JP2007034058A - Gate switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Fabry-Perot etalon structure type gate switch which has a simple structure, responds with high speed, and has high extinction ratio characteristics. <P>SOLUTION: The gate switch is equipped with: at least two etalons 102, 103 formed of a dielectric crystal with a cubic crystal structure and a quadratic electro-optic effect, and arranged on a substrate 101; a mirror 203 making incident light continuously incident on at least two etalons 102, 103; and a switching signal transmission portion to apply identical voltages to the dielectric crystal on the etalons. The incident light passes through the etalon 102, its advancing direction is reversed with the mirror 3 and passes through the etalon 103. Transmittances of the etalon 102 and the etalon 103 are equally controlled with a voltage applied from the switching signal transmission portion to control an output from the etalon 103. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gate switch, and more particularly to a gate switch that controls an optical signal with an electric signal and that can be applied to optical communication, optical measurement, projectors, copiers, printers, scanners, and the like.

  With the recent development of optical communication technology, a gate switch for turning on / off an optical signal at high speed has become important. This gate switch is not limited to the above-described optical communication, but is applied to other devices (for example, a projector, a copier, a printer, a scanner, etc.), and further development is desired. At the same time, it is desired to operate the gate switch at a low voltage from the viewpoint of low power consumption and low cost.

  One way to realize a gate switch is to change the refractive index n of the substance. As a method of changing the refractive index n, there are mainly a thermo-optic (TO) effect, an acousto-optic (AO) effect, and an electro-optic (EO) effect. The TO effect is not suitable for high-speed operation and can only achieve a response speed of about several ms at most. Further, although the AO effect is suitable for high-speed operation, since the amount of change in the refractive index is small, a sufficient change in the refractive index cannot be induced.

  The EO effect is suitable for high-speed operation, and the amount of change in refractive index is large compared to the case where the AO effect is used, and is suitable for switching that requires high-speed operation.

  One gate switch using the EO effect is a Fabry-Perot etalon structure in which a crystal having an EO effect is processed into a parallel plate and a light reflecting film is deposited on parallel surfaces. By changing the refractive index n of the crystal by applying an electric field to the crystal having the EO effect, the transmission center wavelength of the Fabry-Perot etalon is changed, so that the light can be switched.

Yalive, Optoelectronics Fundamentals 5th Edition, March 2000 (Chapter 4, page 136, Fig. 4-3)

  However, particularly when the gate switch is driven at a low voltage, the change in the refractive index n obtained by the EO effect becomes small, and the extinction ratio (ratio of transmitted light power at ON / OFF) which is one of the switching characteristics is Depending on the intended use, it may not be sufficient.

  A gate switch having a Fabry-Perot etalon structure ideally increases the reflectivity of the light reflecting film, and the light transmission characteristics become sharper (finesse increases), and a desired extinction ratio can be obtained ( Non-patent document 1).

  However, in reality, the flatness and parallelism of the Fabry-Perot etalon cannot be ideal, so there is a limit to increasing finesse. That is, there is a limit to increasing the extinction ratio. Therefore, it is conceivable to increase the extinction ratio by a method of arranging a plurality of Fabry-Perot etalons in series along the light traveling direction. In that case, the characteristics of each Fabry-Perot etalon must be precisely matched, so that variations in Fabry-Perot etalon manufacturing must be reduced. Further, since a plurality of wirings between the Fabry-Perot etalon electrode and the voltage driving circuit are generated, the mounting becomes complicated.

  The present invention has been made in view of such problems, and an object thereof is to provide a Fabry-Perot etalon structure type gate switch having a simple structure, capable of high-speed response, and having a high extinction ratio characteristic. It is to be.

  In order to achieve the above object, the present invention provides a gate switch, wherein a voltage is applied to the dielectric crystal provided on the first surface of the dielectric crystal. A voltage is applied to the dielectric crystal, which is provided on a second member opposite to the first surface of the dielectric crystal, the first member that applies and reflects the input light with a predetermined reflectance. A second member that applies and reflects the input light with a predetermined reflectance; first and second etalons composed of the dielectric crystals; and light emitted from the first etalon. It is characterized by comprising means for entering the second etalon, and voltage applying means for applying the same voltage to the dielectric crystal in the first and second etalon.

  According to a second aspect of the present invention, in the first aspect of the invention, the third etalon including the first member, the second member, and the dielectric crystal, and the second etalon. Means for making the light emitted from the first etalon incident on the third etalon, wherein the voltage applying means applies the same voltage to the dielectric crystal in the first to third etalons. To do.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the voltage applying unit includes an electrode provided on the dielectric crystal and a voltage applying unit that applies a voltage to the electrode. The input light is switched when a voltage is applied by the electrodes.

  The invention described in claim 4 is the invention described in any one of claims 1 to 3, wherein the first member and the second member are metal thin film electrodes.

  The invention according to claim 5 is the invention according to any one of claims 1 to 3, wherein the first member and the second member are a transparent electrode provided on a surface of the dielectric crystal, and And a dielectric multilayer film mirror made of a dielectric multilayer film provided on the transparent electrode.

  A sixth aspect of the invention is characterized in that, in the fifth aspect of the invention, a metal thin film electrode is provided between the transparent electrode and the dielectric multilayer mirror.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the first member is the first and second etalons or the first to third etalons. The second member is common and the second member is common.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the light emitted from the first etalon is incident on the second etalon and / or the second etalon. The means for making the light emitted from the second etalon incident on the third etalon is one or a plurality of mirrors.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the dielectric crystal is a single crystal, and one of the crystal axes of the single crystal is irradiated to the dielectric crystal. It is arranged so as to coincide with the light transmission direction.

  The invention according to claim 10 is the invention according to any one of claims 1 to 8, wherein the dielectric crystal is polycrystalline, and at least one of crystal axes of the crystal is irradiated to the dielectric crystal. It is arranged so as to coincide with the light transmission direction.

According to an eleventh aspect of the present invention, in the invention according to any one of the first to tenth aspects, the dielectric crystal comprises K _1-y Li _y Ta _1-x Nb _x O ₃ (0 <x <1, It has a composition of 0 <y <1).

The invention according to claim 12 is the invention according to any one of claims 1 to 10, wherein the dielectric crystal is all of K in KTa _1-x Nb _x O ₃ (0 <x <1), or All of K and Li in K _1-y Li _y Ta _1-x Nb _x O ₃ (0 <x <1, 0 <y <1) are replaced with at least one element of Ba, Sr, and Ca, and Ta And it has the composition which replaced all of Nb with Ti.

The invention according to claim 13 is the invention according to any one of claims 1 to 10, wherein the dielectric crystal is all of K in KTa _1-x Nb _x O ₃ (0 <x <1), or All of K and Li in K _1-y Li _y Ta _1-x Nb _x O ₃ (0 <x <1, 0 <y <1) are replaced with at least one element of Pb and La; and Ta and Nb It is characterized by having a composition in which all of these are replaced by at least one element of Ti and Zr.

  The invention according to claim 14 is the invention according to any one of claims 10 to 13, wherein the x as the first composition ratio in the composition of the dielectric crystal is 0.1 or more and 0.5 or less. The y as the second composition ratio in the composition of the dielectric crystal is greater than 0 and less than 0.1.

  According to the present invention, it is possible to provide a Fabry-Perot etalon structure type gate switch having a simple structure, capable of high-speed response, and having a high extinction ratio characteristic.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Before describing the individual embodiments, the filter characteristics of the Fabry-Perot etalon will be described. A Fabry-Perot etalon (hereinafter referred to as an etalon) has a structure in which a substance having a refractive index n is sandwiched between a pair of mirrors. As main values representing the characteristics of the etalon, there are FSR (Free Spectral Range) and Finesse. The center frequency ν _m of the transmittance of the etalon is expressed by the following formula (1).

In the above formula (1), n is the refractive index of the material sandwiched between the mirrors, d is the resonator length (distance between the mirrors), and θ is the inclination angle of the etalon with respect to the incident light (also called the etalon angle). , C is the speed of light in vacuum. From the equation (1), the center wavelength λ _m of the transmission band of the etalon is represented by the following equation (2).

Since the FSR is an interval between two adjacent sets of the center frequency ν _m of the transmission band expressed by the equation (1), it is expressed by the following equation (3).

  Finesse is a value that expresses the extent of the etalon transmission band. When the etalon is ideally produced, it is related to the reflectance of the mirror by the following equation.

In the above equation (4), Δν _1/2 is the full width at half maximum of the etalon transmission band, and R is the reflectance of the mirror constituting the resonator.

  When the ratio of the transmitted light intensity to the incident light intensity of the etalon is I (dB), it is expressed by the following formula (see Non-Patent Document 1).

  Where δ represents the phase lag within the etalon,

It is.

In order to change the center frequency ν _m of the transmission band of the etalon according to the expression (1), any one of the refractive index n, the resonator length d, and the etalon angle θ of the etalon may be changed. I understand that. Therefore, a tunable filter can be produced by changing these parameters. The commercially available wavelength tunable filter realizes wavelength tunability by mechanically changing the resonator length d. This is because changing the resonator length d among the above three parameters can maximize the wavelength variable band.

A tunable filter configured to change the center frequency ν _m of the etalon transmission band by mechanically changing the resonator length d and the etalon angle θ is not suitable for high-speed operation.

  On the other hand, the wavelength tunable filter configured to change the refractive index n of the substance constituting the etalon can change the center wavelength (center frequency) of the transmission band of the etalon without mechanical operation. As described above, in the case of a refractive index change using the electro-optic effect, a sufficient amount of change can be taken and high speed operation is possible.

  The electro-optic effect includes a primary electro-optic effect (Pockels effect) and a secondary electro-optic effect (Kerr effect). The primary electro-optic effect appears in proportion to the electric field strength, and the refractive index change is expressed by the following equation (7).

In the above formula (7), n ₀ is the refractive index of a dielectric crystal having a first-order electrooptic effect, which is a substance constituting the etalon, in the state where no electric field is applied, and r _eff is An effective value of the first-order electro-optic coefficient, E is an electric field.

  The secondary electro-optic effect appears in proportion to the square of the electric field strength, and the refractive index change is expressed by the following formula (8).

In the above formula (8), n ₀ is the refractive index of the dielectric crystal having a secondary electro-optic effect which is a substance constituting the etalon in the state where no electric field is applied, and E is the electric field. , S ₁₂ is an amount defined by the following formula (9).

In the above formula (9), ε ₀ is the dielectric constant of vacuum, ε _r is the specific dielectric constant of the dielectric crystal having the secondary electro-optic effect, and g ₁₂ is the secondary electro-optic effect. The electro-optic constant of the dielectric crystal.

Next, it will be described with reference to FIG. 10 that a gate switch can be realized by using the above-described filter characteristics by the etalon. For simplicity of explanation, it is assumed that the temperature is constant and the incident angle θ = 0 of the etalon. Let λ _m (V = 0) be the center wavelength of the transmission band of the etalon when the voltage V is not applied to the dielectric crystal, which is the material constituting the etalon. Continuous light having a wavelength λ _in equal to λ _m (V = 0) is incident on the etalon. At this time, the incident continuous light passes through 100% etalon except for the loss of etalon.

Here, assuming that a voltage V = V _op is applied to the dielectric crystal that is a substance that constitutes the etalon, the refractive index of the dielectric crystal that is the substance that constitutes the etalon changes according to the equations (7) to (8). Therefore, the center wavelength λ _m of the transmission band of the etalon changes according to the equation (2). Therefore, the light transmittance at the wavelength λ _in changes. By setting the amount of change in the center wavelength λ _m (center frequency ν _m ) of the etalon transmission band and the Finesse (see Equation (4)) to an appropriate value, the light transmittance at the wavelength λ _in is set to a desired transmittance. can do. That is, it can function as a gate switch.

  The present invention relates to a gate switch (hereinafter, also referred to as an etalon-type gate switch) that uses a filter characteristic of an etalon. The gate switch according to the present invention continuously enters at least two etalons disposed on one dielectric crystal (substrate) having a cubic structure and a secondary electro-optic effect, and incident light on at least two etalons. And means for applying the same voltage to the dielectric crystal in the etalon. According to the present invention, a Fabry-Perot etalon structure type gate switch having a simple structure and capable of high-speed response and having a high extinction ratio characteristic is provided.

Embodiments according to the present invention will be described below with reference to the drawings. In one embodiment, a dielectric crystal having a cubic structure and a secondary electro-optic effect is formed using K _1-y Li _y Ta _1-x Nb _x O ₃ (0 <x <1, 0 <y <1) ( KLTN). However, the material used as the dielectric crystal is not limited to KLTN. For example, KTa _1-x Nb _x O ₃ (0 <x <1) (KTN) is a dielectric having a cubic structure and a secondary electro-optic effect. Any of body crystals may be used.

The dielectric crystal is made of all of K in KTa _1-x Nb _x O ₃ (0 <x <1) (KTN) or K _1-y Li _y Ta _1-x Nb _x O ₃ (0 <x <1 0 <y <1) (KLTN) in which all of K and Li are replaced with at least one element of Ba, Sr, and Ca, and all of Ta and Nb are replaced with Ti May be.

Alternatively, the dielectric crystal is formed by using all of K in KTa _1-x Nb _x O ₃ (0 <x <1) (KTN) or K _1-y Li _y Ta _1-x Nb _x O ₃ (0 <x <1, 0 <y <1) (All of K and Li in KLTN) are replaced with at least one element of Pb and La, and all of Ta and Nb are replaced with at least one element of Ti and Zr You may use what has the composition replaced by.

  In KTN and KLTN, the range of x, which is the stoichiometric coefficient of Nb, is preferably 0.1 or more and 0.5 or less. In KLTN, the range of y, which is the stoichiometric coefficient of Li, is preferably greater than 0 and less than 0.1.

  In the present invention, the dielectric crystal may be a single crystal or a polycrystal. One of the crystal axes of the single crystal is preferably matched with the optical axis of the light incident on the etalon (the transmission direction of the light incident on the etalon). By doing so, the modulation efficiency can be improved and the polarization dependence can be reduced. In the case of a polycrystal, the crystal axis is in various directions, and at least one crystal axis is made to coincide with the optical axis. By adopting such a crystal axis arrangement, the crystal can exhibit an electro-optic effect by applying an electric field, and can realize a modulation operation.

  It should be noted that the embodiments disclosed in the present specification are merely for explaining the present invention, and do not limit the scope of the present invention. Therefore, those skilled in the art can employ various embodiments including each or all of these elements, and these embodiments are also included in the present invention.

(First embodiment)
A first embodiment of a gate switch according to the present invention will be described with reference to FIGS.
The etalon gate switch 100 shown in FIG. 1 includes an optical input port 201, an optical output port 202, two etalons 102 and 103 manufactured on the same substrate 101, and a mirror 203.

  The substrate 101 is made of a dielectric crystal having a cubic structure and a secondary electro-optic effect, and constitutes part of the etalons 102 and 103. The configuration of the etalons 102 and 103 will be described in detail below.

  Since the etalons 102 and 103 function as gate switches, they have electrodes (not shown) for inputting switching signals, and these electrodes are electrically connected in parallel to a switching signal transmission unit (not shown). Connected to be.

When continuous light having a wavelength λ _in (also referred to as continuous light λ _in ) is incident on the optical input port 201, it passes through the etalon 102, its traveling direction is reversed by the mirror 203, passes through the etalon 103, and outputs light. The light exits from the port 202.

FIGS. 2A and 2B show transmission spectra of the etalons 102 and 103 when the voltage V is not applied to the dielectric crystal (substrate 101), which is a substance constituting the etalons 102 and 103, respectively. As shown in FIGS. 2A and 2B, the center wavelength λ _m (V = 0) of the transmission band of the etalon 102 when the voltage V is not applied to the substrate 101 and the center of the transmission band of the etalon 103. The wavelength λ _m (V = 0) is set equal to the wavelength λ _{in of the} continuous light. Since the etalons 102 and 103 are made close to the same substrate 101, the refractive index n and the resonator length d of the etalon are very close to each other. As shown in FIG. Will be very similar. Therefore, the central wavelength of the transmission band of the etalon 102 and the central wavelength of the transmission band of the etalon 103 are extremely close to each other and may be considered to be the same in practice.

FIG. 3 shows a transmission spectrum in the case where continuous light incident when the voltage V is not applied to the substrate 101 passes through the etalons 102 and 103 continuously. As shown in FIG. 3, the transmission spectrum in the case where continuous light continuously passes through the etalons 102 and 103 is obtained by superimposing the transmission spectra of the etalons 102 and 103. When the voltage V is not applied to the substrate 101, the incident continuous light λ _in is transmitted without being attenuated by the etalons 102 and 103 except for the loss of the etalon.

4 (a) and 4 (b), the etalon 102 and the etalon 102 when the voltage V = V _op (electric field E = E _op ) is applied to the dielectric crystal (substrate 101), which is a substance constituting the etalons 102 and 103. 103 shows the transmission spectrum. By making the etalons 102 and 103 close to the same substrate 101, the refractive index n and the resonator length d of the etalon become very close values. In addition, the voltage applied to the etalon is also electrically different from each other. Since it is connected in parallel, it has the same voltage. For this reason, as shown in FIGS. 4A and 4B, the transmission spectra of the etalons 102 and 103 are very similar. Therefore, the center wavelength of the transmission band of the etalon 102 and the center wavelength λ _op = λ _m (V = V _op ) of the transmission band of the etalon 103 are extremely close values, and may be considered to be practically the same.

FIG. 5 shows a transmission spectrum when the incident continuous light continuously passes through the etalons 102 and 103 when the voltage V = V _op is applied to the substrate 101. As shown in FIG. 5, the transmission spectrum when continuous light passes through the etalons 102 and 103 continuously is obtained by superimposing the transmission spectra of the etalons 102 and 103. In addition, since the etalons 102 and 103 are made close to the same substrate 101 as described above, the transmission spectrum of the incident continuous light passing through the etalons 102 and 103 continuously as shown in FIG. The center wavelength is λ _op = λ _m (V = V _op ). Since the transmittance of the incident continuous light λ _in becomes small, the output light intensity becomes weak. Therefore, it functions as a gate switch by switching between the state where the voltage is not applied and the state where the voltage is applied.

  In this way, using a dielectric crystal as a material, multiple etalon is made on the same substrate, the direction of the optical path is changed using an external mirror, etc., and it passes through multiple etalons that can be said to have virtually the same filter characteristics By doing so, a gate switch with an extremely high extinction ratio can be realized.

Next, the configuration of the etalons 102 and 103 in the etalon type gate switch of the present embodiment will be described with reference to FIG.
FIG. 6 shows a more detailed configuration of the etalon type gate switch 100 shown in FIG. The etalon 102 includes a substrate 101 and a first member 104 and a second member 105 that are provided on opposite surfaces of the substrate 101 and have functions of an electrode and a mirror, respectively. Similarly, the etalon 103 includes a first member 107 and a second member 106 that function as electrodes and a mirror.

  The first members 104 and 107 are provided on the same surface of one substrate 101. The second members 105 and 106 are provided on the surface of the one substrate 101 that faces the surface on which the first members 104 and 107 are provided.

  In the present embodiment, the first member 104 and the second member 106 are on the light input side, and the second member 105 and the first member 107 are on the light output side. However, the light emitted from the etalon 102 through the second member 105 may be configured to enter the first member 107 of the etalon 103.

  By using the first members 104 and 107 and the second members 105 and 106 together with the dielectric crystal, light in the vicinity of a predetermined frequency is selectively transmitted, and light having a frequency other than the frequency of the transmitted light is used. Has the function of reflecting the light.

  The first members 104 and 107 are grounded and function as a ground electrode. The second members 105 and 106 are electrically connected in parallel with a switching signal transmission unit for causing the etalons 102 and 103 to function as gate switches, respectively, and between the first member 104 and the second member 105, It functions as an electrode for generating an electric field E between the first member 107 and the second member 106.

  For example, the first member and the second member can be realized by providing a metal thin film electrode on the substrate 101, providing a transparent electrode on the substrate 101 which is a dielectric crystal, and further forming a transparent electrode from a dielectric multilayer film. It can also be realized by providing a dielectric multilayer film mirror. Alternatively, the first member and the second member can be realized by providing a transparent electrode, a metal thin film electrode, and a dielectric multilayer mirror in this order on the substrate 101 that is a dielectric crystal.

  In the above embodiment, the number of etalons is two, but any number of etalons may be used. In addition, the same voltage is applied to each etalon by applying and wiring the electrodes for applying voltage to each etalon independently. However, the same voltage is applied to each etalon. As long as the electrodes have the same polarity, they may be combined into one.

(Second Embodiment)
A second embodiment of the gate switch according to the present invention will be described with reference to FIGS. The gate switch of the second embodiment is an etalon type gate switch in which the number of etalons created on the same substrate is three, and is shared by three etalons, and a pair of electrodes for applying the same voltage to each etalon. Is illustrated.

  The etalon gate switch 300 shown in FIG. 7 includes an optical input port 201, an optical output port 202, three etalons 304 to 306 fabricated on the same substrate 303, and two mirrors 203a and 203b. .

When continuous light λ _in is incident on the optical input port 201, it passes through the etalon 304, the traveling direction is reversed by the mirror 203 a, passes through the etalon 305, the traveling direction is reversed by the mirror 203 b, and passes through the etalon 306. Then, the light is emitted from the light output port 202.

  The substrate 303 is made of a dielectric crystal having a cubic structure and a secondary electro-optic effect, and constitutes part of the etalons 304 to 306.

  The etalons 304 to 306 include a substrate 303 and a first member 301 and a second member 302 that are provided on opposite surfaces of the substrate 303 and have functions of an electrode and a mirror, respectively.

  In the present embodiment, for the etalons 304 and 306, the first member 301 is the light input side, and the second member 302 is the light output side. Regarding the etalon 305, the second member 302 is the light input side, and the first member 301 is the light output side. However, the light emitted from the etalon 304 through the second member 302 is incident on the first member 301 of the etalon 305, and the light emitted from the etalon 305 through the second member 302 is further reflected by the etalon 306. You may comprise so that it may inject into the 1st member 301 or the 2nd member 302. FIG.

  By using the first member 301 and the second member 302 together with the dielectric crystal, the first member 301 and the second member 302 have a function of selectively transmitting light in the vicinity of a predetermined frequency and reflecting light having a frequency other than the frequency of the transmitted light. Have.

  The first member 301 is grounded and functions as an earth electrode. The second member 302 is electrically connected to a switching signal transmission unit for causing the etalons 304 to 306 to function as a gate switch, and generates an electric field E between the first member 301 and the second member 302. Functions as an electrode.

  With such a configuration, it is possible to provide an etalon-type gate switch having a simple structure that requires only two wirings between the switching signal transmission unit (voltage driving circuit) and the etalon.

  The configuration of the etalons 304 to 306 in the etalon type gate switch of the present embodiment will be described with reference to FIG. FIG. 8 is an enlarged view of the etalon 304. The etalon 304 includes a first member 301 including a dielectric crystal (substrate 303), a first electrode 312 and a first mirror 311 which are sequentially provided in contact with the light input side surface of the dielectric crystal. And a second member 302 including a second electrode 314 and a second mirror 315 provided in order in contact with the light output side surface of the dielectric crystal.

  The first mirror 311 and the second mirror 315 are arranged substantially in parallel to constitute a resonator. The electrode 312 and the second electrode 314 apply a voltage to the dielectric crystal (substrate 303).

  The first mirror 311 and the second mirror 315 can be realized using a dielectric multilayer mirror, a metal thin film electrode, or both.

  The first electrode 312 and the second electrode 314 can be realized using a transparent electrode, a metal thin film electrode, or both.

In the above embodiment, the example _in which the wavelength λ _{in of the} input light is selected so as to maximize the transmittance when no voltage is applied has been described, but the input light wavelength is reduced so that the transmittance when no voltage is applied is small. The wavelength λ _in may be selected and executed. This is shown in FIG.

  In addition, by using a dielectric crystal having a cubic structure and a secondary electro-optic effect as the dielectric crystal, it operates regardless of the polarization state of the input light (polarization-independent operation). Is preferred.

It is a schematic diagram of an etalon type gate switch. It is a transmission spectrum of an etalon when no voltage is applied to the dielectric crystal. It is a transmission spectrum when passing through an etalon when no voltage is applied to the dielectric crystal. It is a transmission spectrum of an etalon when a voltage is applied to a dielectric crystal. It is a transmission spectrum when passing through an etalon when a voltage is applied to the dielectric crystal. It is a figure which shows the case where the number of etalon is two. It is a figure which shows the case where the number of etalons is 3 and the number of electrodes of the same polarity is 1. 2 is a configuration diagram of an etalon 304. FIG. It is the figure which showed the operation | movement of the gate switch when setting so that the transmittance | permeability of light may become small when a voltage is not applied. It is the figure which showed the operation | movement of the gate switch when setting so that the transmittance | permeability of light may become the maximum when a voltage is not applied.

Explanation of symbols

100 Etalon type gate switch 101 Substrate (dielectric crystal)
102 etalon 103 etalon 104 first member 105 second member 106 second member 107 first member 201 optical input port 202 optical output port 203 mirror 300 etalon-type gate switch 301 first member 302 second member 303 Substrate (dielectric crystal)
304 etalon 305 etalon 306 etalon 311 first mirror 312 first electrode 314 second electrode 315 second mirror

Claims (14)

A dielectric crystal having a cubic structure and a secondary electro-optic effect;
A first member provided on the first surface of the dielectric crystal, for applying a voltage to the dielectric crystal and reflecting the input light with a predetermined reflectance;
A second member provided on a second surface opposite to the first surface of the dielectric crystal, for applying a voltage to the dielectric crystal and reflecting the input light with a predetermined reflectance; And first and second etalon composed of the dielectric crystal,
Means for injecting light emitted from the first etalon into the second etalon;
And a voltage applying means for applying the same voltage to the dielectric crystal in the first and second etalons. A third etalon composed of the first member, the second member, and the dielectric crystal;
Means for making the light emitted from the second etalon incident on the third etalon;
2. The gate switch according to claim 1, wherein the voltage applying unit applies the same voltage to the dielectric crystal in the first to third etalons.   The voltage application means includes an electrode provided on the dielectric crystal and a voltage application unit that applies a voltage to the electrode, and switches light input by applying a voltage from the electrode. The gate switch according to claim 1 or 2.   The gate switch according to any one of claims 1 to 3, wherein the first member and the second member are metal thin film electrodes.   The first member and the second member are composed of a transparent electrode provided on the surface of the dielectric crystal and a dielectric multilayer film mirror made of a dielectric multilayer film provided on the transparent electrode. The gate switch according to any one of claims 1 to 3.   6. The gate switch according to claim 5, wherein a metal thin film electrode is provided between the transparent electrode and the dielectric multilayer mirror.   2. The first and second etalons, or the first to third etalons, wherein the first member is common and the second member is common. The gate switch in any one of thru | or 6.   The means for injecting light emitted from the first etalon into the second etalon and / or the means for injecting light emitted from the second etalon into the third etalon are one. The gate switch according to claim 1, wherein the gate switch is a plurality of mirrors.   9. The dielectric crystal according to claim 1, wherein the dielectric crystal is a single crystal, and one of the crystal axes of the single crystal is arranged so as to coincide with a transmission direction of light applied to the dielectric crystal. The gate switch in any one of.   9. The dielectric crystal according to claim 1, wherein the dielectric crystal is a polycrystal, and is arranged so that at least one of crystal axes of the crystal coincides with a transmission direction of light applied to the dielectric crystal. The gate switch in any one of. Said dielectric crystal is one of _{K 1-y Li y Ta 1} -x Nb x O 3 claims 1 to 10, characterized in that it has a composition of (0 <x <1,0 <y <1) Gate switch as described in The dielectric crystal includes all of K in KTa _1-x Nb _x O ₃ (0 <x <1), or K _1-y Li _y Ta _1-x Nb _x O ₃ (0 <x <1, 0 < 11. The composition according to claim 1, wherein all of K and Li in y <1) are replaced with at least one element of Ba, Sr, and Ca, and all of Ta and Nb are replaced with Ti. A gate switch according to any one of the above. The dielectric crystal includes all of K in KTa _1-x Nb _x O ₃ (0 <x <1), or K _1-y Li _y Ta _1-x Nb _x O ₃ (0 <x <1, 0 < a composition in which all of K and Li in y <1) are replaced with at least one element of Pb and La, and all of Ta and Nb are replaced with at least one element of Ti and Zr The gate switch according to claim 1. The x as the first composition ratio in the composition of the dielectric crystal is 0.1 or more and 0.5 or less, and the y as the second composition ratio in the composition of the dielectric crystal is greater than 0. 14. The gate switch according to claim 10, wherein the gate switch is less than 0.1.

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