JPH08110537A - Non-linear optical material - Google Patents

Abstract

PURPOSE: To obtain the nonlinear optical material good in transparency and having a large value of high-order nonlinear susceptibility by dispersing the superfine particle of SnO2 with the diameter specified in the matrix of amorphous SnOx . CONSTITUTION: This nonlinear optical material is formed by dispersing the superfine particle of SnO2 having <=200Å, preferably <=100Å, diameter in the matrix of amorphous SnOx . The material is produced, for example, by forming the thin film of the amorphous SnOx matrix on the surface of a quartz substrate in 500-5000Åthickness, dispersing the superfine particle of SnO2 in the matrix and then oxidizing the superfine particle. The superfine particle of SnO2 is dispersed in the SnOx matrix preferably by ion plating, the superfine particle is dispersed in the matrix to form the thin film at 5-30Å/sec, and then the film is heated in oxygen. Consequently, the tertiary nonlinear susceptibility X (3) is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-linear optical material, and more specifically, a non-linear optical thin film in which electrons and excitons exhibit a so-called quantum size effect exhibiting zero-dimensional behavior due to a three-dimensional confinement effect. It is an optical material used for optical bistable elements, optical gate optical switches, wavelength conversion elements, and the like.

[0002]

2. Description of the Related Art The quantum size effect of fine particle dispersions has recently been found and is a phenomenon that has attracted attention. This effect is generally obtained by dispersing ultrafine semiconductor particles of several hundred liters or less in an insulator such as glass. It was produced as a thin film and started to be studied for several years. Regarding such quantum size effect, for example, “Quantum size effect and optical nonlinearity of semiconductor fine particle dispersed glass”, Shino Nakamura, Optics, Vol. 19, No. 1 (January 1990)
p. p. 10-16, "Optical Nonlinearity of Semiconductors and Ultrafine Metal Particles" Katsuo Nakamura, Applied Physics Vol. 59 No. 6 (199)
0) p. p. 738-745, “Nonlinear Optoelectronics in Latest Patents” Takao Fushimi, Industrial Research Committee, “Qua
ntum Size Effect of Semi
onducerMicrocrystallites
Doped in SiO ₂ -Glass Thin
Films prepared by Rf-Spu
tertering ”Keiji Tsummoto et al.
"Japanese Journal of Appl
ied Physics, Volume 28, Issue 10 (1928)
-1933) "and" Optics, Vol. 19, No. 1 (1
Jan. 990, pp. 10-16 "and the like.

In particular, as a recent trend, it has been found that not only semiconductor ultrafine particle dispersed materials but also metal and metal oxide ultrafine particles exhibit strong nonlinearity. A non-linear optical material in which ultrafine metal oxide particles are dispersed is disclosed in JP-A-3-
There is 44031 issue. Here, the quantum size effect and the nonlinear optical effect will be briefly described. The non-linear optical effect is a phenomenon in which when a substance is irradiated with light, the optical characteristics such as the absorption coefficient and the refractive index of the substance change according to the intensity of the light. This makes it possible to realize an all-optical logic element that uses only light as an input. The quantum size effect is that electrons and holes of semiconductor ultrafine particles embedded in transparent glass in the visible light region are confined three-dimensionally by the deep potential created by the glass, but the electrons are considered like waves. Then,
In a small box, the wave pattern is limited to a specific one, so the electronic state becomes discrete and the vibrating electron intensity and nonlinear susceptibility increase.

Therefore, as a non-linear optical material, a material in which semiconductor ultrafine particles are dispersed in a transparent insulating material such as amorphous Al ₂ O ₃ or amorphous SiO ₂ is generally used. However, in this type of conventional nonlinear optical material, it cannot be said that the third-order nonlinear susceptibility X ( ³ ) is still sufficiently large. For example, X ( ³ )
However, if an even larger material can be obtained, there is an advantage that the switching operation can be performed with weaker light, but in the present situation, it is still unsatisfactory.

However, the present inventor has also made many proposals for a nonlinear optical material in which semiconductors and ultrafine metal particles are dispersed in a thin film matrix and exhibiting a quantum size effect, and a manufacturing method thereof (for example, Japanese Patent Application No. 3-348916). No. 3, Japanese Patent Application No. 3-348917, Japanese Patent Application No. 3-69064, Japanese Patent Application No. 4-61131, Japanese Patent Application No. 4-84481, etc.). However, there seems to be room for improvement in these areas as well.

[0006]

The object of the present invention is to provide X ( ³ )
The present invention provides a non-linear optical material that can be applied to various elements used in optical technology.

[0007]

The nonlinear optical material of the present invention is characterized in that ultrafine SnO ₂ particles having a particle size of 200 Å or less are dispersed in a matrix of amorphous SnOx.

The present invention will be described in more detail below. The crystalline SnO ₂ thin film (SnO ₂ polycrystal film) has X ( ³ ) of 10
^-11 (esu) Indicates an order. On the other hand, amorphous S
nOx thin X ⁽³⁾ is said to be several times the X ⁽³⁾ of the crystalline thin film of SnO _2. Based on such a fact, the present inventor thought that the X ( ³ ) was further improved by dispersing the SnO ₂ fine particles in the amorphous SnOx matrix, and confirmed it by the experiment.

The SnO ₂ ultrafine particles used in the present invention have a particle size of 200 Å or less, preferably 100 Å or less.
If the particle size is larger than 200Å, the quantum size effect does not appear, which is not preferable. When the ratio of the SnO ₂ ultrafine particles in the amorphous SnOx matrix is 20 to 50% by volume, particularly good results are shown, but the reason has not been clarified yet.

Actually, in order to manufacture the nonlinear optical material of the present invention, for example, an amorphous SnOx matrix is formed in a thin film of about 500 to 5000 Å thickness on the surface of a quartz substrate, and the amorphous SnOx matrix has a grain size of 2
After the Sn ultrafine particles having a particle size of 00Å or less are dispersed, the Sn ultrafine particles may be subjected to an oxidation treatment.

Amorphous SnOx is prepared by using SnO ₂ ultrafine particles.
Dispersion in the matrix is preferably carried out by the ion plating method. Particularly, the film formation rate is an important factor. If it is too fast, a large amount of Sn in the metal state is present in the film, and conversely, if it is too slow, it is polycrystalline and the particle size is 2
An SnO ₂ film of 00Å or more is formed. Therefore, in the present invention, if ultrafine Sn particles are dispersed in an amorphous SnOx matrix at a film forming rate of about 5 to 30 Å / sec to form a film, and then heat treatment is performed at 300 to 600 ° C. in oxygen, 200 Å or less is obtained. It is possible to obtain ultrafine SnO ₂ particles dispersed in a film made of an amorphous SnOx matrix.

Example 1 An SnOx film having a film thickness of about 3000 Å was prepared on a quartz substrate by the ion plating method under the following conditions (total 6).
Sheet). Evaporation material Sn (99.99%) Support temperature Normal temperature or 450 ° C Back pressure in vacuum chamber 1 x 10 ^-6 Torr Oxygen gas pressure 6 x 10 ^-4 Torr High frequency power 80 W Heat source-to-substrate distance 25 cm Film formation rate 5 When 6 films were examined by 10 or 20 Å / sec X-ray diffractometry, none of the films having a substrate temperature of room temperature was amorphous and no diffraction peak was observed. On the other hand, when the substrate temperature was 450 ° C., the diffraction peak of SnO ₂ was observed in all cases, and when observed by the TEM method, crystalline SnO _{2 of} 200 Å or higher was observed.
When the film forming rate was 10 Å / sec or more, metallic Sn was contained. In addition, the color of the film was dark regardless of the substrate temperature, and the transparency was poor. The three sheets produced at room temperature were heat-treated at 500 ° C. (in air) for 1 hour. 5Å / se
A large amount of crystalline SnO _{2 of} 200 Å or more was found in the c film.
Microcrystalline SnO ₂ below 200Å above 10Å / sec
Was observed. The film produced at 10Å / sec or less was transparent and had a transmittance of 80% or more for visible light. The matrix portions were all amorphous and were Sn and O in composition analysis by EDX (energy dispersive X-ray detector). THG (third harmonic generation method) for X ( ³ ) of 9 films
The results are shown in Table 1 when evaluated for a wavelength of 1.9 μm.

[0013]

[Table 1]

[0014]

The nonlinear optical material of the present invention has a particle size of 200Å
The following SnO ₂ ultrafine particles form a film in which the matrix of amorphous SnOx is dispersed, so that the transparency is good, and the third-order nonlinear optical effect is obtained by using crystalline SnO ₂
It can be made larger than that of an amorphous SnO ₂ film.

Claims (1)

[Claims] 1. A non-linear optical material, characterized in that SnO ₂ ultrafine particles having a particle size of 200 Å or less are dispersed in a matrix of amorphous SnOx.