JPH04128804A - Production of optical waveguide element - Google Patents

Abstract

PURPOSE:To prevent the peeling of a part consisting of an org. material by substituting the end of the part consisting of the ord. material with a resin, then polishing the end face of the element including the part substd. with this resin by using a polishing liquid. CONSTITUTION:A glass fiber 12' generated with a hole 5 on the unprotected end side is immersed in an epoxy adhesive 7 at the end face on the hole 5 side in a hermetic vessel 6 in which a vacuum state is maintained. The epoxy adhesive 7 advances into the hole 5 when the atm. state is restored in the hermetic vessel 6. After the excess adhesive 7 at the end face is wiped away, the fiber is rested for 24 hours at room temp. and the packed epoxy adhesive 7 solidifies. The end face 10b of the glass fiber 12' is thereafter polished to the surface accuracy to the extent of allowing an optical contact. The optical plane plate 13 made of SF 10 glass formed to a disk shape of nearly the same diameter as the diameter of the glass fiber 12' is brought into tight contact with the end face in such a manner as to avoid the intrusion of foreign matter, such as dust, moisture and air, therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing an optical waveguide element having a portion made of an organic material. The present invention relates to a method for manufacturing an optical waveguide element that can prevent a portion from separating from an adjacent portion.

(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. A so-called fiber type device has been proposed as one type of optical wavelength conversion device that performs wavelength conversion in this manner. 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 Vol. 3, Journal of the Micro-Optics Research Group of the Society of Applied Physics. No, 2. An example is shown on pages 28-32. 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. .

Also, for example, JP-A-63-15233, JP-A No. 6B-15
As shown in Japanese Patent No. 234, an optical waveguide type optical wavelength conversion element is also known in which an optical waveguide made of a nonlinear optical material is formed between two substrates serving as cladding layers. Furthermore, a three-dimensional optical waveguide-type optical wavelength conversion element is also known in which a three-dimensional optical waveguide made of a nonlinear optical material is embedded in a glass substrate and emits a wavelength-converted wave into the glass substrate. These optical waveguide type optical wavelength conversion elements also have the above-mentioned features.

Further, in Japanese Patent Laid-Open No. 1-244433, it is described in detail that the sum frequency and the difference frequency are similarly generated by a fiber type wavelength conversion element. Regarding generation of sum-difference frequency in a waveguide type optical wavelength conversion element, Japanese Patent Application Laid-Open No.
It is described in detail in Japanese Patent No. 244434. Furthermore, third harmonic generation using third-order nonlinearity is also fully possible.

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, "Nonliner 0p
ticalProperties of Orga
nic and PolyIIlericMate
reals' AC3SYMPO5IUM 5ERI
ES223. David J, Willian
s edition (American Chemical 5oci
ety, 1983) "Organic Nonlinear Optical Materials" Masao Kato, Supervised by He Nakanishi (CMC, 1985)
Annual), “Non1inear Optical
Properties or OrganicMole
cules and crystals-D,
Edited by S, Chemla and J, Zyss (Acad
emic Press Inc.

(published in 1987), “The Quality and Perf'o” by R.T., Balley et al.
rmance orTheOrganic Non-
Linear 0ptical Mat8ria+(
-) 2- (a -Methylbenzyla
IIIino) -5-N1tropyridine
(MBA-NP) ” (Optics Cowmu
nications, Vol. 65. No.3
MNA (2-methyl-4-nitroaniline), mNA (methanitroaniline), POM (3-methyl-4-nitropyridine-1-oxide), urea, NPP [N-(4 -nitrophenyl)-(S)-prolinol], NPAN
(2-[N-(4-nitrophenyl)-N-methylaminocoacetonitrile, DAN (2-dimethylamino-5-nitroacetanilide), MBA-NP[2
-N, (α-methylbenzylamino)-5-nitropyridine and 3,5-dimethyl-1-(4-nitrophenyl)pyrazole [hereinafter referred to as DMNP] shown in JP-A-62-210432. , 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, 3-methyl-4
-nitropyridine-N-oxide and the like.

(Problems to be Solved by the Invention) By the way, in a fiber-type or optical waveguide-type optical wavelength conversion element obtained by constructing an optical fiber core or an optical waveguide using the above-mentioned organic nonlinear optical material, generally, In order not to disturb the output wavefront of the wavelength-converted wave, and furthermore to ensure high incidence efficiency of the fundamental wave and output efficiency of the wavelength-converted wave, it is necessary to polish the element end face including the end face of the waveguide. This polishing is often performed using a polishing liquid containing water in order to finish the end face of the element into a so-called mirror finish.

However, in conventional fiber-type or optical waveguide-type optical wavelength conversion elements, when the end face is polished using a polishing liquid as described above, the waveguide made of organic nonlinear optical material tends to peel off from the cladding. It was recognized that there was a problem.

The problems with optical wavelength conversion elements have been explained above, but the problem of peeling of the waveguide is not limited to optical wavelength conversion elements, but is widespread in optical waveguide elements (including optical fibers) whose waveguides are made of organic materials. It can happen.

Furthermore, not only the waveguide part but also optical waveguide elements in which the cladding part, protective layer, etc. are formed of organic materials, when polishing the element end face using a polishing liquid, the parts made of the organic material are adjacent to the cladding part and the protective layer. It may peel off from the skin. When the waveguide portion etc. are peeled off in this way, the propagation loss of the guided light increases and the performance of the optical waveguide device deteriorates.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing an optical waveguide element that can prevent the part made of an organic material from peeling off when polishing the end face of the element.

(Means for Solving the Problems) The first method for manufacturing an optical waveguide device according to the present invention is a method for manufacturing a fiber type, two-dimensional optical waveguide type, or three-dimensional optical waveguide type optical waveguide device, at least a part of which is formed from an organic material. When producing a waveguide element, the end of the part made of the organic material is replaced with a resin, and then the end face of the element including the part replaced with the resin is polished using a polishing liquid. It is.

In addition, in the second method for manufacturing an optical waveguide device according to the present invention, instead of performing the above-mentioned replacement, the end portion of the portion made of an organic material is made to be compatible with the resin, and then the portion made of the organic material is made to be compatible with the resin. The device is characterized by polishing the end face of the element including the polishing liquid using a polishing liquid.

(Function) According to research conducted by the present inventors, the above-mentioned peeling of the portion made of an organic material occurs when the polishing liquid is applied to the portion made of the organic material and the portion adjacent thereto when polishing the end face of the element using a polishing liquid. It was found that this phenomenon occurs because the particles penetrate into the interface between the two and the adhesion of this interface decreases.

Therefore, if the end portion of the portion made of this organic material is replaced with a resin or made compatible with the resin, the adhesion of the above-mentioned interface portion at this end portion will be improved. Therefore, even if the element end face including the part replaced with this resin or the part dissolved with the resin is polished using a polishing liquid,
The part made of organic material will not easily peel off.

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

FIGS. 1 and 2 show an optical wavelength conversion device 10, which is an example of an optical waveguide device manufactured by the method of the present invention. This optical wavelength conversion element 10 is an optical fiber in which a core 11 made of a nonlinear optical material is filled in a hollow part 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 11 is particularly formed of the above-mentioned DMNP. And on the element end face 10a including the end face of the core 11 made of DMNP, LOb! , two are an end face protection film 14 and an optical flat plate 13, respectively.
is covered.

where - by way of example, core 11 is the above-mentioned DMNP.

The method for manufacturing the optical wavelength conversion element 10 will be described in the case where the cladding 12 and the plane plate 13 are formed from 5FIO glass.

First, the hollow glass fiber 12° that becomes the cladding 12
will be prepared. For example, this glass fiber 12° has an outer diameter of 1 mm and a hollow portion diameter of about 1.2 μm. Then, as shown in FIG. 3, the DMNPIIo is kept in a molten state in a furnace or the like, and one end of the glass fiber 12' is penetrated into this melt. Then, DMNPII' in a molten state enters the hollow part of the glass fiber 12' due to capillarity. Note that the temperature of the melt is slightly higher than the melting point (102° C.) of DMNPIIo in order to prevent decomposition of DMNPIIo. Thereafter, when the glass fiber 12' is rapidly cooled, the DMNPII' that has entered the hollow portion becomes polycrystalline.

Next, this glass fiber 12' was coated with DMNP11.
DMNPII'' in a molten state is drawn out of the furnace by gradually drawing it from the inside of the furnace maintained at a temperature higher than the melting point (for example, 102.5°C) to the outside of the furnace maintained at a temperature lower than the melting point. Single crystallize the parts.

Thereafter, the glass fiber 12° is taken out, its both end faces are appropriately cut, and a protective film is attached to one end.

Next, this glass fiber 12゛ is heated in a vacuum.
left alone. Then, the unprotected end of DMNP IIo in a single crystal state sublimates. In this embodiment, the sublimation length is, for example, about 1 mm.

The glass fiber 12' with holes 5 formed at its unprotected end in this way is then placed in a sealed container 6 in a vacuum state, as shown in FIG. immersed in adhesive 7. Next, when the inside of the closed container 6 is returned to the atmospheric pressure state, the epoxy adhesive 7 enters into the holes 5.

Next, after the excess adhesive 7 on the end face of the glass fiber 12' is wiped off, it is left at room temperature for 24 hours, during which time the filled epoxy adhesive 7 solidifies (as shown in Figure 5). ).

Thereafter, the end face 10b of the glass fiber 12° is polished to a surface precision that allows optical contact.

This surface accuracy is, for example, a maximum surface roughness equal to or less than λ/10 (λ is the wavelength of incident light). This polishing includes, for example, a roughening/sanding process using a polishing solution containing alumina #800 as an abrasive grain, a polishing solution containing alumina #1500 as an abrasive grain, a polishing solution containing cerium oxide as an abrasive grain, and a polishing solution containing zirconium oxide as an abrasive grain. A polishing process using a polishing liquid containing as abrasive grains.

The polishing process using such a polishing liquid is described in detail in, for example, the Optical Technology Handbook and the Glass Handbook (both published by Asakura Shoten).
Such known polishing methods can be used as appropriate.

Incidentally, the polished shape obtained by the above-mentioned roughening and sanding process is about 500 to 800 μm in total, while the polished shape obtained by the polishing step is about 20 to 50 μm in total.

The total polished shape obtained by both of the above steps is made shorter than the length of the epoxy adhesive 7 filled in the holes 5.

This epoxy adhesive 7 bonds to the glass fiber 12' more strongly than DMNP II', so even if polishing is performed while applying polishing liquid to this part as described above, this epoxy adhesive 7 forming the core will not bond to the glass fiber 12'. 7 will not easily peel off from the glass fiber 12°.

Next, the optical flat plate 13 made of 5FIO glass, which is formed into a disk shape with approximately the same diameter as the glass fiber 12, is polished as described above, while preventing foreign matter such as dust, moisture, and air from entering in between. the fiber. Then, the optical flat plate 13 is bonded to one end face of the fiber by van der Waalska. As described above, the first
．． A fiber type optical wavelength conversion element 1o as shown in FIG. 2 is obtained.

The optical wavelength conversion element 10 is used as shown in FIG. That is, a laser beam (fundamental wave) 15 which is a diverging beam emitted from a semiconductor laser (oscillation wavelength: 870 nm) 16 as a fundamental wave generating means is made into a parallel beam by a collimator lens 17, and further condensed by an objective lens 18. and converges into a small spot on the end face of the core 11 with the same diameter (about 1.2 μm in this example). Thereby, the laser beam 15 enters into the optical wavelength conversion element 10. This fundamental wave 15 is converted by the DMNP constituting the core 11 into a second harmonic wave 15' having a wavelength of 1/2, that is, 435 nm. This second harmonic wave 15' is radiated into the cladding 12, undergoes repeated total reflection between the interface between the outer surface of the cladding 12 and the surrounding medium (usually air), and travels inside the element 10 toward the end face side. Phase matching is
The waveguide mode in the core part of the fundamental wave 15 and the second harmonic 15
(in the case of so-called Cerenkov radiation).

From the output end face 10b of the optical wavelength conversion element 10, the second
A beam 15'' containing a harmonic 15' is emitted. This emitted beam 15'' is passed through a filter (not shown), and a second
Only the 15° harmonic is extracted and used.

Here, in this optical wavelength conversion element 10, since the element end face 10b is polished as described above, the generated second harmonic 15' is emitted without the wavefront being disturbed, and finally a good This makes it possible to obtain a focused light spot.

In the above embodiment, the optical plane plate 13 is attached to the element end face lOb, but even if such an optical plane plate 13 is not provided, in order not to disturb the output wavefront of the wavelength-converted wave, The end face of the element is generally polished;
Even in such a case, the present invention is applicable and produces the above-mentioned effects.

Furthermore, the resin used in the present invention is not limited to epoxy resins, and may be appropriately selected and used depending on the material of the waveguide section and cladding section constituting the optical waveguide element. In particular, in optical wavelength conversion elements that allow wavelength-converted waves to propagate in a waveguide mode in a waveguide, the output end of the waveguide is covered with a resin that absorbs the fundamental wave but allows good transmission of the converted wavelength wave. You can also add a filter effect by replacing it.

Next, another method embodiment of the present invention will be described. In this example, DMN is placed within the glass fiber 12°.
The process of introducing PII' and crystallizing it into a single crystal is exactly the same as in the above embodiment, but the subsequent process up to the polishing of one end of the fiber is different from the above embodiment.

That is, the glass fiber 12'' in which DMNP single crystallization has been completed is appropriately cut at both end faces, and a protective film is attached to one end.Then, the remaining unprotected end face fob is roughened with sandpaper to shape it. It can be arranged.

Next, as shown in FIG. 6, one end surface of the glass fiber 12° is immersed in an epoxy adhesive 7 for about one hour, for example. By doing this, DMNP in a single crystal state
The ends of II' are compatible with the epoxy adhesive 7 over a length of approximately 100 μm, for example. Next, after the excess adhesive 7 on the end face of the glass fiber 12' is wiped off, it is left to stand at room temperature for 24 hours, during which time the above-mentioned compatible portions solidify.

Thereafter, the end face 10b of the glass fiber 12' is polished in the same manner as in the previous embodiment, but in this case, due to the action of the compatible epoxy adhesive 7, the DMNP II
Since the bonding force between ' and the glass fiber 12'' is increased, even if polishing is performed while applying a polishing liquid, the DMNP II' that constitutes the core will remain intact with the glass fiber 12''.
'It will not peel off easily.

The embodiments in which the present invention is applied to a fiber type optical wavelength conversion element have been described above, but the present invention is also applicable to other types of optical wavelength conversion elements consisting of a cladding part and a waveguide part, that is, a two-dimensional optical waveguide type. It is also possible to apply the present invention to an optical wavelength conversion element or a three-dimensional optical waveguide type optical wavelength conversion element.

Furthermore, the present invention is applicable not only to an optical wavelength conversion element that converts a fundamental wave into a second harmonic, but also to an optical wavelength conversion element that converts a fundamental wave into a sum frequency, a difference frequency, or even a third harmonic. is also applicable. Furthermore, the present invention is applicable to optical waveguide devices other than optical wavelength conversion devices.

Further, the present invention is not limited to an optical waveguide element in which the waveguide part is made of an organic material, but also an optical waveguide element in which the cladding part is made of an organic material, and furthermore, a layer (for example, a protective layer) laminated on the waveguide part is made of an organic material. It can also be applied to optical waveguide devices, etc., and in those cases as well, when polishing the end face of the device,
The effect of preventing peeling of the part made of organic material can be obtained.

(Effects of the Invention) As explained in detail above, in the method for manufacturing an optical waveguide element of the present invention, the end portion of a portion made of an organic material is replaced with a resin, or the end portion of a portion made of an organic material is made compatible with the resin, and then the end portion of the portion made of an organic material is Since the end face of the element is polished, the part made of the organic material will not easily peel off even if this polishing is performed using a polishing liquid.

Therefore, according to the present invention, it is possible to prevent an increase in the propagation loss of guided light due to the above-mentioned peeling, and to maintain high performance of the optical waveguide element. Therefore, especially when the present invention is applied to an optical wavelength conversion element, high wavelength conversion efficiency can be achieved.

[Brief explanation of the drawing]

1 and 2 are a perspective view and a schematic side view, respectively, showing an example of an optical waveguide device manufactured by the method of the present invention, and FIGS. 3.4 and 5 illustrate a method for manufacturing the optical waveguide device described above. FIG. 6 is a schematic diagram illustrating one step of another optical waveguide device manufacturing method of the present invention. 5...Vacancy 7...Epoxy adhesive 10...Light wavelength conversion element 10a, 10b...
Element end face 11...core 11'
...DMN PI3...Clad 1
2°...Glass fiber 13...Optical plane plate 15...Fundamental wave 15'...Second harmonic 4th Figure 6

Claims (2)

[Claims] (1) A method for manufacturing an optical waveguide element having an optical waveguide structure and at least a portion of which is formed from an organic material, the method comprising replacing the end portion of the portion made of the organic material with a resin, and then replacing with the resin. 1. A method for manufacturing an optical waveguide device, which comprises polishing an end face of the device including a polished portion using a polishing liquid. (2) A method for producing an optical waveguide element having an optical waveguide structure and at least a part of which is formed from an organic material, comprising dissolving the end portion of the portion made of the organic material with a resin, and then dissolving the resin. The element end face including the part that is compatible with
A method for manufacturing an optical waveguide device, which comprises polishing using a polishing liquid.