JPH03294829A - Nonlinear optical thin film and production thereof - Google Patents

Abstract

PURPOSE:To allow the uniform doping of multiple fine metallic particles into optically transparent materials by alternately depositing the fine metallic particles grown to an island shape and the optically transparent materials grown as a continuous film. CONSTITUTION:This thin film consists of the laminated structure alternately laminated with the fine metallic particles 2 grown to the island shape on a substrate 1 and the optically transparent materials 3 grown as the continuous film. A remarkable and preferable effect is obtainable if the thickness a in the direction perpendicular to the substrate surface of the fine metallic particles 2 grown to the island shape and the thickness b in the direction perpendicular to the substrate 1 surface of the optically transparent materials 3 grown as the continuous film satisfy the relation a<=b. The uniform doping of the fine metallic particles 2 at the unified grain size into the optically transparent materials at a high concn. is possible in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a nonlinear optical thin film having a laminated structure of fine metal particles and an optically transparent material, and a method for manufacturing the same.

Conventional technology: By doping fine metal particles into glass, the third-order nonlinear susceptibility of the metal increases and the optical nonlinearity increases.
Page (Optics Letters, vol, 10
．． 511 (1985)). Gold and silver are used as the metal fine particles, and a metal salt reduction method is used as a method for producing glass doped with metal fine particles. Colored glass with precipitated metal colloids such as gold and copper is also produced by heat-treating glass made by the melting method and mixing fine metal particles to precipitate only specific components.

Problems to be Solved by the Invention The third-order nonlinear susceptibility of glass doped with nine fine gold particles produced by the conventional method is lo-12 to lo-10.
esuO value, which is very small. The reason for this is thought to be that the amount of metal fine particles doped into the glass is very small, 5 ppm or less. However, with conventional manufacturing methods, if the amount of dope is increased beyond this level, it becomes difficult to dope in a uniformly dispersed manner.

The present invention is intended to solve these problems, and aims to provide a nonlinear optical thin film in which an optically transparent material is uniformly doped with a large amount of fine metal particles.

Means for Solving the Problem In order to solve this problem, the present invention (as shown in FIG.
This nonlinear optical thin film has a laminated structure in which at least one kind of metal fine particles grown in an island shape and an optically transparent material grown as a continuous film are alternately deposited. Furthermore, this nonlinear optical thin film is manufactured by sputtering.

Effect: With this configuration, a large amount of fine metal particles with uniform particle sizes can be uniformly dispersed in an optically transparent material, making it possible to manufacture a nonlinear optical thin film with large third-order nonlinear susceptibility. .

Example The structure of the nonlinear optical thin film according to the present invention is shown in FIG.

As shown in the figure, the nonlinear optical thin film of the present invention has a laminated structure in which fine metal particles 2 grown in the form of islands on a substrate 1 and optically transparent material 3 grown as a continuous film are alternately deposited. be. Here, the thickness a of the metal fine particles 2 grown in an island shape in the direction perpendicular to the substrate surface and the thickness b of the optically transparent material 3 grown as a continuous film in the direction perpendicular to the substrate 1 surface have a relationship of a≦b. If it satisfies the above criteria, the effect will be more significant, and it is preferable.The size of the metal island-like fine particles must be small enough to produce a local electric field effect, and should be in the range of several nanometers to several 110 nanometers.
A size of about 0n is appropriate. When the size of the metal fine particles is 1 μm or more), the optical nonlinearity becomes small because the circular properties become large.

The nonlinear optical thin film of the present invention utilizes the fact that the island-like growth material formed in the very early stage of metal thin film production is a fine particle, and uses the island-like growth material as the metal fine particle 2 to form an optically transparent material 3. It is actively used for doping inside the body.

The method for producing a nonlinear optical thin film according to the present invention is characterized in that the fine metal particles 2 can be uniformly doped into the optically transparent material 3 with the particle diameters being uniform.

The reason why metal fine particles 2 having a uniform particle size can be uniformly doped in the present invention will be described. If the metal particles flying onto the substrate 1 from the evaporation source do not have much energy themselves, they lose energy in a direction perpendicular to the substrate 1 in a short period of time and stay on the substrate 1. When the deposited particles reach the substrate, they generally do not reach thermal equilibrium because they are in the transition process between the gas phase and the solid phase.After moving around the surface of the substrate 1, they are captured by adsorption points such as defects on the surface of the substrate 1. and adheres to the substrate 1. If there are no adsorption points, the deposited particles will reevaporate. The successive incoming vapor deposited particles gather together several adhering particles in the vicinity, which become crystal nuclei. After this crystal nucleus is formed, island-like structures grow. When the island-like structure at the initial stage of thin film formation is formed, the flying metal particles are stopped, and the metal island-like fine particles 2 are dispersed on the substrate l. By forming a thin film of an optically transparent substance 3 thereon and covering the entire surface of the metal island-like fine particles 2 with the optically transparent substance 3, the metal fine particles 2 having a uniform particle size are uniformly distributed in the optically transparent substance 3. This makes it possible to dope.

The shape and size of this island-like structure vary depending on the formation conditions, and the size can be controlled to be relatively uniform due to the spherical shape. It is also possible to control the density of metal fine particles. The doping amount of the metal fine particles can be up to 20% by weight, and thin films of various metals are prepared by the above method.The third-order nonlinear susceptibility was measured.The material used as the metal fine particles 2 was Au. ,Ag,C
The present inventors have discovered that metals such as u have a large third-order nonlinear susceptibility. It may be an inorganic glass substance or an organic polymer compound (℃) Specific examples of the present invention will be described.

(Example 1) The multi-source sputtering apparatus shown in FIG. The sputtering source was composed of a SiO2 target 6 and an Au target 7. Between the substrate 4 and the target 6 or 7,
A shutter 8 with apertures 9 at l locations is arranged, and by rotating the shutter 8, the position of the aperture 9 is changed, and it is placed above either the SiO2 target 6 or the Au target 7. I can come. The position and stop time of the aperture 9 are controlled by a computer. Silica glass was used for the substrate 4, and the thin film production conditions were an argon atmosphere and a gas pressure of 3 Pa1.
The substrate was heated to 200°C with a heater 5. The input power to the LSiO2 target 6 was 200 W, and the input power to the Au target 7 was IOW. was stopped on the SiO2 target 6, a SiO2 film of 1100 nm was deposited on the substrate 4, and the aperture 9 was then stopped on the Au target 7.
After depositing Au fine particles, the density of the Au fine particles increases rapidly after a very short relaxation time, crystal nuclei grow, and an island-like structure grows. For example, by leaving the substrate 4 on the Au target for 10 seconds, the average particle size is approximately 5n.
When the size of the metal island-like fine particles reaches 4 to 6 nm, the shutter 8 is rotated again and stopped on the SiO2 target 6, and the SiO2 film is deposited to a thickness of about 6 nm. The operation of alternately depositing Au on the substrate 4 was repeated to form a laminated structure in which metal island fine particles and 8102 film were alternately deposited. This operation was repeated 400 times to produce a nonlinear optical thin film of about 2.5 μm. The doping amount of Au in the thin film prepared by T et al. was 5% by weight, and A
The average particle size of the u particles was 5 nm (Example 2) Using the nonlinear optical thin film manufacturing apparatus used in Example 1, SiO2 was produced in the same manner as in Example 1 using Ag and Cu as metal targets. A nonlinear optical thin film was fabricated by repeating the operation of alternately depositing metal island-like fine particles on a substrate.The doping amounts of Ag and Cu in the fabricated nonlinear optical thin film were 5% by weight and 2% by weight, respectively.
In addition, the average particle diameter of Ag and Cu fine particles is 5 nm each.
(Example 3) Third-order nonlinear susceptibility χ13' of the nonlinear optical thin films prepared in Examples 1 and 2 was measured. (
The excitation wavelength is 0.53 μm), and the χ+31 of the Ag fine particle-doped glass thin film is 5.0*10-”esu (the excitation wavelength is 0.53 μm).
40 μm), the χ+31 of the Cu fine particle-doped glass thin film is 1.0 1O-11 Iesu (excitation wavelength 0.65 μm)
), a Fabry-Perot type resonator was fabricated using the nonlinear optical thin film prepared in Example 1, and a very high switching speed of less than L5 picoseconds was obtained. The nonlinear optical thin film has a laminated structure in which fine metal particles and optically transparent material are alternately deposited, and it is possible to dope the metal fine particles uniformly and at a high concentration into the optically transparent material by aligning the particle size. It is possible to obtain nonlinear optical thin films with nonlinear optical effects.

[Brief explanation of drawings]

Figure 1 is a cross section showing the structure of the nonlinear optical thin film of the present invention.
FIG. 2 is a perspective view showing the configuration of the nonlinear optical thin film manufacturing apparatus. 1-1 substrate, 2-1 metal fine particles, 3-1 optically transparent substance, 4-1 substrate, 6--Si○2 target, 7-
-Au target, 8--Shirt 9 aperture.

Claims (5)

[Claims] (1) A nonlinear optical thin film in which at least one kind of metal fine particles grown in island form and an optically transparent material grown as a continuous film are alternately deposited on a substrate surface. (2) The relationship between the thickness a of the metal fine particles grown in island form on the substrate surface in the direction perpendicular to the substrate surface and the thickness b of the optically transparent material grown as a continuous film in the direction perpendicular to the substrate surface is a≦b. The nonlinear optical thin film according to claim 1, which satisfies the following. (3) The metal fine particles grown in the form of islands on the substrate surface are made of gold (Au).
), silver (Ag), or copper (Cu). (4) A method for manufacturing a nonlinear optical thin film, which comprises alternately depositing on a substrate surface at least one kind of metal fine particles grown in an island shape and an optically transparent material grown as a continuous film. (5) The nonlinear optical system according to claim 4, wherein a thin film having a structure in which fine metal particles grown in island shapes and optically transparent material grown as a continuous film are alternately deposited on the substrate surface is manufactured by a sputtering method. Method for manufacturing thin films.