JPH11194146A - Electric field sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate variance due to change in optical intensity and temperature drift, etc. SOLUTION: The board 2 of this sensor is provided thereon with an incident/ outgoing light waveguide 3 which receives an incident light and emits an outgoing light, and changes a refractive index according to the intensity of applied electric field, a grating 4 for a wavelength modulator which is written in the waveguide 3 and Bragg-diffract the incident light, and electrodes 5 and 5' that are connected with an antenna and are provided adjacent to the grating 4 for the wavelength modulator. Thus, a change in electric field intensity is converted into the wavelength modulation through grating, so that no influence of variance of optical intensity is given. Further, the incident/outgoing light waveguide is divided into two pieces thereof, and the grating for the wavelength modulator can be written in one waveguide and that for temperature compensation be written in the other waveguide. Therefore, a difference of wavelength from the respective grating can be measured as an electric field intensity, thereby eliminating an influence of change of wavelength due to temperature drift, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electric field sensor, and more particularly to an electric field sensor using an optical waveguide type element having an optical waveguide formed on a crystal having an electro-optic effect.

[0002]

2. Description of the Related Art Information devices such as computers, communication devices,
Many electric devices such as controllers used in automobiles and trains are susceptible to malfunctions due to external electromagnetic noise, and there is a concern that electromagnetic waves may affect human bodies. In particular, in the EMC field (noise field), it has become important to accurately measure the magnitude of noise affecting the external electromagnetic environment, the noise generated by the electric device itself, and the like. As a measuring device for measuring this electromagnetic noise, a measuring device using an antenna is generally used, but the electric field distribution is disturbed by the presence of an electric cable such as a coaxial cable, or noise is mixed into the electric cable. There was a fear.

In order to solve such difficulties, an electric field sensor using an optical element for converting an electric field intensity into an optical signal as a sensor has been developed. This electric field sensor includes, for example, a substrate 51, an incident optical waveguide 52, two phase-shifted optical waveguides 53 and 53 ', and an output optical waveguide 54, as shown in FIG. The incident optical waveguide 52 is formed on the substrate 51 and is connected to the incident optical fiber 57. The phase shift optical waveguides 53 and 53 'are formed on the substrate 51 so as to branch off from the incident optical waveguide 52, and the refractive index changes according to the applied electric field intensity. The outgoing optical waveguide 54 is formed on the substrate 51 so as to merge with the phase shift optical waveguides 53 and 53 ', and the outgoing optical fiber 5
8 is connected.

On the substrate 51, U-shaped pattern electrodes 55, 55 'are opposed to each other so as to fit, and are arranged in parallel with the phase shift optical waveguides 53, 53'. Is formed on. Rod antennas 56 and 56 'are connected to respective sides of the U-shaped pattern electrodes 55 and 55'. In the Mach-Zehnder electric field sensor configured as described above, the incident light from the incident optical fiber 57 is incident on the incident optical waveguide 52 and is branched into the phase shift waveguides 53 and 53 '. When an electric field is applied in such a state, the rod antenna 5
6, 56 'induces a voltage in the U-shaped pattern electrodes 55, 55', so that the phase shift waveguides 53, 53 '
Generates electric field components in opposite directions in the depth direction. Therefore, the refractive index changes due to the electro-optic effect, and a phase difference is generated between the light waves propagating through the phase shift waveguides 53 and 53 'according to the magnitude of the applied electric field. When the light waves having the phase difference are merged and coupled by the output light waveguide 58, the light intensity changes due to interference. That is, since the intensity of the emitted light changes according to the intensity of the applied electric field, the intensity of the applied electric field can be measured by measuring the change in the light intensity with a detector.

As a method for detecting an electric field from such a change in light intensity, a method for detecting an electric field (JP-A-7-151804) is described.
Japanese Patent Application Laid-Open No. 8-43467) and an electric field sensor head and an electric field sensor (JP-A-8-43467).

[0006]

However, in such a Mach-Zehnder electric field sensor, since the light output periodically draws a trigonometric function curve with respect to the applied voltage, it is necessary to take a maximum value and a minimum value. In addition, a dynamic range cannot be obtained. As a result, there is a possibility that the measurement capability is lost for an electric field intensity exceeding the maximum value, and a false recognition determination is made. Also, because of the light intensity modulation, it is susceptible to the influence of light intensity fluctuations due to disturbances of the light source or the like. The effects cannot be eliminated at this time. Further, there is a problem that an optical bias changes due to a temperature drift.

[0007] Furthermore, in the case where the light from one fiber is to be supplied to a plurality of electric field sensors by branching, if the power of the incident light is reduced, the C / N ratio is reduced, and the dynamic range is reduced. Therefore, it is not suitable for multiplex transmission. The present invention has been made to solve such a conventional problem, and is not affected by light intensity fluctuation due to disturbance of a light source or the like, and is capable of preventing fluctuation due to environmental change such as temperature drift. It is another object of the present invention to provide an electric field sensor capable of wavelength multiplex transmission of multipoint measurement data.

[0008]

According to the present invention, there is provided an electric field sensor which receives an incident light, emits an outgoing light, and changes a refractive index according to the intensity of an applied electric field. Formed on the substrate are an input / output optical waveguide of a type, a grating for a wavelength modulator written on the input / output optical waveguide and performing Bragg diffraction of incident light, and an electrode connected to an antenna and provided in close proximity to the wavelength modulator grating. It was done.

Further, the electric field sensor of the present invention has an input / output optical waveguide for receiving incident light and emitting output light, and one end coupled to the input / output optical waveguide, and is refracted according to the intensity of the applied electric field. First and second diffused optical waveguides for changing the rate, and written in the first diffused optical waveguide;
An antenna connected to a grating for temperature compensation for Bragg diffraction of one of the branched incident lights, a grating for a wavelength modulator written in the second diffused optical waveguide and Bragg diffracting the other of the branched incident lights, and An electrode provided in close proximity to the wavelength modulator grating is formed on a substrate.

An electric field sensor according to the present invention comprises: an input / output optical waveguide for receiving incident light and emitting output light; and a directional coupling coupled to the input / output optical waveguide for branching incident light from the input / output optical waveguide. And a first and a second diffuser that are coupled to the directional coupler so that each of the incident lights split by the directional coupler is respectively incident, and change the refractive index according to the intensity of the applied electric field. Compensation optical waveguide, a temperature-compensating grating written in the first diffused optical waveguide and Bragg diffracting one of the branched incident lights, and the other branched optical waveguide written in the second diffused optical waveguide. A grating for a wavelength modulator for Bragg diffraction of light and an electrode connected to an antenna and provided in close proximity to the grating for a wavelength modulator are formed on a substrate.

In the electric field sensor according to the present invention, the antenna may be formed on a substrate. Further, in the electric field sensor according to the present invention, it is preferable that the temperature compensating grating and the wavelength modulator grating have a structure in which the same refractive index change is caused by a temperature change.

In such an electric field sensor according to the present invention, when incident light enters the input / output optical waveguide, reflected light having a reference wavelength is reflected by the wavelength modulator grating. Here, when an electromagnetic wave is applied to the antenna, a voltage proportional to the electromagnetic wave is induced at the electrode, so that reflected light having a wavelength corresponding to the applied voltage is reflected from the wavelength modulator grating. By detecting the wavelength difference between the reference wavelength and the wavelength corresponding to the applied voltage, the electric field intensity can be measured. Thus, the change in the electric field intensity can be detected by the wavelength modulation of the light, so that it is not affected by the light intensity fluctuation due to the disturbance of the light source or the like.

Further, if the temperature compensating grating is used in combination, the difference between the reference wavelength from the temperature compensating grating and the wavelength from the wavelength modulator grating can be measured as the electric field intensity. Variations due to changes can be prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an electric field sensor according to the present invention will be described below with reference to the drawings. In the electric field sensor of the present invention, for example, as shown in FIG. 1, an input / output optical waveguide 3, a grating 4 for a wavelength modulator, and two electrodes 5, 5 'are formed on a substrate 2. The substrate 2 is preferably made of a material having a large electro-optical effect, for example, a LiNbO3 (lithium niobate) crystal plate.

The input / output optical waveguide 3 is connected to a polarization-maintaining input / output optical fiber 7 and receives incident light from the input / output optical fiber 7 and emits output light.
This is a diffusion type optical waveguide formed by processing a metal Ti film into a strip line and heat-treating it at a predetermined temperature to diffuse metal Ti into the LiNbO3 crystal. Therefore, the refractive index can be changed according to the intensity of the applied electric field. In addition, the incoming / outgoing optical waveguide 3 is
The output end 2a of the substrate 2 is not cut perpendicularly to the input / output optical waveguide 3 but cut at an angle of, for example, 12 degrees with respect to the virtual vertical plane L. It is formed at the reflection end. This is to prevent the light reflected from the end face from returning to the incident side and to reduce the S / N of the reflected light from the wavelength modulator grating 4.

The wavelength modulator grating 4 Bragg diffracts the incident light from the input / output optical fiber 7 and is written in the input / output optical waveguide 3. Here, Bragg diffraction is diffraction that occurs on a group of lattice planes in the spatial lattice of a crystal, and changes the refractive index periodically. Therefore, since the wavelength modulator grating 4 can reflect the incident light at the written location and modulate the wavelength, the detection sensitivity can be increased and the frequency band can be widened.

The electrodes 5, 5 'are pattern electrodes, are formed to have the same length as the wavelength modulator grating 4 written in the input / output optical waveguide 3, and are provided in close proximity to the wavelength modulator grating 4. Have been. Antennas 6, 6 'are connected to the pattern electrodes 7, 7', respectively. The operation of the electric field sensor 1 configured as described above will be described below.

When incident light having an incident spectrum having a wide band characteristic as shown in FIG. 2A is made incident from an input / output optical fiber 7, the incident light is transmitted to a wavelength modulator grating 4 via an input / output optical waveguide 3. Incident. The incident light is subjected to Bragg diffraction by the wavelength modulator grating 4 and only the wavelength satisfying the Bragg diffraction condition is reflected as reflected light to the input / output optical waveguide 3, so that the wavelength λ =
It becomes 0 reflected light. This reflected light has a reflection spectrum having a narrow band characteristic as shown in FIG.

When an electric field is applied to the electric field sensor 1, a voltage is induced on each of the pattern electrodes 5, 5 'by the antennas 6, 6', and an electric field component in the depth direction is applied to the wavelength modulator grating 4. Occurs. As a result, since the effective refractive index changes in the wavelength modulator grating 4 due to the electro-optic effect, the wavelength of the reflected light from the wavelength modulator grating 4 can be changed to the wavelength λ = x according to the applied voltage. That is, the pattern electrodes 5, 5 'and the grating 4 for a wavelength modulator become a wavelength modulator.

Therefore, the electric field strength can be measured by detecting the difference between the reflection wavelength when no electric field is applied and the reflection wavelength when an electric field is applied. The antenna used for the electric field sensor of the present invention is not limited to this, and as shown in FIG.
The electric field sensor 10 in which 0 'is formed on the substrate 20 may be used. Such an electric field sensor 10 has a pattern antenna 6
0, 60 'and the substrate 20, except for the electric field sensor 1 described above.
Since the configuration is the same as that described above, the description is omitted. Thereby, the same effect as the above-described electric field sensor 1 can be obtained.

The electric field sensor of the present invention is not limited to this. As shown in FIG. 4, the input / output optical waveguide 30, the first and second diffused optical waveguides 8, 8 ', The compensation grating 9, the wavelength modulator grating 11, and the two electrodes 17 and 17 ′ may be formed. The input / output optical waveguide 30 of the electric field sensor 100 is connected to the polarization-maintaining input / output optical fiber 7 to receive the incident light from the input / output optical fiber 7 and output the output light. One end of each of the first and second diffused optical waveguides 8 and 8 'is coupled to the input / output optical waveguide 30, and the refractive index can be changed according to the intensity of the applied electric field. The input / output optical waveguide 30 and the first and second diffused optical waveguides 8 and 8 ′ are formed by processing a metal Ti film into a strip line on the substrate 200, similarly to the above-described electric field sensor 1. It is formed by heat treatment at a temperature and diffusion into LiNbO3 crystal. The first and second diffused optical waveguides 8, 8 '
Are formed up to the output end 200a of the substrate 200. The output end 2a of the substrate 200 is not cut perpendicular to the first and second diffused optical waveguides 8 and 8 ', but is For example, the S / N of the reflected light from the temperature compensating grating 9 and the wavelength modulator grating 11 is formed at the non-reflection end which is cut in a state of being inclined by 12 degrees and returning the light reflected from the end face to the incident side. To prevent the decline.

The temperature compensating grating 9 Bragg diffracts the incident light branched from the input / output optical waveguide 30 to the first diffused optical waveguide 8.
Has been written to. Similarly to the temperature compensating grating 9, the wavelength modulator grating 11 Bragg diffracts the incident light branched from the input / output optical waveguide 30 to the second diffused optical waveguide 8 '. Written in wave path 8 '. In order to reflect the temperature compensating grating 9 and the wavelength modulator grating 11 in the same phase, the waveguide lengths of the first and second diffused optical waveguides 8 and 8 'are made equal, and each of the gratings 9 and 10' is reflected. Have the same structure.

The temperature compensating grating 5 and the wavelength modulator grating 6 configured as described above can reflect and modulate the wavelength at the written portions, respectively, so that the detection sensitivity can be increased and the frequency can be increased. The band can be widened. Electrodes 17, 1
Reference numeral 7 'denotes a pattern electrode which is formed to have the same length as the wavelength modulator grating 11 written in the second diffused optical waveguide 8'.
1 are provided in close proximity to each other. The antennas 6, 6 'are connected to the pattern electrodes 17, 17', respectively.

The operation of the electric field sensor 100 thus configured will be described below. The temperature compensating grating 9 and the wavelength modulator grating 11 have a structure in which the same refractive index change is caused by a temperature change in order to cause an equivalent wavelength change with a temperature change.
When incident light having an incident spectrum having a wide band characteristic as shown in FIG.
This incident light is split into a first diffusion type optical waveguide 8 and a second diffusion type optical waveguide 8 ′ via an input / output optical waveguide 30,
The incident light incident on the first diffusion type optical waveguide 8 is incident on the grating 9 for temperature compensation, and the incident light incident on the second diffusion type optical waveguide 8 ′ is incident on the grating 11 for the wavelength modulator. The incident light incident on the temperature compensating grating 9 and the wavelength modulator grating 11 is subjected to Bragg diffraction by the temperature compensating grating 9 and the wavelength modulator grating 11, respectively. Since the light is reflected by the first diffused optical waveguide 8 and the second diffused optical waveguide 8 ', the reflected light has a wavelength λ = 0. This reflected light has a reflection spectrum having a narrow band characteristic as shown in FIG.

Here, when an electric field is applied to the electric field sensor 100, each of the pattern electrodes 17,
A voltage is induced at 17 ', and an electric field component is generated in the grating 11 for the wavelength modulator in the depth direction. As a result, a change in the refractive index occurs in the wavelength modulator grating 11 due to the electro-optic effect.
The wavelength of the reflected light from 1 can be changed to a wavelength λ = x according to the applied voltage. That is, the pattern electrodes 17, 1
7 'and the grating 11 for a wavelength modulator serve as a wavelength modulator.

Therefore, the temperature compensating grating 9
The intensity of the electric field can be measured by detecting the wavelength difference from the reflected light from the wavelength modulator grating 11 with reference to the reflected light from the. Since the grating 9 for temperature compensation and the grating 11 for wavelength modulator have the same effective refractive index change with respect to temperature change, the influence of wavelength change due to temperature change can be prevented.

As shown in FIG. 6, in order to split the incident light from the input / output optical fiber 7 into the first and second diffused optical waveguides 8 and 8 'via the incident optical waveguides 300 and 300'. , The directional coupler 31 may be used. The directional coupler 31 is formed between the input / output optical fiber 7 and the first and second diffused optical waveguides 8, 8 'by Ti diffusion. That is, one of the input sides of the directional coupler 31 is connected to the input / output optical fiber 7, one of the output sides is connected to the second diffused optical waveguide 8 ', and the other is connected to the first diffused optical waveguide 8 respectively. Have been. Since the configuration is the same as that of the above-described electric field sensor 100 except that the directional coupler 31 is formed, the description is omitted by assigning the same reference numerals to the respective components.

Thus, the incident light from the input / output optical fiber 7 can be branched, and the reflected light from the temperature compensating grating 9 and the wavelength modulator grating 11 can be multiplexed. Grating for wavelength modulator 11 based on light
Wavelength difference from the reflected light from the object. Therefore, the electric field intensity can be measured.

As shown in FIG. 7, an electric field sensor 10000 formed on a substrate 2000 using pattern antennas 60 and 60 'as antennas may be used. Except for the pattern antennas 60 and 60 'and the substrate 2000, the configuration is the same as that of the above-described electric field sensor 100, and a description thereof will be omitted. Thereby, the same effect as the above-described electric field sensor 100 and electric field sensor 1000 can be obtained.

Next, the measurement of the electric field intensity at multiple points using such an electric field sensor will be described. When measuring the electric field strength at multiple points, the measurement signal is wavelength-division multiplexed. In this wavelength multiplex transmission, there are cases where wavelength multiplexing is performed in cascade and cases where wavelength multiplexing is performed in parallel. When wavelength multiplexing is performed in cascade, as shown in FIG.
.. Are connected in series, and the incident light from the main input / output optical fiber 7 connected to the light source is divided by the directional coupler 12 as a branching element at an arbitrary branching ratio, and each electric field is divided. Are made to enter the sensors 100, 100 ',. Specifically, one of the input sides of the directional coupler 12 is connected to the main input / output optical fiber 7, and the other of the output sides is the main transmitting optical light to the plurality of electric field sensors 100 ′. An input / output optical fiber 13 is connected to the other output side, and an input / output optical fiber 14 serving as a trunk for transmitting incident light to the electric field sensor 100 is connected to the other end of the output side. The input / output optical fiber 13 is connected to one of the input sides of the directional coupler 12 ', and the output side of the directional coupler 12' is connected to the main input / output optical fiber 13 'and the electric field sensor 100'. I have. Hereinafter, similarly, the electric field sensors are connected in series.

Each of the electric field sensors 10 connected in series
The reflection wavelengths of 0, 100 ',... Shift the reflection wavelengths by changing the grating intervals of the temperature compensation grating 9 and the wavelength modulator grating 11 provided in the respective electric field sensors 100, 100',. This is adjusted so that the light is reflected at a predetermined wavelength interval.

Each of the electric field sensors 100, 100 ',.
Are combined by the directional couplers 12, 12 ′,... And transmitted to the signal processing unit through the input / output optical fiber 7, and are transmitted to the respective electric field sensors 100 by the band-pass filter of the signal processing unit. , 100 '...
It is configured to be incident on the detector of the signal processing unit. Since the signal processing unit and each electric field sensor are connected by only one optical fiber, the metal part is small and the electric field sensor is electrically insulated, so that the influence on the electromagnetic field is small. The branch element is not limited to the directional coupler, but may be any optical device as long as it can be divided at an arbitrary branch ratio.

On the other hand, when wavelength multiplexing is performed in parallel, as shown in FIG.
0 "... Are connected in parallel, and the incident light from the main input / output optical fiber 7 connected to the light source is equally divided by the star coupler 15 which is a branching element.
0, 100 ', 100 "... More specifically, the input / output optical fiber 7 serving as the main trunk is connected to the input side of the star coupler 15, and the input side is connected to a plurality of output sides branched from the input side. Incoming / outgoing optical fibers 16 and 1 serving as branches
6 ′, 16 ″...
6, 16 ', 16 "...
0, 100 ', 100 "... Note that each of the electric field sensors 100, 100', 10
The reflection wavelength of 0 ″... Is the same as the case of the series connection, the lattice spacing of the temperature compensation grating 9 and the wavelength modulator grating 11 provided in each of the electric field sensors 100, 100 ′, 100 ″. By changing each of them to shift the reflection wavelength, adjustment is made so that the light is reflected at a predetermined wavelength interval.

Also, as in the case of the serial connection, the reflected light from each of the electric field sensors 100, 100 ', 100 "... Is multiplexed by the star coupler 15, and the multiplexed reflected wave is input and output by an optical fiber. 7 and transmitted to the signal processing unit, and each electric field sensor 100, 1
.., And is input to the detector of the signal processing unit. The branch element is not limited to the star coupler 15, and an optical demultiplexing / multiplexing device may be used as long as it can be equally divided.

As described above, since the change in the electric field strength is detected by the wavelength modulation, even if the power of the incident light is reduced, the measurement sensitivity is not affected, so that the method is suitable for multiplex transmission. In the above description of the multipoint electric field strength measurement, the electric field sensor 100 is used. However, the present invention is not limited to this, and the electric field sensor 1, the electric field sensor 10, the electric field sensor 100
It may be 0 or the electric field sensor 10000.

[0036]

EXAMPLES Further, experiments were conducted on the operating performance of the electric field sensor of the present invention under the following conditions. A 3-inch wafer of Z-cut LiNbO3 crystal was used for the substrate, a 60 nm Ti pattern was formed on the substrate, and 1050 ° C. × 10
Thermal diffusion was performed over time to form a Ti-diffused optical waveguide, and a grating for Bragg diffraction of incident light by dry etching (hereinafter referred to as “Bragg grating”) was formed. Further, the wavelength of the incident light source is 1.55 μm and the half width is 1
An EELED (edge-emitter LED) that allows light of 20 nm to enter was used. Each performance was measured using such an electric field sensor.

According to this measurement, the electric field intensity can be measured with the same accuracy when the incident intensity on the electric field sensor is in the range of −18 dBm to −40 dBm, and the half width of the wavelength reflected from the Bragg grating is 0.1 nm. In the following, the performance was recorded with a reflection efficiency of 42%, a wavelength variable range of 0.2 nm or more, and an electric field measurement frequency range of 3 dB bandwidth DC to 1.2 GHz. Therefore, it was found that the measurement accuracy did not decrease even if the incident level was small, so that the effectiveness of the wavelength modulation type electric field sensor in measuring the electric field intensity was proved.

Using the above-mentioned EELED as the incident light source, the incident intensity to the electric field sensor was -18 dBm, and the reflection wavelength from the Bragg grating was prepared at intervals of about 5 nm. As a result, wavelength multiplex transmission by cascade connection of six electric field sensors has become possible. Also, the electric field measurement performance was measured by applying a maximum of 50% level modulation to the light source.
According to this, since it was confirmed that there was no change in measurement accuracy, it was proved that the measurement was not affected by the level fluctuation of the light source and the like as compared with the Mach-Zehnder electric field sensor.

Further, a temperature fluctuation was canceled by providing a Bragg grating for temperature compensation. As a result, the wavelength variation in the operating temperature range of -20 ° C to + 45 ° C was suppressed to 0.0003 nm / ° C.

[0040]

As described above, according to the electric field sensor of the present invention, the change in the electric field intensity is converted into the wavelength modulation by the grating for Bragg diffraction of the incident light. However, without losing the measurement ability, it is possible to measure the electric field strength of an electromagnetic wave propagating in space in the EMC field and detect a signal superimposed on the electromagnetic wave. In addition, since there is no influence of light intensity fluctuation due to disturbance of the light source or the like, measurement error does not occur even when there is much disturbance.

Further, if the temperature compensating grating is used together, the difference between the reference wavelength from the temperature compensating grating and the wavelength from the wavelength modulator grating can be measured as the electric field intensity, so that the environment such as temperature drift can be measured. It is no longer affected by the wavelength fluctuation due to the change.
Further, since a power source is not required, maintenance-free operation is possible, so that a small electric field sensor suitable for remote measurement and also excellent in insulation can be provided.

Further, signals from a plurality of electric field sensors are
Since a transmission system in which wavelength division multiplexing is performed on the optical fiber becomes possible, wavelength division multiplexing transmission of measurement signals whose electric field strengths are measured at multiple points can be easily performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of an electric field sensor of the present invention.

2A is a graph showing characteristics of an incident spectrum of incident light, and FIG. 2B is a graph showing characteristics of a reflection spectrum of a grating for temperature compensation and a grating for a wavelength converter.

FIG. 3 is an explanatory view showing another embodiment of the electric field sensor of the present invention.

FIG. 4 is an explanatory view showing another embodiment of the electric field sensor of the present invention.

5A is a graph showing characteristics of an incident spectrum of incident light, and FIG. 5B is a graph showing characteristics of reflection spectra of a grating for temperature compensation and a grating for a wavelength converter.

FIG. 6 is an explanatory view showing another embodiment of the electric field sensor of the present invention.

FIG. 7 is an explanatory view showing another embodiment of the electric field sensor of the present invention.

FIG. 8 is an explanatory diagram showing a case where wavelength multiplexing is performed in cascade using the electric field sensor of the present invention.

FIG. 9 is an explanatory diagram showing a case where wavelength multiplexing is performed in parallel using the electric field sensor of the present invention.

FIG. 10 is an explanatory view showing a conventional electric field sensor.

[Explanation of symbols]

1, 10, 100, 1000, 10000 ... Electric field sensor 2, 20, 200, 2000 ... Substrate 3, 30, 300, 300 '... Incoming / outgoing optical waveguide 8 ... ..First diffused optical waveguide 8 '... Second diffused optical waveguide 9 ... Grating for temperature compensation 11 ... Grating for wavelength modulator 17, 17' ... ..Pattern electrodes 6, 6 '... Antenna 60, 60' ... Pattern antenna 31 ... Directional coupler

Claims (5)

[Claims] A diffused input / output optical waveguide that receives incident light, emits output light, and changes a refractive index according to the intensity of an applied electric field; An electric field sensor, wherein a grating for a wavelength modulator for Bragg diffracting incident light and an electrode connected to an antenna and provided in close proximity to the grating for a wavelength modulator are formed on a substrate. 2. An input / output optical waveguide that receives incident light and emits output light, and one end of each of the input / output optical waveguides is coupled to the input / output optical waveguide to change a refractive index according to the intensity of an applied electric field. And the second diffused optical waveguide, and the first
A temperature-compensating grating written on the diffused optical waveguide and Bragg-diffraction of one of the branched incident lights; and a Bragg-diffraction of the other incident light written on the second diffused-optical waveguide and branched. An electric field sensor, wherein a grating for a wavelength modulator and an electrode connected to an antenna and provided in close proximity to the grating for a wavelength modulator are formed on a substrate. 3. An incoming / outgoing optical waveguide for receiving incident light and emitting outgoing light, a directional coupler coupled to the incoming / outgoing optical waveguide and branching the incoming light from the incoming / outgoing optical waveguide, and the direction. First and second diffused light guides that are coupled to the directional coupler so that the respective incident lights split by the sexual coupler are respectively incident, and change the refractive index according to the intensity of the applied electric field. A waveguide, a temperature-compensating grating written into the first diffusion-type optical waveguide and Bragg diffracting the one of the branched incident lights, and the other of the other divided and written into the second diffusion-type optical waveguide A wavelength modulator grating for Bragg diffracting the incident light,
An electric field sensor, wherein an electrode connected to an antenna and provided in close proximity to the wavelength modulator grating is formed on a substrate. 4. The electric field sensor according to claim 1, wherein the antenna is formed on the substrate. 5. The electric field sensor according to claim 2, wherein the temperature compensating grating and the wavelength modulator grating have a structure that causes the same change in refractive index with a change in temperature.