JPH02250043A - Optical wavelength converting element - Google Patents

Abstract

PURPOSE:To prevent sublimation or reforming as direct contact with air, etc., is averted by using an org. nonlinear optical material, and providing shielding layers which shut off the end faces of the element including the end faces of this material and an ambient temp. atmosphere on these end faces. CONSTITUTION:The org. nonlinear optical material having high wavelength conversion efficiency is used as the org. nonlinear optical material of an optical fiber formed by packing a core 11 consisting of the org. nonlinear optical material into the hollow part at the center of a clad 12. For example, the core 11 is formed of MNA(2-methyl-4-nitroaniline). The shielding layers 13a, 13b are respectively formed on the element end faces 20a, 20b inclusive of the end face of the core 11 consisting of this MNA. The reflection of basic waves 15 on the element end faces decreases and the incident efficiency of the basic waves 15 are enhanced if the shielding layers are previously formed of the material having the refractive index lower than the refractive index of the materials of the core 11 and the clad 12. The direct contact of the core 11 consisting of the MNA which is the org. material with the atmosphere, such as air is averted and, therefore, the sublimation and reforming of the core 11 are prevented.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is an optical wavelength conversion element that converts a fundamental wave into a second harmonic of half the wavelength thereof, particularly an optical wavelength conversion element that uses an organic nonlinear optical material. The present invention relates to an optical wavelength conversion element.

(Prior Art) Various attempts have been made to convert the wavelength of laser light (shorten the wavelength) by utilizing second harmonic generation 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,
A so-called fiber type has been proposed. This optical wavelength conversion element is an optical fiber whose cladding is filled with a core made of a nonlinear optical material, and is published in Journal of the Micro-Optics Research Group of the Japan Society of Applied Physics, Vol. 3. Na3
．． An example is shown on p28-B2. Since this fiber-type optical wavelength conversion element can easily achieve phase matching between the fundamental wave and the second harmonic, research on this fiber-type optical wavelength conversion element has been actively conducted recently. . In addition, for example, the patent application filed in 1983 by the present applicant
159292 and 61-159293, a leading waveguide type optical wavelength conversion element in which an optical waveguide made of a nonlinear optical material is formed between two substrates serving as a cladding layer is also known. There is. This guided waveguide type optical wavelength conversion element also has the above-mentioned features.

Incidentally, in recent years, various proposals have been made to use single-crystal organic nonlinear optical materials as nonlinear optical materials in these fiber type and optical waveguide type optical wavelength conversion elements.

Since this organic nonlinear optical material has an extremely large nonlinear optical constant compared to inorganic materials, it is possible to obtain high wavelength conversion efficiency by using this organic nonlinear optical material. As this organic nonlinear optical material, for example, Japanese Patent Application Laid-open No. 60-250334 and "Nonlner 0pt
icalPropertles o('Orga
nic and Polymeric Mate
rtals'Acs SYMPO8IUM 5ER
IES 223. Davld J, Willi
ams edition (Aserian Chemical 5o
``Organic Nonlinear Optical Materials,'' edited by Masao Kato and He Nakanishi (CMC Publishing Co., Ltd., 1983).
MNA (2-methyl-4-
nitroaniline), mNA (metanitroaniline)
, POM (3-methyl-4-nitroviridine-1-oxide), urea, and also patent application filed in 1982 by the applicant.
3,5-dimethyl-1 shown in specification No.-53884
-(4-nitrophenyl)pyrazole, 3.5-dimethyl-1-(4-nitrophenyl)-1,2゜4-triazole, 2-ethyl-1-(4-nitrophenyl)imidazole, 1-(4 -nitrophenyl)virol, 2-
Dimethylamino 1-5 nitroacetanilide, 5-nitro-21x'O'J dinoacetanilide, 3-methyl-
Examples include 4-nitropyridine-N-oxide. For example, MNA is LiNbO3, which is an inorganic nonlinear optical material.
It has a wavelength conversion efficiency that is about 2000 times higher than that of organic nonlinear optical materials, 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 that can be used on a boat. By generating the second harmonic as a wave, it is also possible to obtain short wavelength laser light in the blue region.

(Problems to be Solved by the Invention) However, in fiber-type or leading waveguide-type optical wavelength conversion elements obtained by constructing the core of an optical fiber or optical waveguide using the above-mentioned organic nonlinear optical material, conventional It has been recognized that the wavelength conversion efficiency and fundamental wave incident coupling efficiency deteriorate significantly over time.

In other words, the organic nonlinear optical material constituting the optical wavelength conversion element comes into contact with the surrounding air or other atmosphere at its end face, so it sublimes from this part, shortening the single crystal part, or metamorphoses and ceases to be a single crystal. This results in the above-mentioned problem.

Therefore, an object of the present invention is to provide an optical wavelength conversion element that can solve the above problems.

(Means and effects for solving the problem) The optical wavelength conversion element of the present invention is a fiber type or optical waveguide type optical wavelength conversion element using an organic nonlinear optical material as described above. The device is characterized in that a blocking layer is provided on the element end face including the end face of the material to isolate the end face from the surrounding atmosphere.

If the above-mentioned blocking layer is provided, the end face of the organic nonlinear optical material will not be in direct contact with the atmosphere such as air, so that the above-mentioned sublimation or metamorphosis can be prevented.

Furthermore, if the blocking layer on the end face of the element from which the second harmonic is emitted is a filter layer that allows the second harmonic to pass through but absorbs the fundamental wave, it is possible to separate the second harmonic from the fundamental wave. This is preferable because it eliminates the need for a conversion element and a separate filter, and the optical wavelength conversion device can be miniaturized.

Further, the above-mentioned blocking layer may be a thin coated layer, or may be a cap-like structure fitted and fixed to the end of the element.

A barrier layer made of such a cap-like structure is advantageous in that there is no problem of peeling, so the end face is more reliably isolated from the surrounding atmosphere, it is easy to create, and it can be used as an element holding part. be.

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

<First Example> FIGS. 1 and 2 show an optical wavelength conversion element 10 according to a first example of the present invention. This optical wavelength conversion element 1
0 is an optical fiber in which a core 11 made of a nonlinear optical material is filled in a hollow portion at the center of a cladding 12. As the nonlinear optical material, an organic nonlinear optical material with high wavelength conversion efficiency is used as described above. In this example, the core U is particularly formed of MNA. And an element end face 10 including the end face of the core 11 made of this MNA.
Blocking layers 13a and 13b are formed on a and 10b, respectively.

Here, as an example, a method for manufacturing the optical wavelength conversion element 10 will be described in the case where the core 11 is formed from the above-mentioned MNA, the cladding 12 is formed from Pyrex glass, and the blocking layers 13a and 13b are formed from polytrifluoroisopropyl methacrylate. First, a hollow glass fiber 12' which will become the cladding 12 is prepared. This glass fiber 12
For example, the outer diameter is about 100 μm and the diameter of the hollow part is about 2 to 10 μm. Then, as shown in FIG. 3, M N A 11' is kept in a melt state in a furnace or the like, and one end of the glass fiber 12° is immersed into this melt. Then, due to capillarity, MNAllo in a molten state enters the hollow portion of the glass fiber 12'. The temperature of the melt is M N A 11'
In order to prevent decomposition of , the temperature is slightly higher than its melting point (132°C). Then glass fiber 12°
When it was rapidly cooled, MNA 1, which had entered the hollow part,
1' becomes polycrystalline.

Furthermore, more preferably, this optical fiber 12° is M
By gradually drawing out the inside of the furnace, which is maintained at a temperature higher than the melting point of N A 11', to the outside of the furnace, which is maintained at a temperature lower than the melting point, MNA II' in a molten state is made into a single crystal from the part drawn out of the furnace. to become As a result, an extremely long core 11 in a single crystal state with a uniform crystal orientation is formed, and the optical wavelength conversion element 10 can be made sufficiently long.

As is well known, the wavelength conversion efficiency of this type of optical wavelength conversion element is proportional to the length of the element, so the longer the optical wavelength conversion element is, the higher its practical value becomes.

After the core 11 is filled as described above, polytrifluoroisopropyl methacrylate is applied to both end surfaces of the glass fiber 12', which has been cut at both ends, to form barrier layers 13a and 13b. The formation of the barrier layers 13a and 13b is performed by preparing a coating solution by dissolving, for example, 20 g of polytrifluoroisobrobyl methacrylate in methyl ethyl ketone 1z, immersing both ends of the fiber in this solution, and then drying. It is carried out by As a result, an optical wavelength conversion element 10 as shown in FIGS. 1 and 2 is obtained. Note that the blocking layers 13a, 13
b is formed to have a thickness of about 1 μm, for example.

The optical wavelength conversion element 10 is used as shown in FIG. That is, the fundamental wave 15 is the incident end face 1 of the element IO.
The light is input into the core 11 from 0a. For example, a Q-switched YAG laser (wavelength: 101
060n! 8 is used, and by irradiating the laser beam (fundamental wave) 15 focused by the objective lens 17 onto the element end face 10a of the core portion through the blocking layer 18a, the laser beam 15 is made incident into the optical wavelength conversion element 10. let The wavelength of this fundamental wave 15 is 1/1 by the MNA constituting the core 11.
2 is converted into the second harmonic 15″.This second harmonic 1
5' travels within the element 10 by repeating total reflection between the outer surfaces of the cladding 12. For example, the phase matching is based on the fundamental wave 1
The waveguide mode of the second harmonic wave 15' in the core section and the radiation mode of the second harmonic wave 15' to the cladding section (in the case of so-called Cerenkov radiation).

From the output end face tob of the optical wavelength conversion element IO, the second
A beam 15" containing a harmonic of 15° is emitted. This emitted beam 15" passes through the blocking layer 13b and is emitted outside the element, and is passed through a filter (not shown) to produce a second harmonic of 15°.
only those are taken out and used.

Here, a core 11, a cladding 12, a barrier layer 13a, 13
The refractive indexes nl, n2, and n3 of MNA, Pyrex glass, and polytrifluoroisopropyl methacrylate, which constitute b, respectively, will be explained. For example, the refractive indexes for the YAG laser having a wavelength of 11060 nm described above are as follows.

nl 1.496 n2 1,464 n3 1.41 (Here, the value of rJ-1,496 is the effective refractive index.) In this way, the material with a lower refractive index than the material of the core 11 and the cladding 12 If the blocking layer 13a is formed in
Compared to the case where the blocking layer 13a is not provided, the reflection of the fundamental wave 15 at the element end face is reduced, and the incidence efficiency of the fundamental wave 15 is increased.

If the above-described blocking layers 13a and 13b are provided, the core 11 made of MNA, which is an organic material, will not be in direct contact with the atmosphere such as air.
Sublimation and metamorphosis of The effect of preventing sublimation and metamorphosis will be specifically explained below.

The optical wavelength conversion element 10 of this embodiment described above and the blocking layer 1
The optical wavelength converting element 10 of this example and the optical wavelength converting element formed in exactly the same way as the optical wavelength converting element 10 of this example except that 3a and 13b were not formed were left in air at a temperature of 25° C. and a humidity of 10% for two weeks, and then the core 11 We investigated the changes in the end face.

In the optical wavelength conversion element in which the blocking layers 13a and 13b were not formed, sublimation or metamorphosis was observed within a length range of 10 μm from the core end surface, but the blocking layers 13a and 118b
In the optical wavelength conversion element 101 of this embodiment provided with
No changes were observed.

Further, a light wavelength conversion element having a core formed from the above-mentioned 3,5-dimethyl-1-(4nitrophenyl)pyrazole, 3,
5-dimethyl-1-(4-nitrophenyl)-1,2,
4-) The effect of the blocking layer on preventing sublimation or metamorphosis was also investigated under the same temperature and humidity conditions as above for the optical wavelength conversion element formed from lyazole. As a result, in the former case, sublimation or metamorphosis was observed in a length range of 40 μm from the core end face in the case where the barrier layer was not provided, whereas no change was observed in the case where the barrier layer was provided. Further, in the latter case, sublimation or metamorphosis was observed in a length range of 20 μm from the core end face in the case without the barrier layer, whereas no change was observed in the case in which the barrier layer was provided.

Second Embodiment> Next, a second embodiment of the present invention will be described. The optical wavelength conversion element of this second embodiment is different from that of the first embodiment only in the materials of the blocking layers 13a and 13b explained in FIG. It is formed similarly to the conversion element IO.

Therefore, the explanation will be given below using the numbers given in FIG. 1.2. In this embodiment, the barrier layer 13a113b is formed from trifluoroethyl acrylic acid polymer. Specifically, the blocking layer 13aS18b is formed by dissolving 20 g of trifluoroethyl acrylic acid polymer in methyl ethyl ketone 19J, and in particular, for the blocking layer 13b on the second harmonic emission side, 1 g of the dye represented by the following formula is also dissolved. The process involves preparing a coating liquid, applying these liquids to both end faces of the fiber, and then drying. As a result, the optical wavelength conversion element 10 as shown in FIGS. 1 and 2
is obtained. The blocking layers 13a and 13b are formed to have a thickness of, for example, several micrometers to several tens of micrometers.

The optical wavelength conversion element of the second embodiment thus formed is also used as shown in FIG. 2, similarly to the optical wavelength conversion element 1O of the first embodiment. That is, a beam 15'', which is a mixture of the second harmonic 15' and the fundamental wave 15, is emitted from the output end face 1 (lb) of the optical wavelength conversion element. This output beam 15'' is transmitted through the blocking layer 13b. Here, the molecular extinction coefficient ε of the dye contained in this blocking layer 13b is equal to the fundamental wave 1 with a wavelength of 11060n.
15000 for 5, second harmonic 1 with wavelength 530 nm
5' is 1500. Therefore, this blocking layer 13b acts as a filter that absorbs most of the fundamental wave 15, while effectively transmitting the second harmonic 15°, and only the second harmonic 15' is extracted and used by the several layers 13b. .

Here core 11. Cladding 12, barrier layers 13a, 13
Each refractive index nl of MNA, Pyrex glass, and trifluoroethyl acrylic acid polymer constituting b, respectively,
nZ s n3 will be explained. For example, the wavelength 1 mentioned above
Each refractive index for a 1060n YAG laser is as follows.

nl i, 496 n2 1.464 n3 1.407 (Here, the value of nl-1,496 is the effective refractive index.) Also in this case, a material with a lower refractive index than the material of the core 11 and the cladding 12 is used. Since the blocking layer 13a is formed, the reflection of the fundamental wave 15 at the element end face is reduced compared to the case where the blocking layer 13a is not provided, and the incidence efficiency of the fundamental wave 15 is increased.

In this case as well, the provision of the blocking layers 13a and tab prevents the core 11 made of MNA, which is an organic material, from coming into direct contact with the atmosphere such as air, thereby preventing sublimation and metamorphosis of the core 11. The effect of preventing sublimation and metamorphosis will be specifically explained below.

The optical wavelength conversion element of the second embodiment described above and the blocking layer 13
An optical wavelength conversion element formed in exactly the same manner as the optical wavelength conversion element of this example except that the elements a and 13b were not formed was left in air at a temperature of 25° C. and a humidity of 10% for two weeks, and then the core 11 was removed. Changes in the end face were investigated. Barrier layer 13a, llb
In the optical wavelength conversion element that does not have the blocking layer 13a, sublimation or metamorphosis was observed within a length range of 10 μm from the core end surface.

In the optical wavelength conversion element of this example provided with 13b,
No changes were observed.

Also, an optical wavelength conversion element whose core is formed from the above-mentioned 3,5-dimethyl-1-(4nitrophenyl)pyrazole; 3.
5-dimethyl-1-(4-nitrophenyl)-1,2,
4-) The effect of the blocking layer on preventing sublimation or metamorphosis was also investigated under the same temperature and humidity conditions as above for the optical wavelength conversion element formed from lyazole. As a result, in the former case, sublimation or metamorphosis was observed in a length range of 40 μm from the core end face in the case where the barrier layer was not provided, whereas no change was observed in the case where the barrier layer was provided. Further, in the latter case, sublimation or metamorphosis was observed in a length range of 20 μm from the core end face in the case without the barrier layer, whereas no change was observed in the case in which the barrier layer was provided.

Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIG. The optical wavelength conversion element 20 shown in FIG. 4 is of an optical waveguide type, and a leading waveguide 21 is formed by filling an organic nonlinear optical material between two glass substrates 22 and 22 that serve as cladding layers. It has a built-in structure. A blocking layer 23 is formed on the element end face 2Oa, which is the light incident end face. These optical waveguides 21. The substrate 22 and the blocking layer 23 can be formed from, for example, the aforementioned MNA, Pyrex glass, or polytrifluoroisopropyl methacrylate, and the filling of MNA between the substrates 22 and 22 and the formation of the blocking layer 23 are basically the same. This is carried out by the method described in the first embodiment.

The method of forming an optical waveguide by filling the space between the substrates 22 and 22 with an organic nonlinear optical material is described, for example, in Japanese Patent Application No. 159292/1983 and No. 61-61 filed by the present applicant.
A detailed description is given in the specification of No. 159293.

In addition, the upper surface of the glass substrate 22 (the optical waveguide 2
1), there is a focusing grating for emitting the second harmonic.
upler (hereinafter referred to as FGC) 25 is formed.

Hereinafter, the operation of the optical wavelength conversion element 20 of the third embodiment having the above configuration will be explained. For example, the YAG laser-16 mentioned above
is used as a fundamental wave generating means, and the laser beam (fundamental wave) 15 focused by the collimator lens 26 is irradiated onto the element end face 20a through the blocking layer 23, thereby generating the laser beam 1.
5 can be made incident into the optical waveguide 21. A second harmonic is generated from the laser beam 15 as the fundamental wave, and a light beam 15' containing the second harmonic is emitted from the FGC 25 on the substrate 22 and focused on one point.

Also in the optical wavelength conversion element 20 of the third embodiment, since the blocking layer 23 is formed on the element end face 20a including the end face of the optical waveguide 21, the blocking layer 13a is formed in the optical wavelength conversion element IO of the first embodiment. It is possible to obtain the same effects as those obtained by providing this.

In the above embodiment, the blocking layer 23 is formed only on the element end face 20a, which is the fundamental wave incident end face, but other element end faces 20b, 20c where the fundamental wave does not enter or the second harmonic does not exit. A blocking layer may also be provided in order to prevent metamorphosis of the leading waveguide 21 made of an organic nonlinear optical material.

Furthermore, in the embodiment described above, the fundamental wave is made to enter the element from the element end face 20a, but the inner surface of the glass substrate 22 (the surface on the optical waveguide 21 side) is provided with the above-mentioned condensing diffraction grating or linear Diffraction grating (Linear Grat)
ing coupler) may be provided, and the fundamental wave may be made to enter the optical waveguide 21 via this diffraction grating. Even when the fundamental wave is incident and the second harmonic is emitted through the diffraction grating, if a blocking layer is provided on the element end face, the organic nonlinear optical material will gradually sublimate or metamorphose from the end face side. This can be prevented.

Furthermore, even when input and output are performed at the end faces, the same effect can be achieved by providing a blocking layer on the element end faces including the input and output end faces.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIG. The optical wavelength conversion element 29 of this fourth embodiment is also of the guided waveguide type as in the third embodiment, and the optical wavelength conversion element 29 serves as a cladding layer.
It has a structure in which an optical waveguide 21 is formed by filling an organic nonlinear optical material between two glass substrates 22 and 22. Blocking layers 23a and 23b are formed on the element end face 2Oa, which is the light input end face, and on the element end face 20b, which is the light output end face, respectively. These optical waveguides 21. The substrate 22 can be formed from, for example, the aforementioned MNA or Pyrex glass, and the substrate 2
2.Filling MNA between 22 and blocking layer 23a,
23b can also be basically formed by the method described in Embodiments 1.2 and 3. In this example, a coating solution was prepared by dissolving pentafluoropropyl acrylic acid polymer log in methylene chloride IQJ, and especially for the blocking layer 23b, 0.1 g of a dye represented by the following formula was also dissolved. The blocking layers 23a, 23b are formed by applying the liquid onto the element end faces 20a, 2Ob and drying it.

The operation of the optical wavelength conversion element 29 of the fourth embodiment having the above configuration will be explained below. For example, by using the semiconductor laser 27 as a fundamental wave generating means and irradiating a laser beam (fundamental wave) 25 with a wavelength of 840 nm focused by a collimator lens 26 onto the element end face 20a through the blocking layer 23a, the laser beam 25 is optically guided. It can be made to enter the wave path 21. Note that the wavelength 84 of the pentafluoropropyl acrylic acid polymer constituting the blocking layers 23a and 23b is
The refractive index for light of 0 nm is 1.385. A second harmonic is generated from the laser beam 25 as the fundamental wave, and a light beam 15'' containing this second harmonic is transmitted to the element end face 25.
It emits from b. A blocking layer 23b on this element end face 20b
The molecular extinction coefficient ε of the above-mentioned dye contained in
200000 for the fundamental wave 25 of 40 nm, wavelength 42
15000 for the second harmonic of 0 nm. Therefore, while the fundamental wave 25 is almost absorbed by the blocking layer 23b, its second harmonic is well transmitted through the blocking layer 23b, so that only the second harmonic is transmitted from the optical wavelength conversion element 29. taken out.

Also in the optical wavelength conversion element 29 of this fourth embodiment, the element end face 20a includes the end face of the optical waveguide 22.

Since the blocking layers 23a and 23b are formed on the waveguide 20b, the leading waveguide 21 is
It has the effect of preventing metamorphosis and sublimation.

In the optical wavelength conversion element of the above example, the blocking layer provided on the second harmonic output end face is a filter layer,
Since it is possible to extract only the second harmonic, using this element will make the optical wavelength conversion device smaller compared to the case where a separate filter is provided to separate the second harmonic and the fundamental wave. be able to. This also applies to the second embodiment described above.

Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIG. The optical wavelength conversion element 30 of this fifth embodiment is basically formed in the same manner as the optical wavelength conversion element 10 of the first embodiment. However, the blocking layer 33 on the side of the fundamental wave incident end face 30a
The lens a has a curved surface and is formed to double as a condenser lens. By configuring the optical wavelength conversion element 30 in this manner, there is no need to separately provide a condenser lens, so that it is possible to downsize and simplify the optical wavelength conversion device.

In this case, as in the second or fourth embodiment, the blocking layer 33b on the second harmonic output end face side may be formed as a filter layer that transmits the second harmonic while absorbing the fundamental wave. .

<Sixth Embodiment> Next, a sixth embodiment of the present invention will be described with reference to FIGS. 7 and 8. The optical wavelength conversion element 40 of this sixth embodiment is basically an optical fiber type like the optical wavelength conversion element 10 of the first embodiment, and a core 41 is filled in the hollow part at the center of the cladding 42. It becomes. In this example, the core 41 is made of a nonlinear optical material shown by the following molecular formula (3,5-dimethyl-1-(4-nitrophenyl) pyrazole, hereinafter referred to as PRA) in a single crystal state. are doing. This PRA is explained in detail in Japanese Patent Application No. 1988-53884 filed by the applicant of the present application. Further, in this example, the cladding 42 is made of 5F1o glass. An optical fiber including a cladding 42 and a core 41 made of such materials is, for example, a first
It can be formed as described in the embodiments.

Then, it is brought into close contact with the element end face 40a on the fundamental wave incident side and the element end face 40b on the second harmonic output side, respectively.
Cap-like structures 43a and 43b are attached. Each of these cap-like structures 43a143b has a cylindrical recess in the center, and a peripheral portion of the recess is fitted to one end of the fiber to be fixed to the fiber. In this example, these cap-like structures 43
43a and 43b are made of PMMA (polymethyl methacrylate), and the inner peripheral surfaces of the four parts are closely adhered to the outer peripheral surface of the element near the element end faces 40a and 40b using adhesives 44a and 44b such as epoxy or polyurethane adhesives. .

The above-mentioned cap-like structures 43a and 4:(b also act as a blocking layer that blocks the element end faces 40a and 40b from the surrounding atmosphere, so that the same effects as in each of the embodiments described above can be obtained.

In this example, PRA, 5FIO glass,
Core 41 made of PMMA. The refractive indices n1, nz, and n3 of the cladding 42 and the cap-like structure (blocking layer) 43a are as follows:
For example, the following applies to a YAG laser with a wavelength of 11064n.

nl 1.77 nz 1.67 n3 1.48 Also in this case, since the blocking layer 43a has a lower refractive index than the core 41 and the cladding 42, the fundamental wave element is smaller than the case where the blocking layer 43a is not provided. Reflection at the end face is reduced, and the incidence efficiency of the fundamental wave is increased.

Since the cap-like structures 43a and 43b described above can be easily molded using a known method, when producing a large amount of light wavelength conversion elements with a blocking layer, it is better to apply a solution to the end face of the element and dry it. It is preferable because it has good workability and can be easily attached to the element.

In addition, the end of the cladding 42 is made into a tapered shape,
On the other hand, it is preferable to make the concave portions of the cap-like structures 43a and 43b into a tapered shape, since this makes it easier to attach the cap-like structures 43a and 43b. Note that if the outer circumferential surface of the clad 42 is scratched when the cap-like structures 43a, 43b are fitted into the clad 42, the second harmonic will be scattered at that portion. In order to prevent such a thing, for example, the applicant's patent application No. 62-3
As shown in the No. 2914 specification, it is desirable to use an optical fiber device in which a second cladding is further formed on the outside of a cladding filled with a core.

If the second cladding as described above is not formed,
A cladding 4 is used to hold the optical wavelength conversion element 40 on something.
If a holder is attached directly to 2, it will be scratched and the second harmonic will be scattered at that part. However, when using the optical wavelength conversion element 40 of this embodiment, the cap-like structures 43a and 43b can be used as parts held by the element holder, and in this way, the above-mentioned problem can be prevented from occurring. .

Seventh Embodiment> Next, a seventh embodiment of the present invention will be described with reference to FIG. Core 51 of the optical wavelength conversion element 50 of this seventh embodiment
．． The cladding 52 is the same as in the sixth embodiment, and cap-like structures 53a, 53b as barrier layers are included.
The cap-like structures 43a and 43b of the sixth embodiment are also made of the same material. However, in this embodiment, the cap-like structures 53a and 53b are formed sufficiently long,
It covers the entire cladding 52. With such a configuration, damage to the cladding 52 can be more reliably prevented. In FIG. 9, 50a and 150b are element end faces, and 54 is an adhesive.

Even when the blocking layer is formed from a cap-like structure as described above, the cap-like structure attached to the end face side of the element from which the second harmonic is emitted can be used as a filter layer, or the cap-like structure can be used as a filter layer. It can be made into the shape of a lens having a light condensing effect, or it can be made into a shape that fits into the end of the optical waveguide element as shown in FIGS. 4 and 5.

The blocking layer formed on the end face of the element is made of the aforementioned polytrifluoroisopropyl methacrylate, trifluoroethyl acrylic acid polymer, or PMMA, as well as melamine, polyester, acrylic, silicone, epoxy, vinyl chloride, polyethylene, polypropylene, or polyamide. , a resin material such as acetyl cellulose, various glasses including quartz glass, and even transparent oxide crystals such as AQ1203.

Furthermore, in the optical wavelength conversion element of the above embodiment, phase matching is achieved between the waveguide mode of the fundamental wave in the core portion and the radiation mode of the second harmonic wave to the cladding portion. The invention is also applicable to a type of element in which both the fundamental wave and the second harmonic are guided in a core portion or an optical waveguide, and phase matching is achieved between the guided modes of both.

(Effects of the Invention) As explained in detail above, in the optical wavelength conversion element of the present invention, sublimation or metamorphosis of the organic nonlinear optical material is ensured by providing a blocking layer on the end face of the element including the end face of the organic nonlinear optical material. is prevented. Therefore, it is possible to prevent the wavelength conversion efficiency of the organic nonlinear optical material from decreasing, and when the end face provided with the blocking layer is used as the fundamental wave incident end face,
The incident coupling efficiency of the fundamental wave can also be maintained high. Furthermore, when a blocking layer is provided on the output end face, reflection can be reduced and the output efficiency of the second harmonic can be increased.

[Brief explanation of drawings]

1 and 2 are respectively a perspective view and a schematic side view showing an optical wavelength conversion element according to a first embodiment of the present invention; FIG. 3 is a schematic diagram illustrating a method of manufacturing the optical wavelength conversion element; 4 and 5 show the third and fourth embodiments of the present invention, respectively.
6 is a schematic side view showing an optical wavelength conversion element according to a fifth embodiment of the present invention; FIGS. 7 and 8 are respectively a schematic perspective view showing an optical wavelength conversion element according to a fifth embodiment of the present invention. A perspective view and a side sectional view showing an optical wavelength conversion element according to an embodiment, and FIG. 9 is a side sectional view showing an optical wavelength conversion element according to a seventh embodiment of the present invention. 10.20.29.30.40.50... Optical wavelength conversion element 10a, 10b, 20as 20b, 20c, 3
oas 30b, 4Gms 40b, 50g, 50
b-...Element end face 11, 41.51...Core 1
2.42.52...Clad 13a, 13b, 2
3.31a, 38b-blocking layer 15...fundamental wave
15°...Second harmonic 21...Optical waveguide
22...Glass substrates 43a, 41b, 51
a, 53b-...ki+''/tub-shaped structure 44a, 4
4b, 54-...Adhesive 1 tfi 5 B Figure Figure Figure Figure Figure

Claims (7)

[Claims] (1) An optical wavelength conversion element in which an organic nonlinear optical material is covered with a cladding layer having a lower refractive index than the organic nonlinear optical material, and which converts an incident fundamental wave into a second harmonic and outputs the second harmonic, the organic nonlinear optical material An optical wavelength conversion element characterized in that a blocking layer is provided on an end face of the element including an end face of the element to isolate the end face from the surrounding atmosphere. (2) One of the two opposing end faces of the element end faces is a fundamental wave input end face, and the other is a second harmonic output end face. optical wavelength conversion element. (3) The optical wavelength conversion element according to claim 2, wherein at least one of the two blocking layers formed on the end face of the element is a condenser lens. (4) Of the blocking layers, the blocking layer on the fundamental wave incident end face side is
Claim 1 characterized in that it is formed from a material with a lower refractive index than the nonlinear optical material, and the blocking layer on the side of the second harmonic output end face is formed from a material with a lower refractive index than the cladding material. 3. The optical wavelength conversion element according to any one of Items 3 to 3. (5) Among the blocking layers, the blocking layer provided on the end face of the element from which the second harmonic is emitted is a filter layer that transmits the second harmonic while absorbing the fundamental wave. Any one of claims 1 to 4
The optical wavelength conversion element described in . (6) The optical wavelength conversion device according to any one of claims 1 to 5, wherein the blocking layer is made of a cap-like structure fitted to an end of the device. (7) The optical wavelength conversion element according to claim 6, wherein the cap-like structure is formed to cover the entire cladding layer.