JPS5865414A - Magnetooptic element - Google Patents

Abstract

PURPOSE:To make >=35dB isolation possible, by using a garnet film grown on a nonmagnetic garnet substrate of which the surface consists of a face inclined from{110}or{211}an angle within 15 deg. as a Faraday rotating body. CONSTITUTION:A Gd0.2Y2.8Fe3O12 garnet thick film 2 is grown to 190mum on a Gd3Ga5O12 substrate of which the rotating axis is <111> in the{110}facets and of which the surface is inclined by 8 deg. (within 16 deg.) angle in the direction <211> intersecting orthogonally with said axis, while the rotation of the substrate is stopped for one minute at every 30min, in a flux consisting essentially of PbO-B2O3. A chip is cut out from such garnet wafer and its end face is optically polished. An isolator is assembled of such chip by using a magnet 3. With respect to 1.3mum laser light 4, >=35db isolation is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magneto-optical element K1m such as an optical isolator or a router using a Faraday crystal 1411.

In recent years, advances in optical fiber communication technology have been remarkable.

Low-loss fiber and time-making l1ll! With the development of semiconductor lasers that can emit light and withstand loss, the Hikari 7 Ice Technology Center is expected to be a means of providing a low-cost, high-quality communication means in response to the increase in communication volume. However, there is a significant problem in that if the return light reflected from components such as switches thrown in the middle of the optical transmission path enters the semiconductor laser that is the light source, it will impair the stability of the V-laser emission loss.

In order to solve this problem, it is necessary to install an optical isolator after the laser light source.

As reported in the Institute of Electronics and Communication Engineers Technical Research Report OQE7g-133, long-wave borrowed optical isolators with a diameter of 1.3 to 1.8 μm are made using ferromagnetic materials such as a, tricum, and d-.
Gane, ) (Y8'@I'll, YIG) O
A method using 775 days* fruit has been proposed. The YIG used in this report is bulk single #j grown by the flux method! It's a bug.

On the other hand, for rounding in which rotation of the incident-light plane occurs when light passes through the YIG, the YIG must be magnetically saturated in parallel to the direction of incidence of the light. YIG processed into a cylindrical shape
/(When using a single crystal, the external magnetic field for saturation is extremely thick (up to 20,000 mm.
As shown in ji80-53, it has been proposed to use a thin plate-like (polished) YIG Palta single crystal.

However, as long as bulk single crystals are used,
- Obtain high quality YIG bulk single box crystal as shown in #i, #! Happy and feminine, this round j
The cost of raw materials for optical isolators has skyrocketed, hampering optical isolators. To solve this problem, as disclosed in the above-mentioned patent application, it has been proposed to employ a garnet film epitaxially grown on a non-magnetic garnet substrate, as shown in Fig. g1. As a result, the cost of raw materials can be reduced with #J'-.

One of the problems when using a garnet member as a 07 Alladay rotator for an optical inverter was birefringence caused by the difference in lattice constant between the substrate and the garnet relative. Isolation by birefringence.

As shown in Japanese Patent Application No. 56-045195, the difference in lattice constant between the substrate and the substrate is t-0,001^.
I was able to solve the problem by doing the following. Of course, (
111) In the case of the grown garnet thick film, the difference in lattice constant between the substrate and the film is 0.001 A or less.

However, I was unable to secure a maximum hair isolation of 30 dB L.

On the other hand, according to the experiments of the present inventors, it was found that
(JasOs * 4 different magnetic fields were grown on 4 boards and the morphology of the surface was observed, and it was found that when the grain thickness was less than 30 μm, it was found that If the thickness is thicker than this, the members of the
At No. 11, structural a cooling occurs and Q becomes 5, and 7 ace, t, as shown in No. 2161 are generated on the surface. 4111) The occurrence of such severe unevenness on the surface ml of the grown and depleted garnet 4- is explained by Tokoku Sho 56-0.
97213 (as shown, Garnet 4 relative is placed on the base), and it is inconvenient to place M111W against Donnes.

In this experiment, we observed that the facets on the surface of the (111) layer with a thickness of 9 and 1 were made uneven.

Introducing striae by stopping substrate rotation during garnet growth @1nduc@d @mouth1atio
Carefully observed round shape by n'' method, strain-free polishing and phosphorus IA#
The shape of the solid-liquid interface that appears on the end face of the thick film due to the combination of the 2nd process and the 2nd process was as shown in Figures 71 and 8 of 2. In other words, the irregularities on the outer surface of Yangjin with a thickness of 100 μm st were not so severe as shown in Fig. 2, 7I, but as the thickness increased to 100 μm or more, the irregularities gradually increased to 111, and when the thickness became 200 μm, the irregularities on the outer surface became 6. As shown in the figure, the difference in height between the convex and concave surfaces is as much as 1G, aIB, which is a circle.

The fact that traces of the shape of the solid-liquid interface at the time of mass purity are found even in the thickly grown φ indicates poor moldability at a thickness of 1IIK. That is, when structural supercooling occurs, in the case of convex 4, as shown in FIG. Yang Wen storm is strong, heat dissipation is good,
It is large for supercooling and large for IA length 4. On the other hand, in the convex part, the solute IlI&degree is low (IIL11 temperature is low, heat dissipation is poor, the degree of supercooling is small, and the degree of formation interception is small.

This line shows that the distribution coefficients of the garnet structure and impurity ions are different between the concave and convex portions. In other words, the lattice constants of the concave portions and the convex portions are mechanically true, and this means that slight double folding exists via the photoelastic constant of the material. According to the inventor's experiments, the existence of this microscopic birefringence is the reason why the isolation in the mouth L1 expansion was only 3 (ld) at the maximum.

The present inventor has added Garnet-an lI to the JII board of direction.
l! I cultivated the shape of the solid world when Garnet grew up.
IIFL9 Tokoro, 0”(B (15@0faA im
r (1103 or (211)) In the Cζ grown t-a garnet film tilted from (1103 or (211)), the solid-liquid interface shape is flat because these planes are facets of iron garnet, and the crystal The optical properties are good, and there is no microscopic birefringence, and when using this optical isolator as an optical isolator, it is at least 3!*dBv
Also, the unevenness on the surface is less severe than in the case of 1lll'j growth, and polishing of the film surface when placing it on the base is much easier, and the above-mentioned crystallinity The effect was found not only in magneto-optical elements using thick films, but also in magneto-optical elements using thin layers.
This led to an uninvented invention. That is, in a magneto-optical element in which a source is incident on the back surface of a garnet resin epitaxially grown on a non-magnetic substrate and the scissors are used as a Faraday rotator.
This magneto-optical element is grown on a substrate having a surface inclined from 0) or (211), and is characterized by using a Faraday rotator.

The invention will be explained in detail below using a practical example.

Implementation 1i11 1110) The in-plane Q(111) is the rotation axis and the chain (111>
The Sat inclination is 8°O in the (211) direction orthogonal to , and the lattice electric number is 12.601111gkad of 1832 people,
On the Ga@01g base, the lattice articles of incorporation are lλ311140
Mu lattice density is 113840 mu OGd, 1 Y>@F
11＠O12 carne, ) Using a flux method from a fusion tube containing fWho-BsO8 as the main component, garnet expansion O
During the growth, the film was grown to a thickness of 190 μm by stopping the 1 m rotation for 1 minute after 30 minutes of growth.
Processed for S minutes with a warm solution of ovonic acid and sulfuric acid, and by cindering and stopping the rotation of the substrate during growth.
When we observed the shape of the O11 liquid during layer growth from i@a'', as shown in Figure 4, although there was some waviness in the part, it was almost flat compared to the 041)' layer of O, and (111) Il
The crystallinity may be better than that of 1.

I cut out an i4XL41110 chip from this glass, tow, optically polished the tip, and attached an optical isolator that shows 11iK.
By ensuring 37dlIO Eitzley v, y in the laser beam, the surface of this chip is (
111) In the case of oboro, there are severe irregularities (and the polishing of both surfaces when placed on the base is also heavy and round).

The axis of rotation is (111) in the plane of Yimaro #l 4110) and the axis of rotation is (111>
Tilt the table by an angle in the (211) direction K 1" perpendicular to the lattice constant $ 113832 AO50wa% Ljd
s(1m@0° on the substrate, a(1,, *Ys-s'.) with a lattice constant of I!3838X.

A 0° garnet thick film was grown by liquid phase epitaxial growth to a thickness of 130 μm. Example 1 and 11 @indm@@
The shape of the film grown-01 liquid-ascent FM was observed by the d5triaii*m'' method, and as shown in Fig. When the chip cut out from this cube was used as a Faraday 1g1 trochanter of a former fisolator, finage was obtained.

I was able to secure 40dB f as a main power source.

Example 3 (111) with (101) in 101# as 1@ axis
The table JIt inclination is perpendicular to (10・〉 direction by the breath sG angle, and the lattice constant is I La88
On the Ou base, the lattice constant is 12.3832 mu o aa,
,y,,,p,,o,.

A thick garnet film was grown by liquid phase epitaxial growth to a thickness of 140 μm, and a chip cut out from this cube was used as a Faraday trochanter of an optical isolator, ensuring round isolation and y of 15 dB.

Example 4 010) In-plane 0 (211) t-rotation axis <j
The surface is tilted by 2°〇9 degrees in the (111> direction perpendicular to ll) with a lattice constant of HL3834λOGd on a Ga, O□ substrate.

'lTh1Y&IF@$0 with lattice articles of incorporation 11183 art
A chip cut out from Uko O Uni^, which had a thick film grown to a thickness of 11 mm, was used as an optical isolator O7 and a rotator, and was used as an optical isolator O7. Can be secured.

Example 5 (Plating 0 (In6) in 110311 as - rotation axis)
Tilt the breathing reward 4°0jIl in the direction perpendicular to O〉 (I A @) 11 children'lL*#ttssssXO04
G o On @ ji + [Upper K.

Yangzi Kenshu #l&3131mu0? b,, Y,, F
＠＠O,、Garnate thickness was grown to 160μ-〇thick by liquid phase epitaxial growth, and the chip cut out from this Que ATh was used as a Faraday rotator of an optical isolator, and it was possible to secure an isolation of 38 dB. .

Example 6 (If the surface is tilted by an angle in the (311) direction 1c13 within 1000 lines, the lattice constant is 12.1831λ0GdlGa@O
On the st substrate, the lattice constant 111fi12. '4826muO
Gd,,Y,,F*,0. .

Garnet was grown by liquid-phase epitaxial growth to a thickness of 140 mm, and a tip cut from this sea urchin was used as a Faraday 1 g 1 trochanter of an optical fin layer, and an isolation of 36 dB was achieved.

(110) @ (313) direction (0d10 illusion 0□ with surface tilted by 3° angle and lattice constant of 12.3835 mm)
On the substrate, G61Yl-1 with a lattice constant of 12389SA
The film was grown in a 1Kll phase epitaxial layer with a thickness of 1Kll. When I cut out a 9-chip t-t isolator from this wafer and used it as a Faraday rotator, I was able to secure 38 dB of isolation.
T large.

Implementation f4- (11@) 0 in jig 1 G' in <212> direction
If the surface is tilted by an angle of O, the lattice constant is 1tsasoioG
a, am, 08. On the substrate, the lattice constant is 195etoi
'1aeaayssi' *wo*m Gané, Shi membrane 4!
When nine chips cut out from this cube grown to a thickness of μm were used as a Faraday rotator for optical isolation, the isolation was 37 mm.
dB & can be secured.

'Example 9 (2113IN inside 0 (11G) direction by 1°00 angle mtm lattice constant is 11m84・A o G4 g
On the G a B 011 substrate, the lattice constant is 11311
3! Mu0 (346 @ Yp @ F*g O□.

Garnet oboro was grown by liquid phase epitaxial growth to a thickness of 1110 pm. 9. Chips cut from sea urchin^
t, faraday of the isolator - used as a trochanter for nine-point isolation, y as 41) 48 ttll comrade.

Example 1 - ([l) When the surface is tilted by an angle of 15@D in both ^0 (all) directions, the lattice constant is 113831NOGdaGasOss
On the substrate, Gd&l Yt with a lattice constant of 113838 μm
4F@l out Garnet) membrane at 110. A circle is grown by liquid phase epitaxial growth to a thickness of am. Nine parts start from this quest.

When we used the rotator as a Faraday rotator of the original isolator, we were able to secure an isolation level of 35 dB.

Real fillll The surface is tilted by an angle of 6° in the (<jot in the 2111 plane) direction, and the lattice definition is Od, 0 od 01 yo substrate with a lattice definition of 1zagssX, 'I'b>myt with a lattice constant of tz3ssgX
-sr・,0. .

Garnet film 140. A circle is grown by liquid phase epitaxial growth to a thickness of am. When I used a chip cut from this Feno 1 as a Faraday rotator for a party isolator, I was able to secure 371B as an isolation element.

Example 12 1@f) angle l in the (312) direction in the (211) plane
The slope of I is sure to be lattice constant12.38341OG8 B G
a (Io-tY, a'@l01lI-ne, t oboro is Ls) with a lattice constant of tz-3soz
It was grown by liquid phase epitaxial growth to a thickness of about 100 ml. The chip cut out from the quest of c is thinly traced, isolator 07 isolator 7 is layered,
Please secure 364B as /.

Example 13 (0(111) direction in 11111i - tilt the table by the angle of Kl@) is 01118Oml of Yangzi Articles of Incorporation 5tLsasoi
On the 'll substrate, the lattice constant is 11111110 μmOTb
＞2 N＞@T/s @01@Gane, Tori 1
Table 1/ll11Ojl was made into a circle by liquid phase epitaxial growth, and a chip cut out from this sea urchin was used to create a round liquid conduction 1I.
Sui, Chio Isolake, and Y isamt **”e meeting who made J1's light accumulation bribe and nine places named Elements Km.
.

In addition, optical isolator O Ain Lake, y#1 (116
% or (!11), it does not depend on the direction of tilting the substrate surface, but mainly depends on the tilt angle.

It can be used in any direction as it expands and tilts.

As described above, by using this beak, a magneto-optical element that can satisfy the cost of at least $841 can be obtained.

[Brief explanation of the drawing]

Figure 111 shows a Faraday rotator using a garnet thick film. 1 is a non-magnetic garnet substrate, 2 is a garnet thick film, 3 is a magnet, 4 is one rotation of the polarization plane of the incident light, and 5 is the output light. 1 inversion of 1 optical plane at is shown. Figure 2 shows that 7 ace, t are produced by structural supercooling and
111 m) Thickness mollIrit j, 61 is 7 ace, t, 71 is the shape of the solid-liquid interface of the film grown to a thickness of about 100 μm, 8 is the shape of the solid-liquid interface of the film grown to a thickness of about 150 μm, and 9@0 solid-liquid interface. shows. Figure S a shows the situation at the solid-liquid interface when structural supercooling occurs. 9 and 10 are the convex S and 1LA of the solid phase, respectively.
l! It is. 11 shows streamlines in the liquid phase. Figure 114 is (Atsuha O tilted by an angle of 8 degrees from 1107)
As a result of the summary of the edge drawings, 62 is Fase, ), 72 is approximately 130 /
The shape of the solid-liquid interface at the time of growth on the shore of 11111. @S 1lri (110)! Q 101jNl + f inclination ft, l1motaris-book # system, @3 is 7
1st, 卜, 13B have an O solid-liquid extra-picture O shape when they grow to about 10 voices aS-a. Chrysanthemum 1 Figure 2 Figure 1 Figure 3 Figure 4 Figure 5 Procedural amendment (!III) November 22, 1939 Director General of the Japan Patent Office 1, Showa 56 Patent Application No. 153
! 83 No. 2, Title of the invention: Magneto-optical element 3, Relationship to the amended person's case Applicant: 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4, Agent &amp; In the detailed description of the invention in the written statement subject to amendment - & on page 9, line 15 of the specification of contents of amendment
Correct as <101>J.

Claims (1)

[Claims] Garnet was epitaxially grown on a non-magnetic garnet substrate and incident on the surface of the garnet structure.
In a magneto-optical element using 7ARADAY1i3I@child, the inclination from (110) or (211) in Oo〈-≦15@0 field is on a substrate with a round surface as #I11.
1. A magneto-optical element characterized in that a garnet film produced by the above method is used as a 7F 1 trochanter.