JPH06347842A - Optical waveguide crystal and its production - Google Patents

Abstract

PURPOSE:To provide a crystal having an optical waveguide with which the miniaturization of element and the enhancement of laser oscillation efficiency are possible by forming a two-dimensional or three-dimensional optical waveguide different in refractive index from other parts in the depth direction from the surface or the depth direction and the surface direction by using a specific perovskite type crystal. CONSTITUTION:The two-dimensional or three-dimensional optical waveguide different in refractive index from the other parts is formed in the depth direction from the surface or the depth direction and the surface direction by the perovskite type crystal expressed by compsn. formula ABTixAl1-xO4 contg. Ti<3+> as laser active ions. A is Ca<2+> or St<2+>, B is one kind selected from among Y<3+>, Gd<3+> and La<3+>; (x) is 0.001<=x<=0.1. The shape of the optical waveguides of this crystal is the two-dimensional optical waveguide having two-dimensional damage layer smaller in refractive index than that of the other parts of the crystal formed near the ion range by ion implantation or the three-dimensional channel type optical waveguide on which the damage layer varying in depth is formed by the ion implantation after the formation of mask patterns.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is useful as a light-emitting material, and in the field of utilizing coherent light such as optical measurement, optical information processing, optical medical treatment, optical processing, various optical devices such as laser elements and optical amplifiers. TECHNICAL FIELD The present invention relates to an erbium- or praseodymium-doped perovskite optical waveguide crystal effective for downsizing an element, improving efficiency, and coupling with a fiber, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a semiconductor for a laser is known as an optical waveguide crystal. Also, in non-semiconductors, for example,
LiNdO ₃ waveguide crystal added with Nd as an optical waveguide formed by using an ion exchange method, KTiOPO
₄ crystals are known.

The thin-film optical waveguide formed by the sputtering method is a Y ₃ Ga ₅ O containing Nd or Cr.
₁₂ (M.YAMAGA et al, Japanese Journal of Applied Ph
ysics.23,312 (1984), Journal of Luminesence 39,335
(1988)) is known. In addition, an optical waveguide prepared by ion implantation is Nd: Y _{3 produced} by He ⁺ ion implantation.
Al ₅ O ₁₂ (SJField et al, IEEE Journal of QUANTU
M Electoronics 27,423 (1991), PJChandler et al,
Nuclear Instruments and Methods in Physics Researc
h B59 / 60,1223 (1991)), KNb by He ⁺ ion implantation
O ₃ (D.Flick et al, Applied Physics Letter 59,3213
(1991)), C ⁺ ion implanted sapphire (PDTowns
end et al, Electronics Letter 26, 1193 (1990)) are known.

[0004] Further, Ti-doped sapphire crystals He ⁺ or B ^{+ ion-implanted} formed was called titanium sapphire optical waveguide crystals two- or three-dimensional optical waveguide by a wavelength-tunable laser crystal have been proposed ( N. Kodama et al Japanese Patent Application No. 5-92329).

However, the composition formula ABTi _x Al _1-x O ₄ (A: C) containing Ti ³⁺ as the laser active ions is used.
a ²⁺ or Sr ²⁺ , B: Y ³⁺ , Gd ³⁺ , one selected from La ³⁺ , x: 0.001 ≦ x ≦ 0.1) perovskite type crystal represented by He ⁺ ion There is no known perovskite type optical waveguide crystal in which a damage layer is formed in a certain portion of the crystal by injecting the above-mentioned material to form a two-dimensional or three-dimensional optical waveguide having a different refractive index from other portions of the crystal.

[0006]

The present invention is a Ti-doped perovskite single crystal useful as a wavelength tunable laser oscillation material in the near infrared region (1500 to 1650 nm), and is capable of reducing the device size and increasing the laser oscillation efficiency. It is an object of the present invention to provide a crystal having a possible optical waveguide and a manufacturing method thereof.

[0007]

As a result of various studies to achieve the above object, the inventors of the present invention have found that the incident energy on the surface of a Ti-doped perovskite single crystal is changed at 1 MeV or more to achieve He. ^{If a} damage layer having a small refractive index and having a certain thickness is formed within a certain depth range by implanting ⁺ ions, B ⁺ ions or C ⁺ ions, the damage layer is sandwiched between the damage layer and the outermost layer. Light is confined in the layer part formed, a mask pattern is formed on the single crystal surface with a photoresist, Pt is used as an ion implantation mask, and A is used as a base layer for preventing Pt adhesion.
It has been found that light is confined in a channel-type tertiary layer having a depth and a width when a damaged layer having a small refractive index and a different depth is formed by attaching an I film and implanting the ions.

That is, the present invention provides a composition formula ABTi _x Al _1-x O ₄ (A: C) containing Ti ³⁺ as laser active ions.
a ²⁺ or Sr ²⁺ , B: Y ³⁺ , Gd ³⁺ , La ³⁺ , a perovskite-type crystal represented by x: 0.001 ≦ x ≦ 0.1), which is deep from the surface. The present invention relates to a perovskite type optical waveguide crystal in which a two-dimensional or three-dimensional optical waveguide having a different refractive index from other portions is formed in the depth direction or the depth direction and the plane direction.

Next, the present invention will be described in detail. The Ti-doped perovskite single crystal used in the present invention has a composition formula ABT.
i _x Al _1-x O ₄ (A: Ca ²⁺ or Sr ²⁺ , B: Y ³⁺ , G
one selected from d ³⁺ and La ³⁺ , x: 0.001 ≦ x ≦
0.1), which is a normal plate crystal that emits light in the visible region of 400 to 600 nm.

The shape of the crystalline optical waveguide of the present invention is a two-dimensional optical waveguide in which a two-dimensional damaged layer having a smaller refractive index than the other portions of the crystal is formed near the ion range by ion implantation, Alternatively, it is a three-dimensional channel type optical waveguide in which damaged layers having different depths are formed by ion implantation after forming a mask pattern.

In the case of a two-dimensional optical waveguide, the size of these waveguides in the present invention is such that the thickness of the waveguide is 0.2 to 1 μm within a depth range of approximately 20 μm from the surface of the crystal. In addition, in the case of a three-dimensional channel type optical waveguide, it is also a three-dimensional channel type optical waveguide having a depth within about 20 μm from the surface and a width within about 50 μm. Even if a damaged layer is formed to a deeper portion than necessary in the depth direction of the crystal, the effect such as a multi-waveguide mode is small.

In the method of manufacturing a two-dimensional optical waveguide by ion implantation of the present invention, the implanted ion species are He ⁺ , B ⁺ and C.
⁺ Ions are used. When using He ⁺ ions,
The implantation amount is 10 ¹⁶ to 10 ¹⁷ ions / cm ² as a standard. If the injection amount is less than 10 ¹⁶ io / cm ^{2, the} change in the refractive index of the crystal damage layer is small and the intended optical waveguide cannot be formed. On the other hand, if it is larger than 10 ¹⁷ / cm ² , an optical waveguide is formed, but a large number of defects are generated in the crystal, which deteriorates the optical quality of the obtained crystal, which is not preferable.
When B ⁺ and C ⁺ ions are used, the implantation amount is 10 ¹⁵
Approximately 10 ¹⁷ ions / cm ² is a standard. If the injection amount in this case is less than this range, it is not possible to bring about a sufficient change in the refractive index for forming an optical waveguide in the crystal. If the injection amount is more than this range, defects in the crystal increase and the waveguide Optical quality is degraded. B ⁺ and C ⁺ ions need only be implanted in a smaller amount than He ⁺ ions, and have the effect of reducing the strain generated in the crystal.

The implantation direction may be either the a-axis or the c-axis of the crystal. The crystal temperature at the time of ion implantation is preferably maintained in the range of liquid nitrogen temperature of 77K to 350K.

The three-dimensional channel type optical waveguide of the present invention is produced by using, for example, a positive photoresist (for example, AZ-1).
350), and after exposing with UV light to form a mask pattern, an Al film (thickness: about 100 nm) is formed and covered by vapor deposition or sputtering, and an ion mask is formed on the Al film (excluding the surface of the crystal to be ion-implanted). After depositing a Pt film on the surface by vapor deposition or sputtering, the resist is peeled off. After implanting ions by the method described above, the Pt and Al films are peeled off to obtain a three-dimensional channel type optical waveguide.

[0015]

EXAMPLES The present invention will now be described in more detail with reference to Examples.

Example 1 A plate-shaped (5 mm × 10 mm × 2 mm) single crystal of Ti-doped perovskite represented by the composition formula CaGdTi _0.01 Al _0.99 O ₄ was used as a sample, and B ⁺ ions were implanted with a tandem type ion beam accelerator. Implant at 2.01 MeV with a dose of 1 × 10 ¹⁶ ions / cm ² from the c-plane to the entire surface of the crystal 2
A three-dimensional optical waveguide crystal was created. The crystal at the time of injection was cooled so that the crystal holder became 300K. As a result of measuring the refractive index and mode of the obtained crystal using a prism coupler and a He—Ne laser, it was confirmed that a two-dimensional optical waveguide having an optical waveguide layer thickness of 1.6 μm was formed.

FIG. 1 shows the laser incident angle dependence of the transmission intensity measured by using a prism coupler to measure the optical waveguide thickness and the mode refractive index. It was confirmed that the TE mode refractive index of the optical waveguide layer was 1.942, which was higher than the refractive index of the crystal before injection. The structures of the optical waveguide layer and the damaged layer in the crystal were observed with an optical microscope and a transmission electron microscope.

Example 2 An incident energy of 2.0 MeV was applied to the c-plane of a plate-shaped single crystal of Pr-doped perovskite represented by the composition formula CaGdTi _0.01 Al _0.99 O ₄ using a tandem type ion beam accelerator.
C ⁺ ions were implanted at a dose of 2 × 10 ¹⁵ ions / cm ² to prepare a two-dimensional optical waveguide crystal. The obtained crystal was measured for refractive index and mode in the same manner as in Example 1, and the waveguide thickness was 1.
It was confirmed that a 5 μm two-dimensional optical waveguide was formed. Further, as in Example 1, the structures of the optical waveguide layer and the damaged layer in the crystal were observed with an optical microscope and a transmission electron microscope.

Example 3 An Er-doped perovskite single crystal represented by the composition formula CaYTi _0.01 Al _0.99 O ₄ was used as a positive photoresist (AZ).
-1350) was applied to a film thickness of 2 μm and baked at 70 ° C. for 20 minutes, and then an exposure mask pattern was formed by UV light. An Al film having a film thickness of 100 nm was formed on this crystal by a sputtering method, a Pt film serving as an ion mask was formed by the sputtering method, and then the resist was peeled off with acetone.

A tandem ion beam accelerator was used for this sample, the incident energy was 2.0 MeV, and the implantation amount was 10 ^16.
After implanting B ⁺ ions of ions / cm ² , the Pt and Al films were stripped using acid to form a channel type three-dimensional optical waveguide. The obtained crystal was 1.8 μm in depth and 1.5 in width by an optical electron microscope, a transmission electron microscope and a prism coupler method.
It was confirmed that a 3-dimensional optical waveguide of μm was formed.

[0021]

INDUSTRIAL APPLICABILITY The Ti-doped perovskite optical waveguide crystal having the constitution of the present invention has high laser oscillation efficiency and can be used as a small visible wavelength tunable laser and an optical amplifying device.

[Brief description of drawings]

FIG. 1 is a diagram showing the laser incident angle dependence of the transmission intensity of the crystal obtained in Example 1.

Claims (4)

[Claims] 1. A composition formula ABTi _x Al _1-x O ₄ (A: Ca ²⁺ or Sr) containing Ti ³⁺ as laser active ions.
²⁺ , B: Y ³⁺ , Gd ³⁺ , one selected from La ³⁺ , x:
0.001 ≦ x ≦ 0.1), and a two-dimensional or three-dimensional optical waveguide having a refractive index different from that of other portions is formed from the surface in the depth direction or the depth direction and the surface direction from the surface. Perovskite type optical waveguide crystal. 2. He ⁺ as an ion implantation species is 10 ¹⁶ to 10 10.
^The composition formula A is obtained by implanting ¹⁸ ions / cm ² or B ⁺ or C ⁺ at 10 ¹⁵ to 10 ¹⁷ ions / cm ^2.
BTi _x Al _1-x O ₄ (A: Ca ²⁺ or Sr ²⁺ , B:
One selected from Y ³⁺ , Gd ³⁺ and La ³⁺ , x: 0.00
1 ≦ x ≦ 0.1) A perovskite type crystal in which a damaged layer is provided to a perovskite type crystal to form an optical waveguide having a refractive index different from that of other portions in the depth direction from the surface or in the depth direction and the plane direction. A method for manufacturing an optical waveguide crystal. 3. The manufacturing method according to claim 2, wherein the crystal at the time of ion implantation is held at 77 to 350 K and ion implantation is performed. 4. A method of manufacturing a channel type three-dimensional optical waveguide according to claim 2, wherein a mask pattern is formed using a photoresist, and Pt is used as a mask for implanted ions, and Al is used as a base layer of the Pt mask. .