therefore, L=10m
If m, l = 5ncrn, d = 0. tnun, the length of the heating electrode is 10 rrm, and the light beam emitted from nine surfaces is separated by a distance of 4 (= 5 rrrn) from the end of the heating electrode 3, and the frame is 0.1 mm above the extension line of the incident direction. It is sufficient to provide the emission mask 6 having the emission lower at the position. In other words, for an optical switch with such a dimensional relationship, the temperature rise ΔT
The conditions for energizing the heating electrode 3 may be set so that the temperature is about 100°C. By arranging a plurality of heating electrodes of the optical switch in the width direction, an optical switch having the function of turning on and off a plurality of light beams can be constructed. It becomes possible to apply it to FIG. 3 is a schematic diagram showing wJ2 implementation fi' of the present invention. On the surface of the optical transmission medium 2, narrow layered heating electrodes 3a, 3b, 3c, 3 extending in the width direction are provided.
d. 3e, 3f... are arranged in parallel at appropriate intervals in the width direction. Heating electrode 3a$i
, like the heating electrode 3, is made of Ni--Cr and is formed by vapor deposition or the like. The light emitting side ends of the heating electrode 33, etc. are all connected by a common electrode 8, and the light emitting side ends of the heating electrode 3a, etc. are connected to the extraction electrodes 91° 9b, 9C.
, 9d, 9e, 9f..., and are connected to these lead electrodes 91, etc. and the common voltage #A8.
A voltage can be applied individually between the two. An entrance mask 4 is provided on the side surface of the optical transmission medium 2 on the light incidence side, and a position vCri below the eaves from the upper end of the entrance mask 4 is provided.
, heating electrodes 3a, 3b, 3c, 3d. 3e, 3f... (Incidence port 5m. 5b, 5c, 5d, 5e, 5f River-
A light beam 1a, which is a band-shaped parallel light beam, is provided with f.
Ib, lc, 1d, le, If, . An output master 6 is provided near the side surface of the light output side of the optical transmission medium 2, and the output mask 6K> is connected to the light emitted by -A la
, lb, IC, lcl, IelIf... At positions above the extension line of the incident direction by an appropriate dimension, there are output lowers m, 7b, 7C, 7d, 7e. 7f... is drilled. In addition, in this example,
The optical transmission medium 2 and the output mask 6 are separated by a certain distance*, and when the original beam is emitted from the optical transmission medium 2 into the air, it is refracted. The first-class drilling position is slightly above the exit lower in the first embodiment. In this case as well, when the electrode 31 etc. are energized, a temperature distribution that changes in the thickness direction of the optical transmission medium 2 occurs in the area immediately below the electrode 31 etc. of the optical transmission medium 2, and the refractive index changes accordingly. A distribution occurs. As a result, while the light beam la etc. travels through the optical transmission medium 2, the temperature and therefore the refractive index change, and the light beam is deflected toward the upper part, and is emitted from the optical transmission medium 2.
It passes through the emission lower a, etc. - If the heating electrode 3a, etc. is not energized, the light beam 11, etc. corresponding to the heating electrode 33, etc. travels straight through the optical transmission medium 2. In this way, multiple light beams can be turned on and off simultaneously and individually, thus allowing applications in optical switches, displays or printers, etc. FIG. 2 and FIG. 5 are a perspective view and a plan view, respectively, showing a third embodiment of the present invention. teeth,
An entrance opening 51.57 is bored at a position slightly below the upper end, and narrow parallel light beams IX and 1y are directed toward the entrance openings 5x and sy almost perpendicularly to the entrance mask 4. It is incident. And optical transmission medium 20 table Ei
iiKr! , heating electrodes 3X and 3F are formed. The heating electrode 3x, etc. has a straight line shape with a half part of the light input side path located directly above the direction of incidence of the light beam lX, etc., and a half part of the light output side path is flat with respect to the traveling direction of the light beam LX etc. It forms a straight line curved to the right when viewed. and,
The light incident side ends of the heating electrodes 3x and 37 are connected to each other by a common electrode 8, and the light output side ends are connected to extraction electrodes 91: and 1, respectively.
It is individually led out to a power supply (not shown) by vh. An rcFi emission mask 6 is provided near the side surface of the light emission side of the optical transmission medium 2, and the emission mask 6 includes heating electrodes 3X, 3F.
in the tangential direction of the light exit side end in the incident aperture 5x
, 5y are provided with output lowers "t7F", respectively. In the original switch of this embodiment, the extraction electrodes 9x, 9y
A voltage is applied between the heating electrode 3x and the common electrode 8,
3) When electricity is applied to l, the heating electrode 3x. A temperature distribution that changes in the thickness direction is generated inside the optical transmission medium 2- in the area immediately below 3y, and this temperature distribution causes the light beams lx, 1y to be applied to the heating electrode 3 along the curved direction of 3Y. It is deflected from the direction of incidence, curved to the right in the direction of travel in plan view, and exists in the following state. Then, in response to such temperature distribution, a curved portion with a higher refractive index is formed, and the refractive index changes directly under the heating electrodes 3X and 3y, and light is deflected toward the portion with a higher refractive index. Due to the nature of the beam, a leading wavepath is formed in the optical transmission medium 2. Therefore, the light beams IX and 1y that have entered the optical transmission medium 2 from the entrance mask 4 curve to the right in the traveling direction in plan view along the heating electrodes 3x and 3y, and at the same time move toward the surface of the optical transmission medium 2. The light beam propagates along this optical waveguide while being deflected upward toward , exits from the optical transmission medium 2, and passes through the output lower 1.77 of the output iscro. On the other hand, when the heating electrodes 3x and 3y are not energized, the light beams la and lbF'i travel straight through the optical transmission medium 2, so the output mask 6 t)jl
In this way, the heating electrode 3 is turned on and off and the light is not emitted to the outside.
An optical switch is constructed in which on and off correspond to each other. In the optical switch according to the present invention as described above, crosstalk is extremely low and switching speed is high in all of the above embodiments. For example, when the optical transmission medium 2 is quartz, its temperature transfer coefficient α is 6.75×10
-"j/II!, and the rate of temperature rise of the optical transmission medium 2 is proportional to the temperature transfer coefficient α and the square of the width of the heating electrode 3, etc., so a switching speed of about 1 mWc is ensured. By the way, it is possible to further improve the switching speed by appropriately setting the shape and dimensions of the heating electrode and providing the optical switch with a heat sink function. FIG. 6 is a schematic vertical cross-sectional view showing one embodiment of the invention, in which a heating electrode 3 is formed on the surface of an optical transmission medium 20, and an entrance mask 4 is provided with an entrance opening 5 formed on the side surface. Therefore, in this embodiment, the thickness of the frame and the optical transmission medium 2 are made as thin as possible, and the frame is provided in close contact with the metal heat sink 12 on the lower surface of the optical transmission medium 2. In this way, the heat sink function is By having
When the energization sound of pole 3 etc. is turned off for heating, the heating power ff1
It is possible to rapidly cool down the optical transmission medium 2 in the region immediately below the optical switch 3, and therefore, it is possible to further increase the switching speed r of the optical switch.As described above in detail, the optical switch according to the present invention Since the method uses the gradient or change in the refractive index formed in the optical transmission medium by the energization of the heating electrode VC1 to deflect the light beam, the light beam used is subject to restrictions such as polarization state and wavelength. It is also possible to use natural light, which was previously inoperable. In addition, it goes without saying that a polarizer or analyzer is not required, and the electrode shape can be extremely simple, such as a plate. ) can also be easily realized. In addition, instead of weakening the intensity of the light beam with a polarizer as in the past, the light beam is reliably blocked by the output mask when the current is not applied.
Crosstalk is extremely low.Furthermore, since the power supply is simply to cause the heating electrode to generate heat through resistance, it can be operated with low power, such as a DC power supply as shown in the example shown, or a commercial frequency AC power supply. . Note that the present invention is not limited to the specific embodiments described above, and various modifications can be made within the technical scope of the present invention. For example, IElII! The heating electrodes 3, 32, etc. of the embodiment (see Fig. 1) and the second embodiment (see Fig. 3) are arranged over the entire length of the optical transmission medium 20 in the width direction in the same manner as in the @3 embodiment (see Fig. 4). Of course, it may be formed. Also, it goes without saying that the heating electrodes 3, 3a, etc. do not necessarily need to be formed into narrow long plate shapes. Furthermore, when the entire optical transmission medium 2 is at a high temperature such as -, cooling means may be provided in place of the heating means to form a temperature gradient at necessary locations. 4. Brief description of the drawings @1 Figure is a vertical sectional view showing the 111 embodiment of the present invention, 112
The figure is a schematic diagram showing the distribution of the refractive index n, Figure @3 is a perspective view showing the second embodiment of the present invention, Figure tK4 is a perspective view showing the third embodiment of the present invention, and Figure 5 is a plan view as well. , FIG. 6 is a vertical cross-sectional view showing IIE4 implementation fP4tl of the present invention, and FIG. w47 is an explanatory diagram of a conventional optical switch. [Explanation of symbols] 1, la, lb; optical beam A 2; optical transmission medium 3.3M, 3b; heating electrode 4; entrance mask 5.51.5b; entrance port 6; exit mask 7, 7
a, 7b; Output port 12; Metal heat sink Patent applicant Rico Co., Ltd. - Figure 6

Claims (1)

[Claims] 1. An optical transmission medium made of a material whose refractive index changes with temperature; a light beam input means for causing a light beam to enter the optical transmission medium in a first direction; and the light beam through which the light beam passes. temperature control means for forming a temperature gradient in at least a portion of the transmission medium portion, and operating the temperature control means to deflect the light beam in a direction different from the first direction; light switch. λ In the above item 1, the temperature controller IR#-i includes a heating means for heating a part of the optical transmission medium.
A light switch featuring: 3. An optical transmission medium made of a material whose refractive index changes with temperature; ! an input means for allowing only light in a specific direction of incidence along the surface to enter; a resistive heating electrode provided on the surface of the optical transmission medium, at least a part of which is located directly above the direction of incidence of the light; and the optical transmission medium. Output surface @
and an output mask having an output opening outside the extension line of the incident direction of the light.