JP5163850B2 - Electromagnetic field measuring device - Google Patents

Description

  The present invention relates to an electromagnetic field measuring apparatus capable of measuring the strength of each of an electric field and a magnetic field at a certain position, and in particular, an electromagnetic field using an electro-optic crystal irradiated with laser light and a magneto-optic crystal as an electromagnetic field probe. It relates to a measuring device.

Conventionally, as an electromagnetic field measuring apparatus, a measuring apparatus having an antenna as an electromagnetic field sensor (or electromagnetic field probe) at the tip is known. For example, a loop-type magnetic field measurement device that provides a loop antenna at the tip and detects a magnetic field by the law of electromagnetic induction, and an electric field measurement device that has a dipole antenna at the tip are known. There has also been reported an electromagnetic field measurement apparatus that enables simultaneous measurement of an electric field and a magnetic field by performing appropriate signal processing on a signal generated by an electromagnetic field induced by one antenna.
In addition, an electro-optic (EO) material or a magneto-optic (MO) material is used as an electromagnetic field sensor, and an optical measurement device such as a laser and a photoelectric magnetic field measurement system combining these materials are known. This has been used to detect electromagnetic waves generated from circuits or electronic devices. The sensor using the optical material has excellent advantages such as high-speed (broadband) measurement and high spatial resolution measurement that hardly disturb the generated electromagnetic field because no metal is used.
Among those using electro-optic materials and magneto-optic materials, recently, measuring devices built on the basis of optical fiber optics have attracted attention for high performance and good convenience. It is expected that a measurement apparatus using an optical crystal having the above (for example, see Non-Patent Document 1) can constitute a measurement apparatus having both high spatial resolution and high sensitivity.
S. Wakana, T. Ohara, M. Abe, E. Yamazaki, M. Kishi, and M. Tsuchiya: “Fiber-Edge Electrooptic / Magnetooptic Probe for Spectral-Domain Analysis of Electromagnetic Field”, IEEE Trans. Microwave Theory Tech. , Vol. 48, No. 12, pp. 2611-2616 (Dec. 2000).

Conventionally, in most cases, an electric field measurement device is selected for electric field measurement, and a measurement device is selected for magnetic field measurement according to the magnetic field measurement device and the measurement object. In such a case, if you want to measure both electric and magnetic fields, it will take time to use each measuring device, it will be costly, and you will not know accurate information on both the electric and magnetic fields at one point. There was a problem.
If the method of performing simultaneous electric field / magnetic field measurement by signal processing using one antenna as described above is used, the above-mentioned problem is solved. However, in the case of measurement using an antenna, the measured electromagnetic field is disturbed because the antenna is made of metal, and particularly in the measurement of high-frequency electromagnetic fields, in unintended locations due to electromagnetic coupling (locations other than the sensor unit) As a result of the signal being induced and detected, accurate measurement is difficult.
An object of the present invention is to provide a photoelectric magnetic field measuring apparatus capable of suppressing the disturbance of an electromagnetic field to be measured as much as possible using a laser beam and an optical crystal and accurately measuring the relative strengths of the electric field and the magnetic field at a certain position. Is to do.

In order to achieve the above object, according to the present invention, there is provided an electromagnetic field measuring apparatus having an electromagnetic field sensor formed by laminating an electro-optic material layer and a magneto-optic material layer, wherein the electromagnetic field sensor is emitted from a laser light source. In the spectrum showing the wavelength of the laser beam incident on the electromagnetic field sensor and the respective resonance characteristics of the electro-optic material layer and the magneto-optic material layer, the magneto-optic material layer is An electromagnetic field measuring apparatus, wherein the electro-optic material layer shows a mountain at a wavelength where the magneto-optical material layer shows a valley, or the wavelengths showing both valleys coincide with each other . Is provided.

In order to achieve the above object, according to the present invention, there is provided an electromagnetic field measuring apparatus having an electromagnetic field sensor formed by laminating an electro-optic material layer and a magneto-optic material layer on an end face of an optical fiber. In the spectrum showing the wavelength of the laser beam incident on the electromagnetic field sensor emitted from the light source and the respective resonance characteristics of the electro-optic material layer and the magneto-optic material layer, the electro-optic material layer has a trough wavelength. The magneto-optical material layer shows a peak, and the electro-optical material layer shows a peak at a wavelength where the magneto-optical material layer shows a valley, or the wavelengths showing both valleys coincide with each other. An electromagnetic field measuring device is provided.

  Preferably, the electromagnetic field measurement device includes an analyzer, an optical circulator that sends out the emitted light of the laser light source to the electromagnetic field sensor and sends the return light to the analyzer, and the emitted light of the analyzer And a radio frequency spectrum analyzer for detecting an output signal of the photodetector.

The first effect is that the measurement time can be shortened and the cost can be reduced by measuring each of the electric field and the magnetic field at a certain position with one measuring device.
The second effect is that each of an electric field and a magnetic field at a certain position can be measured with high spatial resolution without disturbing the measured electromagnetic field.
The third effect is that the power at a certain position can be measured by appropriate selection of the electro-optic material and the magneto-optic material.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of an electromagnetic field measuring apparatus according to the present invention. As shown in FIG. 1, the measurement apparatus according to the present embodiment includes a laser light source 101 that can continuously oscillate with a variable wavelength laser, a fiber amplifier 102 that amplifies the light emitted from the laser light source 101, and the light emitted from the laser light source 101. The polarization controller 103 for adjusting the plane of polarization of the light, the electromagnetic field sensor 105, the analyzer 106, and the light emitted from the polarization controller 103 are sent to the electromagnetic field sensor 105 and the return light from the electromagnetic field sensor 105 is sent to the analyzer 106. An optical circulator 104 to be transmitted, a photodetector 107 for detecting light intensity, an optical fiber 109 connecting these optical elements, a radio frequency spectrum analyzer 108 for detecting an electric signal output from the photodetector 107, a photodetector 107 and a radio Connection between frequency spectrum analyzer 108 Composed of the signal line 110.. Here, reference numeral 100 denotes a microstrip line that is an example of an object to be measured.
Here, as shown in FIG. 2, the electromagnetic field sensor 105 of the present embodiment includes a stack of an electro-optic material layer 11 composed of an electro-optic crystal and a magneto-optic material layer 12 composed of a magneto-optic crystal. It is composed by the body. The tip of the optical fiber 109 extending from the optical circulator 104 is bonded to the surface of the electro-optical material layer 11 via, for example, a transparent adhesive.

  Next, the operation of the electromagnetic field measurement apparatus according to this embodiment will be described. The wavelength range of light emitted from the laser light source 101 that can continuously oscillate with the variable wavelength laser is, for example, 1500 nm to 1600 nm. The light of each wavelength is amplified by the fiber amplifier 102 and then enters the electromagnetic field sensor 105 through the polarization controller 103 and the optical circulator 104. A part of the incident light is reflected by the surface of the electromagnetic field sensor 105, but the rest is incident on the electromagnetic field sensor 105. The light incident on the electromagnetic field sensor is subjected to multiple reflections between the upper surface and the material layer interface, between the material layer interface and the bottom surface, and between the upper surface and the bottom surface, and then is emitted from the electromagnetic field sensor 105 and returns to the optical fiber again. The return light from the electromagnetic field sensor 105 passes through the optical circulator 104 and then through the analyzer 106 and is then detected by the photodetector 107. The electrical signal output from the photodetector 107 is detected by the radio frequency spectrum analyzer 108.

  The light incident on the electromagnetic field sensor 105 disposed in the environment to which the electric field / magnetic field is applied changes its polarization in the process of passing through the material layer due to the refractive index of the electro-optic material layer 11 being changed by the electric field. The state is modulated. Further, the plane of polarization of light transmitted through the magneto-optical material layer 12 changes depending on the strength of the applied magnetic field. The polarization modulation by the electromagnetic field sensor 105 applied to the incident light is converted into a light intensity change by the analyzer 106. By detecting this change by the photodetector 107 and the radio frequency spectrum analyzer 108, an electric field and a magnetic field are measured. The reason why the electric field and the magnetic field can be measured separately will be described below.

  FIG. 3 shows a reflection spectrum obtained when an electro-optic material layer and a magneto-optic material layer having different refractive indexes and thicknesses exist independently, respectively, and laser light is incident on the electro-optic material layer or the magneto-optic material layer. Represented by solid and dotted lines. In general, the spectrum has a so-called resonance characteristic in which peaks and valleys appear alternately, but the electric field sensor or magnetic field sensor functions as a highly sensitive sensor when the laser wavelength becomes a wavelength corresponding to the valley. The reason is that the degree of polarization modulation increases when the optical material is exposed to an electromagnetic field because multiple reflection of light occurs in the optical material layer at the wavelength. On the other hand, the electro-optic material layer and the magneto-optic material layer do not function as an electromagnetic field sensor at a wavelength corresponding to a mountain. The reason is that, at such a wavelength, light is almost reflected on the surface of the optical material layer. Therefore, even when the optical material is exposed to an electromagnetic field, the degree of light modulation is small, and a signal due to an electromagnetic field exceeding the noise level cannot be detected. The present invention is a sensor that detects each of an electric field and a magnetic field at a certain place by utilizing the characteristics of sensor sensitivity associated with such optical resonance characteristics. In other words, the electro-optic material layer and the magneto-optic material layer are laminated, and the electromagnetic field is generated by setting the resonance wavelength of the electro-optic material to the electric field detection and the resonance wavelength of the magneto-optic material to the wavelength of the incident laser light for the magnetic field detection. To detect. However, these wavelengths need to be in the relationship between peaks and valleys due to the characteristics of both materials (wavelengths A and B in FIG. 3).

  The sensor of the present invention can also measure the relative strength of electric power at a certain position. For this purpose, the laser light source wavelength may be set to the wavelength at the position C in FIG. 3, for example. At this time, since light is multiple-reflected both in the electro-optic material layer and in the magneto-optic material layer, the degree of modulation increases due to both the electric field and the magnetic field, so that the relative strength of the electromagnetic field can be measured. As can be seen from the equation of the pointing vector, the intensity of both the electric field and the magnetic field is related to the electric power. Therefore, the relative intensity of the electric power can be obtained by setting the light source wavelength to the above wavelength. However, it is necessary to select or design the material in advance so that the detection electric field component and the magnetic field component of the electro-optic material layer and the magneto-optic material layer are orthogonal to each other.

  When a sensor in which an electro-optic material layer and a magneto-optic material layer are laminated is used, the resonance wavelength in the laminate is not only the resonance wavelength in the reflection spectrum when each optical material layer is put into an electromagnetic field alone. Observed. Therefore, an electric field or a magnetic field can be measured by selecting the resonance wavelength of each optical material layer alone from the resonance wavelengths of the observed spectrum. That is, the electric field strength can be detected by measuring the intensity at the wavelength A, and the electric field strength can be detected by measuring the intensity at the wavelength B. Further, the power can be detected by measuring the intensity at the wavelength of C. Thus, when using the measuring apparatus of the present invention, it is necessary to obtain in advance each reflection spectrum when each optical material layer is present alone. That is, it is necessary to know in advance at which wavelength the electro-optic material layer and the magneto-optic material layer resonate.

  Although the electromagnetic field sensor 105 in the above-described embodiment is a simple laminate of an electro-optic material layer and a magneto-optic material layer, the electromagnetic field sensor 105 is not limited to such a form in the present invention. For example, as shown in a perspective view in FIG. 4, a transparent dielectric layer 13 as a spacer may be provided between the electro-optic material layer 11 and the magneto-optic material layer 12. When the refractive indexes of the electro-optic material layer and the magneto-optic material layer are close to each other, there is usually no resonance independently in each material. It is difficult to measure. In such a case, as shown in FIG. 4, by providing a dielectric layer 13 between both optical material layers, resonance at wavelengths corresponding to A and B in FIG. 3 can be generated.

  Further, as shown in FIGS. 5 and 6, the laminate including the electro-optic material layer 11 and the magneto-optic material layer 12 may be formed on the end face of the optical fiber 14 having the core 14 a and the clad 14 b. In addition, a transparent dielectric layer 14 as a spacer may be present between both optical material layers. As a method of forming an optical material on the end face of the optical fiber, for example, an aerosol deposition (AD) method exists. In the AD method, an electro-optic material layer of 1 μm or more, a magneto-optic material layer, and a transparent oxide dielectric material can be formed on the end face of the optical fiber, and the respective materials can be sequentially laminated. When the electromagnetic field sensor 105 with the optical fiber is configured as described above, the optical fiber 14 of the electromagnetic field sensor 105 is connected to the optical fiber 109 extending from the optical circulator 104 via the optical connector.

  Further, as shown in FIGS. 7 and 8, even if the light reflecting film 15 is formed on the back surface of the magneto-optical material layer 12 or on the surface of the electro-optical material layer 11 and the back surface of the magneto-optical material layer 12. Good. The light reflecting film 15 is a dielectric multilayer film, and can be formed by, for example, an ion plating method. By providing the light reflecting film, the interference effect in the optical material layer can be further increased (because the resonance Q value can be increased), so that the degree of light modulation is increased and the sensor sensitivity can be increased.

The electro-optic material layer can be formed using lead zirconate titanate or lead zirconate titanate to which lanthanum is added, and the magneto-optic material layer is any one of garnet structure, spinel structure, and hexagonal structure. It can be formed using the ferrite which has.
Next, embodiments of the present invention will be described with reference to the drawings.

  In Example 1 of the present invention, the electromagnetic field sensor 105 shown in FIG. 6 was used. FIG. 9 is a calculated value of a reflection spectrum for explaining the first embodiment of the present invention. In the figure, the dotted line is the spectrum when an electro-optic material layer with a refractive index of 2.5 and a thickness of 13 μm is formed on the end face of the optical fiber, and the chain line is the case when a magneto-optic material layer with a refractive index of 2.35 and a thickness of 5 μm is formed. Represents the spectrum. A solid line represents a spectrum when the electro-optic material layer, a refractive index of 1.82, a transparent dielectric layer having a thickness of 11 μm, and the magneto-optic material layer are sequentially formed on the end face of the optical fiber. The wavelength at the position D in the figure corresponds to the position of the valley on the dotted line, the peak on the broken line, and the valley on the solid line. Therefore, when the sensor is prepared so as to satisfy the above conditions, and arranged at the electromagnetic field measurement point and the wavelength of the incident light is set to the D position, resonance occurs in the electro-optic material layer, so that the electric field can be measured. Further, the wavelength at the position E in the figure corresponds to the position of the peak in the dotted line, the valley in the broken line, and the valley in the solid line. Therefore, when the sensor is at the same place and the wavelength of incident light is at the E position, resonance occurs in the magneto-optical material layer, so that the magnetic field can be measured. That is, the design values of the electro-optic material layer, the magneto-optic material layer, and the dielectric layer are set as described above and sequentially formed on the end face of the optical fiber, so that each of the electric field and the magnetic field at a certain place can be measured. Is possible. The sensor according to the present embodiment can be formed by sequentially laminating lead zirconate titanate as an electro-optic material layer, optical glass as a transparent dielectric material, and yttrium iron garnet as a magneto-optic material layer, for example, using an AD method.

  In Example 2, the electromagnetic field sensor 105 shown in FIG. 5 was used. FIG. 10 is a calculated value of the reflection spectrum for explaining the second embodiment of the present invention. In the figure, the dotted line is the spectrum when an electro-optic material layer with a refractive index of 2.5 and a thickness of 10 μm is formed on the end face of the optical fiber, and the chain line is the case when a magneto-optic material layer with a refractive index of 2.35 and a thickness of 6 μm is formed. Represents the spectrum. A solid line represents a spectrum when the electro-optic material layer and the magneto-optic material layer are sequentially formed on the end face of the optical fiber. The wavelength at the position F in the figure corresponds to the position of the valley in the dotted line, the valley in the broken line, and the valley in the solid line. Therefore, when the sensor is created so as to satisfy the above conditions, and arranged at the electromagnetic field measurement point and the wavelength of the incident light is set to the F position, resonance occurs in both the electro-optic material layer and the magneto-optic material layer. Occurs, so that power can be measured. That is, it is possible to measure electric power at a certain place by sequentially forming the design values of the electro-optic material layer and the magneto-optic material layer as described above and sequentially forming them on the end face of the optical fiber. The sensor of the present embodiment can be formed by sequentially laminating lead zirconate titanate as the electro-optic material layer and yttrium iron garnet as the magneto-optic material layer, for example, using the AD method.

  As an application example of the present invention, there is an electromagnetic field measuring device as a mounting electrical design support tool or a circuit failure diagnosis tool. That is, it is possible to perform electromagnetic field measurement using the measuring apparatus of the present invention on an LSI or in the vicinity of an LSI package, to acquire information for feedback to electrical design, or to perform circuit operation verification.

The block diagram which shows one Embodiment of the electromagnetic field measuring apparatus of this invention. The perspective view of the electromagnetic field sensor used in one Embodiment of the electromagnetic field measuring apparatus of this invention. The schematic diagram of a reflection spectrum when light injects into each of a magneto-optical material layer and an electro-optical material layer. The perspective view which shows the example of a change of the electromagnetic field sensor used for the electromagnetic field measuring apparatus of this invention. The schematic diagram which shows the example of a change of the electromagnetic field sensor used for the electromagnetic field measuring apparatus of this invention. The schematic diagram which shows the example of a change of the electromagnetic field sensor used for the electromagnetic field measuring apparatus of this invention. The schematic diagram which shows the example of a change of the electromagnetic field sensor used for the electromagnetic field measuring apparatus of this invention. The schematic diagram which shows the example of a change of the electromagnetic field sensor used for the electromagnetic field measuring apparatus of this invention. The reflection spectrum for demonstrating Example 1 of this invention. The reflection spectrum for demonstrating Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Electro-optic material layer 12 Magneto-optic material layer 13 Dielectric layer 14 Optical fiber 14a Core 14b Clad 15 Light reflection film 100 Microstrip line 101 Laser light source 102 Fiber amplifier 103 Polarization controller 104 Optical circulator 105 Electromagnetic field sensor 106 Analyzer 107 Photo detector 108 Radio Frequency Spectrum Analyzer 109 Optical Fiber 110 Signal Wiring

Claims (8)

An electromagnetic field measuring apparatus having an electromagnetic field sensor formed by laminating an electro-optic material layer and a magneto-optic material layer, the wavelength of incident laser light entering the electromagnetic field sensor emitted from a laser light source and the electro-optics In the spectrum showing the respective resonance characteristics of the material layer and the magneto-optical material layer, the wavelength of the electro-optical material layer indicates a valley and the wavelength of the magneto-optical material layer indicates a valley at a wavelength where the electro-optical material layer indicates a valley. In the electromagnetic field measuring apparatus, the electro-optic material layer shows a mountain or the wavelengths showing the valleys of the two coincide with each other . An electromagnetic field measurement apparatus having an electromagnetic field sensor formed by laminating an electro-optic material layer and a magneto-optic material layer on an end face of an optical fiber, the wavelength of incident laser light entering the electromagnetic field sensor emitted from a laser light source In the spectrum showing the respective resonance characteristics of the electro-optic material layer and the magneto-optic material layer, the magneto-optic material layer shows a mountain at the wavelength where the electro-optic material layer shows a valley, and the magneto-optic material layer The electromagnetic field measuring apparatus according to claim 1, wherein the electro-optic material layer has a peak at a wavelength indicating a valley, or the wavelengths indicating the valleys of the two coincide with each other . An analyzer, an optical circulator for sending the emitted light of the laser light source to the electromagnetic field sensor and sending the return light to the analyzer, a photodetector for detecting the emitted light of the analyzer, and an output signal of the photodetector The electromagnetic field measurement apparatus according to claim 1, further comprising a radio frequency spectrum analyzer for detection. Between the laser light source and the optical circulator, a polarization controller that adjusts a polarization plane of the emitted light of the laser light source, or a polarization controller that adjusts a polarization plane of the emitted light of the laser light source is disposed. The electromagnetic field measuring apparatus according to claim 3, wherein 5. The electromagnetic field measuring apparatus according to claim 1, wherein a dielectric layer is provided as a third material layer between the electro-optic material layer and the magneto-optic material layer. A light reflecting film is formed on one or both of the surface of the electro-optic material layer opposite to the magneto-optic material layer and the surface of the magneto-optic material layer opposite to the electro-optic material layer. The electromagnetic field measurement apparatus according to claim 1, wherein the electromagnetic field measurement apparatus is an electromagnetic field measurement apparatus. The electromagnetic field measuring apparatus according to claim 1, wherein the electro-optic material layer and the magneto-optic material layer are formed by an aerosol deposition method. The material of the electro-optic material layer is lead zirconate titanate, lead zirconate titanate to which lanthanum is added, and the material of the magneto-optic material layer is ferrite having a garnet structure, spinel structure, or hexagonal structure The electromagnetic field measuring apparatus according to claim 1.

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