JP2000235172A - Magneto-optical device material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical device material which can be used as a material of an optical isolator which can be practically used for blue laser light of 0.38 to 0.49 μm use wavelength region. SOLUTION: This magneto-optical device material consists of a single crystal having the compsn. of Zn1-xMgxSe in which the proportion of Mg compounded is selected from the range of 0.05<=x<=0.90, and the Zn1-xMgxSe single crystal is prepared as a zincblende structure having a Verdet const. By controlling the carrier density which represents the degree of the amt. of impurities in the Zn1-xMgxSe single crystal to <=2.0×1014 cm-3 and by controlling the practical transmission loss of light to <=0.7 dB (in the optical path length for 45 deg. Faraday rotation angle), the material can be used for 0.38 to 0.49 μm wavelength region. When a Faraday rotator produced from the aforementioned magneto-optical device material as an optical isolator material is used for an optical isolator, the obtd. optical isolator has the use wavelength region ranging from 0.38 to 0.49 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical isolator, which is an optical device for preventing return light of a light source mainly using a blue laser having a wavelength range of 0.38 to 0.51 (.mu.m). A magneto-optical element material to be used as a material.
m).

[0002]

2. Description of the Related Art In recent years, with the development of next-generation optical communication technology, next-generation large-capacity storage technology, network technology such as commercial services using the Internet, etc., there is a possibility that multimedia will be developed with high-definition images at high speed. Trying to access a field that does.

[0003] In this background, in research and development by a research group of Nichia Chemical in 1997, continuous oscillation of a blue semiconductor laser at room temperature, which was considered difficult to commercialize until the 21st century, and 3000 The results of unexplored technology whose long-term reliability has been confirmed by a long-term use durability test are given. Shortening the wavelength of a semiconductor laser is an indispensable technology for high-definition images and high-speed communication, but at the same time, it is the only element technically regarded as a problem.

That is, since no short-wavelength semiconductor laser existed before this, there was no demand for an optical isolator in such a short-wavelength region, and a material composition having a promising magneto-optical element material in this short-wavelength region. There are very few research reports.

[0005]

In the case of the above-mentioned existing magneto-optical element materials, examples of the material applicable to the short wavelength region reported in a paper or the like include, for example, chalcopyrite-based semiconductor, TGG single crystal, and lead. Glass, ZnSe crystal, and the like can be cited, and any of the existing magneto-optical element materials known for use in the short wavelength region has light that can be practically used with a blue laser having a used wavelength region of 0.38 to 0.49 (μm). It cannot be used as an isolator material, and it is impossible to construct an optical isolator having a working wavelength range of 0.38 to 0.49 (μm).

More specifically, although chalcopyrite-based semiconductors exhibit a magneto-optical effect at low temperatures, they have not been studied as practical materials because the magneto-optical effect at room temperature is extremely small. TGG single crystal and lead glass use wavelengths of 510 nm or more, have a low Verdet constant,
Moreover, it is not practical because of large light absorption. The ZnSe crystal has a Verdet constant of 0.0 at a used wavelength of 500 nm.
Although it is 15 deg / cm · Oe, the band gap energy is 470 nm in terms of wavelength. On the other hand, the transparent region of light transmission loss that can be sufficiently used as an optical isolator is on the wavelength side of about 50 nm long. λ ≦ 550 nm. Therefore, Zn
Se crystal cannot be used at all as an optical isolator material for a short wavelength region.

[0007] By the way, the working wavelength range of 0.38 to 0.4
If a magneto-optical element material that can be used with a 9 (μm) blue laser is developed, it will be optimal as an optical isolator material having a small optical absorption and a large magneto-optical effect, but an optical isolator including such an optical isolator material Is positioned as an indispensable optical device in optical systems that use optical fibers composed of blue semiconductor lasers, and is strongly considered by systems related to network technologies such as large-capacity storage technology and commercial services using the Internet. It will be requested.

The present invention has been made to solve such a problem, and the technical problem thereof is that the working wavelength range is 0.1.
An object of the present invention is to provide a magneto-optical element material that can be used as a material for an optical isolator that can be used with a blue laser of 38 to 0.49 (μm).

[0009]

According to the present invention, the composition of the main component is represented by the general formula Zn _1-x Mg _x Se (where x is 0.05
≦ x ≦ 0.9) Zn _1-x Mg
together with the _x Se single crystals, magneto-optical element material the Zn _1-x Mg _x Se single crystal having a line of zinc blende type structure.

Further, according to the present invention, in the magneto-optical device material, the Zn _1-x Mg _x Se single crystal has a carrier concentration indicating a degree of impurity of 2.0 × 10 ¹⁴ (cm ⁻³ ) or less. The magneto-optical element material controlled in this manner is obtained.

Further, according to the present invention, in any one of the above-mentioned magneto-optical element materials, the usable wavelength range is 0.38 to 0.4.
A magneto-optical element material applicable with a 9 (μm) blue laser is obtained.

In addition, according to the present invention, an optical isolator can be obtained in which the above-mentioned magneto-optical element material is used as an optical isolator material and the wavelength range used is 0.38 to 0.49 (μm). In this optical isolator, it is preferable to provide a Faraday rotator manufactured using an optical isolator material.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description of embodiments of the present invention, with reference to the accompanying drawings.

First, the outline of the magneto-optical element material of the present invention will be briefly described. This magneto-optical element material has a main component composition of the general formula Zn _1-x Mg _x Se (where x is 0.05 ≦
x ≦ 0.9) Zn _1-x Mg _x
In addition to having a Se single crystal, the Zn _1-x Mg _x Se single crystal has a zinc-blende structure. However, in this case, the carrier concentration of the Zn _1-x Mg _x Se single crystal, which indicates the amount of impurities, is controlled to 2.0 × 10 ¹⁴ (cm ⁻³ ) or less.

In this magneto-optical element material, Zn _1-x Mg
_x indicating the amount of Mg in the _x Se single crystal is 0.1 ≦
When x ≦ 0.9, the optimum composition is selected. On this basis, a Zn _1-x Mg _x Se single crystal is made to have a zinc-blende structure to have a Verdet constant, and Zn _{1− x} Mg _x S
The carrier concentration, which indicates the amount of impurities in the single crystal, is 2.0
By controlling the light transmission loss to 0.7 dB (optical path length at a Faraday rotation angle of 45 degrees) or less by controlling the light transmission loss to less than × 10 ¹⁴ (cm ⁻³ ), the working wavelength range is 0.38 to 0.49.
(Μm) is effective.

That is, the selection of the Mg composition here is based on Zn
_1-x Mg _x Se single crystal using wavelength range 0.38 ~
In order to obtain practical performance as an optical isolator material that can be used with a blue laser of 0.49 (μm), Zn _1-x Mg
Adjust the band gap energy of the _x Se single crystal, the light transmission loss in the used wavelength region is set to be a transparent area. Although the Verde constant of Zn _1-x Mg _x Se single crystal is small, it depends on the used wavelength region and the band gap energy. Therefore, when selecting the Mg composition, select a composition point where the Verde constant is as large as possible. . Further, since the light transmission loss and the Verdet constant are in an inconsistent relationship, the composition point is selected so that both are the best. However, even if such a composition point is selected, the light transmission loss per optical path length at a Faraday rotation angle of 45 degrees is 0.7 dB.
It is extremely difficult to: Therefore, with respect to improvement of this point, Zn _1-x Mg x Se control the amount of impurities in the single crystal becomes important, Zn _1-x Mg x Se single crystal carrier concentration 2.0 × 10 ¹⁴ (cm ^-3 ) By controlling so as to be less than or equal to 0.38 to 0.51 (μ
m) The light transmission loss is improved, and a magneto-optical element material satisfying the target specifications can be obtained.

If such a magneto-optical element material is used as an optical isolator material, the operating wavelength range is from 0.38 to 0.38.
An optical isolator of 0.49 (μm) is obtained. The optical isolator may be provided with a Faraday rotator manufactured using such an optical isolator material.

Therefore, the method of manufacturing the magneto-optical element material will be specifically described below. FIG. 1 shows Zn _1-x Mg _x which is a main component of a magneto-optical element material according to one embodiment of the present invention.
FIG. 2 is a side sectional view showing a basic configuration of a crystal manufacturing apparatus for growing and manufacturing a Se single crystal together with a vertical temperature distribution in a pressurized electric furnace 5. However, here, Zn _1-x Mg
_As an example of xSe single crystal, (Zn _0.3 Mg _0.7 ) Se
A case where a single crystal is grown and manufactured will be described.

In this crystal manufacturing apparatus, a pressurized electric furnace 5 using an electromagnetic coil is provided in a pressurized container 6, and a quartz crucible 4 into which a component metal material is loaded is provided in the pressurized electric furnace 5. It is configured.

Therefore, first, Z is used as a constituent metal material.
n, Mg, the _{Se (Zn 0.3 Mg 0. 7)} Se (1 + 3)
After being weighed so as to have a composition point of, it was charged into the quartz crucible 4, sealed in a vacuum, melted by the electric furnace 5 under pressure, and quenched to obtain the melt 2 for crystal growth.

Next, as a similar composition metal material, Z
n, Mg, Se as target polycrystalline composition (Zn _0.3 Mg _0.7 )
After being weighed so as to be Se, it is charged into a quartz crucible 4 and sealed in a vacuum, and then melted by a pressurized electric furnace 5 to perform high-pressure synthesis (however, the melting point is about 1520 ° C. and the pressurization is 50 a.
tm), and then quenched to obtain a polycrystalline body 3 of (Zn _0.30 Mg _0.7 ) Se. Incidentally, in the quartz crucible 4, there is a temperature range ΔE in which melting can be performed as shown in the vertical temperature distribution in the pressurized electric furnace 5.

Further, a separately prepared seed crystal ZnSe single crystal 1 was prepared by using the above-described steps (Zn _0.3 M
g _0.7 ) Melt 2 for crystal growth of Se (1 + 3) and (Z
The polycrystalline body 3 of n _0.30 Mg _0.7 ) Se was loaded into the quartz crucible 4 in this order and sealed in a vacuum. Then, the quartz crucible 4 (the state shown in FIG. 1) manufactured in this manner was pressurized. Moderate temperature gradient by furnace 5 [30 to 100 (° C)
/ Cm] at _{(Zn 0.3 Mg 0. 7) Se} (1 + 3) from the crystal growth for the melt 2 of the temperature above the melting point (from about 1200 ° C.) by crystal growth crucible descending speed 5 mm / day of (Zn _0.3 Mg _0.7 ) A Se single crystal was grown. However,
In this crystal growth, the atmosphere in the pressure vessel 6 was filled with Ar gas, and the pressure was increased to 10 atm.

Thus, (Zn _0.3 Mg _0.7 ) S
together with the e single crystal, it is possible to manufacture the magneto-optical element material having the (Zn _{0. 3} Mg _0.7) Se monocrystalline Striped zinc blende type structure.

Next, as another embodiment, several magneto-optical element materials made of a Zn _1-x Mg _x Se single crystal having a composition different from the composition described above were used as an optical isolator material in a Faraday rotator, and a comparative example was used. Some optical isolators were manufactured using existing magneto-optical element materials such as TGG crystal, Faraday glass (lead glass), and ZnSe crystal as optical isolator materials for Faraday rotators.
When the characteristics of each of these optical isolators were examined, the results shown in Table 1 were obtained.

[0025]

[Table 1]

In Table 1, the diameter φ and length L (mm) of each optical isolator are almost unified as shown.
In the apparatus having the Faraday rotator made of a ZnMgSe single crystal magneto-optical element material according to each embodiment, the measurement wavelength (μm) is slightly changed for each optical isolator.

From Table 1, it can be seen that the optical isolators according to the respective embodiments provided with the Faraday rotator made of the ZnMgSe single crystal magneto-optical element material have a crystal loss (light transmission characteristic) that is higher than that of the comparative example. It can be seen that the forward loss (dB), which is important as dB and isolator characteristics, is significantly improved.

FIG. 2 shows the correlation of the optical transmission loss (dB) with the carrier concentration (cm ^-3 ) of the optical isolator according to each embodiment shown in Table 1. Here, the light transmission loss (dB) indicates a value that makes the rotation angle of the Faraday rotator 45 degrees with a magnet when an optical isolator having a diameter φ of 20 mm and a length L of 20 mm is manufactured. ing.

FIG. 2 and the above results show that Zn _1-x Mg
_x indicating the amount of Mg in the _x Se single crystal is 0.1 ≦
The optimum composition is selected within the range of x ≦ 0.9, and the carrier concentration may be set to 2.0 × 10 ¹⁴ (cm ⁻³ ) or less so that the correlation between the carrier concentration and the light transmission loss becomes good. You can see clearly.

[0030]

As described above, according to the magneto-optical device material of the present invention, the M _{1 in} the Zn _1-x Mg _x Se single crystal is used.
The composition selection is performed by setting x indicating the compounding amount of g in a range of 0.05 ≦ x ≦ 0.9, and a Zn _1-x Mg _x Se single crystal is provided with a Verdet constant as a zinc-blende structure, and Zn
By appropriately controlling the carrier concentration indicating the degree of the impurity amount of the _1-x Mg _x Se single crystal to obtain a practical light transmission loss, a blue laser with a wavelength range of 0.38 to 0.49 (μm) can be used. Therefore, if a Faraday rotator made of this novel magneto-optical element material as an optical isolator material is provided, the wavelength range that could not be manufactured by the conventional method is 0.38 to 0.49 (μm ) Is obtained, which is extremely useful in industry.

[Brief description of the drawings]

FIG. 1 shows a basic configuration of a crystal manufacturing apparatus for growing and manufacturing a Zn _1-x Mg _x Se single crystal as a main component of a magneto-optical element material according to one embodiment of the present invention in a pressurized electric furnace. FIG. 4 is a side sectional view shown together with the vertical temperature distribution of FIG.

FIG. 2 shows a light transmission loss (d) with respect to a carrier concentration (cm ⁻³ ) of the optical isolator according to each of the examples shown in Table 1.
It shows the correlation of B).

[Explanation of symbols]

 Reference Signs List 1 seed crystal ZnSe single crystal 2 melt for crystal growth 3 polycrystal 4 quartz crucible 5 pressurized electric furnace 6 pressurized vessel

Claims (5)

[Claims] 1. The composition of a main component having a general formula Zn _1-x Mg _x Se
(However, in the range of 0.05 ≦ x ≦ 0.9 and x) and has a Zn _1-x Mg x Se single crystal represented by, the Zn _1-x Mg x Se single crystal Striped zinc blende A magneto-optical element material having a structure. 2. The magneto-optical device material according to claim 1, wherein the Zn _1-x Mg _x Se single crystal has a carrier concentration indicating a degree of an impurity amount of 2.0 × 10 ¹⁴ (cm ⁻³ ) or less. A magneto-optical element material characterized by being controlled. 3. The magneto-optical device material according to claim 1, wherein the material is applicable to a blue laser having a wavelength range of 0.38 to 0.49 (μm). 4. An optical isolator, wherein the material of the magneto-optical element according to claim 3 is used as an optical isolator material, and an operating wavelength range is 0.38 to 0.49 (μm). 5. The optical isolator according to claim 4, further comprising a Faraday rotator manufactured using said optical isolator material.