JPH0453932A - Production of nonlinear optical element - Google Patents

Abstract

PURPOSE:To easily form the nonlinear optical element in a large amt. at one time at a good yield by subjecting a material which is transparent in an objective wavelength region to dry etching to form an optical waveguide groove and crystallizing an org. nonlinear optical material in the optical waveguide groove. CONSTITUTION:The central part consists of a blank material having a high nonlinear optical characteristic and the circumference thereof is constituted of a material (including air) which is transparent in the objective wavelength region. The optical waveguide groove is formed by the direct dry etching method and the org. nonlinear optical material is packed into this optical waveguide groove and is subjected to crystal growth at the time of constituting a three-dimensional optical waveguide structure. The dry etching method id used in such a manner. The element production in the large amt. at one time at the good yield is thus executed relatively easily in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing an optical waveguide in a nonlinear optical element that converts the wavelength of laser light.

(Conventional wave i) Among the many types of nonlinear optical phenomena, second harmonic generation (S
Since HG) can easily shorten the wavelength of laser light by half, visual research is being conducted on its application to optical recording and light sources such as light sources for optical disks and light sources for laser printers in the field of optoelectronics.

Recently, 2-methyl-4-nitroanili
Organic crystals with a π-electron conjugated system, represented by ne (MNA), have extremely high second-order nonlinear optical properties, and are superior to conventional KDP (KHzPOa) and LN (L1Nbo).
3) Compared to well-known inorganic crystals such as
It is expected that the efficiency will be about 3 times higher, and many studies have been conducted.

Furthermore, since nonlinear optical phenomena require high optical power density, methods of confining the light in as narrow a region as possible are being studied. The methods include: (1) growing an organic nonlinear optical single crystal thin film between two glass substrates to form a slab-type optical waveguide; (2) providing a spacer between the two glass substrates. Therefore, methods of filling the gap with an organic nonlinear optical material and then growing crystals to form a three-dimensional optical waveguide are being considered.

(Problems to be Solved by the Invention) In general, even with materials such as MNA that have high nonlinear optical properties, it is difficult to put them into practical use unless the material is efficiently filled into a narrow area and a crystal-grown optical waveguide is formed. The effect will be reduced.

In the slab type optical waveguide of (1) above, light can be confined in the vertical direction, but light can not be confined in the horizontal direction, so the nonlinear optical effect is reduced.

In addition, in the three-dimensional optical waveguide of (2) above, the vertical direction.

Although it is possible to confine light both in the horizontal direction, conventionally, spacers have often been provided when producing optical waveguide grooves, making it difficult to easily obtain an arbitrary capillary shape. As a result, the yield rate was poor and the working efficiency was also reduced, which was unfavorable in the manufacturing process of nonlinear optical elements.

(Means and Effects for Solving the Problems) An object of the present invention is to create a three-dimensional optical waveguide that has a narrow area in which an organic nonlinear optical crystal can be confined in both the vertical and horizontal directions, with better reproducibility than conventional optical waveguides. An object of the present invention is to provide an organic nonlinear optical element that can be produced and bring out higher nonlinear optical effects than ever before, and a method for manufacturing the same.

The nonlinear optical element of the present invention is a planar nonlinear optical element whose central part is made of a material with high nonlinear optical properties and whose surroundings are made of a material that is transparent (including air) in the target wavelength range. When configuring the waveguide structure, an optical waveguide groove T is formed by a direct dry etching method, and an organic nonlinear optical material is filled in the leading wave groove.
It is obtained by growing crystals.

We have reached the conclusion that by using the dry etching method to form optical waveguide grooves, nonlinear optical elements can be produced simply and in large quantities at a time with a high yield.

[Example] An example of the present invention will be described using FIGS. 1 to 3, but the present invention is not limited thereto.

FIG. 1 fal to fil are steps for manufacturing an optical waveguide groove.

In this example, reactive ion etching (RIE: Rea
Active Ion Etching is hereinafter referred to as RIE. ) was used. The process is a normal etching process. However, when RIE is used in the semiconductor process, it is not necessary to etch as deeply as the etching depth is from several tens of nanometers to several hundred nanometers.
m), a positive photoresist is sufficient for the mask, but in the present invention, since the etching depth can be arbitrarily set on the order of microns, both the metal and the positive photoresist are overlapped. Using. This is because sufficient etching depth cannot be obtained with photoresist alone.

The following will be explained using FIGS. 1(al to il).

After thoroughly cleaning the glass substrate (24aw x 241w x 1), a layer of gold was applied using a vacuum evaporation method. A (Cu) film is formed, and a positive photoresin is applied to a thickness of 4 to 5 μm using a spin coater. After prebaking, contact exposure and development are performed to form linear grooves approximately 5 μm in width. Thereafter, the exposed metal is etched by dipping in dilute nitric acid to form a mask, and RIE is performed. After etching the glass to a depth of about 10 μm, there is no unnecessary resist.
Ash and remove with 2 gases. Then, the metal is removed by soaking it in dilute nitric acid. FIG. 2 shows a schematic diagram of the RIE apparatus used here.

In the gap created by overlapping the substrate without grooves on the top surface of the substrate with optical waveguide grooves produced in this way,
An optical waveguide was formed by filling a large number of MNAs by the capillary rise method and growing polycrystals by the horizontal Bridgman method. Further, by peeling off the upper substrate after this, it is possible to use the upper crab layer as a leading wave path for air (FIG. 8).

In this example, the horizontal Prifgeman method was used for crystal growth, but a solvent evaporation method may also be used.

(Effects of the Invention) The nonlinear optical element and the manufacturing method thereof of the present invention have the following effects.

(1) In the nonlinear optical element of the present invention, the center of the optical waveguide is formed in a narrow and limited area both in the vertical and horizontal directions, so light is effectively confined and the element is highly efficient. ing.

(2) According to the manufacturing method of the present invention, organic crystals can be grown not only in the vertical direction but also in a narrowly limited portion in the horizontal direction. Therefore, the obtained nonlinear optical element has high optical power density and high efficiency.

(3) Since the production method according to the present invention can be applied to crystals that can be produced by the Bridgman method or the solvent evaporation method, it can be applied to many materials.

(4) In the production of the optical waveguide groove according to the present invention, a dry etching method is used, so it is relatively simple, and devices can be produced in large quantities at a time with a high yield.
This will lead to a reduction in manufacturing costs.

[Brief explanation of the drawing]

1(a) to (i) are diagrams showing the manufacturing process of the optical waveguide groove, FIG. 2 is a schematic diagram of the RIE apparatus used in the present invention, and FIG.
Figure [al] is a sectional view of the nonlinear optical element obtained according to the present invention, and Figure 8 [bl] is a plan view of the nonlinear optical element obtained according to the present invention. Agent Patent Attorney Ume 1) Masaru (2 others) (Cl) [
=2===koI boundary<r)b=]2=koq in Figure 1Figure 3

Claims (1)

[Claims] 1. The center portion is made of an organic material with high nonlinear optical properties,
In a method for manufacturing a nonlinear optical element made of one or more materials whose surroundings are transparent in a target wavelength range, an optical waveguide groove is formed by performing dry etching on the material that is transparent in the target wavelength range. . A method for manufacturing a nonlinear optical element, which comprises growing a crystal of an organic nonlinear optical material in the optical waveguide groove.