JPH11183540A - Sensor head and electric field sensor utilizing magneto-optic effect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend temperature range for operation, and to permit reliable operation under a severe temperature condition by arranging a Peltier element having a heat-generating function and heat-abobing function and a light modulating element, integrating them or in close vicinity. SOLUTION: On a board 21 made of an X-board of lithium niobate crystals representing an electrochemical effect, a Peltier element 2 and a light modulating element 4 having an interference-type photowaveguide and a modulating electrode are integrated or arranged in close vicinity, and a sensor head 1 is formed. A light having passed an optical fiber 6 connected by an optical connector 16 and the photowaveguide, is stretch-modulated according to an applied voltage, and emitted from an optical connector 17. On this occasion, the Peltier element 2 generates/absorbs heat according to the direction and magnitude of a current from a photo electric converter 3, and controls the temperature of the light modulating element 4. Consequently, the temperature range of the light modulating element 4 extends up to an extent of -40 to +80 deg.C, and the operable temperature range of the sensor head 1 extends, and its use extension can be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor head using an optical modulation element for modulating a voltage signal into a light intensity signal, and an environment where the temperature fluctuates, such as outdoors, or an environment exceeding a certain temperature range. The present invention relates to an optical electric field sensor used.

[0002]

2. Description of the Related Art An optical modulator using an optical modulator composed of an interference type optical waveguide element formed on a crystal substrate exhibiting an electro-optical effect such as lithium niobate is used for measuring an electric field in a space or for a specific broadcast. It is used as a sensor head of an optical electric field sensor for receiving waves.

An electric field intensity signal input from the antenna of the optical electric field sensor to the sensor head is modulated into a light intensity signal. In addition, the optical electric field sensor does not require a power supply to operate the sensor head, and the optical intensity signal can be transmitted over a long distance over an optical fiber with little attenuation. A major feature is that there is no exchange.

[0004] Therefore, a sensor head using an optical waveguide type light modulation element is suitable for being incorporated in a system that operates for a long period of time, such as a fixed-point electric field measurement, a broadcast wave reception system, or a broadcast wave relay system.

[0005]

It is desirable that an optical modulator used as a sensor head for an optical electric field sensor operates in a wide temperature range, like many other electronic components. This light modulation element is designed so that the temperature dependence of the intensity of emitted light (hereinafter referred to as an optical bias) when no voltage is applied is small, and is usually designed and manufactured to operate at -10 to + 60 ° C. I was

However, the operating environment of a system such as an optical electric field sensor which is operated outdoors for a long period of time often exceeds the applicable operating temperature range at the time of the above design.

Therefore, the present invention provides a sensor head for an optical electric field sensor that provides more reliability in operation under severe temperature conditions, expands the operation temperature range than before, and does not depend on the environmental temperature, and the sensor head. Another object of the present invention is to provide an optical electric field sensor using the same.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a sensor head using a light modulation element in which incident light is modulated to the intensity of emitted light in accordance with an applied voltage, in which a light is generated by irradiation light. A sensor head that uses a photoelectric converter as a power source and is integrated with a functional element that generates and absorbs heat, or the functional element is disposed close to the functional element.

According to the present invention, there is provided a sensor head that receives light emitted from a light source, modulates the light intensity according to the applied electric field intensity, and emits the light, a receiving antenna that receives an electric field and inputs the same to the sensor head, and a sensor head. The sensor head is used in a photodetector that detects emitted light and converts it into an electric signal, and an optical electric field sensor that includes a light source and a sensor head, and an optical fiber that optically connects the sensor head and the photodetector, respectively. This is an optical electric field sensor.

In the optical electric field sensor of the present invention, the irradiation light source of the photoelectric converter and the light source of the light modulator may be independent or integrated, and at least one of them is a semiconductor-excited YAG laser light source. .

Further, in the optical electric field sensor according to the present invention, the irradiation light source of the photoelectric converter and the light source of the optical modulator are integrated,
Irradiation light from the photoelectric converter is configured to be incident through an optical attenuator.

Furthermore, in the optical electric field sensor according to the present invention,
The sensor head is composed of an element to which an electric field is applied and an element to which no electric field is applied, and the emitted light of the light source is respectively incident on the element to which the electric field is applied and the element to which the electric field is not applied. The output signal of the photodetector relating to the element to which the electric field is not applied and which is incident on the connected photodetector is fed back so as to control the output intensity of the irradiation light source or the optical attenuator.

In the present invention, an element to which an electric field is applied and an element to which no electric field is applied are formed on the same substrate.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a sensor head according to the present invention. In FIG. 1, the sensor head 1
The light modulation device 4 and the Peltier device 2 each having an interference type optical waveguide and a modulation electrode formed on a substrate 21 made of a lithium niobate crystal X plate exhibiting an electro-optic effect are integrally formed. Optical connector 1 of this sensor head 1
Light that is connected by 6 and enters the optical waveguide through the optical fiber 6 is intensity-modulated in accordance with the applied voltage, and is emitted from the optical connector 17.

Further, the Peltier element 2 generates and absorbs heat in accordance with the direction and magnitude of the current from the photoelectric converter 3 passing through the Peltier element 2, and can control the temperature of the light modulation element 4. The sensor head 1 receives output light of a semiconductor-excited YAG laser light source (not shown) as irradiation light,
A photoelectric converter for converting to a direct current is housed, and serves as a power supply for the Peltier device 2.

FIG. 2 is a sectional view showing a specific structure of the sensor head according to the embodiment shown in FIG. In FIG. 2, when the Peltier device 2 absorbs heat on one surface, it generates heat on the opposite surface. Therefore, the back surface of the Peltier device 2 attached to the package 9 is exposed to free space, or a heat supply / heat absorber. Preferably.

Since the light modulation element 4 needs to be protected mechanically, it is usually housed in a package 9. FIG.
Here, the Peltier element 2 is fixed to the outer surface of the package 9 and is configured to maintain the temperature inside the package 9 within a certain range in response to a change in the operating environment temperature.

It has been confirmed that the sensor head 1 operates sufficiently in a temperature range of -40 to + 80 ° C., though it depends on the flow rate of the exposed outside air. Since the measurement target of the sensor head 1 is usually a high-frequency signal, the DC current supplied from the photoelectric converter 3 to the Peltier element 2 via the conducting wire 5 does not affect the measurement.

Hereinafter, an embodiment of an optical electric field sensor using the sensor head of the present invention using an optical modulation element whose temperature is directly or indirectly controlled by heating and cooling by a Peltier element will be described.

Incidentally, the Peltier element requires a photoelectric converter that receives irradiation light and generates an electric power. The irradiation light source, temperature control means, and the like will be described in the following embodiments.

FIG. 3 shows a first example of the optical electric field sensor according to the present invention.
An embodiment will be described.

In FIG. 3, the electric field information received by the receiving antenna 13 is guided to the modulation electrode of the sensor head 1 and applied to the phase shift optical waveguide as a voltage signal. With the semiconductor laser as the light source 11, the light incident on the sensor head 1 is intensity-modulated according to the voltage signal, emitted, and received by the photodetector 10a.

On the other hand, the photoelectric converter 3 is a semiconductor-excited YAG
The output light of the irradiation light source 12 using a laser is converted into electricity and supplied to the Peltier device 2. Since the Peltier element 2 is fixed to the outer surface of the package and maintains the temperature inside the package within a certain range in response to the fluctuation of the environmental temperature, the fluctuation of the optical bias of the light modulation element 4 inside the package is suppressed. Is done. The fluctuation of the optical bias detected together with the electric field intensity information by the photodetector 10 a is fed back to the output light intensity of the light source 11.

FIG. 4 shows a second embodiment of the optical electric field sensor according to the present invention.
An embodiment will be described.

In FIG. 4, a light source for irradiating the sensor head 1 and the photoelectric converter 3 is common, and a light source 11 using a semiconductor-excited YAG laser is branched by an optical branching device 14 for use. In the present embodiment, as in the first embodiment, the Peltier element 2 is fixed to the outer surface of the package, and maintains the temperature inside the package within a certain range in response to the fluctuation of the environmental temperature. ing. The power supply to the Peltier element 2 is adjusted by adjusting the irradiation light intensity by the optical attenuator 15 immediately before the irradiation light enters the photoelectric converter 3.

FIG. 5 shows a third embodiment of the optical electric field sensor according to the present invention.
It is a figure showing composition of an embodiment.

In FIG. 5, the light source 11 of the sensor head 1
The output light of the semiconductor laser is split into two by an optical splitter 14 immediately before the sensor head 1 and is incident on two light modulation elements 4 constituting the sensor head 1. Receiving antenna 13
Is connected to the light modulation element 4a, which transmits information on the electric field strength to the photodetector 10a. In the other light modulation element 4b to which the receiving antenna 13 is not connected, the sensor head 1
The intensity of the emitted light changes according to the temperature characteristics. This change in light intensity is detected by the photodetector 10b, and fed back to the semiconductor-excited YAG laser light source, which is the irradiation light source 12 of the photoelectric converter 3, to control the output light intensity.

FIG. 6 shows a fourth embodiment of the optical electric field sensor according to the present invention.
It is a figure showing composition of an embodiment.

In FIG. 6, the irradiation light source of the photoelectric converter 3 and the light source 11 of the sensor head are common, and the irradiation light intensity of the photoelectric converter 3 is the same as the light attenuator attached immediately before the photoelectric converter 3. It is adjusted by 15 controls. In order for the two light modulation elements 4 to have the same or similar temperature characteristics, it is characterized in that they can be formed on the same substrate most easily and in a small size.

FIG. 7 is a diagram showing the configuration of the light modulation element 4 used in the sensor head of the optical electric field sensor shown in FIGS.

As shown in FIG. 7, the light modulating element 4
It comprises two light modulation elements 4a and 4b formed on a substrate 21. One has a function of directly detecting the electric field, and the other has a function of monitoring the temperature characteristics of the sensor head. Therefore, the receiving antenna is connected to the modulation electrode 23 of the former light modulation element 4a, and the latter light modulation element 4b has no modulation electrode.

As described above, the operating temperature range of the light modulation element is widened to -40 to + 80 ° C. Similarly, in the case of an optical electric field sensor using this light modulation element as a sensor head, the operating temperature range is similarly increased. Are expected to be further expanded.

Further, the temperature state of the sensor head is grasped through the fluctuation of the optical bias, fed back to the irradiation light intensity of the photoelectric converter, and maintained in a certain range by heat generation and heat absorption by the Peltier element.

The power supply of the Peltier element fixed to the sensor head or the package of the sensor head is generated by using the irradiation light transmitted to the vicinity thereof by the optical fiber, so that there is no particular problem in remote transmission.

[0036]

As described above, according to the present invention, it is possible to provide an optical modulator having an increased reliability by expanding the operating temperature range as compared with the conventional one, for operation under severe temperature conditions. The sensor head used and the optical electric field sensor using the sensor head were realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an embodiment of a sensor head according to the present invention.

FIG. 2 is a sectional view of a specific example of the embodiment shown in FIG. 1;

FIG. 3 is a diagram showing the configuration of a first embodiment of the optical electric field sensor according to the present invention.

FIG. 4 is a diagram showing a configuration of an optical electric field sensor according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of an optical electric field sensor according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of an optical electric field sensor according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a light modulation element used in a sensor head of the optical electric field sensor shown in FIGS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor head 2 Peltier element 3 Photoelectric converter 4, 4a, 4b Optical modulation element 5 Conductor 6, 7, 8 Optical fiber 9 Package 10a, 10b Photodetector 11 Light source 12 Irradiation light source 13 Receiving antenna 14 Optical splitter 15 Optical attenuation Apparatus 16, 17 Optical connector 21 Substrate 22 Optical waveguide 23 Modulation electrode

Claims (8)

[Claims] 1. A sensor head using a light modulation element in which incident light is modulated to the intensity of light emitted in accordance with an applied voltage, wherein the light modulation element is integrated with a functional element that generates and absorbs heat. A sensor head which is provided without or in proximity to the sensor head. 2. The sensor head according to claim 1, wherein the functional element is connected to a photoelectric converter which generates electricity by irradiation light of an irradiation light source. 3. A sensor head using a light modulating element that receives light emitted from a light source, modulates the light intensity depending on the applied electric field intensity, and emits the light, and receives an electric field and inputs the electric field to the sensor head. Antenna, a photodetector that detects light emitted from the sensor head and converts it into an electric signal, the light source and the sensor head, and the sensor head and the photodetector,
3. An optical electric field sensor comprising optical fibers which are optically connected to each other, wherein the sensor head is the sensor head according to claim 1 or 2. 4. The optical electric field sensor according to claim 3, wherein an irradiation light source of the photoelectric converter is independent of a light source of the sensor head. 5. The optical electric field sensor according to claim 3, wherein at least one of the light source and the irradiation light source is a semiconductor-excited YAG laser light source. 6. An irradiation light source of the photoelectric converter is integrated with a light source of the sensor head, and one of the light beams emitted from the light source is incident on the photoelectric converter through an optical attenuator. The optical electric field sensor according to claim 3, wherein 7. The sensor head includes an element to which an electric field is applied and an element to which no electric field is applied, and light emitted from the light source is respectively incident on an element to which the electric field is applied and an element to which the electric field is not applied. 6. An output signal of the irradiation light source according to claim 4 or 5, wherein an output signal of the photodetector relating to an element to which the electric field is not applied while being incident on a photodetector connected for each emission light is output. The optical electric field sensor according to any one of claims 4 to 6, further comprising a configuration for feeding back the light intensity or controlling the optical attenuator according to the sixth aspect. 8. The optical electric field sensor according to claim 7, wherein the element to which the electric field is applied and the element to which the electric field is not applied are formed on the same substrate.