JP2000086396A - Bismuth-substituted type garnet thick-film material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a bismuth-substituted type garnet thick-film material capable of repelling the absorption at about >=1.6 μm wavelength essentially possessed by a TbBi-based garnet and improved in temperature change ratio of the Faraday rotation angle θf for a GdBi-based garnet and to provide a method for producing the bismuth-substituted type garnet thick-film material and further a Faraday rotation element usable within the wavelength band exceeding about 1.5 μm even in the wavelength. SOLUTION: This bismuth-substituted type garnet thick-film material is a garnet thick film for optical use grown on a garnet substrate according to a liquid-phase growth method and consisting essentially of Gd, Yb, Bi, Fe and Al and the compositional formula of the garnet thick film is represented by Gd3-x-yYbxBiyFe5-zAlzO12 [0<(x) <=0.45; 0.85<=(y)<=1.55 and 0<(z)<=0.95].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an optical garnet material having a Faraday rotation effect, comprising bismuth (B
i) The present invention relates to a substitution type garnet and a method for producing the same, and more particularly, to a GdBi-based garnet single crystal thick film grown by a liquid phase epitaxial growth method (LPE method) and a method for producing the same.

[0002]

2. Description of the Related Art Hitherto, devices using Faraday rotation in optical communication have been developed and put into practical use. In optical communication using a semiconductor laser oscillator, when reflected light from an optical fiber cable, a connector, or the like returns to the oscillation unit, the oscillation becomes unstable or stops. Therefore, an optical isolator is used to block return light to the semiconductor laser and to secure a stable oscillation state.

A Bi-substituted rare earth iron garnet having a large Faraday rotation is grown by an LPE method, a flux method, or the like, and is used as an isolator in the near infrared region. In particular, garnet thick films grown by the LPE method have excellent productivity, and most of them are currently produced by this method.

At present, bands of 1.31 μm and 1.55 μm are used for long-distance communication using fiber cables. In addition, about 1.6-
Wavelengths in the range of 2.0 μm are used.

As a material for a Faraday rotator for near-infrared rays, a TbBi-based garnet thick film and a GdBi-based (Ga, Al-substituted) garnet thick film produced by the LPE method are commercially available.

In the former, the temperature change rate θ _{F / T} of the Faraday rotation angle θf is as small as about 0.04 to 0.06 deg (degrees) / ° C., but the applied magnetic field strength Hs is as high as about 800 to 1200 Oe. Although a permanent magnet is required, the magnetization reversal temperature T
_comp is about −50 ° C. or less, and can be used in a wide temperature range.

On the other hand, the latter is the temperature change rate θf of θf.
_{F / T} is as large as about 0.08 deg / ° C, but Hs is about 3
Since it is as small as 00 Oe and the magnetization reversal temperature T _comp is as high as about −10 ° C., the operating temperature range is near the living temperature. Therefore, the demand of the market is to increase TbBi-based garnet materials having good temperature characteristics.

[0008]

However, in the rare earth Bi-based garnet, the Journal of Applied Phy
sics Vd.38, No.3, p.1038, “Effect of Impurities o
n the Optical Properties of Yttrium Iron Garnet ”
In the figure shown in the document entitled, the wavelength is 1.6 μm.
Above m, an absorption spectrum related to Tb ions is observed, and it is estimated that the TbBi-based garnet material may lose its function in this wavelength band.

On the other hand, for a GdBi-based (Ga, Al-substituted) garnet thick film, its manufacturing conditions and the like are described by Jo.
urnal of Crystal Growth 64 (1983) p.275, “LPE Grow
th of Bismuth Substituted Gadolinium Iron Garnet L
ayers: Systematization of Experimental Result ", a GdBi system (Yb, Al
There is no suggestion regarding the optical properties of the (substituted) garnet thick film and the GdBi-based (Yb, Ga-substituted) garnet thick film and the GdBi-based (Yb, Al, Ga-substituted) garnet thick film.

Here, the optical isolator has a higher transmittance in the forward direction with respect to the propagation of light, and has a higher transmittance in the reverse direction.
It is desirable to show lower transmittance.

Therefore, the technical problem of the present invention is that TbBi
Bismuth-substituted garnet thick film material which avoids absorption at wavelengths of about 1.6 μm or more inherent in garnets and improves the rate of temperature change θ _{F / T} of θd of GdBi garnets and method for producing the same Is to provide.

Another technical object of the present invention is to provide a Faraday rotator usable in a wavelength band exceeding about 1.5 μm, and an optical isolator using the same.

[0013]

In the present invention, the specific characteristics required for a GdBi-based garnet thick film are as follows. (1) High transmittance (low insertion loss) even in a wavelength band exceeding about 1.5 μm. (2) The average temperature change rate θ _{F / T in} the temperature range of −20 ° C. to + 80 ° C. of the Faraday rotation angle θf is the same as that of a commercially available G
0.07 deg / ° C or less, which is better than that of a dBi-based garnet material (about 0.08 deg / ° C). (3) The magnetization reversal temperature T _comp is −20 ° C. or less (can be used in a normal living environment room temperature range). (4) The insertion loss (IL) at a thickness at which the Faraday rotation angle θf is about 45 deg is 0.2 dB or less (usually 0.3 dB or less is acceptable). (5) The reduced insertion loss (IL) of the garnet decreases the minimum applied magnetic field required to reach the saturation state (the saturation magnetic field H required to align the magnetic spins of the garnet in one direction).
s) is 500 Oe or less (a strong permanent magnet is not required because a large applied magnetic field is not required, which is advantageous for inexpensiveness and miniaturization). (6) Faraday rotation capability θ _F (hereinafter simply referred to as θ _F ) is the same as the conventional one (θ _{F at a} wavelength of 1.62 μm is 700 de)
g / cm) or more. The above is defined as the applicable range of the garnet material in the present invention.

[0014] As the Faraday rotator, the larger Faraday rotary theta _F is, it is possible to reduce the thickness of the element. Further, in the LPE method, as the grown film thickness increases, industrial disadvantages such as deterioration of crystallinity, increase in crack generation, and increase in growing time are often observed.

Therefore, when a thick film thickness (about 800 μm or more) is required, a plurality of Faraday rotation elements are used.

However, as the number of uses increases,
Disadvantages such as an increase in cost, a decrease in performance, and the like, such as an increase in variation, an increase in the number of constituent members, an increase in the size of the isolator, an increase in insertion loss, and the like, are significantly increased.

Therefore, in the present invention, it is essential that the number of garnet thick films used is two or less, and that the film has a characteristic that can be used. This corresponds to, for example, θ _{F at} a wavelength of 1.55 μm.
Is 800 deg / cm or more, such a condition is sufficiently satisfied, and this was set as the setting condition of θ _F.

Θ _F cannot be easily changed by changing a simple factor, but can be optimized and realized by adapting various solution (melt) compositions and growing conditions.

As a result, Gd, Yb, Bi, Fe, Al
Growing a garnet thick film mainly composed of: a garnet thick film on an NGG substrate; growing the garnet thick film in an atmosphere having an oxygen content of 10 to 100% at 950 to 1140 ° C. By carrying out the heat treatment at a temperature of the above, the above-mentioned problems have been solved and the present invention has been accomplished.

A garnet thick film mainly composed of Gd, Yb, Bi, Fe, and Ga is grown by the LPE method; a garnet thick film is grown on an NGG substrate;
The above problem has been solved by carrying out a heat treatment for maintaining the garnet thick film at a temperature of 950 to 1140 ° C. in an atmosphere having an oxygen content of 10 to 100%, and the present invention has been accomplished.

Gd, Yb, Bi, Fe, Al, G
growing a garnet thick film containing a as a main component by an LPE method, growing a garnet thick film on an NGG substrate, and forming a garnet thick film having an oxygen content of 10 to 100%.
By carrying out a heat treatment at a temperature of 950 to 1140 ° C. in the atmosphere described above, the above-mentioned problem has been solved and the present invention has been accomplished.

Gd, Yb, Bi, Fe, and Al are the main components, and any one of PbO, B ₂ O _3, or PtO ₂ is used.
Growing a garnet thick film containing 0 to 4.0 wt% (not including 0) by the LPE method, growing a garnet thick film on an NGG substrate, and adding a garnet thick film having an oxygen content of 10 950 to 100% atmosphere
By carrying out a heat treatment at a temperature of 1140 ° C., the above-mentioned problems have been solved and the present invention has been accomplished.

Gd, Yb, Bi, Fe, and Ga are the main components, and any one of PbO, B ₂ O _3, or PtO ₂ is used.
Growing a garnet thick film containing 0 to 4.0 wt% (not including 0) by the LPE method, growing a garnet thick film on an NGG substrate, and adding a garnet thick film having an oxygen content of 10 950 to 100% atmosphere
By carrying out a heat treatment at a temperature of 1140 ° C., the above-mentioned problems have been solved and the present invention has been accomplished.

Gd, Yb, Bi, Fe, Al, G
growing a garnet thick film containing 0 to 4.0 wt% (not including 0) of any one of PbO, B ₂ O _{3 and} PtO ₂ by the LPE method, Growing the film on an NGG substrate, forming the garnet thick film in an atmosphere having an oxygen content of 10 to 100%,
Performing heat treatment at a temperature of 50 to 1140 ° C .;
As a result, the problems described above have been solved, and the present invention has been accomplished.

Further, Gd, Yb, Bi, Fe, and Al are the main components, and B ₂ O ₃ and PbO are each 0 to 4.0 wt%.
Garnet thick film containing (but not including 0) LP
E method, garnet thick film on NGG substrate, garnet thick film with oxygen content of 1
By carrying out a heat treatment at a temperature of 950 to 1140 ° C. in an atmosphere of 0 to 100%, the above-mentioned problem has been solved and the present invention has been accomplished.

Gd, Yb, Bi, Fe, Ga are the main components, and B ₂ O ₃ and PbO are each 0 to 4.0 wt%.
Garnet thick film containing (but not including 0) LP
E method, garnet thick film on NGG substrate, garnet thick film with oxygen content of 1
By carrying out a heat treatment at a temperature of 950 to 1140 ° C. in an atmosphere of 0 to 100%, the above-mentioned problem has been solved and the present invention has been accomplished.

Gd, Yb, Bi, Fe, Al, G
a as a main component, and B ₂ O ₃ and PbO each in 0 to 4.0 w
growing a garnet thick film containing t% (but not including 0) by the LPE method;
The above problem is solved by growing the garnet thick film on a substrate and performing a heat treatment at a temperature of 950 to 1140 ° C. in an atmosphere having an oxygen content of 10 to 100%, thereby forming the present invention. It has been reached.

Gd, Yb, Bi, Fe and Al are the main components, and B ₂ O _3, PbO and PtO ₂ are each 0 to 4.
0 wt% (however, not including 0), and the total of two or more types is 0 to 9.0 wt% (however, does not include 0)
Growing the garnet thick film containing by the LPE method, growing the garnet thick film on the NGG substrate,
The above problem has been solved and the present invention has been accomplished by performing a heat treatment of maintaining the garnet thick film at a temperature of 950 to 1140 ° C. in an atmosphere having an oxygen content of 10 to 100%.

Gd, Yb, Bi, Fe, and Ga are the main components, and B ₂ O _3, PbO, and PtO ₂ are each 0 to 4.
Growing a garnet thick film in the range of 0 wt% (but not including 0) and containing a total of three types of 0 to 9.0 wt% (but not including 0) by the LPE method;
The above problem is solved by growing a garnet thick film on an NGG substrate and performing a heat treatment of maintaining the garnet thick film at a temperature of 950 to 1140 ° C. in an atmosphere having an oxygen content of 10 to 100%. The present invention has been accomplished.

Gd, Yb, Bi, Fe, Al, G
a as a main component, B ₂ O _3, PbO and PtO ₂ are each in the range of 0 to 4.0 wt% (excluding 0), and the total of the three types is 0 to 9.0 wt% (however, , 0, 0), the garnet thick film is grown by the LPE method, the garnet thick film is grown on an NGG substrate, and the garnet thick film is grown at 950 in an atmosphere having an oxygen content of 10 to 100%. By carrying out a heat treatment at a temperature of １1140 ° C., the above-mentioned problem has been solved and the present invention has been accomplished.

That is, according to the present invention, Gd, Yb, Bi, and Gd grown on a garnet substrate by a liquid phase growth method.
A garnet thick film containing Fe and Al as main components, and the composition formula of the garnet thick film is represented by Gd3 _-xy Yb _x Bi _y Fe
_5-z Al _z O ₁₂ (where 0 <x ≦ 0.45, 0.55 ≦ y
≦ 1.55, 0 <z ≦ 0.95), thereby obtaining a GdBi-based garnet thick film material.

Further, according to the present invention, Gd, Yb, Bi, and Gd grown on a garnet substrate by a liquid phase growth method.
Fe, a garnet thick film composed mainly of Ga, the composition formula of the garnet thick _{film, Gd 3-xy Yb x Bi} y Fe
_5-z Ga z O ₁₂ (where, 0 <x ≦ 0. 40,0.55 ≦ y
≤ 1.10, 0.15 ≤ z ≤ 0.60), thereby obtaining a GdBi-based garnet thick film material.

Further, according to the present invention, Gd, Yb, Bi, Gd grown on a garnet substrate by a liquid phase growth method.
A garnet thick film mainly composed of Fe, Al, and Ga, wherein the composition formula of the garnet thick film is Gd _3-xy Yb _x Bi
_{y Fe 5-z (Al a} Ga b) z O 1 2 ( and however, 0.05 ≦ a /
(a + b) ≦ 0.90, 0 <x ≦ 0.50, 0.85 ≦ y ≦
1.60, 0.20 ≦ z ≦ 1.00, thereby obtaining a GdBi-based garnet thick film material.

Further, according to the present invention, the above-described Gd
0 to 4.0 wt% PbO in Bi-based garnet thick film material
% (But not including 0), thereby obtaining a bismuth-substituted garnet thick film material characterized by containing the same.

Further, according to the present invention, the Gd described above
B ₂ O ₃ in Bi-based garnet thick film material is 0 to 4.0 wt.
% (But not including 0), thereby obtaining a bismuth-substituted garnet thick film material characterized by containing the same.

According to the present invention, the Gd described above is used.
PtO ₂ is 0~4.0wt the Bi garnet thick film material
% (But not including 0), thereby obtaining a bismuth-substituted garnet thick film material.

Further, according to the present invention, the Gd described above
B ₂ O ₃ and each 0-4 of PbO to Bi garnet thick film material. 0 wt% (not inclusive of 0) bismuth-substituted garnet thick film material characterized by containing obtain.

Further, according to the present invention, the above-described Gd
B ₂ O ₃ and PbO and P in Bi-based garnet thick film material
The tO ₂ is in the range of 0 to 4.0 wt% (however, not including 0), and the total of the three types is 0 to 9.0 wt% (however, not including 0). A bismuth-substituted garnet thick film material is obtained.

Further, according to the present invention, the Gd described above
A Faraday rotator characterized by being substantially composed of a Bi-based garnet thick film material is obtained.

Further, according to the present invention, there is provided an optical isolator comprising the Faraday rotator.

According to the present invention, the GdBi-based garnet thick film material is grown on a neodymium gallium garnet (NGG) substrate. A method for producing a membrane material is obtained.

Further, according to the present invention, the GdBi-based garnet thick film material according to any one of the above, wherein the GdBi-based garnet thick film material is subjected to a heat treatment for keeping the temperature in a range of 950 to 1140 ° C. Is obtained.

Further, according to the present invention, there is provided the above-described method for producing a GdBi-based garnet thick film material, wherein the oxygen content of the atmosphere in the heat treatment is in the range of 10 to 100%.

In the present invention, the reason why the GdYbBi-based (Ga, Al-substituted) garnet thick film is targeted is that the GdYbBi-based (Ga, Al-substituted) garnet thick-film material has a wavelength band of 1.6 μm or more. This is because no light absorption peak is observed.

The composition of a GdYbBi-based garnet thick film material that satisfies the above-mentioned optical characteristics in a single crystal thick film grown by the LPE method is represented by 0 <x ≦
0.45, 0.55 ≦ y ≦ 1.55, and 0 ≦ z ≦ 0.95.

In the present invention, the reason why the GdYbBi-based garnet thick film material is targeted is that the TbBi-based garnet thick film material has a clear light absorption peak in a wavelength region of about 1.5 μm or more. This is because a GdYbBi-based garnet thick film material does not show a light absorption peak in a wavelength region of about 1.2 μm or more.

In the present invention, the range of x is 0 <x
≦ 0.45 because θ _{f / T} decreases as x increases,
It improved the possible, and, when x exceeds 0.45, because the saturation magnetization 4PaiM _S is equal to or greater than 500G.

The reason why the range of y is set to 0.55 ≦ y ≦ 1.55 is that when y exceeds 0.55, the Faraday rotation ability becomes 500 deg / cm or more, and when y exceeds 1.55. This is because the insertion loss increases sharply.

[0049] In addition, to that the range of z and 0 <z ≦ 0.95 is the saturation magnetization 4PaiM _S with increasing z decreases, when z exceeds 0.95, theta _{f / T} sharply This is because it tends to increase. The change in these characteristics is caused by the magnetic moment of each ion constituting the crystal.

Further, in the present invention, the heat treatment temperature range of the single crystal thick film is set to 950 to 1140 ° C.
At temperatures below, the atoms in the crystal are not sufficiently homogenized,
No reduction in insertion loss was observed, and at temperatures exceeding 1140 ° C., GdYbBi-based garnet crystals, particularly Bi ₂
This is because insertion loss increases due to decomposition due to evaporation of O ₃ .

Further, in the garnet thick film material of the present invention, one of B ₂ O ₃ , PbO and PtO ₂ is used in an amount of 0 to 0.4.
The content of 0 wt% (not including 0) or the inclusion of two or more types in the range of 0 to 9.0 wt% (not including 0) means that the insertion loss (IL) is within this range. This is because they have found a decrease. Note that B ₂ O ₃ , PbO,
The effect of reducing the insertion loss (IL) due to the inclusion of PtO ₂ is presumed to be an effect of adjusting the ionic state of the crystal constituent element in the garnet composition.

In the present invention, the garnet thick film for optical use is grown on the NGG substrate by the LPE method because the NGG substrate having a lattice constant slightly larger than the SGGG substrate often used in the present growth method is used. This is because the compatibility with the garnet film in the present invention is better, and even when a thick film exceeding 500 μm is grown, the occurrence of cracks can be significantly reduced as compared with the growth on the SGGG substrate.

Incidentally, as the wavelength used becomes longer, the required film thickness becomes larger. Therefore, being able to grow into a thick film is extremely useful in practical use.

Further, in the method for producing a garnet thick film material of the present invention, the garnet thick film material may be 950-11.
When the heat treatment is performed at a temperature in the range of 40 ° C., the effect of reducing the insertion loss (IL) is recognized in this range.
If the temperature is lower than 50 ° C., the composition is insufficiently homogenized due to the low temperature. If the temperature exceeds 1140 ° C., garnet is decomposed (evaporation of Bi ₂ O ₃ contained therein).

The reduction of the insertion loss (IL) due to the heat treatment is due to the improvement of homogenization (reduction of variations in crystal lattice and ion balance) due to diffusion of atoms.

Further, in the method for producing a garnet thick film material of the present invention, the oxygen content of the atmosphere in the heat treatment is set to a range of 5% or more because the effect of the heat treatment at a temperature higher than this is recognized. If it is less than 5%, insertion loss (IL) increases due to lack of oxygen.

The change in the characteristics depending on the composition value of the main component of the garnet thick film material of the present invention is deeply related to the substitution of each atom in the crystal lattice and the magnetic spin. Is the optimal area of

[0058]

Embodiments of the present invention will be described below.

A liquid phase growth method (L) of a Bi-substituted garnet for a Faraday rotator used in an optical isolator or the like.
The PE method is performed as follows.

First, PbO, Bi ₂ was placed in a platinum crucible.
O ₃ , B ₂ O _3, etc. are used as flux components, and garnet components (Gd ₂ O ₃ , Yb ₂ O ₃ , Tb ₂ O ₃ , Fe ₂ O ₃ , Al
The ₂ O _3, Ga ₂ O _3, etc.) were dissolved at about 900 to 1100 ° C., after preparing the solution (melt), the temperature was lowered to a supercooled state (supersaturated solution state). A garnet substrate is immersed in the melt and rotated for a long time to grow a Bi-substituted garnet thick film.

Among the Bi-substituted garnets, Gd
Bi-based garnet has relatively high Faraday rotation capability θ _F
And the characteristic that a required applied magnetic field to the garnet is small. The required applied magnetic field (saturation magnetic field H _s ) here means that the insertion loss of garnet decreases.
This is the minimum magnetic field required to reach saturation.
Physically, it is a magnetic field required to align the magnetic spins of the garnet in one direction.

Generally, the applied magnetic field is supplied from a permanent magnet disposed around the garnet film. Therefore, when the saturation magnetization 4PaiM _s garnet film is low, H _s is also lowered, properties of the magnet to be used can be reduced. In addition, downsizing, weight reduction, and the like can be achieved, which is industrially beneficial.

The change in the characteristics due to the composition value of the main component of the GdBi-based garnet thick film material of the present invention is deeply related to the substitution of each atom in the crystal lattice and the magnetic spin.
The composition region of the present invention is an optimum region of the optical characteristics.

[0064]

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

Example 1 High-purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), ferric oxide (Fe ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ )
Powders of bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO) and boron oxide (B ₂ O ₃ ) were used. Using these powders, an NGG substrate (chemical formula: Nd ₃ Ga ₅ O) is formed by an LPE method using PbO—Bi ₂ O ₃ —B ₂ O ₃ as a flux.
₁₂ ) On top, Gd _1.7 Yb _0.1 Bi _1.2 Fe _4.7 Al _0.3 O ₁₂
A GdYbBi-based garnet single crystal thick film having the following composition was grown to a thickness of about 700 μm.

For comparison, terbium oxide (Tb
₂ O ₃ ) and the like, and similarly by the LPE method,
SGGG substrate [Chemical formula (GdCa) ₃ (GaMgZr) ₅
O ₁₂ ], the composition of Tb _2.0 Bi _1.0 Fe ₅ O ₁₂
A Bi-based garnet single crystal thick film was grown to a thickness of about 700 μm.

Next, the substrate was removed from the garnet single crystal thick film, and both surfaces were mirror-polished to a thickness of about 600 μm. FIG. 1 shows these GdY grown by the LPE method.
It is a figure which shows the wavelength dependence of the transmittance | permeability of a bBi-system garnet single crystal thick film and a TbBi-system garnet single crystal thick film.
As is clear from FIG. 1, the GdYbBi-based garnet single crystal thick film has a high transmittance in a wavelength range of about 1.2 to 2.2 μm.

On the other hand, the wavelength range in which the TbBi-based garnet single crystal thick film shows a high transmittance is only about 1.2 to 1.5 μm. From this result, a GdYbBi-based garnet single crystal thick film is useful in a wavelength band of 1.5 μm or more.

(Example 2) In the same manner as in Example 1, N
On a GG substrate, Gd _2.2-x Yb _x Bi _0.8 Fe _4.5 Al _0.5
In the chemical formula of O ₁₂ , x = 0, 0.05, 0.1, 0.2, 0.2.
3, 0.4, 0.5 GdYbBi-based garnet thick film,
It was grown to a thickness of about 700 to 900 μm.

The substrate was removed in the same manner as in Example 1,
In an atmosphere with an oxygen concentration of about 40%, at a temperature of 1050 ° C. and 20
A heat treatment for holding for a time was performed. After that, the wavelength 1.62μ
In m, the thickness was adjusted so that the Faraday rotation angle was about 45 degrees, and SiO ₂ antireflection films were provided on both surfaces. For these GdYbBi-based garnet thick film materials, the insertion loss at a wavelength of 1.62 μm under an applied magnetic field of 600 Oe, the Faraday rotation capability, and θ _{f / T} near room temperature were determined. The saturation magnetization was also measured using a vibrating magnetometer (VSM). Note that these GdYbB
The composition of the i-based garnet thick film material was confirmed in advance by EPMA analysis prior to applying the antireflection film.

FIG. 2 is a diagram showing the results of measurements of the GdYbBi-based garnet thick film material in this example. FIG. 2A is a diagram showing a measurement result of the saturation magnetization, and FIG. 2B is a diagram showing a value of θ _{f / T.} From FIG. 2, the saturation magnetization is less than 500 G when x is less than 0.4. Further, θ _{f / T} is expressed as x =
It can be seen that, in the range of 0 to 0.4, at 0.08 deg / ° C. or less, the value monotonically decreases as x increases.

Further, all the Gd's targeted in this embodiment
For a YbBi-based garnet thick film material, the insertion loss is 0.4 to 0.8 dB, and the Faraday rotator is about 700 to 80.
It was 0 deg / cm.

From these results, Gd _2.2-x Yb _x Bi
_0.8 Fe _4.5 of garnet single crystal thick film represented by Al _0.5 O _12, the composition range of x = 0-.40 can be said to be useful.

(Embodiment 3) In the same manner as in Embodiment 2, N
On a GG substrate, Gd _2.9-y Yb _0.1 Bi _y Fe _4.8 Al _0.2
In the chemical formula of O ₁₂ , y = 0.5, 0.55, 0.6, 0.6.
Gd of 7, 0.9, 1.1, 1.3, 1.4, 1.5, 1.6
A thick YbBi-based garnet single crystal film having a thickness of about 500 to 1
It grew up to 200 μm.

In the same manner as in Example 2, the substrate was removed from these samples, and the temperature was increased to 105% in an atmosphere having an oxygen concentration of about 40%.
Heat treatment was performed at 0 ° C. for 20 hours. Thereafter, the thickness was adjusted so that the Faraday rotation angle was about 45 degrees at a wavelength of 1.62 μm, and SiO ₂ antireflection films were provided on both surfaces. For these GdYbBi-based garnet thick film materials, the insertion loss at a wavelength of 1.62 μm under an applied magnetic field of 600 Oe, the Faraday rotation capability, and θ _{f / T} near room temperature were determined. In addition, a vibrating magnetometer (V
SM), the saturation magnetization was also measured. The composition of the GdYbBi-based garnet thick film material was confirmed in advance by EPMA analysis prior to the formation of the antireflection film.

FIG. 3 is a diagram showing the results of measurements of the GdYbBi-based garnet thick film material in this example. FIG. 3A shows the measurement results of the Faraday rotation ability, and FIG.
(B) is a figure which shows an insertion loss value, respectively. From FIG. 3, the Faraday rotation ability is 500 de when y = 0.55 or more.
When it exceeds g / cm, and when y exceeds 1.5, the insertion loss sharply increases.

Further, all the Gd's targeted in this embodiment
For a YbBi-based garnet thick film material, θ _{f / T} is about 0.5.
06-0.075deg / ° C, saturation magnetization is about 200-4
It was 50G. From these results, Gd _2.9-y Yb _0.1
Among the garnet single crystal thick films represented by Bi _y Fe _4.8 Al _0.2 O ₁₂ , it can be said that a composition in the range of y = 0.55 to 1.50 is useful.

(Embodiment 4) In the same manner as in Embodiment 2, N
On a GG substrate, Gd _1.9 Yb _0.1 Bi _1.0 Fe _5-z Al _z O
_{In the} chemical formula ₁₂ , z = 0, 0.1, 0.2, 0.3, 0.3.
GdYbBi-based garnet single crystal thick films of 4, 0.5, 0.6, 0.7 and 0.8 were grown to a thickness of about 700 to 1000 μm.

The removal of the substrate, the heat treatment of maintaining the temperature at 1050 ° C. for 20 hours in an atmosphere having an oxygen concentration of about 40%, and the formation of an antireflection film were performed in the same manner as in Example 2.

Then, in the same manner as described above, the insertion loss, the Faraday rotation ability, θ _{f / T} , and the saturation magnetization were measured.

FIG. 4 is a diagram showing the results of measurements of a GdYbBi-based garnet thick film material in this example. FIG. 4A shows the measurement results of θ _{f / T} , and FIG.
(B) is a figure which shows a saturation magnetization, respectively.

FIG. 4 shows that when z exceeds 0.7, θ _{f / T} sharply increases. Further, the saturation magnetization is 500 G or less in the range of z = 0 to 0.7.

Further, all the Gd's targeted in this embodiment
For the YbBi-based garnet thick film material, the Faraday rotation ability is about 900 deg / cm, and the insertion loss is 0.0.
It was 4-0.07 dB.

From these results, Gd _1.9 Yb _0.1 Bi
Among the garnet single crystal thick films represented by _1.0 Fe _5-z Al _z O ₁₂ , it can be said that a composition in the range of z = 0 to 0.7 is useful.

(Embodiment 5) In the same manner as in Embodiment 2, N
On a GG substrate, Gd _1.7 Yb _0.1 Bi _1.2 Fe _4.7 Al _0.3
A GdYbBi-based garnet single crystal thick film represented by O ₁₂ was grown to a thickness of about 700 to 1000 μm.

After removing the substrate, the GdYbBi-based garnet single crystal thick film is removed at 950 ° C., 1000 ° C., 1050 ° C., 1100 ° C., in an atmosphere having an oxygen concentration of about 50% or more.
Heat treatment was performed at 1130 ° C. and 1150 ° C. for 10 hours.

Thereafter, the thickness was adjusted so that the Faraday rotation angle was about 45 degrees at a wavelength of 1.62 μm, and SiO ₂ antireflection films were provided on both surfaces. Then, similarly to the second embodiment, the insertion loss, θ _f , θ _{f / T} , and the saturation magnetization 4πM _S
Was measured.

FIG. 5 is a diagram showing the insertion loss of a GdYbBi-based garnet thick film material in this embodiment. From FIG. 5, it can be seen that by performing the heat treatment in the temperature range of 950 to 1130 ° C., the insertion loss is lower than before the heat treatment (non-treatment).

Further, all the Gd's targeted in this embodiment
Regarding the YbBi-based garnet thick film material, the Faraday rotation ability is about 1100 deg / cm, and the θ _{f / T} is about 0.06 de.
g / ° C., and the saturation magnetization was about 400 G.

(Embodiment 6) In the same manner as in Embodiment 2, N
On a GG substrate, Gd _1.7 Yb _0.1 Bi _1.2 Fe _4.7 Al _0.3
A GdYbBi-based garnet single crystal thick film represented by O ₁₂ was grown to a thickness of about 700 to 1000 μm.

After removing the substrate from the GdYbBi-based garnet single crystal thick film, the oxygen concentration was changed to 0, 5, 10, 20, 4 or less.
0, 60, 80, and 100% in each atmosphere, temperature 1
Heat treatment was performed at 050 ° C. for 10 hours.

Thereafter, the thickness was adjusted so that the Faraday rotation angle was about 45 degrees at a wavelength of 1.62 μm, and SiO ₂ antireflection films were provided on both surfaces. Then, as in Example 2, the insertion loss, θ _f , θ _{f / T} , and the saturation magnetization were measured.

FIG. 6 is a diagram showing the insertion loss of a GdYbBi-based garnet thick film material in this embodiment. FIG. 6 shows that the heat treatment in an atmosphere with an oxygen concentration of 5% or more
It can be seen that the insertion loss is lower than before the heat treatment (non-treatment).

Further, all the Gd's targeted in this embodiment
Regarding the YbBi-based garnet thick film material, the Faraday rotation ability is about 1100 deg / cm, and the θ _{f / T} is about 0.06 de.
g / ° C., and the saturation magnetization was about 400 G.

From these results, Gd _1.7 Yb _0.1 Bi
GdYb represented by the chemical formula _1.2 Fe _4.7 Al _0.3 O ₁₂
It can be said that heat treatment in an atmosphere having an oxygen concentration of 5% or more is useful for a Bi-based garnet single crystal thick film.

Further, with respect to all the GdYbBi-based garnet thick film materials targeted in Examples 1 to 6 described above, the magnetization reversal temperatures T _comp are all -5 ° C. or less, and more specifically, most of them are − It was confirmed that the temperature was 50 ° C. or less.

Example 7 High-purity gadolinium oxide (Gd ₂ O ₃ ), yttrium oxide (Yb ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ ), ferric oxide (α-Fe ₂ O ₃ ) ,
Aluminum oxide (Al ₂ O ₃ ), bismuth oxide (Bi ₂
O ₃ ), lead oxide (PbO) and boron oxide (B ₂ O ₃ )
Of PbO—Bi ₂ O ₃ —B ₂ O ₃
Using the system as a flux, the main component ratio was Gd _1.9 Yb _0.1 Bi _1.0 Fe _4.8 Al _0.2 O ₁₂ on an NGG substrate (lattice constant: 12.509 angstroms) by the LPE method.
A GdBi-based garnet film having a composition containing about 1.0 wt% of bO was grown to a thickness of about 700 μm.

Similarly, on a SGGG substrate (with a lattice constant of 12.496 angstroms), the main component ratio is
The TbBi garnet film of Tb _2.0 Bi _1.0 Fe ₅ O ₁₂ comprising composition was grown to a thickness of about 700 .mu.m.

Next, the substrates of these samples were removed, and
After mirror polishing to a thickness of 00 μm, the light transmittance of the garnet thick film in the wavelength range of 0.9 to 2.2 μm was measured using a variable wavelength spectrometer. FIG. 7 shows the result. In addition, on each side of each of these samples, 5 points each were E
The above composition value is obtained by performing PMA analysis and calculating the average value.

In the relationship between the wavelength and the transmittance of the garnet thick film shown in FIG. 7, the solid line shows the relationship between the transmittance and the wavelength of each thick film of the GdYbBi-based garnet, and the broken line shows the relationship between the transmittance and the wavelength of the TbBi-based garnet. GdYbBi-based garnet shows high transmittance in a wavelength region of about 1.2 μm or more. On the other hand, in a TbBi-based garnet thick film, the wavelength band showing high transmittance is about 1.2 to 1.5 μm.
Range. Therefore, in the wavelength band of 1.5 μm or more, the GdYbBi-based garnet is particularly useful.

[0102] Note that the GdYbBi garnet thick film, polishing the both sides of the sample was adjusted to a thickness of the Faraday rotation at the wavelength 1.62μm is about 45 deg, performs non-reflection coating treatment with SiO _2, the electromagnet A magnetic field is applied up to about 500 Oe using a wavelength of 1.62 μm.
, The Faraday rotation capability θ _F , and the saturation magnetic field H _s were determined.

Similarly, the temperature is changed, the temperature change rate θ _{F / T of the} Faraday rotation angle, the magnetization reversal temperature T _comp
I asked. As a result, IL was 0.09 dB, and Hs was about 4 dB.
00 Oe, θ _F is about 900 deg / cm, θ _{F / T} is about
06 deg / ° C and T _comp were -40 ° C or less. Therefore, it can be said that the GdYbBi-based garnet thick film is extremely useful as a Faraday rotating element.

(Embodiment 8) In the same manner as in Embodiment 7, NG
On the G substrate, the main component ratio is Gd _1.75 Yb _0.05 Bi _1.2 F
e _4.7 Al _0.3 O ₁₂ with PbO of 0, 1.0, 2.0, 3.
After growing a GdYbBi-based garnet film having a composition containing 0.4, 5.0 and 5.0 wt% to a thickness of about 700 μm, a sample was prepared and measured.

As a result, for all the samples, Hs was about 300 Oe, θ _F was about 1100 deg / cm, θ _{F / T} was about 0.06 to 0.07 deg / ° C., and T _comp was −40 ° C. or less. .

FIG. 8 shows the relationship between IL and the content of PbO. From FIG. 8, it is found that the content of PbO decreases the IL, and in the region where PbO exceeds 4.0 wt%, the IL is reduced.
It can be seen that has increased significantly. Therefore, PbO
Is useful in the range of 0 to 4.0 wt% (however, excluding 0).

(Example 9) In the same manner as in the eighth embodiment, the main component ratio was Gd _2.1 Yb _0.1 Bi _0.8 Fe _4.9 Al
A garnet film containing 1.3 wt% of PbO was grown to a thickness of about 900 μm with _0.1 O ₁₂ .

Next, this sample was heated at 950 ° C., 1000 ° C., 1050 ° C., 110
It was kept at each of 0 ° C., 1130 ° C., and 1150 ° C. for 10 hours and heat-treated.

Next, these samples were processed at a wavelength of 1.62 μm.
After adjusting the thickness (about 650 μm) so that the Faraday rotation angle becomes about 45 deg, each characteristic was measured in the same manner as in the first embodiment.

As a result, for all samples, Hs was about 350 Oe, θ _F was about 700 deg / cm, θ _{F / T} was about 0.06 deg / ° C., and T _comp was −40 ° C. or less.

FIG. 9 shows the results of IL and heat treatment temperature. FIG. 9 shows that the effect of reducing the IL by the heat treatment is recognized when the heat treatment temperature is in the range of 950 to 1130 ° C. Therefore, it can be said that heat treatment in a temperature range of 950 to 1130 ° C. is useful.

(Example 10) In the same manner as in Example 9, the main component ratio was Gd _1.3 Yb _0.2 Bi _1.5 Fe _4.4 Al _0.6 O ₁₂
A garnet film containing about 0.7 wt% of PbO was grown to a thickness of about 600 μm.

Next, this sample was heated at a temperature of 1050 ° C.
The oxygen concentration of the atmosphere is 0, 10, 20, 40, 60, 8
After setting the temperature to 0,100% and holding and heat-treating for 20 hours, a sample was prepared and measured.

[0113] Consequently, for all samples, H _s is about 450 Oe, theta _F is about 1300deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -40 ℃ less.

FIG. 10 shows the results of IL and the oxygen concentration of the atmosphere. From FIG. 10, the oxygen concentration of the atmosphere is 10
In the range of 100%, the effect of reducing the IL by the heat treatment is recognized. Therefore, it can be said that an oxygen concentration of 10 to 100% in the heat treatment atmosphere is useful.

Example 11 High-purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ ), ferric oxide (α-Fe)
₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO) and boron oxide (B
Powder ₂ O ₃₎ was used as a raw material, PbO-Bi ₂ O ₃ -
Using a B ₂ O ₃ flux as a flux, the main component ratio was Gd _1.9 Yb _0.1 Bi _1.0 Fe _4.8 Al _0.2 O ₁₂ on an NGG substrate (lattice constant: 12.509 Å) by the LPE method.
Thus, a GdBi-based garnet film having a composition containing about 1.0 wt% of B ₂ O ₃ was grown to a thickness of about 700 μm.

Similarly, on a SGGG substrate (with a lattice constant of 12.496 angstroms), the main component ratio is
A TbBi-based garnet film having a composition of Tb _2.0 Bi _1.0 Fe ₅ O ₁₂ was grown to a thickness of about 700 μm.

Next, the substrates of these samples were removed, and
After mirror polishing to a thickness of 00 μm, the light transmittance of the garnet thick film in the wavelength range of 0.9 to 2.2 μm was measured using a variable wavelength spectrometer. The result is shown in FIG. In addition, on each side of each of these samples, 5 points each were E
PMA analysis was performed, and the average value was the above composition value. Note that B ₂ O ₃ was determined by atomic absorption spectrometry.

In the relationship between the wavelength and the transmittance of the garnet thick film shown in FIG. 11, the solid line shows the relationship between the transmittance and the wavelength of each thick film of the GdYbBi-based garnet, and the broken line shows the relationship between the transmittance and the wavelength of the TbBi-based garnet. GdYbBi-based garnet shows high transmittance in a wavelength region of about 1.2 μm or more. On the other hand, in a TbBi-based garnet thick film, the wavelength band showing high transmittance is about 1.2 to 1.5 μm.
Range. Therefore, in a wavelength band of 1.5 μm or more, a GdYbBi-based garnet is particularly useful.

[0119] Note that the GdYbBi garnet thick film, polishing the both sides of the sample was adjusted to a thickness of the Faraday rotation at the wavelength 1. 62 .mu.m of about 45 deg, performs non-reflection coating treatment with SiO _2, the electromagnet A magnetic field is applied up to about 500 Oe using a wavelength of 1.62 μm.
, The Faraday rotation capability θ _F , and the saturation magnetic field H _s were determined.

Similarly, the temperature was changed, and the temperature change rate θ _{F / T of} the Faraday rotation and the magnetization reversal temperature T _comp were obtained. As a result, I.L. Is 0.08 dB, H _s is about 40
0 Oe, θ _F is about 900 deg / cm, θ _{F / T} is about 0.0
6 deg / ° C. and T _comp were −40 ° C. or less. Therefore, it can be said that the GdYbBi-based garnet thick film is extremely useful as a Faraday rotating element.

(Example 12) In the same manner as in the eleventh embodiment, the main component ratio was Gd _1.75 Yb on the NGG substrate.
_0.05 Bi _1.2 Fe _4.6 Al _0.4 O ₁₂ , B ₂ O ₃ is _0.1 .
GdY of composition containing 0, 2.0, 3.0, 4.0 wt%
After growing the bBi-based garnet film to a thickness of about 700 μm,
A sample was prepared and measured.

[0122] Consequently, for all samples, H _s is about 300 Oe, theta _F is about 1100deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -40 ℃ less.

FIG. 12 shows the relationship between IL and B ₂ O ₃ content. From Figure 12, the content of B ₂ O _3, I.L.
In the region where B ₂ O ₃ exceeds 3.5 wt%,
It can be seen that L. has increased significantly. Therefore, B ₂
O ₃ content is 0 to 3.5 wt% (however, 0 is not included)
Is useful. Further, preferably, by B ₂ O ₃ is in the range of 0.4～3.5Wt%, it is possible to I.L. The a 0.1dB or less.

[0124] (Example 13) In the same manner as in the twelfth embodiment, is the main component _{ratio, Gd 2.1 Yb 0.1 Bi 0.8 Fe} 4 .9 A
A garnet film containing about 0.5 wt% of B ₂ O ₃ was grown to a thickness of about 900 μm with l _0.1 O ₁₂ .

Next, this sample was placed in an atmosphere of about 50% oxygen concentration at 950 ° C., 1000 ° C., 1050 ° C., 110 ° C.
It was kept at each of 0 ° C., 1130 ° C., and 1150 ° C. for 10 hours and heat-treated.

Next, these samples were processed at a wavelength of 1.62 μm.
After adjusting the thickness (about 650 μm) so that the Faraday rotation angle becomes about 45 deg, each characteristic was measured in the same manner as in the first embodiment.

[0127] Consequently, for all samples, H _s is about 350 Oe, theta _F is about 700deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp were -40 ℃ less.

The results of IL and heat treatment temperature are shown in FIG.
3 is shown. From FIG. 13, the heat treatment temperature is 950 to 1130.
Within the range of ° C., the effect of reducing IL by heat treatment is recognized. Therefore, it can be said that heat treatment in a temperature range of 950 to 1130 ° C. is useful.

(Example 14) In the same manner as in Example 13,
Main component _{ratio, Gd 1.3 Yb 0.3 Bi 1.5 Fe} 4.4 Al 0. 6 O
_{In step 12} , a garnet film containing about 3.5 wt% of B ₂ O ₃ was grown to a thickness of about 600 μm.

Next, this sample was heated at a temperature of 1050 ° C.
The oxygen concentration of the atmosphere is 0, 10, 20, 40, 60, 8
After setting the temperature to 0,100% and holding and heat-treating for 20 hours, a sample was prepared and measured.

[0131] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 1300deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp were -40 ℃ less.

FIG. 14 shows the results of IL and the oxygen concentration of the atmosphere. From FIG. 14, the oxygen concentration of the atmosphere is 10
In the range of 100%, the effect of reducing the IL by the heat treatment is recognized. Therefore, it can be said that an oxygen concentration of 10 to 100% in the heat treatment atmosphere is useful.

Example 15 High-purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), ferric oxide (α-Fe ₂ O ₃ ), aluminum oxide (Al
₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO)
And boron oxide (B ₂ O ₃ ) powder. Using these powders, the _{PbO-Bi 2 O 3 -B 2} O 3 system LPE method with flux, NGG substrate (lattice constant 1
To 2.509 angstroms) on, Gd _{1.7 5} Yb _0.05
Bi _1.2 Fe _4.6 Al _0.4 O ₁₂
GdYbBi-based garnet single crystal thick film containing about 1.0 wt% of ₂ was grown to a thickness of about 700 μm.

For comparison, terbium oxide (Tb
₂ O ₃ ) and the like, and similarly by the LPE method,
A TbBi-based garnet single crystal thick film having a composition of Tb ₂ BiFe ₅ O ₁₂ was grown to a thickness of about 700 μm on an SGGG substrate (with a lattice constant of 12.496 Å).

Next, the substrate was removed from the garnet single crystal thick film, and both surfaces were mirror-polished to a thickness of about 600 μm. After that, the wavelength is set to 0.
The light transmittance of the garnet thick film in the range of 9 to 2.2 μm was measured. The above-mentioned composition values were obtained by conducting EPMA analysis on each of five points on each side of these samples and calculating the average value.

FIG. 15 shows the thick GdYbBi-based garnet single crystal and TbBi grown by the LPE method.
4 shows the wavelength dependence of the transmittance of a thick garnet single crystal film.
In FIG. 15, the solid line is a GdYbBi-based garnet,
The broken line is a TbBi-based garnet.

As is apparent from FIG. 15, GdYbBi
The system garnet single crystal thick film has a high transmittance in a region of about 1.2 μm or more. On the other hand, the wavelength range in which the TbBi-based garnet single crystal thick film shows a high transmittance is about 1.
It is only 2-1.5 μm. From this result, it is understood that a GdYbBi-based garnet single crystal thick film is useful in a wavelength band of 1.5 μm or more.

[0138] Note that this GdYbBi garnet thick film, polishing the both sides of the sample was adjusted to a thickness Faraday rotation of about 45deg at a wavelength of 1.62, subjected to non-reflection coating treatment with SiO _2, the electromagnet To apply a magnetic field up to about 500 Oe and a wavelength of 1.62 μm.
m, IL, θ _F , and H _s were determined. Similarly, the temperature was changed, and θ _{F / T} and T _{comp. Were} determined. IL
Is 0.08 dB, H _s is about 300 Oe, theta _F is about 1
100 deg / cm, θ _{F / T} is about 0.07 deg / ° C.,
T _comp. Was −40 ° C. or less. Therefore, it is understood that the GdYbBi-based garnet thick film of the present invention is extremely useful as a Faraday rotator.

(Example 16) In the same manner as in Example 15, the main component ratio was Gd _1.9 Yb _0.1 Bi on an NGG substrate.
_1.0 Fe _4.8 Al _0.2 O ₁₂ , PtO ₂ is 0, _1.0 , ₂ .
GdYbBi containing 0, 3.0, 4.0, 5.0 wt%
After growing a system garnet thick film to a thickness of about 800 μm,
A sample was prepared and each characteristic was measured.

FIG. 16 shows GdYbBi in this embodiment.
Is a graph showing the results of IL measurement of a garnet-based thick film material. From FIG. 16, the inclusion of PtO ₂ makes IL
In a region where PtO ₂ exceeds 3.5 wt%, the IL.
Has increased significantly.

In addition, all the Gd's targeted in this embodiment
For Bi garnet thick film materials, H _s is about 400
Oe and θ _F are about 900 deg / cm, and θ _{F / T} is about
06 deg / ° C. and T _comp. Were −40 ° C. or less.
Therefore, it is useful that the PtO ₂ content is in the range of 0 to 3.5 wt% (excluding 0). Further, preferably, Pt
When O ₂ is in the range of 0.4 to 3 wt%, IL is 0.1 dB, which is useful.

(Example 17) In the same manner as in Example 16, the main component ratio was Gd _2.1 Yb _0.1 Bi on an NGG substrate.
A GdBi-based garnet thick film of _0.8 Fe _4.9 Al _0.1 O ₁₂ and containing about 0.5 wt% of PtO ₂ was formed to a thickness of about 900 μm.
m.

This GdBi-based garnet single crystal thick film was
In an atmosphere having an oxygen concentration of about 50%, at 950 ° C. and 1000
° C, 1050 ° C, 1100 ° C, 1130 ° C, 1150 ° C
Was held at each temperature for 10 hours and heat-treated.

Thereafter, these samples were processed at a wavelength of 1.62 μm.
The thickness was adjusted so that _θf was about 45 degrees at
After that, each characteristic was measured in the same manner as in Example 1.

FIG. 17 shows GdYbBi in this embodiment.
Is shown for the garnet-based thick film material. FIG.
7, it can be seen that performing the heat treatment in the temperature range of 950 to 1130 ° C. has a lower IL than before the heat treatment (untreated).

Further, all the Gd's targeted in this embodiment
For YbBi garnet thick film materials, H _s is about 3
50 Oe, θ _F were about 700 deg / cm, θ _{F / T} was about 0.06 deg / ° C., and T _comp . Therefore, it is understood that heat treatment in a temperature range of 950 to 1130 ° C. is useful.

(Embodiment 18) In the same manner as in Embodiment 17, the main component ratio was Gd _1.2 Yb _0.3 Bi on an NGG substrate.
A GdYbBi-based garnet thick film of _1.5 Fe _4.4 Al _0.6 O ₁₂ and containing about 3.5 wt% of PtO ₂ was formed to a thickness of about 600
It grew to μm.

The GdYbBi-based garnet single crystal thick film was prepared at 0,10,20,40,6 at a temperature of 1050 ° C.
After holding for 20 hours at an oxygen concentration of 0, 80, and 100% in an atmosphere, and heat-treating, a sample was prepared and each characteristic was measured.

FIG. 18 shows GdYbBi in this embodiment.
Is shown for the garnet-based thick film material. FIG.
8, it can be seen that the IL is reduced by performing the heat treatment at an oxygen concentration in the atmosphere in the range of 10 to 100% as compared to before the heat treatment (non-treatment).

Further, all the Gd's targeted in this embodiment
For YbBi garnet thick film materials, H _s is about 4
50 Oe, θ _F is about 1300 deg / cm, θ _{F / T} is
About 0.07 deg / ° C., T _comp. Was −40 ° C. or less. Therefore, it can be seen that heat treatment at an oxygen concentration in an atmosphere of 10 to 100 ° C. is useful.

Example 19 High-purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ ), ferric oxide (α-Fe)
₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO) and boron oxide (B
Powder ₂ O ₃₎ was used as a raw material, PbO-Bi ₂ O ₃ -
Using a B ₂ O ₃ flux as a flux, the main component ratio was Gd _1.4 Yb _0.2 Bi _1.4 Fe _4.3 Al _0.7 O ₁₂ on an NGG substrate (lattice constant: 12.509 angstroms) by the LPE method.
A GdBi-based garnet film having a thickness of about 700 μm
Nurtured.

Similarly, on a SGGG substrate (with a lattice constant of 12.496 angstroms), the main component ratio is
A TbBi-based garnet film having a composition of Tb _2.0 Bi _1.0 Fe ₅ O ₁₂ was grown to a thickness of about 700 μm.

Next, the substrates of these samples were removed, and
After mirror polishing to a thickness of 00 μm, the light transmittance of the garnet thick film in the wavelength range of 0.9 to 2.2 μm was measured using a variable wavelength spectrometer. The result is shown in FIG. In addition, on each side of each of these samples, 5 points each were E
PMA analysis was performed, and the average value was the above composition value.

FIG. 19 shows the relationship between the wavelength and the transmittance of the garnet thick film. In the drawing, the solid line shows the relationship between the transmittance of each thick film and the wavelength for the GdBi-based garnet, and the broken line shows the relationship for the TbBi-based garnet.

In FIG. 19, the GdBi-based garnet shows high transmittance in a wavelength region of about 1.2 μm or more. On the other hand, in a TbBi-based garnet thick film, the wavelength band showing high transmittance is about 1.2 to 1.5 μm.
Range. Therefore, in a wavelength band of 1.5 μm or more, a GdBi-based garnet is particularly useful.

The GdBi-based garnet thick film was polished on both sides of the sample and adjusted to a thickness such that the Faraday rotation at a wavelength of 1.55 μm was about 45 deg.
An anti-reflection coating treatment with SiO ₂ was performed, and a magnetic field was applied up to about 500 Oe using an electromagnet to determine an insertion loss (IL) at a wavelength of 1.55 μm, a Faraday rotation capability θ _F , and a saturation magnetic field H _s .

Similarly, by changing the temperature, the temperature change rate θ _{F / T of the} Faraday rotation angle, the magnetization reversal temperature T _comp
I asked.

[0158] As a result, I.L. Is 0.10 dB, H _s is about 400 Oe, theta _F is about 1300deg _/ cm, θ _F / _T is about 0.04deg / ℃, T _comp is a at -40 ℃ below Was.

Therefore, the GdBi-based garnet thick film is
It can be said that it is extremely useful as a Faraday rotation element.

(Example 20) In the same manner as in Example 19,
On the NGG substrate, the main component ratio is Gd _1.6-x Yb _x Bi _1.4
For Fe _4.1 Al _0.9 O ₁₂ , x = 0, 0.10, 0.20,
After growing a GdBi garnet film having a composition of 0.30, 0.40, 0.50 to a thickness of about 700 μm, a sample was prepared and measured.

As a result, for all samples, θ _F was about 1300 deg / cm, and θ _{F / T} was about 0.02 to 0.06 d.
eg / ° C. and T _comp were −40 ° C. or less.

FIG. 20 shows the relationship between the composition value x, θ _{F / T} and H _s .

FIG. 20 shows that IL increases with an increase in x. Also, H _s is increased by the increase in x, x has a value of over 500Oe at 0.45 or more.

Therefore, the composition value of x is 0 <x ≦ 0.45
Is useful.

(Example 21) In the same manner as in the twentieth embodiment, the main component ratio was Gd _2.8-y Yb _0.2 on the NGG substrate.
Bi _y Fe _4.2 Al _0.8 O ₁₂ , y = 0.80, 0.90,
1.00, 1.10, 1.20, 1.30, 1.40, 1.5
After growing a GdBi garnet film having a composition of 0. 1.60 to a thickness of about 600 µm, a sample was prepared and measured.

[0166] Consequently, for all samples, H _s is about 200~450Oe, θ _{F / T} is about 0.02~0.07de
g / ° C. and T _comp were −40 ° C. or less.

FIG. 21 shows the relationship between the composition value y and θ _F , IL.

[0168] From Figure 21, theta _F that exceeds 800 deg / cm is obtained at y is 0.85 or more. Also, I.
L. shows a tendency to increase significantly when y exceeds 1.55.

Therefore, the composition value of y is 0.85 ≦ y ≦ 1.0.
A range of 55 may be useful. It is presumed that the increase in IL in the region where y exceeds 1.55 is caused by distortion of the crystal lattice of the garnet crystal and variation in ion balance.

(Example 22) In the same manner as in Example 20,
On an NGG substrate, the main component ratio is Gd _1.4 Yb _0.3 Bi _1.3
For Fe _5-z Al _z O ₁₂ , z = 0.20, 0.30, 0.4
0, 0.50, 0.60, 0.70, 0.80, 0.90,
A GdBi garnet film having a composition of 1.00
After growing to 0 μm, a sample was prepared and measured.

As a result, for all samples, θ _F was about 1200 deg / cm, and θ _{F / T} was about 0.04 to 0.06 d.
eg / ° C. and T _comp were −40 ° C. or less.

FIG. 22 shows the relationship between the composition value z and H _s , IL.

[0173] From FIG. 22, H _s is 500Oe or less, z
Is obtained at 0.25 or more. In addition, in IL, Z is 0.
It can be seen that the increase is sharply at 95 or more.

Therefore, the composition value of z is 0.25 ≦ z ≦ 0.2.
A range of 95 may be useful. The increase in IL in the region where z is 0.95 or more is presumed to be caused by distortion of the crystal lattice of the garnet crystal and variation in ion balance.

(Example 23) In the same manner as in Example 20,
Main component _{ratio, Gd 2.0 Yb 0.1 Bi 0.9 Fe} 4.5 Al 0. 5 O
A garnet film having a composition of ₁₂ was grown to a thickness of about 700 μm.

Next, this sample was heated at 950 ° C., 1000 ° C., 1050 ° C., 110
Heat treatment was performed at 0 ° C., 1130 ° C., and 1150 ° C. for 10 hours.

Next, these samples were processed at a wavelength of 1.55 μm.
After adjusting the Faraday rotation angle to a thickness (about 550 μm) at which the Faraday rotation angle becomes about 45 deg, each characteristic was measured in the same manner as in the first embodiment.

[0178] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 850deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp were -40 ℃ less.

The results of IL and heat treatment temperature are shown in FIG.
3 is shown.

As shown in FIG. 23, the heat treatment temperature was 950 to 114.
Within the range of 0 ° C., the effect of reducing the IL by the heat treatment is recognized.

Therefore, it can be said that heat treatment in the temperature range of 950 to 1140 ° C. is useful.

(Example 24) In the same manner as in Example 20,
Main component _{ratio, Gd 1.6 Yb 0.2 Bi 1.2 Fe} 4.3 Al 0. 7 O
A garnet film having a composition of ₁₂ was grown to a thickness of about 600 μm.

Next, the oxygen concentration of the atmosphere was adjusted to 0, 10, 20, 40, 6 at each temperature of 1050 ° C.
After performing heat treatment at 0, 80, and 100% and holding for 20 hours, a sample was prepared and each characteristic was measured.

[0184] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 1100deg _/ cm, θ _F / _T is about 0.04deg / ℃, T _comp were -40 ℃ less.

FIG. 24 shows the relationship between IL and the oxygen concentration in the atmosphere.

FIG. 24 shows that the oxygen concentration of the atmosphere was 10 to 10.
Within the range of 100%, the effect of reducing IL by heat treatment is recognized.

Therefore, it can be said that the oxygen concentration of the heat treatment atmosphere in the range of 10 to 100% is useful.

Example 25 High purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), ferric oxide (Fe ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ )
Using powders of bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO) and boron oxide (B ₂ O ₃ ) as raw materials, PbO
The -Bi ₂ O ₃ -B ₂ O ₃ system as a flux at LPE method, on the substrate (lattice constant 12.509 Å) NGG, contained about 0.5 wt% of PbO, is the main component ratio, Gd _1.4 Yb _0.3 Bi _1.3 Fe _4.4 Al _0.6 O ₁₂ and B ₂
G having a composition containing 0,1,2,3,4,5 wt% of O ₃
A dBi-based garnet film was grown to a thickness of about 500 μm.

Next, the substrates of these samples were removed, and both surfaces were polished to adjust the thickness so that the Faraday rotation at a wavelength of 1.55 μm was about 45 deg. In addition, the above-mentioned composition is obtained by EP
MA analysis was performed and the average value was obtained.
For B ₂ O ₃ , a sample piece was determined by atomic absorption spectrometry.

Next, after subjecting these sample plates to a non-reflective coating treatment with a SiO ₂ film, a magnetic field was applied to about 0.5 kOe using an electromagnet, and the transmittance was saturated at a wavelength of 1.55 μm. Applied magnetic field (saturation magnetic field H
_s ), insertion loss (IL), and Faraday rotation capability θ _F ,
And the temperature change rate θ _F between −20 ° C. and + 80 ° C.
_{F / T} was determined.

[0191] As a result, for all samples, H _s about 4
00 Oe, θ _F about 1200 deg / cm, θ _{F / T} about 0.0
6 deg / ° C and T _comp -40 ° C or less.

FIG. 25 shows the relationship between IL and B ₂ O ₃ content.

As can be seen from FIG. 25, IL is B ₂
It can be seen that the content is reduced by the content of O ₃ and is remarkably increased in a region exceeding 4.0 wt%. As a result, the effect of reducing IL is recognized in the range of 0 to 4.0 wt% (however, excluding 0). Therefore, the content of B ₂ O ₃ is 0 to
A range of 4.0 wt% (excluding 0) is useful. In particular, a range of 1 to 3.2 wt% is preferable.

(Example 26) In the same manner as in Example 25,
Gd containing about 0.5 wt% of B ₂ O ₃ is Gd
_1.7 Yb _0.2 Bi _1.1 Fe _4.6 Al _0.4 O ₁₂ , GdB having a composition containing 0, 1, 2, 3, 4.5 wt% of PbO
After growing the i-type garnet film to a thickness of about 600 μm, a sample was prepared and measured.

[0195] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 1100deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp were -40 ℃ less.

FIG. 26 shows the relationship between IL and PbO content.

FIG. 26 shows that the inclusion of PbO caused the IL.
In the region where PbO exceeds 4.0 wt%,
It can be seen that L. has increased significantly. Therefore, Pb
It can be said that the content of O is preferably in the range of 0 to 4.0 wt% (excluding 0). More preferably, PbO is 0.4.
By setting the range of ~ 4.0 wt%, IL is set to 0.0.
It can be 8 dB or less. In particular, 1.0 to 1.0
The range of 4.0 wt% is preferable.

(Example 27) In the same manner as in Example 25,
Main component _{ratio, Gd 1.1 Yb 0.4 Bi 1.5 Fe} 4.1 Al 0. 9 O
_{In step 12} , a garnet film containing about 0.7 wt% of B ₂ O ₃ was grown to a thickness of about 500 μm.

Next, this sample was placed in an atmosphere of about 50% oxygen concentration at 950 ° C., 1000 ° C., 1050 ° C., 110 ° C.
It was kept at each of 0 ° C., 1130 ° C., and 1150 ° C. for 10 hours and heat-treated.

Next, both surfaces of these samples were polished, and the Faraday rotation angle at a wavelength of 1.55 μm was about 4 μm.
It was measured after adjusting to a thickness of 5 deg.

[0202] Consequently, for all samples, H _s is about 300 Oe, theta _F is about 1400deg _/ cm, θ _F / _T is about 0.05 deg / ° C., T _comp were -40 ℃ less.

FIG. 2 shows the results of IL and heat treatment temperature.
FIG.

As shown in FIG. 27, the heat treatment temperature was 950-114.
Within the range of 0 ° C., the effect of reducing the IL by the heat treatment is recognized. Therefore, it can be said that heat treatment in a temperature range of 950 to 1140 ° C. is useful.

(Example 28) In the same manner as in Example 25,
When the main component ratio is Gd _2.0 Yb _0.1 Bi _0.9 Al _0.2 O ₁₂ and B
A garnet film containing about 1.5 wt% of ₂ O ₃ and about 1.5 wt% of PbO was grown to a thickness of about 700 μm.

Next, this sample was heated at a temperature of 1050 ° C.
The oxygen concentration of the atmosphere is 0, 10, 20, 40, 60, 8
After setting the temperature to 0,100% and holding and heat-treating for 20 hours, a sample was prepared and measured.

[0206] Consequently, for all samples, H _s is about 500 Oe, theta _F is about 900deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -40 ℃ less.

FIG. 2 shows the relationship between IL and the heat treatment temperature.
FIG.

FIG. 28 shows that the oxygen concentration in the heat treatment atmosphere was 1
In the range of 0 to 100%, the effect of reducing IL by heat treatment is recognized. Therefore, it can be said that an oxygen concentration of 10 to 100% in the heat treatment atmosphere is useful.

Example 29 High Purity Gadolinium Oxide (Gd ₂ O ₃ ), Ytterbium Oxide (Yb ₂ O ₃ ), Terbium Oxide (Tb ₂ O ₃ ), Ferric Oxide (α-Fe)
₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), lead oxide (PbO), boron oxide (B
₂ O ₃₎ and a powder of platinum oxide (PtO ₂₎ was used as a raw material, a _{PbO-Bi 2 O 3 -B 2} O 3 system as a flux at the LPE method, NGG substrate (lattice constant 12.509
Angstrom) and the main component ratio is Gd _1.4 Yb
_0.3 Bi _1.3 Fe _4.4 Al _0.6 O ₁₂ and about 1.5 watts of Bi ₂ O ₃
t%, PbO about 2.0wt%, the PtO ₂ about 2.0wt
%, A GdBi-based garnet film having a composition of about 7%
It was grown up to 00 μm.

Similarly, on a SGGG substrate (with a lattice constant of 12.496 angstroms), the main component ratio is
A TbBi-based garnet film having a composition of Tb _2.0 Bi _1.0 Fe ₅ O ₁₂ was grown to a thickness of about 700 μm.

Next, the substrates of these samples were removed, and
After mirror polishing to a thickness of 00 μm, the light transmittance of the garnet thick film in the wavelength range of 0.9 to 2.2 μm was measured using a variable wavelength spectrometer. The result is shown in FIG. In addition, on each side of each of these samples, 5 points each were E
PMA analysis was performed, and the average value was the above composition value. B ₂ O ₃ was determined by atomic absorption spectrometry.

FIG. 29 shows the relationship between the wavelength and the transmittance of the garnet thick film. In the drawing, the solid line shows the relationship between the transmittance of each thick film and the wavelength for the GdBi-based garnet, and the broken line shows the relationship for the TbBi-based garnet.

In FIG. 29, GdBi-based garnet shows high transmittance in a wavelength region of about 1.2 μm or more. On the other hand, in a TbBi-based garnet thick film, the wavelength band showing high transmittance is about 1.2 to 1.5 μm.
Range. Therefore, in a wavelength band of 1.5 μm or more, a GdBi-based garnet is particularly useful.

The GdBi-based garnet thick film was polished on both sides of the sample to adjust the thickness so that the Faraday rotation at a wavelength of 1.55 μm was about 45 deg.
An anti-reflection coating treatment with SiO ₂ was performed, and a magnetic field was applied up to about 500 Oe using an electromagnet to determine an insertion loss (IL) at a wavelength of 1.55 μm, a Faraday rotation capability θ _F , and a saturation magnetic field H _s .

Similarly, the temperature is changed, the temperature change rate θ _{F / T of the} Faraday rotation angle, the magnetization reversal temperature T _comp
I asked.

[0216] As a result, I.L. Is 0.07 dB, H _s is about 400 Oe, theta _F is about 1200deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp is a at -40 ℃ below Was.

Therefore, the GdBi-based garnet thick film is
It can be said that it is extremely useful as a Faraday rotation element.

(Example 30) In the same manner as in Example 29,
On the NGG substrate, the main component ratio is Gd _1.7 Yb _0.2 Bi _1.1
Fe _4.6 Al _0.4 O ₁₂ , about 0.5 wt% of B ₂ O ₃ , Pb
O is about 0.5 wt% and PtO ₂ is 0.1.10, 0.2.
GdB of composition containing 0.30, 0.40, 0.50
After growing the i-type garnet thick film to a thickness of about 600 μm,
A sample was prepared and measured.

As a result, for all samples, Hs was about 400 Oe, θ _F was about 1100 deg / cm, θ _{F / T} was about 0.06 deg / ° C., and T _comp was −40 ° C. or less.

FIG. 30 shows the relationship between IL and PtO ₂ .
Shown in

FIG. 30 shows that the increase in PtO ₂ resulted in
L. shows a tendency to decrease, and IL significantly increases in a region where PtO ₂ exceeds 4.0 wt%.

[0222] Therefore, the composition value of PtO ₂ is, 0 <PtO ₂
It can be said that the range of ≦ 0.40 wt% is useful. In particular,
The range is preferably 0.4 to 3.6 wt%.

(Example 31) As in Example 29,
Principal component ratio NGG substrate _{is, Gd 2.0 Yb 0.1 Bi 0. 9} F
e _4.8 Al _0.2 O ₁₂ , about 3.5 wt% of PbO, PtO ₂
After growing a GdBi garnet thick film containing about 0.5% by weight of, a sample of 950 ° C., 1000 ° C., 1050 ° C., 1
Heat treatment was performed by holding at 100 ° C., 1130 ° C., and 1150 ° C. for 10 hours.

Next, both surfaces of these samples were polished to a thickness such that the Faraday rotation at a wavelength of 1.55 μm was about 45 deg.

[0225] Consequently, for all samples, H _s is about 500 Oe, theta _F is about 900deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -40 ℃ less.

FIG. 3 shows the relationship between IL and heat treatment temperature.
It is shown in FIG.

As shown in FIG. 31, the heat treatment temperature was 950-114.
In the range of 0 ° C., the effect of reducing IL by heat treatment is recognized.

Therefore, it can be said that a heat treatment in the range of 950 to 1140 ° C. is useful.

(Example 32) As in Example 29,
On the NGG substrate, the main component ratio is Gd _1.1 Yb _0.4 Bi _1.5
Fe _4.1 Al _0.9 O ₁₂ , about 3.5 wt% of B ₂ O ₃ , Pt
A GdBi garnet thick film containing about 3.5 wt% of O ₂ was grown to a thickness of about 500 μm.

Next, this sample was heated at a temperature of 1050 ° C. and the oxygen concentration of the atmosphere was changed to 0, 10, 20, 40, 60, 80,
After heat treatment at 100% and holding for 20 hours, a sample was prepared and measured.

[0231] Consequently, for all samples, H _s is about 300 Oe, theta _F is about 1400deg _/ cm, θ _F / _T is about 0.05 deg / ° C., T _comp were -40 ℃ less.

FIG. 3 shows the relationship between IL and heat treatment temperature.
It is shown in FIG.

FIG. 32 shows that the oxygen concentration in the heat treatment atmosphere was 1
In the range of 0 to 100%, the effect of reducing IL by heat treatment is recognized.

Therefore, it can be said that the oxygen concentration of the heat treatment atmosphere in the range of 10 to 100% is useful.

Example 33 High-purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ ), ferric oxide (α-Fe)
₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), bismuth oxide (B
i ₂ O ₃ ), lead oxide (PbO) and boron oxide (B
Powder ₂ O ₃₎ was used as a raw material, PbO-Bi ₂ O ₃ -
Using a B ₂ O ₃ flux as a flux, the main component ratio was Gd _1.9 Yb _0.2 Bi _0.9 Fe _4.6 Ga _0.4 O on an NGG substrate (lattice constant: 12.509 angstroms) by the LPE method.
A GdBi-based garnet film having a composition of ₁₂
m.

Similarly, on a SGGG substrate (with a lattice constant of 12.496 angstroms), the main component ratio is
A TbBi-based garnet film having a composition of Tb _2.0 Bi _1.0 Fe ₅ O ₁₂ was grown to a thickness of about 700 μm.

Next, the substrates of these samples were removed, and
After mirror polishing to a thickness of 00 μm, the light transmittance of the garnet thick film in the wavelength range of 0.9 to 2.2 μm was measured using a variable wavelength spectrometer. The result is shown in FIG. In addition, on each side of each of these samples, 5 points each were E
PMA analysis was performed, and the average value was the above composition value.

FIG. 33 shows the relationship between the wavelength and the transmittance of the garnet thick film. In the drawing, the solid line shows the relationship between the transmittance of each thick film and the wavelength for the GdBi-based garnet, and the broken line shows the relationship for the TbBi-based garnet.

In FIG. 33, the GdBi-based garnet shows high transmittance in a region having a wavelength of about 1.2 μm or more. On the other hand, in a TbBi-based garnet thick film, the wavelength band showing high transmittance is about 1.2 to 1.5 μm.
Range. Therefore, in a wavelength band of 1.5 μm or more, a GdBi-based garnet is particularly useful.

The GdBi-based garnet thick film was polished on both sides of the sample to adjust the thickness so that the Faraday rotation at a wavelength of 1.62 μm was about 45 deg.
A non-reflective coating treatment with SiO ₂ was performed, and a magnetic field was applied to about 500 Oe using an electromagnet to determine an insertion loss (IL) at a wavelength of 1.62 μm, a Faraday rotation capability θ _F , and a saturation magnetic field H _s .

Similarly, the temperature is changed, the temperature change rate θ _{F / T of the} Faraday rotation angle, the magnetization reversal temperature T _comp
I asked.

[0242] As a result, I.L. Is 0.08 dB, H _s is about 400 Oe, theta _F is about 750deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp is a at -40 ℃ below Was.

Therefore, the GdBi-based garnet thick film is
It can be said that it is extremely useful as a Faraday rotation element.

(Example 34) In the same manner as in the thirty-third embodiment, the main component ratio was Gd _2.2-x Y b on an NGG substrate.
_x Bi _0.8 Fe _4.5 Ga _0.5 O ₁₂ , where x = 0.
After growing a GdBi garnet film having a composition of 10, 0.20, 0.30, 0.40, 0.50 to a thickness of about 800 µm, a sample was prepared and measured.

As a result, for all samples, θ _F was about 700 deg / cm and θ _{F / T} was about 0.07 to 0.08 deg.
g / ° C. and T _comp were −10 ° C. or less.

FIG. 34 shows the relationship between the composition value x and θ _F , IL.

[0247] From Figure 34, substitution with x, I.L. Significantly reduced, H _s is x it can be seen that a less 500Oe at 0.4 or less.

Therefore, the composition value of x is 0 <x ≦ 0.40
Is useful. The increase in IL in the region where x is 0.10 or less is presumed to be due to distortion of the crystal lattice of the garnet crystal and variation in ion balance.

(Example 35) In the same manner as in Example 34,
The main component ratio on the NGG substrate is Gd _2.7-y Yb _0.3 Bi _y F
e _4.4 Ga _0.6 O ₁₂ , y = 0.50, 0.60, 0.7
After a GdBi garnet film having a composition of 0.80, 0.80, 0.90, 1.00, 1.10, 1.20 was grown to a thickness of about 900 μm, a sample was prepared and measured.

[0250] Consequently, for all samples, H _s is about 500 Oe, theta _{F / T} is about 0.06~0.08deg / ℃,
T _comp was −40 ° C. or less.

FIG. 35 shows the relationship between the composition value y and θ _F , IL.

[0252] From Figure 35, theta _F that exceeds 600deg / cm is, y is obtained by 0.55 or more. Also,
IL tends to increase significantly when y exceeds 1.10.

Therefore, the composition value of y is 0.55 ≦ y ≦ 1.0.
A range of 10 may be useful. It is presumed that the increase in IL in the region where y is 1.10 or more is caused by distortion of the crystal lattice of the garnet crystal and variation in ion balance.

(Example 36) In the same manner as in Example 34,
On the NGG substrate, the main component ratio is Gd _1.8 Yb _0.2 Bi _1.0
For Fe _5-z G _az O ₁₂ , z = 0.10, 0.20, 0.3
G having a composition of 0.40, 0.40, 0.50, 0.60, 0.70
After growing the dBi garnet film to a thickness of about 800 μm,
A sample was prepared and measured.

As a result, for all samples, IL was 0.1 dB or less, θ _F was about 800 deg / cm, and T _comp was −40 ° C. or less.

FIG. 36 shows the relationship between the composition value z and θ _{F / T} , H _s .

FIG. 36 shows that θ _{F / T} is 0.08 deg / ° C. or less and z is 0.60 or less. In addition, H _s 5
In the case of 00 Oe or less, z is obtained at 0.15 or more.

Therefore, the composition value of z is 0.20 ≦ z ≦ 0.2.
A range of 60 may be useful.

(Embodiment 37) As in Embodiment 34,
Main component _{ratio, Gd 2.2 Yb 0.1 Bi 0.7 Fe} 4.7 Ga 0. 3 O
A garnet film having a composition of ₁₂ was grown to a thickness of about 900 μm.

Next, this sample was placed in an atmosphere of about 50% oxygen concentration at 950 ° C., 1000 ° C., 1050 ° C., 110 ° C.
Heat treatment was performed at 0 ° C., 1130 ° C., and 1150 ° C. for 10 hours.

Next, these samples were processed at a wavelength of 1.62 μm.
Was adjusted (about 650 μm) to a thickness at which the Faraday rotation angle was about 45 deg, and then the characteristics were measured in the same manner as in Example 33.

[0262] Consequently, for all samples, H _s is about 300 Oe, theta _F is about 650deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -30 ° C. or less.

The results of IL and heat treatment temperature are shown in FIG.
FIG.

As shown in FIG. 37, the heat treatment temperature was 950-113.
In the range of 0 ° C., a decrease in IL due to heat treatment is observed.

Therefore, it can be said that heat treatment in the temperature range of 950 to 1130 ° C. is useful.

(Example 38) In the same manner as in Example 35,
Main component _{ratio, Gd 1.5 Yb 0.3 Bi 1.1 Fe} 4.5 Ga 0. 5 O
A garnet film having a composition of ₁₂ was grown to a thickness of about 600 μm.

Next, the oxygen concentration of the sample was adjusted to 0, 10, 20, 40, and 6 at each temperature of 1050 ° C.
After performing heat treatment at 0, 80, and 100% and holding for 20 hours, a sample was prepared and each characteristic was measured.

[0268] Consequently, for all samples, H _s is about 450 Oe, theta _F is about 900deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -40 ℃ less.

FIG. 38 shows the relationship between IL and the oxygen concentration of the atmosphere.

From FIG. 38, it is found that the oxygen concentration of the atmosphere is 10 to 10.
In the range of 100%, the effect of reducing IL by heat treatment is recognized.

Therefore, it can be said that the oxygen concentration of the heat treatment atmosphere in the range of 10 to 100% is useful.

Example 39 High-purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), ferric oxide (Fe ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), oxide bismuth (Bi ₂ O _3), a powder of lead oxide (PbO) and boron oxide (B ₂ O ₃₎ was used as a raw material, PbO-B
Using the i ₂ O ₃ -B ₂ O ₃ system as a flux by the LPE method,
NGG substrate (Lattice constant 12.509 angstroms)
Above, the main component ratio is Gd _1.7 Yb _0.3 Bi _1.0 Fe _4.5 Ga
_{With 0.5} O ₁₂ , B ₂ O _{3 is changed} to 0, 1.0, 2.0, 3.0, 4.
GdBi-based garnet films having a composition of 0.5 wt% were grown to a thickness of about 600 μm.

Next, after removing the substrates of these samples,
Both surfaces were polished, and the thickness was adjusted so that the Faraday rotation at a wavelength of 1.58 μm was about 45 deg. In addition, the above-mentioned composition has E points of 5 points on both sides of these samples.
PMA analysis was performed to determine the average value, and B ₂ O ₃ was determined by atomic absorption analysis of a sample piece.

Next, after subjecting these sample plates to a non-reflection coating treatment with a SiO ₂ film, the magnetic field was reduced to about 5 by an electromagnet.
The voltage was applied up to 00 Oe, and the insertion loss (IL) at a wavelength of 1.58 μm, the Faraday rotation capability θ _F , and the minimum applied magnetic field at which the transmittance reached saturation (saturated magnetic field H _s ) were determined.

Similarly, the temperature was changed to -20.
The temperature change rate θ _{F / T} of the Faraday rotation angle θ _F and the magnetization reversal temperature T _comp between ° C. and + 80 ° C. were determined.

[0276] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 900deg _/ cm, θ _F / _T is about 0.06deg / ℃, was T _comp -40 ° C. or less.

FIG. 39 shows the relationship between IL and B ₂ O ₃ content.

As can be seen from FIG. 39, IL is B ₂
It can be seen that the content is reduced by the content of O ₃ and is remarkably increased in a region exceeding 4.0 wt%. As a result, the effect of reducing IL is recognized in the range of 0 to 4.0 wt% (however, excluding 0).

Accordingly, the content of B ₂ O ₃ is from 0 to 4.0 w
A range of t% (excluding 0) is useful. In particular,
The range of 1-3 wt% is preferred.

(Example 40) As in Example 39,
The NGG substrate main component ratio Gd _2.0 Yb _0.2 Bi _{0 .8} F
e _4.7 Ga _0.3 O ₁₂ , PbO is 0, 1.0, 2.0, 3.
After growing a GdBi-based garnet thick film having a composition containing 0, 4.0, 5.0 wt% to a thickness of about 700 µm, a sample was prepared and measured.

[0281] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 800deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -40 ℃ less.

FIG. 40 shows the relationship between IL and PbO content.

As shown in FIG. 40, the inclusion of PbO caused the IL.
In the region where PbO exceeds 4.0 wt%,
It can be seen that L. has increased significantly.

Therefore, the content of PbO is from 0 to 4.0 w
It can be said that the range of t% (not including 0) is useful. Further, desirably, by setting PbO to be in the range of 0.4 to 4.0 wt%, IL can be reduced to 0.08 dB or less. In particular, the range of 1.0 to 4.0 wt% is preferable.

(Example 41) As in Example 40,
On the NGG substrate, the main component ratio is Gd _1.5 Yb _0.4 Bi _1.1
Fe _4.4 Ga _0.6 O ₁₂ , PtO ₂ was changed to 0, 1.0, 2.0,
After growing a GdBi-based garnet thick film containing 3.0, 4.0 and 5.0 wt% to a thickness of about 600 μm, a sample was prepared and measured.

[0286] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 1000deg _/ cm, θ _F / _T is about 0.06deg / ℃, was T _comp -40 ° C. or less.

FIG. 41 shows the relationship between IL and PtO ₂ content.

As shown in FIG. 41, the inclusion of PtO ₂ allows
It can be seen that L. decreases, and IL significantly increases in a region where PtO ₂ exceeds about 4.0 wt%.

Therefore, the content of PtO ₂ is from 0 to 4.0 w
It can be said that the range of t% (not including 0) is useful. In addition, especially, the range of 0.4 to 3.8 wt% is preferable.

(Example 42) As in Example 40,
On the NGG substrate, the main component ratio is Gd _1.9 Yb _0.2 Bi _0.9
Fe _4.6 Ga _0.4 O ₁₂ , containing two or more types of B ₂ O ₃ , PbO and PtO ₂ , the total amount of which is 0, 1.0, 2.0, 4.
Gd containing 0, 6.0, 8.0, 9.0, 10.0 wt%
After growing a Bi-based garnet thick film to a thickness of about 600 μm,
A sample was prepared and measured.

[0291] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 900deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp were -40 ℃ less.

Further, IL and B ₂ O ₃ , PbO, PtO ₂
Is shown in FIG.

From FIG. 42, it is found that the content of B ₂ O ₃ , PbO and PtO ₂ decreases the IL and the content becomes about 9.0 wt%.
It can be seen that the IL shows a tendency to increase in the region exceeding.

Therefore, when the content of B ₂ O ₃ , PbO, and PtO ₂ is in the range of 0 to 9.0 wt% (but not including 0), the IL is clearly reduced, and it is considered useful. I can say.

(Example 43) In the same manner as in Example 40,
On the NGG substrate, the main component ratio is Gd_2.1Yb_0.1Bi _0.7
Fe_4.8Ga_0.2O₁₂And B_TwoO_ThreeAbout 1 wt%, PbO
About 2 wt%, and PtO_TwoContaining about 2 wt% of
An i-type garnet thick film was grown to a thickness of about 700 μm.

Next, this sample was placed in an atmosphere of about 50% oxygen concentration at 950 ° C., 1000 ° C., 1050 ° C., 110 ° C.
It was kept at each of 0 ° C., 1130 ° C., and 1150 ° C. for 10 hours and heat-treated.

Next, both surfaces of these samples were polished, and the Faraday rotation angle at a wavelength of 1.58 μm was about 4 μm.
After adjusting the thickness to 5 deg, a sample was prepared and measured.

[0298] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 700deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -40 ℃ less.

FIG. 43 shows the relationship between IL and the heat treatment temperature.
Shown in

As shown in FIG. 43, the heat treatment temperature was 950-114.
In the range of 0 ° C., the effect of reducing IL by heat treatment is recognized.

Therefore, it can be said that heat treatment in the temperature range of 950 to 1140 ° C. is useful.

(Example 44) As in Example 43,
Main component ratio, in _{Gd 1.7 Yb 0.2 Bi 1.1 Ga 0.6} O 12, B
About 2.0 wt% of ₂ O ₃ , about 3.0 wt% of PbO, PtO
The GdBi garnet film containing ₂ to about 2 wt% was grown to a thickness of about 600 .mu.m.

Next, this sample was heated at a temperature of 1050 ° C.
The oxygen concentration of the atmosphere is 0, 10, 20, 40, 60, 8
After heat treatment at 10% for 10 hours, the Faraday rotation angle at a wavelength of 1.58 μm is about 45 de.
After adjusting to a thickness of g, a sample was prepared and each characteristic was measured.

[0304] Consequently, for all samples, H _s is about 300 Oe, theta _F is about 1000deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp were -40 ℃ less.

FIG. 44 shows the relationship between IL and the oxygen concentration in the heat treatment atmosphere.

FIG. 44 shows that the oxygen concentration in the heat treatment atmosphere was 1
In the range of 0 to 100%, the effect of reducing IL by heat treatment is recognized.

Therefore, it can be said that an oxygen concentration of 10 to 100% in the heat treatment atmosphere is useful.

Example 45 High-purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ ), ferric oxide (α-Fe)
₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), lead oxide (P
bO) and boron oxide (B ₂ O ₃ ) powder as raw materials, and a PbO—Bi ₂ O ₃ —B ₂ O ₃ system as a flux by an LPE method using an NGG substrate (with a lattice constant of 12.509).
Angstrom), and the main component ratio is Gd _1.5 Yb
_{0.1 Bi 1.3 Fe 4 .4 Al 0.6} Ga 0.1 O 12 made of the composition Gd
A Bi-based garnet film was grown to a thickness of about 700 μm.

Similarly, on a SGGG substrate (with a lattice constant of 12.496 angstroms), the main component ratio is
A TbBi-based garnet film having a composition of Tb _2.0 Bi _1.0 Fe ₅ O ₁₂ was grown to a thickness of about 700 μm.

Next, the substrates of these samples were removed, and
After mirror polishing to a thickness of 00 μm, the light transmittance of the garnet thick film in the wavelength range of 0.9 to 2.2 μm was measured using a variable wavelength spectrometer. The result is shown in FIG. In addition, on each side of each of these samples, 5 points each were E
PMA analysis was performed, and the average value was the above composition value.

FIG. 45 shows the relationship between the wavelength and the transmittance of the garnet thick film. In the drawing, the solid line shows the relationship between the transmittance of each thick film and the wavelength for the GdBi-based garnet, and the broken line shows the relationship for the TbBi-based garnet.

In FIG. 45, GdBi-based garnet shows high transmittance in a wavelength region of about 1.2 μm or more. On the other hand, in a TbBi-based garnet thick film, the wavelength band showing high transmittance is about 1.2 to 1.5 μm.
Range. Therefore, in a wavelength band of 1.5 μm or more, a GdBi-based garnet is particularly useful.

The GdBi-based garnet thick film was polished on both sides of the sample and adjusted to a thickness such that the Faraday rotation at a wavelength of 1.55 μm was about 45 deg.
An anti-reflection coating treatment with SiO ₂ was performed, and a magnetic field was applied up to about 500 Oe using an electromagnet to determine an insertion loss (IL) at a wavelength of 1.55 μm, a Faraday rotation capability θ _F , and a saturation magnetic field H _s .

Similarly, the temperature was changed, and the temperature change rate θ _{F / T of the} Faraday rotation angle and the magnetization reversal temperature T _comp were determined.

[0315] As a result, I.L. Is 0.09 dB, H _s is about 400 Oe, theta _F is about 1100deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp is a at -40 ℃ below Was.

Therefore, the GdBi-based garnet thick film is
It can be said that it is extremely useful as a Faraday rotation element.

(Example 46) In the same manner as in Example 45,
On the NGG substrate, the main component ratio is Gd_1.6Yb_0.1Bi _1.3
Fe_4.3(Al_a, Ga_b)_0.7O₁₂And a / (a + b) =
0, 0.10, 0.20, 0.30, 0.40, 0.50,
0.60, 0.70, 0.80, 0.90, 1.00
Grown GdBi garnet film to a thickness of about 600μm
After that, a sample was prepared and measured.

[0318] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 1200deg _/ cm, θ _F / _T was about 0.05 deg / ° C..

FIG. 46 shows the relationship between the composition ratio a / (a + b) and T _comp and IL.

From FIG. 46, it can be seen that T _comp tends to decrease as a / (a + b) increases. When a / (a + b) is 0.05, T _comp is significantly lower than −20 ° C. You can see that. Note that a / (a + b) is 0.2.
In the above, it was confirmed that T _comp was −40 ° C. or less, but it was difficult to quantify it.
As shown. In addition, IL is such that a / (a + b) is 0.9.
Above shows a tendency to remarkably increase.

Accordingly, the composition ratio a / (a + b) is 0.0
It can be said that the range of 5 ≦ a / (a + b) ≦ 0.90 is useful.
In the region where a / (a + b) exceeds 0.90, the IL.
Is presumed to be caused by distortion of the crystal lattice of the garnet crystal and variation in ion balance.

(Example 47) As in Example 46,
Principal component ratio NGG substrate _{is, Gd 1.6-x Yb x Bi} 1. 4 F
e _4.0 Al _0.6 Ga _0.4 O ₁₂ , where x = 0.0.10,0.2
After growing a GdBi garnet film having a composition of 0.30, 0.40, 0.50, 0.60 to a thickness of about 600 μm,
A sample was prepared and measured.

As a result, for all samples, θ _F was about 1300 deg / cm, and θ _{F / T} was 0.04 to 0.07 deg.
g / ° C. and T _comp were −40 ° C. or less.

[0324] The relation between the composition value x and H _s and I.L. Figure 47.

From FIG. 47, it can be seen that IL is increased by increasing the composition value x.
Indicates a decreasing tendency. Also, H _s is increased by the increase in x, H _s when x exceeds 0.50, the above 500 Oe.

Therefore, the composition value of x is 0 <x ≦ 0.50
Is useful.

(Example 48) In the same manner as in Example 46,
On the NGG substrate, the main component ratio is Gd _2.8-y Yb _0.2 Bi _y
In _{Fe 4.1 Al 0.6 Ga 0.3 O 12} , y = 0.80,0.9
0, 1.00, 1.10, 1.20, 1.30, 1.40,
After growing a GdBi garnet film having a composition of 1.50, 1.60, and 1.70 to a thickness of about 700 μm, a sample was prepared and measured.

[0328] Consequently, for all samples, H _s is about 200~450Oe, θ _{F / T} is about 0.04~0.07de
g / ° C. and T _comp were −40 ° C. or less.

FIG. 48 shows the relationship between the composition value y and θ _F and IL.

FIG. 48 shows that θ _F is 800 deg / cm or more and y is 0.85 or more. In addition, IL
Shows a tendency to increase markedly when y exceeds 1.60.

Therefore, the composition value of y is 0.85 ≦ y ≦ 1.0.
A range of 60 may be useful. The increase in IL in the region where y exceeds 1.60 is presumed to be caused by distortion of the crystal lattice of the garnet crystal and variation in ion balance.

(Example 49) As in Example 46,
On an NGG substrate, the main component ratio is Gd _1.5 Yb _0.2 Bi _1.3
Fe _5-z (Al _0.8 Ga _0.2 ) _z O ₁₂ and z = 0,0.1
0, 0.20, 0.30, 0.40, 0.50, 0.60,
After growing a GdBi garnet film having a composition of 0.70, 0.80, 0.90, 1.00, 1.10 to a thickness of about 600 μm, a sample was prepared and measured.

As a result, for all samples, θ _F was about 1200 deg / cm and θ _{F / T} was about 0.04 to 0.06 d.
eg / ° C. and T _comp were −40 ° C. or less.

[0334] Further illustrating the relationship between the composition value z and H _s and I.L. Figure 49.

[0335] From Figure 49, H _s is 500Oe less is obtained by z is 0.20 or more. Further, IL rapidly increases when z is 1.00 or more.

Therefore, the composition value of z is 0.20 ≦ z ≦ 1.0.
A range of 00 is useful. It is presumed that the increase in IL in the region where z exceeds 1.00 is caused by distortion of the crystal lattice of the garnet crystal and variation in ion balance.

(Example 50) In the same manner as in Example 46,
Main component _{ratio, Gd 1.2 Yb 0.3 Bi 1.5 Fe} 4.0 Al 0. 8 G
a A garnet film having a composition of _0.1 O ₁₂ having a thickness of about 500 μm
I grew up.

Next, this sample was heated at 950 ° C., 1000 ° C., 1050 ° C., 110
Heat treatment was performed at 0 ° C., 1130 ° C., and 1150 ° C. for 10 hours.

Next, these samples were processed at a wavelength of 1.55 μm.
After the Faraday rotation angle was adjusted to about 45 deg (about 300 μm), each characteristic was measured in the same manner as in the first embodiment.

[0340] Consequently, for all samples, H _s is about 450 Oe, theta _F is about 1400deg _/ cm, θ _F / _T is about 0.04deg / ℃, T _comp was about -40 ° C..

The results of IL and heat treatment temperature are shown in FIG.
0 is shown.

According to FIG. 50, the heat treatment temperature was 950 to 114.
Within the range of 0 ° C., the effect of reducing the IL by the heat treatment is recognized.

Therefore, it can be said that heat treatment in a temperature range of 950 to 1140 ° C. is useful.

(Example 51) In the same manner as in Example 46,
Main component _{ratio, Gd 1.9 Yb 0.1 Bi 1.0 Fe} 4.5 Al 0. 4 G
a A garnet film having a composition of _0.1 O ₁₂ having a thickness of about 600 μm
I grew up.

Next, the oxygen concentration of the atmosphere was adjusted to 0, 10, 20, 40, and 6 at each temperature of 1050 ° C.
After performing heat treatment at 0, 80, and 100% and holding for 20 hours, a sample was prepared and each characteristic was measured.

[0346] Consequently, for all samples, H _s is about 350 Oe, theta _F is about 950deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp were -40 ℃ less.

FIG. 51 shows the relationship between IL and the oxygen concentration of the atmosphere.

FIG. 51 shows that the oxygen concentration of the atmosphere is
In the range of 100%, the effect of reducing IL by heat treatment is recognized.

Therefore, it can be said that the oxygen concentration of the heat treatment atmosphere in the range of 10 to 100% is useful.

Example 52 High purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), ferric oxide (Fe ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ )
Gallium oxide (Ga ₂ O ₃ ), bismuth oxide (Bi
₂ O ₃ ), lead oxide (PbO) and boron oxide (B ₂ O ₃ )
Of PbO—Bi ₂ O ₃ —B ₂ O ₃
Using the system as a flux, about 0.5 wt% of PbO was contained on an NGG substrate (lattice constant: 12.509 angstroms) by the LPE method, and the main component ratio was Gd _1.4 Yb _0.3.
Bi _1.3 Fe _4.2 at _{Al 0 .2 Ga 0.6 O 12,} B 2 O 3 0,
A GdBi-based garnet film having a composition containing 1.0, 2.0, 3.0, 4.0, 5.0 wt% was grown to a thickness of about 500 μm.

Next, the substrates of these samples were removed, and both surfaces were polished to adjust the thickness so that the Faraday rotation at a wavelength of 1.55 μm was about 45 deg. In addition, the above-mentioned composition is obtained by EP
MA analysis was performed and the average value was obtained.
For B ₂ O ₃ , a sample piece was determined by atomic absorption spectrometry.

Next, after subjecting these sample plates to a non-reflection coating treatment with a SiO ₂ film, a magnetic field was applied to about 0.5 kOe using an electromagnet, and the transmittance was saturated at a wavelength of 1.55 μm. Applied magnetic field (saturation magnetic field H
_s ), insertion loss (IL), and Faraday rotation capability θ _F ,
And the temperature change rate θ _{F / T} of θ _F between −20 ° C. and + 80 ° C. was determined.

[0353] As a result, for all samples, H _s about 4
00 Oe, θ _F about 1200 deg / cm, θ _{F / T} about 0.0
It was 5 deg / ° C and T _comp -40 ° C or less.

FIG. 52 shows the relationship between IL and B ₂ O ₃ content.

As can be seen from FIG. 52, IL is B ₂
It can be seen that the content is reduced by the content of O ₃ and is remarkably increased in a region exceeding 4.0 wt%. As a result, the effect of reducing IL is recognized in the range of 0 to 4.0 wt% (however, excluding 0).

Therefore, the content of B ₂ O ₃ is from 0 to 4.0 w
A range of t% (excluding 0) is useful. In particular,
The range of 1-3 wt% is preferred.

(Example 53) In the same manner as in Example 52,
The B ₂ O ₃ and contained about 0.5 wt%, the main component ratio, Gd _1.7
Yb _0.2 Bi _1.1 Fe _4.5 Al _0.3 O ₁₂ with PbO of 0,
After growing a GdBi-based garnet film having a composition containing 1.0, 2.0, 3.0, 4.0, and 5.0 wt% to a thickness of about 600 μm, a sample was prepared and measured.

[0358] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 1100deg _/ cm, θ _F / _T is about 0.06deg / ℃, T _comp were -40 ℃ less.

FIG. 53 shows the relationship between IL and PbO content.

From FIG. 53, it can be seen that the inclusion of PbO caused the IL.
In the region where PbO exceeds 4.0 wt%,
It can be seen that L. has increased significantly.

Therefore, the content of PbO is from 0 to 4.0 w
It can be said that the range of t% (not including 0) is useful. Further, desirably, by setting PbO in the range of 0.2 to 4.0 wt%, IL can be reduced to 0.08 dB or less. In particular, a range of 1.0 to 3.5 wt% is preferable.

(Example 54) In the same manner as in Example 52, the main component ratio was Gd _1.1 Yb _0.4 Bi _1.5 Fe _4.1 Al.
A garnet thick film of _0.4 Ga _0.5 O ₁₂ containing about 0.7 wt% of B ₂ O ₃ and about 0.7 wt% of PbO has a thickness of about 500
It grew to μm.

Next, this sample was placed in an atmosphere of about 50% oxygen concentration at 950 ° C., 1000 ° C., 1050 ° C., 110 ° C.
Heat treatment was performed at each of 0 ° C., 1130 ° C., and 1150 ° C. for 10 hours.

Next, both surfaces of these samples were polished, and the Faraday rotation angle at a wavelength of 1.55 μm was about 4 μm.
After adjusting the thickness to 5 deg, a sample was prepared and measured.

[0365] Consequently, for all samples, H _s is about 500 Oe, theta _F is about 1400deg _/ cm, θ _F / _T is about 0.04deg / ℃, T _comp were -40 ℃ less.

FIG. 5 shows the results of IL and heat treatment temperature.
It is shown in FIG.

As shown in FIG. 54, the heat treatment temperature was 950 to 114.
Within the range of 0 ° C., the effect of reducing the IL by the heat treatment is recognized. Therefore, it can be said that heat treatment in a temperature range of 950 to 1140 ° C. is useful.

(Example 55) In the same manner as in Example 52,
Main component _{ratio, Gd 2.0 Yb 0.1 Bi 0.9 Fe} 4.7 Al 0. 2 G
a _0.1 O ₁₂ , about 1.5 wt% of B ₂ O ₃ and about 1.
A garnet film containing 5 wt% was grown to a thickness of about 700 μm.

Next, this sample was heated at a temperature of 1050 ° C.
The oxygen concentration of the atmosphere is 0, 10, 20, 40, 60, 8
After setting the temperature to 0,100% and holding and heat-treating for 20 hours, a sample was prepared and measured.

[0370] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 900deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -40 ℃ less.

FIG. 5 shows the relationship between IL and the heat treatment temperature.
It is shown in FIG.

From FIG. 55, it is found that the oxygen concentration in the heat treatment atmosphere is 1
In the range of 0 to 100%, the effect of reducing IL by heat treatment is recognized. Therefore, it can be said that an oxygen concentration of 10 to 100% in the heat treatment atmosphere is useful.

(Example 56) High-purity gadolinium oxide (Gd ₂ O ₃ ), ytterbium oxide (Yb ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), terbium oxide (Tb ₂ O ₃ )
Ferric oxide (γ-Fe ₂ O ₃ ), aluminum oxide (Al
₂ O ₃ ), bismuth oxide (Bi ₂ O ₃ ), lead oxide (Pb
O), boron oxide (B ₂ O ₃ ) and platinum oxide (PtO ₂ )
Of PbO—Bi ₂ O ₃ —B ₂ O ₃
Using the system as a flux, the main component ratio was Gd _1.4 Yb _0.3 Bi _1.3 Fe _4.3 Al _0.2 Ga _0.5 O on an NGG substrate (lattice constant: 12.509 angstroms) by the LPE method.
_{In step 12} , about 1.5 wt% of B ₂ O ₃ and about 0.5 wt% of PbO
%, And a GdBi-based garnet thick film having a composition containing about 1.0 wt% of PtO ₂ was grown to a thickness of about 700 μm.

Similarly, on a SGGG substrate (with a lattice constant of 12.496 angstroms), the main component ratio is
A TbBi-based garnet film having a composition of Tb _2.0 Bi _1.0 Fe ₅ O ₁₂ was grown to a thickness of about 700 μm.

Next, after removing the substrates of these samples and polishing both surfaces to a mirror finish of about 600 μm in thickness, the wavelength was in the range of 0.9 to 2.2 μm using a variable wavelength spectrometer. Was measured for the light transmittance of the garnet thick film.

Also, on each side of these samples, 5
EPMA analysis was performed for each point, and the average value was the above composition value. B ₂ O ₃ is obtained by analyzing a sample piece by atomic absorption analysis.

FIG. 56 shows the relationship between the wavelength and the transmittance of the garnet thick film. In the drawing, the solid line shows the relationship between the transmittance of each thick film and the wavelength for the GdBi-based garnet, and the broken line shows the relationship for the TbBi-based garnet.

In FIG. 56, the GdBi-based garnet shows high transmittance in a wavelength region of about 1.2 μm or more. On the other hand, in the case of a TbBi-based garnet thick film, the wavelength band showing high transmittance is in the range of about 1.2 to 1.5 μm. Therefore, in the wavelength band of 1.5 μm or more, the GdBi-based garnet is particularly useful.

The GdBi-based garnet thick film was polished on both sides of the sample and adjusted to a thickness such that the Faraday rotation at a wavelength of 1.55 μm was about 45 deg.
An anti-reflection coating treatment with SiO ₂ was performed, and a magnetic field was applied up to about 500 Oe using an electromagnet to determine an insertion loss (IL) at a wavelength of 1.55 μm, a Faraday rotation capability θ _F , and a saturation magnetic field H _s .

Similarly, by changing the temperature, the temperature change rate θ _{F / T of the} Faraday rotation angle, the magnetization reversal temperature T
asked for _comp .

[0381] As a result, I.L. Is 0.05 dB, H _s is about 400 Oe, theta _F is about 1200deg _/ cm, θ _F / _T is about 0.05deg / ℃, T _comp is a at -40 ℃ below Was.

Therefore, the GdBi-based garnet thick film is
It can be said that it is extremely useful as a Faraday rotation element.

(Example 57) In the same manner as in Example 56,
On the NGG substrate, the main component ratio is Gd _1.7 Yb _0.2 Bi _1.1
Fe _4.4 Al _0.3 Ga _0.3 O ₁₂ , B ₂ O ₃ of about 0.5 wt.
%, PbO is about 0.5 wt%, and PtO ₂ is 0.1, 1.0,
After growing a GdBi-based garnet thick film having a composition containing 2.0, 3.0, 4.0, and 5.0 to a thickness of about 500 μm, a sample was prepared and measured.

As a result, for all the samples, Hs was about 400 Oe, θ _F was about 1200 deg / cm, θ _{F / T} was about 0.06 deg / ° C., and T _comp was −40 ° C. or less.

FIG. 57 shows the relationship between IL and PtO ₂ .
Shown in

From FIG. 57, it can be seen that the increase in PtO ₂ caused
L. shows a tendency to decrease, and IL significantly increases in a region where PtO ₂ exceeds 4.0 wt%.

Therefore, the content of PtO ₂ is 0 <PtO ₂
It can be said that the range of ≦ 0.40 wt% is useful. In particular,
The range of 0.4 to 3.8 wt% is preferable.

(Example 58) In the same manner as in Example 56,
Principal component ratio NGG substrate _{is, Gd 1.1 Yb 0.4 Bi 1. 5} F
e _4.1 Al _0.5 Ga _0.4 O ₁₂ , about 3.5 wt% of PbO,
After growing a GdBi garnet thick film containing about 0.5 wt% of PtO ₂ to a thickness of about 500 μm, this sample was reduced to about 50%
950 ° C, 1000 ° C, 1050 in an oxygen concentration atmosphere of
1100 ° C, 1130 ° C, and 1150 ° C
Heat treatment was performed for holding for 0 hour.

Next, both surfaces of these samples were polished to a thickness such that the Faraday rotation at a wavelength of 1.55 μm was about 45 deg. Samples were prepared and measured.

[0390] Consequently, for all samples, H _s is about 500 Oe, theta _F is about 1400deg _/ cm, θ _F / _T is about 0.04deg / ℃, T _comp were -40 ℃ less.

FIG. 5 shows the relationship between IL and heat treatment temperature.
FIG.

As shown in FIG. 58, the heat treatment temperature was 950 to 114.
Within the range of 0 ° C., the effect of reducing the IL by the heat treatment is recognized.

Therefore, it can be said that a heat treatment in the range of 950 to 1140 ° C. is useful.

(Example 59) As in Example 56,
On the NGG substrate, the main component ratio is Gd _2.0 Yb _0.1 Bi _0.9
In _{Fe 4.7 Al 0.2 Ga 0.1 O 12} , B 2 O 3 about 3.5wt
%, And about 3.5 wt% of PtO ₂ were grown to a thickness of about 600 μm.

Next, this sample was heated at a temperature of 1050 ° C. and the oxygen concentration of the atmosphere was adjusted to 0, 10, 20, 40, 60, 80,
After heat treatment at 100% and holding for 20 hours, a sample was prepared and measured.

[0396] Consequently, for all samples, H _s is about 400 Oe, theta _F is about 900deg _/ cm, θ _F / _T is about 0.07deg / ℃, T _comp were -40 ℃ less.

FIG. 5 shows the relationship between IL and the heat treatment temperature.
It is shown in FIG.

From FIG. 59, it can be seen that the oxygen concentration in the heat treatment atmosphere is 1
In the range of 0 to 100%, the effect of reducing IL by heat treatment is recognized.

Therefore, it can be said that the oxygen concentration of the heat treatment atmosphere in the range of 10 to 100% is useful.

[0400]

As described above, according to the present invention, the absorption at a wavelength of about 1.6 μm or more inherently possessed by TbBi-based garnets is avoided.
i system improved bismuth-substituted garnet thick film material of the temperature change rate of the garnet in the theta _f and a manufacturing method thereof can be provided.

Further, according to the present invention, it is possible to provide a Faraday rotator usable in a wavelength band exceeding about 1.5 μm among wavelengths.

Further, according to the present invention, it is possible to provide an optical isolator characterized by comprising the Faraday rotator.

[Brief description of the drawings]

FIG. 1 is a diagram showing the wavelength dependence of the transmittance of a GdYbBi-based garnet single-crystal thick film and a TbBi-based garnet single-crystal thick film grown by the LPE method in Example 1.
In the figure, the solid line is a GdYbBi-based garnet thick film, and the broken line is T
The characteristics for a bBi-based garnet thick film are shown.

FIG. 2 is a diagram showing measurement results of a GdYbBi-based garnet thick film material in Example 2. The measurement results of FIG. 2 (a) saturation magnetization 4PaiM _S, also the values of FIG. 2 (b) the temperature coefficient of the Faraday rotation angle theta _{f / T,} shows respectively.

FIG. 3 is a diagram showing measurement results of a GdYbBi-based garnet thick film material in Example 3. FIG. 3A is a diagram showing a measurement result of the Faraday rotation ability, and FIG. 3B is a diagram showing an insertion loss.

FIG. 4 is a diagram showing measurement results of a GdYbBi-based garnet thick film material in Example 4. FIG. 4A shows the measurement results of the temperature coefficient θ _{f / T} of the Faraday rotation angle,
FIG. 4B is a diagram illustrating the saturation magnetization.

FIG. 5 is a diagram showing insertion loss of a GdYbBi-based garnet thick film material in Example 5.

FIG. 6 is a diagram showing insertion loss of a GdYbBi-based garnet thick film material in Example 6.

FIG. 7 is a diagram showing the relationship between the wavelength of light and the transmittance of a garnet thick film in Example 7. In the figure, the solid line is GdYb
The Bi-based garnet thick film and the broken line show the characteristics with respect to the TbBi-based garnet thick film.

FIG. 8 is a diagram showing the relationship between the PbO content and the insertion loss (IL) for a GdYbBi-based garnet thick film in Example 8.

FIG. 9 is a diagram showing the relationship between the heat treatment temperature and the insertion loss (IL) for a GdYbBi-based garnet thick film in Example 9.

FIG. 10 is a view showing the relationship between the oxygen concentration in a heat treatment atmosphere and the insertion loss (IL) for a GdYbBi-based garnet thick film in Example 10.

FIG. 11 is a diagram showing the relationship between the wavelength of light and the transmittance of a garnet thick film in Example 11. In the figure, the solid line is Gd
The YbBi-based garnet thick film and the broken line indicate the characteristics with respect to the TbBi-based garnet thick film.

FIG. 12 shows B ₂ O ₃ content and insertion loss (IL) of a GdYbBi-based garnet thick film in Example 12.
FIG.

FIG. 13 is a view showing the relationship between the heat treatment temperature and the insertion loss (IL) for a GdYbBi-based garnet thick film in Example 13.

FIG. 14 is a graph showing the relationship between the oxygen concentration in a heat treatment atmosphere and the insertion loss (IL) for a GdYbBi-based garnet thick film in Example 14.

FIG. 15 shows a GdYbBi-based garnet single crystal thick film and TbBi grown by the LPE method in Example 15.
FIG. 3 is a graph showing the wavelength dependence of the transmittance of a system garnet single crystal thick film. In the figure, the solid line shows the characteristics for the GdYbBi-based garnet thick film, and the broken line shows the characteristics for the TbBi-based garnet thick film.

FIG. 16 is a view showing the relationship between the PtO ₂ content and the IL for a GdYbBi-based garnet thick film in Example 16.

FIG. 17 is a diagram showing a relationship between a heat treatment temperature and IL for a GdYbBi-based garnet thick film in Example 17.

FIG. 18 is a graph showing the relationship between the oxygen concentration in a heat treatment atmosphere and IL for a GdYbBi-based garnet thick film in Example 18.

FIG. 19 is a graph showing the relationship between light wavelength and transmittance for a garnet thick film in Example 19. In the figure, the solid line is Gd
The Bi-based garnet thick film and the broken line show the characteristics with respect to the TbBi-based garnet thick film.

FIG. 20 shows the relationship between the Yb composition value and the saturation magnetic field H _s and the insertion loss for GdBi garnet thick film in Example 20 (I.L.).

FIG. 21 is a diagram showing a relationship between a Bi composition value, a Faraday rotation ability θ _F and an insertion loss (IL) of a GdBi-based garnet thick film in Example 21.

FIG. 22 shows the relationship between the Al composition value and the saturation magnetic field H _s and the insertion loss for GdBi garnet thick film in Example 22 (I.L.).

FIG. 23 is a graph showing the relationship between the heat treatment temperature and the insertion loss (IL) for a GdBi-based garnet thick film in Example 23.

FIG. 24 is a graph showing the relationship between the oxygen concentration and the insertion loss in the heat treatment atmosphere for a GdBi-based garnet thick film in Example 24 (I.
L.).

FIG. 25 is a graph showing the relationship between the B ₂ O ₃ content and the insertion loss (IL) for a GdBi-based garnet thick film in Example 25.

FIG. 26 is a graph showing the relationship between the PbO content and the insertion loss (IL) for a dBi-based garnet thick film in Example 26.

FIG. 27 is a graph showing the relationship between the heat treatment temperature and the insertion loss (IL) for a GdBi-based garnet thick film in Example 27.

FIG. 28 is a view showing the relationship between the oxygen concentration in a heat treatment atmosphere and the insertion loss (IL) for a GdBi-based garnet thick film in Example 28.

FIG. 29 is a diagram showing the wavelength dependence of the transmittance of a GdBi-based garnet single crystal thick film and a TbBi-based garnet single crystal thick film grown by the LPE method in Example 29. In the figure, the solid line shows the characteristics for the GdBi-based garnet thick film, and the broken line shows the characteristics for the TbBi-based garnet thick film.

FIG. 30 is a view showing the relationship between the PtO ₂ content and the insertion loss (IL) for a GdBi-based garnet thick film in Example 30.

FIG. 31 is a diagram showing the relationship between the heat treatment temperature and the insertion loss (IL) for a GdBi-based garnet thick film in Example 31.

FIG. 32 is a graph showing the relationship between the oxygen concentration and the insertion loss of the heat treatment atmosphere for a GdBi-based garnet thick film in Example 32 (I.
L.).

FIG. 33 is a diagram showing the relationship between the wavelength of light and the transmittance of a garnet thick film in Example 33. In the figure, the solid line is Gd
The Bi-based garnet thick film and the broken line show the characteristics with respect to the TbBi-based garnet thick film.

Figure 34 is a graph showing a relation of Yb composition value and the saturation magnetic field H _s and the insertion loss for GdBi garnet thick film in Example 34 (I.L.).

FIG. 35 is a diagram showing a relationship between a Bi composition value, a Faraday rotation ability θ _F and an insertion loss (IL) of a GdBi-based garnet thick film in Example 35.

FIG. 36 is a diagram showing a relationship between a Ga composition value, a temperature change rate θ _{F / T of} Faraday rotation, and a saturation magnetic field H _s for a GdBi-based garnet thick film in Example 36.

FIG. 37 is a diagram showing a relationship between a heat treatment temperature and an insertion loss (IL) for a GdBi-based garnet thick film in Example 37.

FIG. 38 shows the oxygen concentration and the insertion loss of the heat treatment atmosphere for the GdBi-based garnet thick film in Example 38 (I.
L.).

FIG. 39 is a view showing the relationship between the B ₂ O ₃ content and the insertion loss (IL) for a GdBi-based garnet thick film in Example 39.

FIG. 40 is a graph showing the relationship between the PbO content and the insertion loss (IL) of a GdBi-based garnet thick film in Example 40.

FIG. 41 is a graph showing the relationship between the PtO ₂ content and the insertion loss (IL) for a GdBi-based garnet thick film in Example 41.

FIG. 42 is a view showing the relationship between the total content of B ₂ O ₃ , PbO, and PtO ₂ and the insertion loss (IL) for a GdBi-based garnet thick film in Example 42.

FIG. 43 is a view showing the relationship between the heat treatment temperature and the insertion loss (IL) for a GdBi-based garnet thick film in Example 43.

FIG. 44 shows the oxygen concentration and the insertion loss of the heat treatment atmosphere for the GdBi-based garnet thick film in Example 44 (I.
L.).

FIG. 45 is a graph showing the relationship between the wavelength of light and the transmittance of a garnet thick film in Example 45. In the figure, the solid line is Gd
The Bi-based garnet thick film and the broken line show the characteristics with respect to the TbBi-based garnet thick film.

FIG. 46 shows a composition ratio of Al and Ga and a magnetization reversal temperature (T) of a GdBi-based garnet thick film in Example 46.
_comp ) and the insertion loss (IL).

Figure 47 is a graph showing a relation between the Yb composition value and the saturation magnetic field H _s and the insertion loss for GdBi garnet thick film of Example 47 (I.L.).

FIG. 48 is a view showing a relationship between a Bi composition value, a Faraday rotation ability θ _F and an insertion loss (IL) of a GdBi-based garnet thick film in Example 48.

[49] (Al, Ga) for GdBi garnet thick film in Example 49 illustrates the relationship between the composition value and the saturation magnetic field H _s and insertion loss (I.L.).

FIG. 50 is a graph showing the relationship between the heat treatment temperature and the insertion loss (IL) for a GdBi-based garnet thick film in Example 50.

FIG. 51 is a graph showing the relationship between the oxygen concentration in the heat treatment atmosphere and the insertion loss (I.
L.).

FIG. 52 is a graph showing the relationship between the B ₂ O ₃ content and the insertion loss (IL) of a GdBi-based garnet thick film in Example 52.

FIG. 53 is a graph showing the relationship between the PbO content and the insertion loss (IL) of a GdBi-based garnet thick film in Example 53.

FIG. 54 is a view showing the relationship between the heat treatment temperature and the insertion loss (IL) for a GdBi-based garnet thick film in Example 54.

FIG. 55 shows the oxygen concentration and the insertion loss of the heat treatment atmosphere for the GdBi-based garnet thick film in Example 55 (I.
L.).

FIG. 56 is a view showing the relationship between the wavelength of light and the transmittance of a garnet thick film in Example 56. In the figure, the solid line is Gd
The Bi-based garnet thick film and the broken line show the characteristics with respect to the TbBi-based garnet thick film.

FIG. 57 is a view showing the relationship between the PtO ₂ content and the insertion loss (IL) of a GdBi-based garnet thick film in Example 57.

FIG. 58 is a view showing the relationship between the heat treatment temperature and the insertion loss (IL) for a GdBi-based garnet thick film in Example 58.

FIG. 59 shows the oxygen concentration and insertion loss of the heat treatment atmosphere for a GdBi-based garnet thick film in Example 59 (I.
L.).

 ──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. Hei 10-134340 (32) Priority date April 28, 1998 (1998. 4.28) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 10-152213 (32) Priority date May 14, 1998 (May 14, 1998) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 10-165920 (32) Priority date May 29, 1998 (May 29, 1998) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 10-194990 ( 32) Priority date June 24, 1998 (June 24, 1998) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 10-211923 (32) Priority date 1998 July 10 (July 10, 1998) (33) Countries claiming priority Japan (JP)

Claims (13)

[Claims] 1. A garnet thick film mainly composed of Gd, Yb, Bi, Fe, and Al grown on a garnet substrate by a liquid phase growth method, and the composition formula of the garnet thick film is Gd. _3-xy Yb _x Bi _y Fe _5-z Al _z O ₁₂ (however,
0 <x ≦ 0.45, 0.55 ≦ y ≦ 1.55, 0 <z ≦
0.95). A GdBi-based garnet thick film material characterized by being 0.95). 2. A garnet thick film mainly composed of Gd, Yb, Bi, Fe, and Ga grown on a garnet substrate by a liquid phase growth method, wherein the composition formula of the garnet thick film is Gd. _{3-xy Yb x Bi y Fe} 5-z Ga z O 12 ( where
0 <x ≦ 0.40, 0.55 ≦ y ≦ 1.10, 0.15 ≦
z ≦ 0.60) A GdBi-based garnet thick film material, wherein z ≦ 0.60). 3. A garnet thick film mainly composed of Gd, Yb, Bi, Fe, Al, and Ga grown on a garnet substrate by a liquid phase growth method, wherein the composition formula of the garnet thick film is , Gd _3-xy Yb _x Bi _y Fe _5-z (Al _a G
a _b ) _z O ₁₂ (where 0 <x ≦ 0.50, 0.85 ≦ y ≦
1.60, 0.20 ≦ z ≦ 1.00, 0.05 ≦ a / (a +
b) ≦ 0.90) A GdBi-based garnet thick film material, characterized in that: 4. The Gd according to claim 1, wherein
0 to 4.0 wt% PbO in Bi-based garnet thick film material
% (But not including 0) of a bismuth-substituted garnet thick film material. 5. The Gd according to claim 1, wherein
B ₂ O ₃ in Bi-based garnet thick film material is 0 to 4.0 wt.
% (But not including 0) of a bismuth-substituted garnet thick film material. 6. Gd according to claim 1, wherein
PtO ₂ is 0~4.0wt the Bi garnet thick film material
% (But not including 0) of a bismuth-substituted garnet thick film material. 7. The Gd according to claim 1, wherein:
B ₂ O ₃ and each 0-4 of PbO to Bi garnet thick film material. 0 wt% (not inclusive of 0) bismuth-substituted garnet thick film material characterized by containing. 8. Gd according to claim 1, wherein
B ₂ O ₃ and PbO and P in Bi-based garnet thick film material
The tO ₂ is in the range of 0 to 4.0 wt% (however, not including 0), and the total of the three types is 0 to 9.0 wt% (however, not including 0). Bismuth substitution type garnet thick film material. 9. The Gd according to claim 1, wherein:
A Faraday rotator substantially consisting of a Bi-based garnet thick film material. 10. An optical isolator comprising the Faraday rotator according to claim 9. 11. The GdBi-based garnet thick film material according to claim 1, wherein the GdBi-based garnet thick film material is grown on a neodymium gallium garnet (NGG) substrate. Manufacturing method. 12. The G according to claim 1, wherein the GdBi-based garnet thick film material is subjected to a heat treatment for maintaining the thickness in a range of 950 to 1140 ° C.
A method for producing a dBi-based garnet thick film material. 13. The method according to claim 12, wherein the oxygen content in the atmosphere in the heat treatment is in the range of 10 to 100%.