JPH0442216A - Production of organic single crystal optical waveguide - Google Patents

Abstract

PURPOSE:To obviate the generation of thermal decomposition of an org. material by irradiating the surface of a substrate on which grooves are formed with an ICB of an org. material to deposit the single crystal of this org. material by evaporation in the grooves and growing the single crystal. CONSTITUTION:The straight grooves 11b are formed by photolithography and etching on the surface 11a of the substrate 11 consisting of glass, plastic, etc., and the substrate surface 11a thereof is irradiated with the ion cluster beam (ICB) of the org. material to deposit the single crystal of the org. material in the grooves 11b and to grow the single crystal. The material to be deposited by evaporation is the org. material but there is no need for melting this material in the case of vapor deposition of the org. material on the substrate 11 and, therefore, the thermal decomposition does not arise. The clusters of the material to be deposited by evaporation collide against the substrate 11 and are thereby moved and diffused. The thickness of the optical waveguide is controlled uniformly to a desired value without generating thermal decomposition of the org. nonlinear optical material 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, and in particular,
The present invention relates to a method for manufacturing a three-dimensional optical waveguide made of a single crystal of an organic material.

(Prior Art) Various attempts have been made to convert the wavelength of laser light into a second harmonic or the like (shorten the wavelength) using nonlinear optical materials. Specifically, as an optical wavelength conversion element that performs wavelength conversion in this way, for example, there is a bulk optical device as shown in "Fundamentals of Optoelectronics JA," written by YARIV, translated by Kunio Tada and Takeshi Kamiya (Maruzen Co., Ltd.), pages 200-204. Crystal type devices are well known. However, since this optical wavelength conversion element uses the birefringence of the crystal to satisfy the phase matching condition, it is possible to use materials with no or small birefringence even if the nonlinearity is large. The problem was that it was not available.

As an optical wavelength conversion element that can solve the above problems,
For example, as shown in Japanese Unexamined Patent Publication No. 64-35424, a three-dimensional optical waveguide type in which a three-dimensional optical waveguide made of a nonlinear optical material is embedded in a substrate serving as a crystal layer has been proposed. There is.

Since this three-dimensional optical waveguide type optical wavelength conversion element can easily achieve phase matching between the fundamental wave and the wavelength-converted wave, research on this three-dimensional optical waveguide type optical wavelength conversion element has recently been conducted. is being actively carried out.

Incidentally, in recent years, various proposals have been made to use single-crystal organic nonlinear optical materials as the nonlinear optical material in such optical waveguide type optical wavelength conversion elements. Since this organic nonlinear optical material has a significantly larger nonlinear optical constant than an inorganic material, high wavelength conversion efficiency can be achieved by using this organic nonlinear optical material.

As this organic nonlinear optical material, for example, JP-A-60-
Publication No. 250334 and “Nonliner 0pti
Cal Properties of Orga
nie and Polymeric Mate
ials"AC3SYMPO3IUMSERIES
223. David J, William
S edition (American Chemical 5oci
ety, 1983), "Organic Nonlinear Optical Materials", supervised by Masao Kato and He Nakanishi (CMC, 1985)
), “Non1inear 0ptical
PropertiesorOrganicMo1e
cules and crystals”D,
Edited by S, CheIII a and J, Zyss (
Academic Press Inc., 1987), The Q by R.T., Ba1ley et al.
quality and performance of
Tlee Organic Non-Ljne
ar 0ptical Matcrial
(−) 2 − (α −Methylbenzy
lan+1no) -5Nitropyridine
(MBA-NP)” (Optics Community
cations, Vol. 85. No.3,
MNA (2-methyl-
4-nitroaniline), mNA (metanitroaniline), POM (3-methyl-4-nitropyridine-1-
oxide), urea, NPP [N-(4-nitrophenyl)-(S)-prolinolco, NPAN (2[
N-(4-nitrophenyl)-N-methylaminocoacetonitrile, DAN (2-dimethylamino-5-
Nitroacetanilide), MBANP [2-N (
α-methylbenzylamino)-5 nitropyridine] Furthermore, 3, 5 shown in JP-A No. 62-210432
-dimethyl-1-(4-nitrophenyl)pyrazole,
3,5-dimethyl-1-(4-nitrophenyl)-1,
2゜4-triazole, 2-ethyl-1-(4-nitrophenyl)imidazole, 1-(4-nitrophenyl)
Pyrrole, 2-dimethylamino 1-5-nitroacetanilide, 5-nitro-2-pyrrolidinoacetanilide,
Examples thereof include 3-methyl-4-nitropyridine-N-oxide, TRI shown in JP-A-2-28, and ENIM shown in Japanese Patent Application No. 2-58654 filed by the present applicant.

For example, MNA is LiNbO, which is an inorganic nonlinear optical material.
It has a wavelength conversion efficiency about 2,000 times higher than that of 3, so if an optical wavelength conversion element is formed using this organic nonlinear optical material, it is possible to convert infrared laser light from a small and low-cost semiconductor laser on a boat. By generating a second harmonic or the like as the fundamental wave, it is also possible to obtain short wavelength laser light in the blue region.

As a method for manufacturing a three-dimensional optical waveguide type optical wavelength conversion element using the above-mentioned organic nonlinear optical material, for example, as shown in the above-mentioned Japanese Patent Application Laid-Open No. 64-35424, at least one of two substrates is manufactured. Multiple grooves are formed on one surface,
A good method is to stack these substrates with the above-mentioned one surface inward, then fill the spaces between the side substrates with an organic nonlinear optical material, and then single-crystallize this organic nonlinear optical material using a Bridgman furnace. Are known.

(Problem to be solved by the invention) The above method is very simple and practical, but on the other hand,
Since the organic nonlinear optical material is used in a melted state, there is a problem in that the material may undergo thermal decomposition.

Further, in the above method, there is a problem that it is difficult to strictly control the thickness of the optical waveguide and keep it constant. If the thickness of the optical waveguide cannot be controlled to a predetermined value, phase matching between the fundamental wave and the wavelength-converted wave may not be achieved.
Alternatively, disadvantages arise, such as a reduction in the degree of freedom in conditions other than the thickness of the optical waveguide for achieving this phase matching.

The present invention has been made in view of the above circumstances, and provides an organic single crystal optical guide that does not cause thermal decomposition of organic nonlinear optical materials and can uniformly control the thickness of the optical waveguide to a desired value. The object of the present invention is to provide a method for manufacturing a wave path.

(Means and effects for solving the problems) The method for manufacturing an organic single crystal optical waveguide according to the present invention is an application of the so-called JCB (ion cluster beam) public notice method, in which grooves are formed on the surface of a substrate, and grooves are formed on the surface of the substrate. The method is characterized in that a single crystal of the organic material is deposited and grown in the groove by irradiating the surface of the substrate with an ion cluster beam of the organic material.

In the ICE deposition method, the deposition material is ejected in a high vacuum,
This method forms clusters (massive atomic groups) of this material through adiabatic expansion, ionizes them with an electron shower, accelerates them with voltage, and deposits them onto a substrate.

In the method of the present invention, the above-mentioned vapor deposition substance is an organic material, or when the organic material is vapor deposited on the substrate in this manner, there is no need to melt the material, so that thermal decomposition thereof is not caused.

Further, since the clusters of the vapor deposited material collide with the substrate and move and diffuse, a homogeneous and smooth vapor deposited film can be obtained. Therefore, the three-dimensional optical waveguide made of this vapor-deposited film has a uniform thickness. The thickness of the vapor-deposited film can be controlled to an individual order by controlling the vapor-deposition conditions, and therefore it is easy to precisely set the thickness of the optical waveguide to a desired value.

It should be noted that the method of depositing an organic material onto a substrate using the ICB deposition method itself has been known for a long time, and the method of forming a groove on a substrate and growing a single crystal of an organic material in the groove has not been conventionally known. It had not been done. In other words, the conventional I
When forming an organic material thin film using the CE deposition method, it is impossible to grow a single crystal of the organic material on a desired portion of the substrate, and the organic material thin film actually obtained has several irregular grain boundaries. It was polycrystalline.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 shows the procedure for manufacturing an organic single crystal optical waveguide by the method of the present invention. In this example, −
As an example, a three-dimensional optical waveguide that becomes an optical wavelength conversion element as described above is manufactured.

First, as shown in FIG. 1(1), a substrate 11 made of glass, plastic, or the like is prepared, and a linear groove 11b is formed on the surface Lla of this substrate 11 by photolithography and etching. This groove 11b has a width of, for example, 1 μm.
The depth is approximately 1 μm.

Next, a thin film 10 of an organic nonlinear optical material is formed on the surface 11a of this substrate 11, as shown in FIG. 2(2).

In this example, the organic nonlinear optical material is 3゜5-dimethyl-1-(4-nitrophenyl)pyrazole (hereinafter referred to as DM
(referred to as NP). The thin film 10 of DMNP is
It is formed using the ICB vapor deposition apparatus shown in FIG. below,
The formation of this thin film 10 will be explained with reference to FIG.

The purified DMNP 12 is stored in a crucible 2 in a closed container 20.
It can be stored in 1. Note that the inside of this airtight container 20 is, for example]
, maintained at a high degree of vacuum of X 10' Torr.

This DMNP 12 is heated by the heating filament 22 and becomes steam 12', and the melt is passed through 21 minute nozzles 2
It is ejected into the vacuum from 1a.

This DMNP vapor 12' generates a cluster I2'' due to an adiabatic expansion effect. This cluster I2'' passes through an electron shower 25 generated by an ionizing filament 23 and a grid electrode 24, and is ionized.

The ionized clusters 12'' are voltage-accelerated by the accelerating electrode 26 and collide with the surface 11a of the substrate 11. As a result, the MNP thin film 10 is formed on the substrate surface 11a as shown in FIG. 1(2). .

When the DMNP thin film 10 is formed as described above, the DMNP
The NP grows in a single crystal state within the groove 11b of the substrate 11, and becomes a three-dimensional optical waveguide 10A. Since the MNP clusters 12'' collide with the substrate surface 11a and move and diffuse, a homogeneous and smooth deposited thin film IO can be obtained. Therefore, the optical waveguide IOA has a uniform thickness. The thickness of the optical waveguide 10A can be controlled to an individual order by controlling the deposition conditions, and therefore, it is convenient to set the thickness of the optical waveguide 10A exactly to a desired value.

Next, as shown in FIG. 1(3), a protective film 13 is formed on the DMNP thin film 10. This protective film 13 is made of, for example, acrylic resin, silicone resin, epoxy resin, fluororesin, gelatin, casein, collagen, cellulose, polyvinyl alcohol, polyvinyl acetate, polyethylene terephthalate, polyurethane, unsaturated polyester, etc.
It can be formed by applying a melt or solution of phenol, polyamide, alkyd resin, etc. to the surface of the element and drying it.

Incidentally, the application of the above-mentioned melt or solution can be performed by, for example, a spin cord method. In addition to the coating method described above, this protective film 13 can be applied to the IC by using the apparatus shown in FIG.
It can also be formed by the E vapor deposition method.

By providing the above-mentioned protective film 1B, the organic material D
MNPs are isolated from the surrounding atmosphere and their sublimation and metamorphosis are prevented. Note that such a protective film 13 is preferably provided also on the end face side of the optical waveguide 10A.

As described above, the optical wavelength conversion element 30 is obtained in which the three-dimensional optical waveguide 10A made of DMNP, which is an organic nonlinear optical material, is formed in the groove 11b of the substrate 11.

This optical wavelength conversion element 30 is used as shown in FIG. That is, a laser beam (fundamental wave) 15, which is a diverging beam emitted from a semiconductor laser (wavelength: 870 nm) 1B as a fundamental wave generating means, is made into a parallel beam by a collimator lens 17, and is further converted into a parallel beam by an objective lens 18.
The light is focused onto a small spot with a diameter comparable to that of the end face 10a of the optical waveguide 10A. Thereby, the laser beam 15 enters into the optical waveguide 10A.

The fundamental wave 15 that has entered the optical waveguide 10A is
The wave is guided by repeating total reflection between the interface between 0A and the surrounding medium (substrate 11 or protective film 13). The fundamental wave 15 guided in this way is
The NP converts it into a second harmonic 15' whose wavelength is 1/2 (-435 nm). This second harmonic wave of 15° is radiated into the substrate 11 and travels inside the element 30 toward the end face side. Phase matching is achieved, for example, between the waveguide mode of the fundamental wave 5 in the optical waveguide 10A and the radiation mode of the second harmonic 15° to the substrate II (in the case of so-called Cerenkov radiation).
.

From the output end face 30b of the optical wavelength conversion element 30, the second
A beam 15' containing harmonics of 15° is emitted. This emitted beam 15'' is passed through a filter (not shown), and only the second harmonic 15' is extracted and used.

According to the method of the present invention, not only the Cerenkov radiation type optical wavelength conversion element described above but also phase matching is achieved between the waveguide mode of the fundamental wave and the waveguide mode of the wavelength-converted wave in the optical waveguide. It is also possible to form a so-called waveguide-waveguide type optical wavelength conversion element.

Furthermore, the method of the present invention is not limited to the DMNP described above,
The present invention can be similarly applied to cases where three-dimensional optical waveguides are formed using other organic materials.

Furthermore, the method for manufacturing an organic single crystal optical waveguide according to the present invention is applicable not only to manufacturing the three-dimensional optical waveguide type optical wavelength conversion device described above, but also to manufacturing other three-dimensional optical waveguide devices. applicable.

(Effects of the Invention) As explained above in detail, in the method for manufacturing an organic single crystal optical waveguide according to the present invention, an ion cluster beam of an organic material is irradiated onto the surface of a substrate in which grooves are formed, and the organic material is Since the single crystal is deposited and grown, thermal decomposition of the organic material does not occur. Therefore, according to this method, a high-quality three-dimensional optical waveguide can be formed, and the yield in manufacturing thereof can also be improved, and the cost of the optical waveguide can be reduced.

In the method of the present invention, since the optical waveguide is formed by the ICB deposition method as described above, it is possible to accurately control the thickness of the optical waveguide to a desired value by controlling the deposition conditions. Become.

Further, in this method, since the substrate is not heated to a high temperature, it is possible to use a low melting point plastic or the like as the substrate, and the degree of freedom in selecting the substrate material is greatly improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the procedure of a method for manufacturing an organic single crystal optical waveguide according to an embodiment of the present invention, FIG. 2 is a schematic side view showing an example of an ICB vapor deposition apparatus used in the present invention, and FIG. The figure is a schematic side view showing a state in which a three-dimensional optical waveguide type optical wavelength conversion element manufactured by the method of the present invention is used. 10... DMNP thin film 10A... Optical waveguide 11
...Substrate 11a...Substrate surface 11b.
...Substrate groove 12...DMNP12°...D
MNP steam 12″...DMNP cluster 15...
Fundamental wave 15°...Second harmonic 20...Airtight container 21...Crucible 22...Heating filament 23...Ionization filament

Claims (1)

[Claims] The method is characterized by forming grooves on the surface of a substrate, irradiating the substrate surface with an ion cluster beam of an organic material, and depositing and growing a single crystal of the organic material in the grooves. A method for manufacturing an organic single crystal optical waveguide.