JPH07239356A - Photoelectric field sensor - Google Patents

Abstract

PURPOSE:To measure without depending on a direction in which environmental electromagnetic waves such as electromagnetic pulses or the like come, or on polarization components, by connecting a plurality of antennas with modifying electrodes of a plurality of optical modifiers formed on the same crystal substrate. CONSTITUTION:Three sets of phase shift optical waveguides 2 are formed on the surface of a substrate 1 of lithium niobate through thermal diffusion of Ti. Moreover, modifying electrodes 3 are arranged in the vicinity of each optical waveguide 2. An optical modifier is constituted in this manner. Three series of antenna elements 4 are set in directions orthogonal to each other (X, Y, Z directions) at an outer wall of a package 7 incorporating the optical modifiers. The antenna elements 4 are connected to the modifying electrodes 3 of the optical modifiers to constitute the photoelectric field sensor. Intensity of an electric field of polarization components in each of three X-axis, Y-axis, Z-axis directions orthogonal to each other is detected by the photoelectric field sensor of three series independently of each other. Therefore, it is not necessary to change a direction of the sensor for every measurement. Moreover, the intensities in three directions can be measured at one time. In other words, the sensor is not directive and can detect also direction of a source generating electromagnetic waves at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical electric field sensor, which is represented by EMC measurement (noise measurement) and is used for measuring the electric field strength in a specific region.

[0002]

2. Description of the Related Art Information equipment such as computers and communication equipment,
Many electric devices such as robots and other FA devices, automobiles, railways, and other controllers are always at risk of malfunctioning due to electromagnetic noise from the outside.
In the field C, it is important to accurately measure the magnitude of noise that affects the external electromagnetic environment, the noise generated by itself, and the like.

Conventionally, in the measurement of electromagnetic noise as described above, (a) a method of receiving with a normal antenna and guiding it to a measuring instrument with a coaxial cable, and (b) detecting a received signal with an antenna. A method of converting to an optical signal and guiding to a measuring instrument with an optical fiber, (c) converting the electric field intensity to a light intensity using an optical element configured so that the intensity of transmitted light changes according to the electric field intensity, and the above optical There is a method of connecting the element, the light source, and the photodetector connected to the measuring instrument with an optical fiber.

The present invention relates to an optical electric field sensor according to the method (c). In this method, since an optical fiber is used instead of an electric cable such as a coaxial cable, there is no problem that the electric field distribution is disturbed or noise is mixed in the middle of the cable. Further, since it does not require an electric circuit or a battery, it is small in size, and further has high electric field detection sensitivity and high response speed.

Further, in this method, a crystal having an electro-optical effect is used as an optical element for converting the electric field intensity into a change in intensity of transmitted light. The structure of the device is that the light emitted from the optical fiber is made into parallel light by the lens and passes through the crystal with a small antenna attached, the polarization state is changed by the electric field in the crystal, and the intensity is changed by the analyzer, and then again. There are a bulk type element coupled to an optical fiber and a waveguide type element that constitutes the above optical element by an optical waveguide provided on a crystal. Usually, the waveguide type has a detection sensitivity 10 times or more higher than that of the bulk type.

FIG. 5 shows a configuration example of a conventional optical electric field sensor using a waveguide type element. An incident optical waveguide 52 by diffusing titanium on a lithium niobate crystal substrate 1 cut out at a right angle to the c-axis, and two phase shift optical waveguides 5 branched therefrom.
3, and the two phase shift optical waveguides are coupled again to form the emission optical waveguide 56. Incident optical waveguide 5
An input optical fiber 57 is coupled to the incident end of No. 2 and an output optical fiber 58 is connected to the outgoing end of the outgoing optical waveguide 56. Further, a pair of modulation electrodes 3 is installed on the phase shift optical waveguide 53 and connected to the antenna element 4. In FIG. 5, the incident light 11 from the input optical fiber 57 enters the incident optical waveguide 52, and then the energy is split into two phase shift optical waveguides 53. When an electric field is applied, the modulation electrode 3 is moved by the antenna element 4.
A voltage is induced in the two phase shift optical waveguides 53 to generate electric fields in opposite directions. As a result, a change in refractive index occurs due to the electro-optical effect, and a phase difference corresponding to the magnitude of the applied electric field occurs between the light waves propagating through the two phase shift optical waveguides 53, and they merge to the output optical waveguide 56. When combined, the light intensity changes due to interference. That is, the intensity of the emitted light 12 emitted to the output optical fiber 58 changes depending on the applied electric field intensity, and the intensity of the applied electric field can be measured by measuring the change in the optical intensity with a photodetector.

[0007]

When an electric field is measured using an optical electric field sensor, it is often impossible to predict the arrival direction or polarization plane of an environmental electromagnetic wave such as an electromagnetic pulse to be measured. In this case, the optical electric field sensor must be arranged in various directions during measurement, and the maximum intensity direction must be found and measured. Further, since the dipole antenna that constitutes the optical electric field sensor has a strong directivity, when the electromagnetic wave generation sources are in multiple directions, the electric field strengths are measured in three directions orthogonal to each other at a large number of measurement points,
It is necessary to analyze, and there are problems in handling and reliability of measurement.

The present invention has been made to solve the above problems.
Provide a compact and easy-to-manufacture optical electric field sensor that does not need to change the receiving direction each time it is measured and can perform measurement without depending on the direction of arrival of environmental electromagnetic waves such as electromagnetic pulses to be measured or polarization components. .

[0009]

In order to achieve the above object, a first invention is an incident optical waveguide formed on a crystal substrate exhibiting an electro-optical effect, and two phase shifts branched from the incident optical waveguide. In an optical electric field sensor including an optical waveguide, an output optical waveguide where the two phase shift optical waveguides merge, and a modulation electrode formed in the vicinity of the phase shift optical waveguide, a plurality of independent optical modulations are provided on the same crystal substrate. And a plurality of antennas having different directivities are connected to the respective modulation electrodes to form an optical electric field sensor.

According to a second aspect of the invention, an incident optical waveguide formed on a crystal substrate exhibiting an electro-optical effect, two phase shift optical waveguides branched from the incident optical waveguide, and an exit where the two phase shift optical waveguides merge. An optical electric field sensor comprising an optical waveguide and a modulation electrode formed in the vicinity of a phase shift optical waveguide, characterized in that a pair of antennas arranged orthogonal to each other in three directions is connected to the modulation electrode. Is an optical electric field sensor.

[0011]

The first aspect of the present invention provides an optical electric field sensor capable of coping with an omnidirectional electromagnetic wave generation source, and the second aspect of the invention provides a multi-directional optical electric field sensor.

First, in the first aspect of the invention, there is a directivity
Set a pair of dipole antennas in three orthogonal axes (X, Y, Z
Axis), and each input is led separately to the modulation electrodes of three optical modulators independently formed on the same substrate. As a result, each electric field sensor measures each polarization component depending on the directivity of each antenna, and the three electric field sensors enable omnidirectional measurement. The optical electric field sensor with this configuration has features such as small size, easy manufacture, and uniform characteristics, as compared with a case where three individual optical electric field sensors according to the prior art are simply assembled.

Further, in the second invention, an electric field sensor having a multi-directional function is provided by introducing a set of antennas arranged in three directions orthogonal to each other to a modulation electrode of a single optical modulator. obtain. The electric field sensor of this type is
It is possible to simultaneously measure polarization components in a plurality of directions without increasing the size of the device, and improve the measurement efficiency.

[0014]

EXAMPLES The present invention will be described below with reference to examples.

(Embodiment 1) FIG. 1 shows the configuration of an optical modulator according to an embodiment of the first invention. Lithium niobate (LiNbO ₃ ) having the property of electro-optic effect (hereinafter referred to as LN
That is, three sets of phase shift optical waveguides 2 are formed on the surface of a crystalline X substrate 1 by thermal diffusion of Ti, and modulation electrodes are arranged in the vicinity of the phase shift optical waveguides 2 to form an optical modulator. To do. The light entering and exiting the optical waveguide of each optical modulator is introduced and output by the incident optical waveguide and the outgoing optical waveguide for each independently formed optical modulator. As shown in FIG. 2, the polarization maintaining optical fiber 5 is connected to the light incident side so that the TE wave is input, and the single mode optical fiber 6 is connected to the light emitting side. The antenna element 4 is provided on the outer wall of the package 7 containing the optical modulator,
Three series are arranged in directions (X, Y, Z directions) orthogonal to each other and connected to the modulation electrodes of the respective optical modulators to form an optical electric field sensor.

As a result, the electric field strengths of the respective polarization components in the three directions of the X, Y, and Z axes which are orthogonal to each other are detected by the independent three series of optical electric field sensors, so that the direction is changed at each measurement. It is not necessary and it is possible to measure simultaneously. That is, it has no directivity and at the same time has a function of detecting the direction of the electromagnetic wave generation source.

(Embodiment 2) FIG. 3 shows the configuration of an optical modulator according to another embodiment of the first invention. LN crystal Z substrate 1
Three sets of phase-shifting optical waveguides 2 are formed on the surface of by thermal diffusion of Ti, and the modulation electrode 3 is arranged on the optical waveguides. As shown in the figure, a structure is formed in which one incident light is divided into three sets of phase shift optical waveguides and one optical waveguide into four optical branch circuits, and the incident light is guided to the optical waveguides of three optical modulators. And A constant polarization optical fiber 5 (see FIG. 2) is connected to the light incident side so that the TM wave is input, and a single mode optical fiber 6 (see FIG. 2) is connected to the light emitting side. As in the first embodiment, as shown in FIG. 2, the antenna elements 4 are arranged on the outer wall of the package 7 containing the optical modulator in three series in the directions orthogonal to each other, and the modulation electrodes of the respective optical modulators are arranged. To form an optical electric field sensor.

Since the electric field strengths of the respective polarization components in the three directions of the X, Y, and Z axes which are orthogonal to each other are detected by the independent three-series optical electric field sensors, it is not necessary to change the direction every measurement. , And it is possible to measure simultaneously. That is, it has no directivity and at the same time has a function of detecting the direction of the electromagnetic wave generation source. The other one of the branched lights is an independent outgoing light, which can be used for monitoring.

(Embodiment 3) FIG. 4 shows the configuration of an optical modulator according to an embodiment of the second invention. A set of phase shift optical waveguides 2 is formed on the surface of an X substrate 1 of LN crystal by thermal diffusion of Ti, and modulation electrodes are arranged in the vicinity of the optical waveguides to form an optical modulator. Light entering and exiting the optical waveguide of the optical modulator is introduced and output by the incident optical waveguide and the outgoing optical waveguide that are respectively formed.

A constant polarization optical fiber 5 (see FIG. 2) is connected to the light incident side so that the TE wave is input, and a single mode optical fiber 6 (see FIG. 2) is connected to the light emitting side. Similar to the first embodiment, the antenna element 4
As shown in FIG. 2, is a package 7 containing an optical modulator.
An optical electric field sensor having a multi-directional function is configured by connecting a set of antennas, which are arranged in three directions orthogonal to each other on the outer wall of, to the modulation electrode 3 of a single optical modulator.

[0021]

As described above, the present invention realizes a small-sized and easy-to-manufacture optical electric field sensor, which makes it unnecessary to change the receiving direction each time measurement is performed, and to measure environmental electromagnetic waves such as electromagnetic pulses to be measured. It enables measurement that does not depend on the direction of arrival or the polarization component.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an optical modulator according to a first invention.

FIG. 2 is an explanatory diagram showing a configuration of an optical electric field sensor including antenna elements according to the first and second inventions.

FIG. 3 is an explanatory diagram showing another configuration example of the optical modulator according to the first invention.

FIG. 4 is an explanatory diagram showing a configuration of an optical modulator according to a second invention.

FIG. 5 is a configuration diagram of a conventional optical electric field sensor using a waveguide type element.

[Explanation of symbols]

1 (LiNbO ₃ ) substrate 2 phase shift optical waveguide 3 modulation electrode 4 antenna element 4X X-axis direction dipole antenna 4Y Y-axis direction dipole antenna 4Z Z-axis direction dipole antenna 5 constant polarization optical fiber 6 single mode optical fiber 7 package 11 incident light 12 outgoing light 52 incident optical waveguide 53 phase shift optical waveguide 56 outgoing optical waveguide 57 input optical fiber 58 output optical fiber

Claims (2)

[Claims] 1. An incident optical waveguide formed on a crystal substrate exhibiting an electro-optical effect, two phase shift optical waveguides branched from the incident optical waveguide, an outgoing optical waveguide in which the two phase shift optical waveguides join, and In an optical electric field sensor including an optical modulator including a modulation electrode formed in the vicinity of the phase shift optical waveguide and an antenna connected to the modulation electrode, a plurality of independent optical modulations are provided on the same crystal substrate. And a plurality of antennas having different directivities are connected to respective modulation electrodes to form an optical electric field sensor. 2. An incident optical waveguide formed on a crystal substrate exhibiting an electro-optical effect, two phase shift optical waveguides branched from the incident optical waveguide, an outgoing optical waveguide in which the two phase shift optical waveguides join, and An optical electric field sensor including an optical modulator formed of a modulation electrode formed in the vicinity of the phase shift optical waveguide and an antenna connected to the modulation electrode, and a pair of antennas arranged orthogonal to each other in three directions. Is connected to the modulation electrode, and an optical electric field sensor is provided.