JPS63229383A - Optical sensor - Google Patents

Abstract

PURPOSE:To reduce working time, by arranging a magnetooptical crystal grown epitaxially on a substrate and one or more polarizers provided at one end or both ends thereof to eliminate an optical axis matching process at a sensor section. CONSTITUTION:Light introduced from a fiber passes through a polarizer 101 and turned to linearly polarized light to be incident into a ZnSe epitaxial layer. When light passes through the ZnSe epitaxial layer 106, a polarization surface of the light is turned by an angle theta proportional to the length (5mm) of a stripe and an external magnetic field. The light passing through the ZnSe epitaxial layer 106 is made incident into a analyzer 109 and changes in the quantity of light after the passage through the analyzer 109 takes place in terms of the quantity of light proportional to an angle theta of rotation. This enables the formation of a magnetooptical crystal and a polarizer on the same substrate using the conventional semiconductor process art to eliminate a process for optical axis matching at a sensor section thereby reducing optical axis matching time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical sensor used for optical measurement.

2. Description of the Related Art In recent years, light emitting/receiving elements, optical fibers, etc. have rapidly developed. Along with these developments, optical measurement using optical sensors has rapidly developed due to its characteristics such as being immune to electromagnetic induction noise, high insulation, and the low loss of optical fibers, allowing long-distance measurement. I've been doing it. Among these, optical applied magnetic field (current) sensors take advantage of these characteristics and are being applied particularly to high voltage systems as the demand for electric power has increased in recent years.

Figure 3 shows the overall structure of the optical magnetic field (current) sensor.

Light from a light source 301 provided in an optical transmitter 300 passes through an optical fiber 302, converts the magnetic field strength into light intensity at a sensor unit 303, passes through the optical fiber 302 again, and reaches a light receiving element 3.
04. The optical receiver 306 converts the signal into an electrical signal, and the signal processing unit 306 processes the signal. The sensor unit 303 is a polarizer 3o
7° Faraday element 3o8. The analyzer 309 is configured.

FIG. 4 is a diagram showing a configuration diagram of a conventional sensor section. In the figure, light that has passed through a polarizer 401 becomes linearly polarized light and passes through a magneto-optic crystal 402 having a certain thickness, at which time the plane of polarization is rotated by an angle θ proportional to the crystal thickness and the external magnetic field.

The rotation angle θ is converted into a change in light amount by an analyzer 403 arranged at an angle of 46 degrees with the polarizer 401. The amount of light after passing through the analyzer 403 is proportional to the rotation angle θ. As shown in FIG. 3, the optical magnetic field sensor is mainly configured by using an optical fiber 302 as a transmission path and attaching the sensor section to the tip of the optical fiber 302, in which polarizers 3o7, . Analyzer 3o9. Parts such as prisms and Faraday elements (magneto-optical crystals) 3o8 were used in combination one by one.

Problems to be Solved by the Invention The sensor section of the above-mentioned conventional example has a bulk crystal 402. Flat plate polarizer using rutile etc. (polarizer 401, analyzer 403), prism 404. It consists of a rod lens 406, etc., and has a large number of components, so it takes a very long time to align the optical axis with high precision.
■Individual parts are fixed using (thermocoin type) adhesive, etc.
To fix it, it is necessary to fix each part with the optical axis aligned using a manipulator and leave it for a long time in high temperature, which may cause the optical axis to shift. Adhesives are unreliable and can be used for a long time. This has disadvantages such as the risk of peeling off, and (1) mass production is difficult because individual parts are adhered one by one.

Means for Solving the Problems The technical means of the present invention for solving the above-mentioned problems is to use a substrate such as GaAs', Si, gadolinium gallium garnet (GGG), or Ca-Mg-Z.
A polarizer made of a magneto-optical crystal epitaxially grown on a substrate such as r-substituted GGG, such as an m-■ group semiconductor, an m-v group semiconductor, or a garnet crystal, and a multi-layer stack of alternating metals and dielectrics. It is an optical application sensor characterized by including at least one or more.

Effects The present invention, with the above structure, does not require the adhesive used to fix the magneto-optic crystal and the polarizer, and is effective in solving the above problems ① and ②, and dramatically improves reliability. . In addition, regarding the above problems (1) and (2), since conventional semiconductor processes can be used for the magneto-optic crystal and polarizer, 1. Q/7m
The optical axis can be aligned with the following accuracy, leading to a reduction in the time for optical axis alignment. Furthermore, since semiconductor processes can be used, it is also effective for mass production.

Example A first embodiment of the present invention will be described below based on the drawings.

In FIG. 1, 106 is a Zn5e magneto-optic crystal.
The layer is a taxially grown layer, and the film thickness is 701 tm. 108 and 109 are metal-dielectric multilayer thin films that are polarizers and analyzers. AI for metals, Si for dielectrics
Using O2, each layer has a thickness of 6000 and 78008, and is laminated alternately 100 times. Reference numeral 107 is a GaAs substrate that has been etched in advance to form a step. The light guided from the fiber passes through the polarizer 108 shown in the figure.
The light becomes linearly polarized light and enters the Zn5e pitaxial layer. When light passes through this Zn5e pitaxial layer 106, the plane of polarization is rotated by an angle θ proportional to the length of the stripe (5) and the external magnetic field. The light that has passed through the Zn5e pitaxial layer 106 is incident on the analyzer 109, and the amount of light that changes after passing through the analyzer 109 is proportional to the rotation angle θ.

Next, a method of manufacturing this device will be explained. In the present invention, a metal organic vapor phase epitaxy method is used as an epitaxial growth method. First, after applying appropriate pretreatment to the GaAg substrate, S
1000 iO2 films were deposited, and 5 questions x 110 with long sides in the 011> direction were created using photolithography.
This SiO2 film is selectively removed in a stripe shape of 1t. Using this as a mask, striped grooves are formed on the substrate using an oxalic acid etchant. The four sides of the stripe have (111) A sides, and the bottom side has (100)
It is a surface. The depth of the stripes is 6011 m.

A Zn5e epitaxial layer is formed on the substrate.

Although the growth conditions depend considerably on the equipment, for example, Zn5
In the case of e, the substrate temperature is 650℃, dimethyl zinc (DMZ
) H2 flow rate (0°C) = 2.5 cc/min.

Flow rate of H2 in dimethyl selenium (DMSe) (15°C)
= g cc/min, total flow rate of H2 1.51
/min.

A good epitaxial film is obtained under a reduced pressure of 100 Torr, and furthermore, since it selectively grows only on the (100) plane, a mesa stripe-shaped Zn5e epitaxial layer is formed. Thereafter, the Zn5e film on the SiO2 film is selectively removed, and an etching mask is formed and dry etching is performed twice to form a sloped portion for forming a polarizer.

The inclined parts located at both ends of the Zn5e pitaxial layer are
They have an inclination of about 22 degrees with respect to the (10o) plane of the substrate, and are arranged so as to intersect with each other at 46 degrees. A metal-dielectric multilayer thin film, which will serve as a polarizer and an analyzer, is formed on the slope thus formed. These laminated films can be created by using a device in which a high-frequency sputtering device and a vacuum evaporation device are connected and separated by a gate valve, and the sample is alternately moved back and forth between the devices.

Further, the temperature during sputtering of S z 02 and evaporation of AI was 300'C, so there was no crystal deterioration or generation of defects.

In this example, the magneto-optic crystal was formed using a selective epitaxial growth method, but a mesa stripe-shaped crystal may also be formed by selective etching using photolithography. In this case, Zn is used as the magneto-optic crystal.
5e was used, but ZnS, ZnS, Se1, (0<X
<1) may be used, and sandwich structures of these materials, e.g. ZnS/Zn5e/ZnS, ZnS/Z
An optical waveguide may be formed using nSSe/ZnS or the like.

Further, in this embodiment, a case where a ■-■ group semiconductor is used as the magneto-optic crystal is shown, but a ■-V group semiconductor may also be used. Below, GaAs1 or A I Ga A
The selective epitaxial growth conditions for s are shown as an example. In the case of Ga As, trimethyl gallium (TMG
) (-1s°C) H2 flow rate = 9 cc/min.

Arsine (AH3) (10%) flow rate 500 cc/m
in.

In the case of Gao, 8A10.2As, TMG (-1ts℃
) H2 flow rate = 8 cc/min, ) H2 flow rate of remethylaluminum (TMA) (2o℃) = 4 c
c/min.

The flow rate of AH3 (10%) was 500 cc/min. Growth was performed at a total H2 flow rate of 51/min and a reduced pressure of 10 Torr, and the growth temperature was 700°C. A SiNx or S102 mask was used for this selective epitaxial growth. Under the above growth conditions, no polycrystals were deposited on the mask, and good crystals were obtained only in the exposed portions of the GaAs substrate. G a A s obtained under these conditions
The crystals can also be used as high quality magneto-optic crystals.

Furthermore, as an application of this sensor, it is also possible to form the element of the present invention on a substrate on which a light emitting element and a light receiving element have been formed in advance.

As a second embodiment of the present invention, an optical magnetic field (current) sensor using garnet as the magneto-optic crystal will be described with reference to FIG. Using gadolinium gallium garnet (GGG) as the substrate, PbO-B2O3
(Tb
0.19Yo81)3Fe6o12((TbY)IG)
I grew 206. A crystal with this composition has the advantage of being excellent in temperature stability as a sensor. The thickness of the grown crystal is 100/jm. The part where the analyzer 209 of the crystal plane is created using the dry etching method is 1
0 Q Etch in 1tm depth direction. Thereafter, the uneven bottom surface formed by dry etching is flattened by bias sputtering 3102, and then a metal-dielectric multilayer thin film, which is the analyzer 209, is formed in the same manner as in Example 1. At this time, if a polarization-maintaining fiber is used, linearly polarized light can be guided to the sensor section, so the polarizer can be omitted and the eigenaxis of the polarization-maintaining fiber and the analyzer 20 can be used.
By tilting 9 by 46 degrees, the number of polarizers can be reduced to one. Next, this crystal is 2 to 10 groups long and 30,071 m wide.
Cut out the sensor part using a dicing saw or the like.

Furthermore, if Bi-substituted garnet, such as B'1.2Y1.8"5012, is used as the garnet crystal, a highly sensitive sensor section can be obtained because the Faraday rotation angle per unit length is large. In this case, Because the ionic radius of Bi is large, Ca-Mg with a large lattice constant is used as a substrate.
-Zr substituted GGG is required. The linear polarization plane of the input light is inclined at 45 degrees with respect to the analyzer 109.

Effects of the Invention As described above, according to the present invention, a magneto-optic crystal and a polarizer can be formed on the same substrate using conventional semiconductor process technology, thereby eliminating steps such as aligning the optical axis of the sensor section. Reliability is also improved since there is no need to use resins such as adhesives.

Furthermore, many elements can be created at the same time with the same precision.
It is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an optical magnetic field (current) sensor section in a first embodiment of the present invention, and FIG. 2 is a perspective view of an optical magnetic field (current) sensor section in a second embodiment of the present invention. FIG. 3 is a block diagram of the optical magnetic field (current) sensor, and FIG. 4 is a block diagram of the optical magnetic field (current) sensor section. 1o1...Polarizer, 106...Magneto-optical crystal (epitaxial film), 107...Substrate, 1
08゜109...Polarizer, analyzer (multilayer film of metal and dielectric), 206-... (TbY) IG magneto-optic crystal, 207...GGG substrate, 209-・・・
...Analyzer. Name of agent: Patent attorney Toshio Nakao and one other person
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Claims (8)

[Claims] (1) An optical sensor having a magneto-optic crystal epitaxially grown on a substrate and one or more polarizers provided at one or both ends of the magneto-optic crystal. (2) The optical sensor according to claim 1, wherein the polarizer is a multi-layered structure of alternating layers of metal and dielectric. (3) The optical sensor according to claim 1, wherein the magneto-optic crystal is a II-VI group semiconductor, a III-V group semiconductor, or a garnet crystal. (4) II-VI group semiconductors are ZnSe, ZnS, ZnS_X
The optical application sensor according to claim 3, wherein Se_1_−_X (0<X<1). (5) Group III-V semiconductor is GaAs, Al_XGa_1
Claim 3 which is ____XAs (0<X<1)
Optical application sensor described in section. (6) Garnet crystal is (Tb_XY_1_-_X)_
3Fe_5O_1_2 (0.1≦X≦0.3), or
The optical application sensor according to claim 3, which is Bi-substituted garnet. (7) The optical sensor according to claim 1, wherein the substrate is a semiconductor or a garnet crystal. (8) The optical sensor according to claim 7, wherein the substrate is GaAs, Si, gadolinium gallium garnet (GGG), or Ga-Mg-Zr substituted GGG.