JPH02103015A - Optical modulating device and modulating method formed by using superconducting material - Google Patents

Abstract

PURPOSE:To provide the simple optical switch having the construction to enable the switch to be operated at a high speed by projecting incident light to a superconducting material provided with a means for transferring the switch to a superconducting state and a normal conducting state. CONSTITUTION:A film consisting of a YBaCuO system is formed as the superconducting material 3 of a thin film state on a substrate 4. A power source 9 and a switch 10 are connected to a junction part 8 at both ends thereof. The superconducting state is made to the normal conducting state by passing the current above the critical current to the superconducting 3 by closing the switch 10. Then, the incident light 5 transmits the superconducting material 3 from which transmitted light 7 is emitted. The impression of the current to the superconducting material 3 is stopped and the superconducting state is restored when the switch 10 is opened. Since the incident light 5 reflects on the surface, the optical switch which makes the high-speed operation is obtd.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a light modulation device and a light modulation method using superconducting materials, and in particular to various optical heads, optical shutters, or optical path switching and light intensity adjustment. The present invention relates to an optical modulation device and an optical modulation method suitable for use as an optical switch that performs modulation.

Furthermore, the present invention relates to a detection device and detection method using a superconducting material, and particularly to a detection device and detection method suitable for use in a mechanism for reading external signals such as an electric field, a magnetic field, temperature, or pressure.

[Conventional technology]

In recent years, optical communication systems using optical fibers have reached the stage of practical use, and the development of optical systems consisting of basic components, ie, a light source, a transmission line, and a light receiver, is progressing.

In addition to the above-mentioned basic components, the development of optical switches, optical modulators, etc. is strongly desired in order to realize more sophisticated optical systems.

Optical switches are used for switching in the event of failures in optical transmission lines and light receiving and emitting elements, and for future optical exchange. Optical, (5)
It is divided into thermo-optical method, (6) method using molecular orientation, etc.

As an optical switch, an optical switch is considered in which several boats are provided in a PLZT waveguide layer and the optical path is switched using changes in the refractive index of PLZT due to voltage application.

This type of optical switch is described in, for example, Technical Research Report of the Institute of Electronics and Communication Engineers, OQE 84-16, (1984
2007), page 57~.

As an optical modulation element, a traveling wave type using a LiNb0a waveguide is being researched.

As this type of optical modulation element, for example, the Journal of the Institute of Electronics and Communication Engineers 69
(1986), page 141~.

[Problem to be solved by the invention]

These conventional techniques described above utilize a change in the refractive index of a substance due to the electro-optic effect.

Since this change in refractive index is as small as 1% or less, it has only been possible to switch the optical path of light propagating within the waveguide, for example.

The object of the present invention is to provide an optical modulator and optical modulator with a simple structure that has improved reaction speed and can operate without using a waveguide by applying a superconducting material that has not been considered in the past to an optical device. The purpose is to provide a method.

Another object of the present invention is to provide a simple-configuration detection device and detection method that is used in a mechanism for reading external signals such as electric fields, magnetic fields, temperature, or pressure by applying superconducting materials to optical devices. There is a particular thing.

[Means to solve the problem]

The optical modulator of the present invention includes a superconducting material that reversibly transitions between a superconducting state and a normal conducting state.

Furthermore, it has means for transitioning the superconducting material to a superconducting state or a normal conducting state.

Since an element using a superconducting material operates at high speed, as typified by a Josephson element, the optical modulator of the present invention can also operate at high speed.

The detection device of the present invention includes a superconducting material that reversibly transitions between a superconducting state and a normal conducting state, a light source that generates incident light that irradiates the superconducting material, and a modulated light emitted from the superconducting material. and means for detecting light.

When an external signal, such as an electric field, magnetic field, temperature, or pressure, is applied to a superconductor at a threshold value or higher, the superconductor undergoes a phase transition.

This phase transition changes the optical properties of the superconductor and modulates the incident light.

External signals can be detected by observing the modulated light.

Furthermore, when a second type of superconducting material is used, a mixed state of a superconducting phase and a normal conducting phase is generated during phase transition.

Therefore, phase transition occurs continuously, and switching and sensing can be performed continuously.

The intensity of the modulated light is generally modulated by changes in the optical properties of the superconducting material.

Modulated light with an optical path deflected can be obtained by forming the superconducting material into a trapezoidal shape or the like, or by making the incident light incident at an acute angle.

The superconducting material used in the present invention is supported by a support member, and the support member is preferably transparent.

Further, the optical modulator or the detection device can be used as an optical switch or an optical sensor.

[Effect]

Superconducting materials transition between superconducting and normal conducting phases.

Superconducting materials undergo a transition depending on factors such as temperature, magnetic field, electric current, and pressure.

Figure 18 shows the superconducting phase of superconducting materials - normal conduction and temperature,
The relationship between external magnetic field and applied current is shown.

The hatched portion inside the curved surface is the superconducting phase 1, and the portion outside the curved surface is the normal conducting phase 2.

That is, the superconducting phase can be changed to normal conduction by increasing the temperature, external magnetic field, and applied current.

Further, FIG. 19 shows the relationship between the superconducting phase and normal conduction phase of a superconducting material, temperature, and pressure.

The portion inside the curve is the superconducting phase 1, and the portion outside the curve is the normal conducting phase 2.

That is, the superconducting phase can also be changed to normal conductivity by increasing the pressure.

This pressure-induced transition also affects current, magnetic field, etc.

Qualitatively, the relationship between pressure, external magnetic field, applied current, etc. is
The relationship is such that any axis in FIG. 18 can be replaced with the vertical axis in FIG. 19.

On the other hand, the transmittance, reflectance, and refractive index of a superconducting material change between a superconducting state and a normal conducting state, as shown in FIGS. 20, 21, and 22.

In FIGS. 20, 21, and 22, reference numeral 1 indicates a superconducting phase, and reference numeral 2 indicates a normal conducting phase.

Depending on which state the superconducting material is in, different output lights can be obtained for a given input light.

A superconducting material is a material that exhibits complete conductivity and complete diamagnetic property when cooled below a critical temperature, and is classified into type 1 superconducting materials and type 2 superconducting materials depending on their magnetic properties.

FIG. 23 shows the characteristics of the first type superconducting material.

When a magnetic field H is applied to a type 1 superconducting material, the completely diamagnetic state is broken at a critical value Hc, and a transition to a normal conductive state occurs.

Many of these materials include single-element metals such as Pb, In, and Sn.

FIG. 24 shows the characteristics of the second type superconducting material.

When a magnetic field H is applied to a type 2 superconducting material, the lower critical value H
At c1, in the superconducting material, h/2e=2. The magnetic flux line νortex quantized by 1×10−”(Wb) enters and forms a mixed state.

When the magnetic field H is further strengthened, the state transitions to a normal conduction state at an upper critical value HCZ.

Many of these materials include alloys and compound materials such as NbTi and Nb3Sn.

FIG. 25 schematically shows the relationship between the reflectance of the second type superconducting material and the applied magnetic field.

The reflectance gradually changes between the magnetic fields HC1 and HCZ.

When light is irradiated onto a superconducting material, the light is reflected by the Meissner effect.

In a type 2 superconducting material, superconductivity and normal conductivity coexist in a mixed state.

When using a type 2 superconducting material, it is utilized that in a mixed state, a continuous change in superconductivity corresponds to a continuous change in the optical properties of the superconducting material.

This continuous change can be made continuously by applying a magnetic field to the superconducting material.

In other words, it is possible to continuously change the amount of reflected light in the mixed state.

Furthermore, by appropriately selecting the thickness of the superconductor, it is possible to arbitrarily set the change in the amount of reflected light or the amount of transmitted light, that is, the dynamic range of modulation.

When a substance is transformed into a normal conduction state by temperature, electric current, magnetic field, pressure, etc., the Meissner effect disappears and the amount of one reflected light decreases.

At this time, by appropriately selecting the thickness of the superconducting material, the change in reflectance or transmittance between the superconducting state and the normal conducting state can be set arbitrarily.

Regarding changes in the optical properties of superconducting materials that transition between superconductivity and normal conductivity, see ■[Introduction to Solid State Physics, Part 2 (Charles Kit
tel) 5th edition, page 348, states that the transmittance increases in a superconducting state in a very thin metal film, ■ rPhy
sical Review Letters J vo
Q, 59, Na19 (1987) pp, 22
20-2221 or rJapanese Journal
l of Applied PhysicsJvoQ2
6. No.4 (1987) pp, 479
-480, it is stated that in the case of ceramics, the transmittance increases in the superconducting state.

A case where the present invention is applied to an optical switch will be explained using FIGS. 26 and 27.

FIG. 26 shows a case where light is incident on an optical switch in which the superconductor 3 is in a superconducting state.

The incident light 5 is reflected by the Meissner effect of the superconductor 3.

Reference numeral 6 indicates the reflected light.

This is turned off.

FIG. 27 shows a case where light is incident on an optical switch in which the superconductor 3 is in a normal conduction state.

The incident light 5 is transmitted through the superconductor 3 because it has no Meissner effect.

Reference numeral 7 indicates the transmitted light.

This is set to the on state.

Changes in reflectance and transmittance between the on state and the off state can be changed by changing the thickness of the superconductor.

This will be explained below using the amount of transmitted light as an example.

The magnetic field penetration depth λB of the superconductor is λa=(m/e2μons)' It is expressed as

In this case, m represents the mass of the electron, e represents the charge of the electron, μ0 represents the magnetic permeability in vacuum, and ns/2 represents the density of the superconducting electron pair.

Since light is an electromagnetic wave, the light penetration depth λS in the superconductor is approximately equal to the magnetic field penetration depth λB.

That is, the thickness of the superconductor is d, which is λ8 to λB, and the amount of transmitted light in the off state T o
Think about in.

d) When λS, Taxi”O.

As d is gradually reduced, transmitted light begins to appear when d2λs, and Tozi>O.

As d is further reduced, when d(λS, To11
~1.

The relationship between T o t t and d is shown in FIG.

In the on state, the superconductor is in a normal conducting state, so the Meissner effect does not occur.

Therefore, the light penetration depth λ□ in the normal conducting state is larger than the light penetration depth λS in the superconducting state.

That is, λ. 〉λS.

The relationship between the film thickness d and the amount of transmitted light T on is as shown in FIG. 29.

At this time, the extinction ratio (Ton/ToI□1) exhibits a characteristic as shown in FIG. 30, and takes a maximum value at d=do.

Since an optical switch having a large extinction ratio is generally desired, the IF5 thickness of the superconductor is preferably dO.

Furthermore, if it is desired to set the extinction ratio depending on the application, this can be done by changing the thickness of the superconductor.

In that case, if O<d<d o, then do<d
Since T on is large compared to , the light source power is small.

Although the case where transmitted light is used is shown here, reflected light can also be used.

In this case, by changing the incident angle, the optical axes of the incident light and the reflected light can be separated, and both the transmitted light and the reflected light can be used.

Furthermore, by doing so, it is possible to realize an optical switch in which each light does not interfere with each other.

In addition to superconductors, optical switches that are actually used often use a combination of a substrate, a waveguide layer, and a protective layer.

The main points of the present invention are that a superconducting material is used in an optical switch, etc., and that the state change between superconductivity and normal conduction is utilized, and
The point is to increase the extinction ratio by setting the film thickness of the superconductor to about the magnetic field penetration depth λB.

Furthermore, since a small device can be realized without using a waveguide, it is possible to switch light of different wavelengths.

Furthermore, since the element using a superconductor operates at high speed, the optical switch of the present invention also operates at high speed.

The principle when a type 2 superconductor is used as a modulation element can be similarly explained.

As shown in FIG. 24, a type 2 superconductor is in a superconducting state when the applied magnetic field H is H<Hcl.

Therefore, the incident light 5, which is an electromagnetic wave, cannot enter the inside of the superconductor 3 and is reflected.

The reflected light 6 becomes maximum.

This is turned off.

The applied magnetic field H is increased, and a mixed state occurs when HCI<H<HCZ.

Incident light 5 begins to enter the inside of the superconductor.

At this time, transmitted light 7 appears, and reflected light 6 gradually decreases.

The applied magnetic field is further increased, and when HCZ<H, a normal conduction state is achieved and the Meissner property disappears.

The reflected light 6 becomes the minimum, and the transmitted light 7 becomes the maximum.

This is set to the on state.

The intensity of incident light can be modulated by utilizing continuous changes in the amount of transmitted light and reflected light between the on state and the off state.

The invention relating to a detection device, etc. that uses a superconducting material to detect current, magnetic field, temperature, pressure, etc. is an application of the principle of the invention relating to a light modulation device, etc. using a superconducting material.

Whether a superconducting material is in a superconducting state or a normal conducting state can be easily determined by i atq of transmitted light or reflected light.

This makes it possible to detect whether the temperature at which the superconducting material is placed, the external magnetic field, the applied current, and the pressure are larger or smaller than the set values.

In particular, by changing three dependent variables other than the main variable to be detected among temperature, external magnetic field, applied current, and pressure, the set value of the main variable that undergoes a phase transition can be changed.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 17.

FIG. 1 shows an embodiment of an optical switch operated by electric current.

A thin film of superconducting material 3 is deposited on substrate 4 .

Junctions 8 between the electric wire and the superconducting material are provided at both ends of the superconducting material 3.

The i'11 line forms a circuit via a power supply 9 and a switch 10 for supplying current.

When the switch 10 is closed, a current is applied to the superconducting material 3.

By passing a current higher than the critical current through the superconducting material 3,
It is possible to change a superconducting state to a normal conducting state.

As a result, the incident light 5 passes through the superconducting material 3, and the transmitted light 7
is emitted.

When the switch 10 is opened, the current application to the superconducting material 3 is stopped and the superconducting material 3 returns to the superconducting state.

From this point, the incident light 5 is reflected almost on the surface of the superconducting material 3.

By such an operation, switching can be performed in the emission state of the transmitted light 7.

The characteristics of an optical switch were evaluated using a YBaCuO thin film as a superconducting material.

At a temperature of 77, a current with a current density of 104 A/aJ is applied.

The superconducting state transitions to the normal conducting state, and the transmittance increases from 5% to 1
It increased to 2%.

If the crystallinity, orientation, film thickness, etc. of the superconducting material are considered and used in an optimized state, the extinction ratio can be further increased.

FIG. 2 shows an application of the embodiment shown in FIG. 1 to an optical switch array for an optical printer.

Reference numeral 12 indicates a superconducting material array in which the optical switches shown in FIG. 1 are finely arranged in a linear manner.

Each optical switch in the superconducting material array 12 selectively transmits or reflects incident light 5 from the light source 13.

The transmitted light 7 changes the heavy electrical conductivity on the surface of the photoreceptor drum 14 to control whether or not toner is attached.

Conventionally, a liquid crystal has been used for an optical gate array corresponding to the superconducting material array 12 of the present invention.

By applying the present invention, 0N1 of the switch array
The reaction rate of 0FF can be improved and the structure can be simplified.

FIG. 3 shows an embodiment in which the optical switch of the present invention is applied to a waveguide type optical path switch.

Reference numeral 4 represents a substrate, reference numeral 15 a waveguide layer, and reference numerals 16 to 19 each port of the waveguide.

The superconducting material 3 is joined to electric wires at both ends, and the electric wires form a circuit via a power source 9 and a switch 10 for supplying current.

Light incident from the A port 16 is reflected and emitted from the B boat 17 when the superconducting material 3 is in a superconducting state, and is transmitted to the C port 1 when the superconducting material 3 is in a normal conducting state.
It is emitted from 8.

In this way, a waveguide type optical path switch can be realized.

The characteristics of an optical switch were evaluated using a YBaCuO thin film as a superconducting material.

A 2 μm 5i02 layer is deposited as a buffer layer on the Si substrate.

On top of that, a ridge waveguide and a Y B a Cu 0 layer are formed using Corning #7059 glass.

At a temperature of 77, HeNe laser light was input from port 16 into A port 1, and the optical output at port C 18 was measured.

With no current flowing, a light output of 0.05 mW was detected, and with a current flowing (current density 10'A/an), a light output of 0.15 mW was detected.

Indicates that the light output has increased.

If the crystallinity, orientation, film thickness, or intersection angle of the waveguides of the superconducting material are considered and used in an optimized state, the characteristics can be further improved.

FIG. 4 shows an embodiment in which the optical switch of the present invention is applied for communication.

A thin film of superconducting material 3 having a high slope at one end and a low slope at the other end is deposited on a substrate 4 .

The superconducting material 3 is connected to electric wires at both ends, and the electric wires form a circuit via a power source 9 and a switch 10 for supplying current.

Furthermore, a slit plate 20 is added to the lower part of the substrate 4.

When the switch 10 is closed, a current is applied to the superconducting material 3.

By passing a current higher than the critical current through the superconducting material 3,
It is possible to change a superconducting state to a normal conducting state.

As a result, the incident light 5 passes through the path 7B to the slit plate 2.
It is emitted from 0.

When the switch 10 is opened, the current application to the superconducting material 3 is stopped and the superconducting material 3 returns to the superconducting state.

As a result, the incident light 5 passes through the path 7A to the slit plate 2.
Blocked by 0.

This path change is due to the change in the refractive index of the superconducting material 3.

Switching can be performed by passing either the emitted light 7A or 7B through the slit plate 20.

A YB a Cu O thin film is used as the superconducting material 3, and a laser beam with a wavelength of 830 nm is incident as the incident light 5.
It operates at a temperature of 77.

The angle of the acute angle part of the superconducting material 3 is 43°, and the thickness of the light incident part is 50 nm.

A quartz plate with a thickness of 1.1 mm was used as the substrate 4.

Current density 10'A/cn? By opening and closing the switch 10 in this state, the superconducting material 3 is transitioned between the superconducting state and the normal conducting state.

As a result, from 9 slits with a diameter of 110 nm, switch 1
To obtain a device that emits light when the switch 10 is closed and does not emit light when the switch 10 is open.

This configuration increases the extinction ratio,
The S/N ratio can be increased.

Therefore, a communication optical switch with fewer transfer errors can be achieved.

FIG. 5 shows an embodiment of an optical switch operated by a magnetic field.

A thin film of superconducting material 3 is deposited on substrate 4 .

A magnetic field generating section 21 is installed above the superconducting material 3.

The magnetic field generating section 21 is connected to an electric wire at both ends, and the electric wire forms a circuit via a power source 9A for generating a magnetic field and a switch 10.

When the switch 10 is closed, a magnetic field is generated in the magnetic field generating section 21.

By generating a magnetic field greater than the critical magnetic field, a superconducting state can be changed to a normal conducting state.

As a result, the incident light 5 passes through the superconducting material 3, and the transmitted light 7
is emitted.

When switch 10 is opened, magnetic field generation stops and the superconducting state returns.

As a result, the incident light 5 is reflected almost on the surface of the superconducting material 3.

The characteristics of an optical switch were evaluated using a 180 nm thick YBaCuO thin film as a superconducting material.

At a temperature of 77, an external magnetic field of lomT is applied to the superconducting material 3.

The superconducting state transitions to the normal conducting state, and the transmittance increases from 4% to 1
It increased to 2%.

If the crystallinity, orientation, film thickness, etc. of the superconducting material are considered and used in an optimized state, the extinction ratio can be further increased.

FIG. 6 shows an embodiment of an optical sensor that utilizes a change in optical properties based on the transition between a superconducting state and a normal conducting state of a superconducting material.

A thin film-like superconducting material 3 is formed on the transparent carrier 11 by sputtering.

Incident light 5 is reflected by superconducting material 3, and reflected light 6 is detected.

This reflected light 6 determines whether the superconducting material 3 is in a superconducting phase or a normal conducting phase.

The superconducting material 3 moves on the magnetic body 22 or the magnetic body 22 moves.

Depending on the magnetization state of the magnetic body 22, the superconducting material 3 changes from a superconducting state to a superconducting state.

This change is detected by reflected light 6.

Therefore, with such a structure, the magnetization state of the magnetic body 22 can be read out digitally.

As a superconducting material, the thickness is 50 nm and the size is 100 nm.
A YBaCuO thin film of 1100 nm was used and was created on quartz.

A laser beam with a wavelength of 830 nm is applied at a temperature of 80 nm.

When the external magnetic field is 10 mT or more, the superconducting material 3 transitions from a superconducting state to a normal conducting state.

At this time, the output of the reflected light decreases by 13%.

Based on changes in this reflected light, the external magnetic field applied to the superconducting material can be determined in a binary manner.

FIG. 7 shows an embodiment of a temperature-operated optical switch.

A thin film of superconducting material 3 is deposited on substrate 4 .

A heating section 23 is provided at both ends of the superconducting material 3.

Reference numeral 9B indicates a heating power source, and reference numeral 10 indicates a switch.

When the switch 10 is closed, the heating section 23 generates heat, and the temperature of the superconducting material 3 increases due to heat conduction.

When this temperature exceeds the critical temperature, the thermally conductive material 3 transitions from a superconducting state to a normal conducting state.

The incident light 5 is transmitted in a normal conduction state, and transmitted light 7 is emitted.

When the switch 10 is opened, the temperature of the superconducting material 3 decreases,
Returns to superconducting state.

The incident light 5 is reflected.

The characteristics of an optical switch were evaluated using a YBaC:uo-based film as a superconducting material.

The temperature of the superconducting material increased from 77K to 300K, and the transmittance increased from 4% to 14%.

If the crystallinity, orientation, film thickness, etc. of the superconducting material are considered and used in an optimized state, the extinction ratio can be further increased.

Figures 8 and 9 show embodiments of pressure-operated optical switches.

A superconducting material 3 is deposited on a substrate 4.

Reference numeral 24 is a medium that applies pressure to the superconducting material 3.

By moving the medium 24 up and down, the pressure applied to the superconducting material 3 is changed.

When a pressure equal to or higher than a critical pressure is applied to the superconducting material, the superconducting material 3 transitions from a superconducting state to a normal conducting state.

In the embodiment of FIG. 8, the incident light 5 incident on the superconducting material 3
Switching is performed by detecting changes in the reflected light 6 relative to the change in the reflected light 6.

In the embodiment of FIG. 9, the incident light 5 incident on the superconducting material 3
Switching is performed by detecting changes in the transmitted light 7 relative to the transmitted light.

In the embodiment shown in FIG. 8, '/BaCuO is used as the superconducting material.
The characteristics of the optical switch were evaluated using

At a temperature of 81, a laser beam with a wavelength of 830 nm was applied to operate.

The thickness of the superconducting material 3 is 18 μm, and the substrate 4 is a quartz plate.

By using a metal plate as the medium 24 and applying a pressure cuff of 10 kg/d, the transmittance changed by 13%.

FIG. 10 shows an embodiment of an optical switch that operates using light as a heat source.

After depositing a thin film of superconducting material 3 on substrate 4, light absorption film 25 is deposited.

Reference numeral 5 represents incident light, reference numeral 7 represents transmitted light, and reference numeral 26 represents control light for operating the optical switch.

The light absorption film 25 does not absorb the incident light 5 but can absorb the control light 26.

As for specific measures.

(1) The intensity of the control light 26 is made sufficiently strong compared to the incident light 5.

(2) Change the wavelengths of the two lights.

etc.

In such a configuration, when the intensity of the control light 26 is changed, the amount of light absorbed changes, and the temperature of the light absorption film 25 changes.

The temperature of the superconducting material 3 can be controlled by thermal conduction.

If this is done around the critical temperature, the optical switch can be operated.

A YBaCuO thin film is used as the superconducting material.

The characteristics of the optical switch were evaluated.

At a temperature of 77, a HeNe laser beam with a wavelength of 633 nm and an output of 1 mW is used as the incident light 5, and a wavelength of 4 is used as the control light 26.
Ar/laser light with a wavelength of 88 nm and an output of 2.5 mW was used.

When the control light 26 was irradiated and the transmittance of the incident light 5 was measured, the transmittance increased from 6% to 11%.

Crystallinity, orientation, film thickness, and incident light of superconducting materials.

If the wavelength and output of the control light are considered and used in an optimized state, the extinction ratio can be further increased.

FIG. 11 shows an embodiment of an optical switch that operates using the fact that light is an electromagnetic wave.

A thin film of superconducting material 3 is deposited on substrate 4 .

Reference numeral 5 represents incident light, reference numeral 7 represents transmitted light, and reference numeral 26 represents control light for operating the optical switch.

Since light is an electromagnetic wave, it can operate as an optical switch if a field greater than the critical magnetic field of a superconducting material is used.

FIG. 12 also shows an embodiment of an optical switch that operates using the fact that light is an electromagnetic wave.

On the substrate 4, a thin film of superconducting material 3 is deposited, and a waveguide WJ 27 is further deposited.

Reference numeral 5 represents incident light, reference numeral 7 represents transmitted light, and reference numeral 26 represents control light for operating the optical switch.

In the embodiment shown in FIG. 12, the control light 26 is not directly incident on the superconducting material 3, but passes through a waveguide layer 27 provided adjacent to the superconducting material 3.

At this time, the electromagnetic field of the control light 26 penetrates into the superconducting material 3 by a penetration depth γ expressed by 7.

Here, ko represents the wave number of the control light 26 in vacuum, N represents the isolateral refractive index of the waveguide layer 27, and n represents the refractive index of the superconductor 3.

Therefore, if γ is made larger than the film thickness of the superconducting material 3, the optical switch of the present invention can be operated by the electromagnetic field of the control light 26.

This configuration allows uniform switching over a wide area.

Optical switch characteristics were measured using a YBaCuO thin film as superconducting material 3.

On the superconducting material 3, a Si○2 buffer layer with a thickness of 0.4 μm is formed.

Additionally, Corning #7059 glass was used.

A waveguide layer 27 with a thickness of 3 μm is deposited.

The incident light 5 includes HeN with a wavelength of 633 nm and an output of 1 mW.
Uses e-laser light.

The control light 26 includes A with a wavelength of 488 nm and an output of 2.5 mW.
An r+ laser beam is used and guided into the waveguide layer 27 using a prism coupler.

When the control light 26 is incident at a temperature of 77.

The transmittance of incident light 5 increased from 4% to 9%.

It is also possible to change the waveguide mode by changing the buffer layer.

If the crystallinity, orientation, thickness of the superconducting thin film, thickness of the waveguide layer, etc. are taken into consideration and used in an optimized state, the extinction ratio can be further increased.

When using the embodiments shown in FIGS. 10 to 12 as an optical switch, a light source, a control system, etc. are required.

In this embodiment, a superconducting material is transferred and an optical switch is operated by using light as a heat source or light as an electromagnetic field.

FIG. 13 shows an embodiment of an optical switch operated by an electric field.

A lower transparent electrode 41 is deposited on the substrate 4.

Further, after forming the superconducting material 3 with a lower insulating layer 42 interposed therebetween, an upper transparent electrode 44 is deposited with an upper insulating layer 43 interposed therebetween.

The upper transparent electrode 44 and the lower transparent electrode 41 are connected by an electric wire via a power source 9 and a switch 10 for supplying current.

When the switch 10 is closed, the upper insulator 43 and the lower insulator 42 are connected via the upper transparent electrode 44 and the lower transparent electrode 41.
7! ! A current is applied.

An electric field is applied to the superconducting material 3.

With this configuration, the superconducting material 3 undergoes a phase transition and switching is performed.

In this configuration, compared to the case where a current is directly applied to the superconducting material 3, a current is induced in the superconductor by the movement of the superconducting electron pairs, so the power supply capacity may be smaller.

Furthermore, since a joint between the superconductor and the electric wire is not required, manufacturing is facilitated.

By continuously controlling the magnetic field, temperature, ffi current, pressure, electric field, etc., it is possible to cause the superconducting material to undergo continuous phase transition changes.

Therefore, this allows continuous changes in the optical properties of the superconducting material.

Specifically, the optical switch is operated by continuously changing the magnetic field or the like using a variable resistor or the like.

Figure 14 shows that the magnetic field is continuously changed by a variable resistance,
An example of an optical switch operated by the magnetic field is shown.

A thin film of superconducting material 3 is deposited on substrate 4 .

A magnetic field generating section 21 is provided above the superconducting material 3.

The magnetic field generating section 21 has 1 at both ends! The electric wires form a circuit via a power source 9A for generating a magnetic field, a switch 10, and a variable resistor 28.

When the switch 10 is closed, a magnetic field is generated in the magnetic field generating section 21.

By generating a magnetic field greater than the critical magnetic field, a superconducting state can be changed to a normal conducting state.

As a result, the incident light 5 is transmitted through the superconducting material 3 and the transmitted light 7 is emitted.

When switch 10 is opened, magnetic field generation stops and the superconducting state returns.

As a result, the incident light 5 is reflected almost already on the surface of the superconducting material 3.

The characteristics of an optical switch were evaluated using a YBaCuO thin film as a superconducting material.

At a temperature of 77, superconducting material 3 is heated from 8 mT to 11 m
An external magnetic field is continuously applied in the range of T.

The superconducting state transitioned to the normal conducting state, and the transmittance gradually increased from 6% to 9%.

In the embodiment shown in FIG. 14, the optical switch is operated by a magnetic field, but the same operation is also possible by the ffi current, temperature, etc.

Further, in the embodiments described above, an optical switch operated by one means such as electric current or Fa field is shown, but it is also possible to operate the optical switch by combining two means.

For example, if the critical temperature of the superconducting material used in the optical switch is much higher than the operating temperature of the optical switch, the superconducting material is heated to near the critical temperature, and then a small magnetic field is applied to the superconducting material. can be transferred.

A similar effect can be obtained by changing the current applied to the superconducting material.

It is also possible to operate by keeping the external magnetic field constant and changing the temperature, current, etc.

This is because the critical conditions change by changing the temperature, current, etc., which is the same as changing the applied magnetic field relatively.

FIG. 15 is a block diagram of an optical attenuator using the optical modulation element of the present invention.

Reference numeral 29 is a control unit that changes the strength of the magnetic field applied to the light modulation element 30.

Let the intensity of the incident light 31 be Io.

If the intensity of the transmitted light 32 is I, ■ is 0 < I −
tn<I<I-ax<I.

Continuously changes by 1 within the range of .

Here, I sin and I +aax indicate the amount of transmitted light when the superconducting material of the light modulation element 30 is in a superconducting state and a normal conducting state, respectively.

FIG. 16 is a block diagram of an optical amplifier using the optical modulation element of the present invention.

The intensity information of the signal light 34 detected by the detection unit 33 is transmitted to the control unit 2.
Enter 9.

This causes the light modulation element 30 to operate.

It is assumed that the incident light 31 is a DC light having sufficiently higher intensity than the signal light 34.

The transmitted light 32 is an amplified signal light 34.

The amplification factor can be set by the control unit 29 and the intensity of the incident light 31.

Furthermore, by intensity modulating the incident light 31, the multiplication device can also be used as a calculator.

Furthermore, by changing the wavelengths of the incident light 31 and the signal light 34, it can also be used as a wavelength converter.

FIG. 17 is an example of an optical amplifier that operates directly with light.

The light modulation element 30 shown in FIGS. 15 and 16 is used.

The function is the same as the optical amplifier explained in FIG.

Since it does not include an electrical circuit system, it is resistant to noise and can be expected to operate at high speed.

Since the optical modulation element of the present invention utilizes a state change in the second type superconducting material, if this is considered optically as a change in refractive index, a waveguide type optical modulation element can also be constructed.

Suitable superconducting materials for carrying out the present invention are (1) those exhibiting superconductivity at room temperature, and (2) those whose interaction strength with light changes significantly due to phase transition.

In the conventionally known material system, NbTi.

Alloy systems such as Nb5sn have a low critical temperature (approximately 3
(below 0).

Furthermore, since it has electrical conductivity even in a normal conduction state, the strength of interaction with light does not change much.

In comparison, La-Ba-Cu-○, Y-Ba-Cu
Oxide-based superconducting materials represented by the -○ system have a high critical temperature (approximately 77 or higher).

Furthermore, since it is an insulator in the normal conduction state, the strength of its interaction with light changes significantly as it transitions.

〔Effect of the invention〕

According to the present invention, the structure of the light modulation device can be simplified and the reaction speed can be improved.

Furthermore, as a detection device for magnetic fields, currents, temperatures, pressures, etc., the structure is simple and it is possible to detect minute parts.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an optical switch operated by electric current,
Fig. 2 is a block diagram when the optical switch shown in Fig. 1 is applied to an optical printer, Fig. 3 is a block diagram when the optical switch operated by electric current is applied to an optical path switching device, and Fig. 4 is a block diagram when the optical switch in Fig. 1 is applied to an optical printer.
A configuration diagram of an optical switch operated by electric current when the shape of the superconducting material is trapezoidal. Figure 5 is a configuration diagram of an optical switch operated by a magnetic field. Figure 6 is a schematic diagram of a detection device that detects a magnetic field. , FIG. 7 is a block diagram of an optical switch operated by temperature, FIGS. 8 and 9 are block diagrams of an optical switch operated by pressure, and FIG. 10. Figures 11 and 12 are block diagrams of an optical switch operated by light, Figure 13 is a block diagram of an optical switch operated by an electric field, and Figure 14 is a block diagram of an optical switch operated by a magnetic field.
FIG. 15 is a block diagram of an optical attenuator using the optical modulation element of the present invention.
FIG. 16 is a block diagram of an optical amplifier using the optical modulation element of the present invention, FIG. 17 is a block diagram of an optical amplifier that operates directly with light, and FIG. Relationship diagram between conduction, temperature, external magnetic field, and applied current. Figure 19 shows the superconducting phase of superconducting materials - normal conduction and temperature,
Figure 20 shows the relationship between transmittance and wavelength using the superconducting phase and normal conduction as parameters, and Figure 21 shows the reflection using the superconducting phase and normal conduction as parameters. Figure 22 is a diagram showing the relationship between refractive index and wavelength, with parameters for superconducting phase and normal conduction, and Figure 23 is a diagram showing the relationship between refractive index and wavelength.
Figure 24 is a diagram showing the relationship between the magnetic flux density and the applied magnetic field for the first type superconducting material, Figure 24 is a diagram showing the relationship between the magnetic flux density and the applied magnetic field for the second type superconducting material, and Figure 25 is the reflection diagram for the second type superconducting material. Figures 26 and 27 are schematic diagrams showing the operation of the optical switch. Figures 28 and 29 are diagrams showing the relationship between transmittance and film thickness of superconducting material. Figure 30 shows
FIG. 3 is a relationship diagram between extinction ratio and film thickness of superconducting material. Figure 3 Tea 4 Circle No. ZrIJ Ascension 5 Certain Roux Steamed Tea δ Kasumi J: T First Difficulty Tea 9 No Millet 10 Figure 3 Tea Section 1/7 Taten Figure 2A 3rd Theta 8 Chome ≠ / q Mouth Tea Zo Figure Nemu's wet eyes R Cha 17th Cha z Kuchi Tadocho 2nd I - Anti # Mu (Serving Hitome Mei 9 Cha z ZriJ # Rate (<Leg4 畦) Leather 23 Figure 24th ρ Jincho H Kyo 27 (￥1 z3 #25, $2 Otsuguchi 2qguchi Figure 30

Claims (1)

[Claims] 1. A superconducting material that reversibly transitions between a superconducting state and a normal conducting state; a light source that generates incident light that irradiates the superconducting material; 1. A light modulation device using a superconducting material, characterized in that it has means for transitioning to a conductive state or a normal conductive state. 2. Applying incident light from a light source to a superconducting material that reversibly transitions between a superconducting state and a normal conducting state; A superconductor characterized by applying a transition signal for transitioning to a state, modulating the incident light by changing optical properties of the superconducting material, and emitting modulated light from the superconducting material. Light modulation method using substances. 3. A superconducting material that reversibly transitions between a superconducting state and a normal conducting state, a light source that generates incident light that irradiates the superconducting material, and converting the superconducting material into a superconducting state or a normal conducting state. 1. A detection device using a superconducting material, comprising: an external signal for transferring to a superconducting material; and means for detecting modulated light from the superconducting material. 4. A superconducting material that reversibly transitions between a superconducting state and a normal conducting state changes its state between the superconducting state and the normal conducting state by an external signal, and It is characterized by: applying incident light; modulating the incident light by changing the optical properties of the superconducting material; detecting the modulated light from the superconducting material and determining the external signal. Detection method using superconducting materials. 5. The optical modulation method using a superconducting material according to claim 2, wherein the transition signal is at least one of an electric field, a magnetic field, temperature, or pressure. 6. The optical modulation method using a superconducting material according to claim 2, wherein the modulated light is intensity-modulated modulated light or optical path-deflected modulated light. 7. The detection method using a superconducting material according to claim 4, wherein the external signal is at least one of an electric field, a magnetic field, temperature, or pressure. 8. A detection method using a superconducting material according to claim 4, wherein the modulated light is intensity-modulated modulated light or optical path-deflected modulated light. 9. The optical modulation device using a superconducting material according to claim 1, wherein the superconducting material is supported by a support member. 10. The light modulation device using a superconducting material according to claim 9, wherein the supporting member is transparent. 11. A detection device using a superconducting material according to claim 3, wherein the superconducting material is supported by a support member. 12. A detection device using a superconducting material according to claim 11, wherein the supporting member is transparent. 13. The optical modulation device using a superconducting material according to claim 1 or 9, wherein the superconducting material is a second type superconducting material. 14. A detection device using a superconducting material according to claim 3 or 11, wherein the superconducting material is a second type superconducting material. 15. An optical switch comprising: a superconducting material that reversibly transitions between a superconducting state and a normal conducting state; and means for transitioning the superconducting material to the superconducting state or the normal conducting state. 16. A superconducting material that reversibly transitions between a superconducting state and a normal conducting state; a light source that generates incident light that irradiates the superconducting material; and means for detecting modulated light from the superconducting material. An optical sensor comprising: