JP2867736B2 - Magneto-optical material, method of manufacturing the same, and optical element using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical material having extremely good wavelength characteristics, a method of manufacturing the same, and an optical element such as an optical isolator, an optical circulator, a magnetic field sensor, and an optical switch using the magneto-optical material.

[0002]

2. Description of the Related Art In optical communications, optical elements such as 1.3 μm and 1.55 μm long wavelength optical isolators are bismuth-substituted gadolinium irons having a large Faraday effect and manufactured by a flux method or a floating zone method. garnet _{(Gd 3-x Bi X Fe} 5 O 12;. hereinafter referred to as GdBiIG) or yttrium iron garnet (. hereinafter referred to as YIG) the Faraday rotator using a single crystal is used.

[0003]

However, GdB
Since iIG and YIG have a large change in the wavelength of the Faraday rotation coefficient, if the wavelength of the light source changes, the characteristics of an optical element such as an optical isolator are degraded or cannot be used. Therefore, there is a demand for the development of an optical element with less deterioration in characteristics even when the wavelength of the light source changes.

[0004]

SUMMARY OF THE INVENTION The present inventors have developed an optical communication system.
The wavelength change of the Faraday rotation coefficient at the wavelength used
Developing less magneto-optic material and wider wavelength band
To develop optical devices such as optical isolators with good characteristics.
For the purpose of growing various rare earth iron garnets,
As a result of measuring the magneto-optical effect, bismuth and
And aluminum, chromium or indium
Rubium iron garnet (Tb_ThreeFe_FiveO ₁₂Hereinafter, Tb
Described as IG. ) And the optical element using it
Having found that the above objects can be achieved,
Was.

That is, the gist of the present invention is that the main component composition is T
b in _{3-x Bi x Fe 5-} y M y O 12 ( wherein, M is aluminum, chromium, or indium, x is 0.22 ≦ x
≤ 0.55, and y is 0 <y ≤ 0.3. ), A method of manufacturing the same, and an optical element using the same.

Hereinafter, the present invention will be described in detail. In the present invention, the wavelength change rate of the Faraday rotation coefficient is abbreviated as FWC. FWC at a wavelength of 1.55 μm
Is defined by the following equation in consideration of the fact that the wavelength change under normal use conditions of the semiconductor laser is 0.02 μm or less. In the formula, θ _{F 1.55} and θ _{F 1.57} are each 1.
The Faraday rotation coefficients at 55 μm and 1.57 μm.

FWC = | (θ _{F 1.55} −θ _{F 1.57} ) / θ _{F 1.55} × 100 | In the magneto-optical material of the present invention, the main component composition is Tb _3-x Bi
_{x Fe 5-y M y O} 12 ( wherein, M is aluminum, chromium, or indium.) bismuth represented by, and aluminum was replaced with chromium or Indium T
bIG.

[0008] The bismuth substitution amount is in the range of 0.22 to 0.55 per molecule. The substitution amount of aluminum, chromium or indium is in the range of 0.3 or less per molecule. The bismuth of the present invention and TbIG substituted with aluminum, chromium or indium can be grown from a single crystal by a flux method, a liquid phase epitaxial method, a Bridgman method, a Czochralski method, or the like. Moreover, it can also be manufactured as a polycrystalline body by a sintering method. In particular, it is preferable to grow a single crystal by a flux method and a liquid phase epitaxial method.

In the case of the flux method, lead oxide (Pb
O), boron oxide (B ₂ O ₅ ), lead fluoride (Pb
F ₂ ), bismuth oxide (Bi ₂ O ₃ ), potassium fluoride (KF), etc.
A saturated solution is prepared at a high temperature, and a single crystal is deposited and grown by gradually cooling the solution. In the case of the liquid phase epitaxial method, Gd ₃ Ga ₅ O ₁₂ , (GdCa) ₃ (GaMgZ
r) to ₅ O _12, Sm ₃ Ga ₅ nonmagnetic garnet substrate of O ₁₂ or the like, a single crystal film is epitaxially grown on the substrate by contacting the saturated solution prepared as in the case of the flux method. In this case, if the difference in lattice constant between the substrate and the single crystal film is large, cracks occur in the single crystal film. Therefore, it is necessary to select a substrate that matches the lattice constant of the single crystal film to be grown.

The bismuth thus obtained and Tb substituted with aluminum, chromium or indium
When an IG is used, even if the wavelength of the light source changes, there is little deterioration in characteristics, and an optical element having good characteristics in a wide wavelength band can be manufactured. Examples of such an optical element include an optical isolator, an optical circulator, an optical switch, and a magnetic field sensor.

[0011]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples unless it exceeds the gist. Example 1 A single crystal having a composition of Tb _2.64 Bi _0.36 Fe _4.95 Al _0.05 O ₁₂ was grown by a flux method. The Faraday rotation coefficient at a wavelength of 1.55 μm of the obtained single crystal was −3.
62 deg / cm and FWC were 1.2%. Example 2 A single crystal having a composition of Tb _2.46 Bi _0.54 Fe _4.85 Al _0.15 O ₁₂ was grown by a flux method. The Faraday rotation coefficient at a wavelength of 1.55 μm of the obtained single crystal was −6.
00deg / cm and FWC were 1.7%.

Example 3 A single crystal having a composition of Tb _2.76 Bi _0.24 Fe _4.75 Al _0.25 O ₁₂ was grown by a flux method. The Faraday rotation coefficient at a wavelength of 1.55 μm of the obtained single crystal was −1.
80 deg / cm and FWC were 0.2%. Example 4 PbO—Bi ₂ O ₃ was deposited on an Sm ₃ Ga ₅ O ₁₂ single crystal substrate.
A single crystal film having a composition of Tb _2.66 Bi _0.34 Fe _4.95 In _0.05 O _{12 was} grown from a system flux by a liquid phase epitaxial method. The Faraday rotation coefficient at a wavelength of 1.55 μm of the obtained single crystal film was −335 deg / cm, and the FWC was 1.1%.

EXAMPLE 5 PbO—Bi ₂ O ₃ was deposited on a single crystal substrate of Sm ₃ Ga ₅ O _12.
The single crystal film having a composition of _{Tb 2.75 Bi 0.25 Fe 4.85 In 0.15} O 12 from KeiToruzai were grown by liquid phase epitaxial method. The Faraday rotation coefficient at a wavelength of 1.55 μm of the obtained single crystal film was −205 deg / cm, and the FWC was 0.3%. Example 6 PbO—Bi ₂ O ₃ was deposited on an Sm ₃ Ga ₅ O ₁₂ single crystal substrate.
A single crystal film having a composition of Tb _2.66 Bi _0.34 Fe _4.95 Cr _0.05 O _{12 was} grown from a system flux by a liquid phase epitaxial method. The Faraday rotation coefficient at a wavelength of 1.55 μm of the obtained single crystal film was −331 deg / cm, and the FWC was 1.0%.

Comparative Example 1 A single crystal having a composition of Y ₃ Fe ₅ O ₁₂ was grown by a (YIG) flux method. The wavelength of the obtained single crystal is 1.5
The Faraday rotation coefficient at 5 μm is 176 deg / c
m and FWC were 1.9%. Comparative Example 2 PbO—Bi ₂ O ₃ was formed on an Sm ₃ Ga ₅ O ₁₂ single crystal substrate.
A single crystal film having a composition of Tb _2.82 Bi _0.18 Fe ₅ O _{12 was} grown from a system flux by a liquid phase epitaxial method. The Faraday rotation coefficient at a wavelength of 1.55 μm of the obtained single crystal was −104 deg / cm, and the FWC was 5.9%.

Comparative Example 3 A single crystal having a composition of Tb _2.60 Bi _0.40 Fe _4.65 Al _0.35 O ₁₂ was grown by a flux method. The Faraday rotation coefficient at a wavelength of 1.55 μm of the obtained single crystal was −3.
52 deg / cm and FWC were 2.1%. Comparative Example 4 A single crystal having a composition of Tb _2.25 Bi _0.75 Fe _4.95 Al _0.05 O ₁₂ was grown by a flux method. The Faraday rotation coefficient at a wavelength of 1.55 μm of the obtained single crystal was −9.
00deg / cm and FWC were 2.0%.

[0016]

According to the present invention, it is possible to obtain a magneto-optical element having a very small change in the Faraday rotation coefficient at a practical wavelength of 1.55 .mu.m, which is a practical wavelength used for optical communication. Optical isolators, optical switches,
Optical elements such as optical circulators and magnetic field sensors can be manufactured, and are extremely useful in industry.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takahiko Tamaki 1-10-11 Kinuta, Setagaya-ku, Tokyo Japan Broadcasting Corporation Research Institute of Broadcasting Technology (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1 / 09 501 C01G 49/00 C30B 9/04 C30B 19/02 C30B 29/28 G02B 27/28

Claims (4)

(57) [Claims] 1. The method according to claim 1, wherein the main component composition is Tb _{3-x B x} Fe _5-y
M _y O ₁₂ , wherein M is aluminum, chromium or indium, x is 0.22 ≦ x ≦ 0.55, and y
Is 0 <y ≦ 0.3. ) Is a magneto-optical material. 2. The composition of a main component having a composition of Tb _{3-x B x} Fe _5-y
M _y O ₁₂ , wherein M is aluminum, chromium or indium, x is 0.22 ≦ x ≦ 0.55, and y
Is 0 <y ≦ 0.3. A) producing a single crystal by a flux method. 3. The main component composition is Tb _{3-x B x} Fe _5-y
M _y O ₁₂ , wherein M is aluminum, chromium or indium, x is 0.22 ≦ x ≦ 0.55, and y
Is 0 <y ≦ 0.3. A) producing a single crystal film by a liquid phase epitaxial method. 4. An optical element using the magneto-optical material according to claim 1.