JP2002372603A - Optical part for optical communication and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical part satisfying conditions required for an optical element for optical communication and manufactured at a low cost and a method for manufacturing the same. SOLUTION: By using a lens array 1 with eight pieces of lenses (in two lines) manufactured with quartz glass (ϕ=30 mm) shown in (a) as a master, a die 2 is manufactured with Ni electroforming thereof (b). An ultraviolet curing resin 3 composed of 70 pts.wt. of acetal glycol diacrylate, 30 pts.wt. of at least one or more kinds of urethane acrylates and a suitable amount of an added photo-polymerization initiator is made to drip off on the die 2 (c). The resin layer is slowly pressed down with a sheet of plate glass 4 from above so as to make 1 mm resin layer thickness and, at the time of being uniformly stretched, is hardened by ultraviolet rays irradiation through the plate glass 4. After being hardened, the resin layer is released from the die 2 and is cut up into 4.2 mm×2 mm size. Thus, a collimator lens array 5 with a lens shape of 0.3103 mm curvature radius and 0.270 mm effective diameter is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical component for optical communication (in this specification, only an optical component which changes the traveling direction of light by refraction or reflection or causes a diffraction phenomenon).
Such a component that simply transmits light is not included in the category of “optical component”), and relates to a method of manufacturing the same.

[0002]

2. Description of the Related Art Inorganic optical materials such as glass and Si are used for optical parts for optical communication, and are produced by ion exchange, photothermal, ion beam etching, and reactive ion etching. . Optical components made of these materials have excellent near-infrared optical properties and excellent environmental resistance, but the manufacturing process is complicated, so the cost must be increased. In the future, with the spread of the high-speed technology "WDM" of the optical network, the demand for the cost reduction at the same time as the establishment of the mass production technology of the optical components used for the optical communication becomes inevitable.

Further, there is a strong demand for optical communication optical components to reduce the number of optical components for cost reduction. Therefore, it is desired that one optical component has different optical functions on one surface and the other surface.

As one of the productivity improving methods, a method of obtaining a surface shape having a predetermined optical surface shape by taking a replica using a resin can be considered.

[0005] However, resins having transparency in the near infrared region and environmental resistance (particularly heat resistance and hygroscopicity) used for optical communication have not been found so far. For example, typical resins such as PMMA (polymethyl methacrylate) and PC (polycarbonate), which are thermoplastic and excellent in transparency,
In addition, CR39, which is a thermosetting resin used for spectacle lenses, absorbs near infrared rays, has high hygroscopicity and low heat resistance, and cannot be used for optical communication.

[0006] As a resin that compensates for these drawbacks, there are a transparent fluororesin and an optical polyimide resin, but these resins undergo large shrinkage upon curing. There is only a track record as a film with a thickness of at most several tens of microns.

When optical surfaces are formed on surfaces facing each other, the optical axes of the optical surfaces formed on the respective surfaces must be shared.

[0008]

[Problems to be Solved by the Invention] There are the following properties that optical components for optical communication should have: high transmittance in the near-infrared region having a wavelength of 800 nm or more, when mounted on an optoelectronic printed circuit board; Withstands the soldering temperature (approximately 260 ° C) of printed circuit boards. When formed of resin, etc., has a low shrinkage rate during curing. Good shape stability when molded into tens of μm to several mm ( Low internal stress) Good environmental resistance (especially heat resistance and low moisture absorption) The present invention has been made in view of such circumstances,
It is an object of the present invention to provide an optical component for optical communication which satisfies the above conditions and can be manufactured at low cost.

When an optical component for optical communication having optical surfaces on one side and the other side is manufactured using a resin, an optical component formed on each side has a common optical axis. An object of the present invention is to provide a method for manufacturing a communication optical component.

[0010]

A first means for solving the above-mentioned problem is that the resin is a resin obtained by polymerizing acetal glycol diacrylate and at least one urethane acrylate, and is used exclusively in a wavelength range of 800 nm or more. An optical component for optical communication (claim 1).

Acetal glycol diacrylate is
It is a compound represented by the chemical structural formula 1, wherein the urethane acrylate is a polyfunctional urethane acrylate represented by the chemical structural formula 2, a polyfunctional urethane acrylate represented by the chemical structural formula 3, and a There are various types as represented by 7. In this means, the optical component for optical communication comprises a resin obtained by polymerizing acetal glycol diacrylate and at least one of these urethane acrylates. (Chemical structural formula 1)

[0012]

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(Chemical structural formula 2)

[0014]

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(Chemical structural formula 3)

[0016]

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(Chemical structural formula 4)

[0018]

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Chemical structural formula 5

[0020]

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Chemical formula 6

[0022]

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An acetal glycol diacrylate;
FIG. 1 shows an example of the internal transmittance of a resin obtained by polymerizing urethane acrylate at a thickness of 0.1 mm. According to FIG. 1, this resin has a viscosity of 9 nm from the visible region of 400 nm or more to the near infrared region.
Has a high internal transmittance of 5% or more. Heat deformation temperature is also 1
70 ° C. or higher, which is 30 to 50 ° C. higher than that of CR39 or polycarbonate having relatively high heat resistance among conventional transparent resins.

Further, as shown later, this resin
Even after passing through an atmosphere at a temperature of 1 ° C. twice, no change in the shape of the resin is observed, and the resin can sufficiently withstand high temperatures during soldering. This is probably because the molecular weight of acetal glycol diacrylate is relatively small, so that it has a structure capable of having extremely high heat resistance.

This resin has a specific gravity of about 0.8-1.3, a refractive index of about 0.8-1.3, by changing the kind and mixing ratio of the urethane acrylate, which is a mixture of two or more kinds of substances.
A product with a viscosity of about 1.4-1.8 and a viscosity of about 10-4,800 CPS (all at 25 ° C.) can be obtained. That is, the desired optical characteristics (refractive index, etc.) and viscosity can be changed by changing the mixing ratio of the polyfunctional urethane acrylate, so that the desired values for the optical components for optical communication can be obtained. The manufacture of optical components is facilitated.

It is preferable to add an appropriate amount of a known photopolymerization initiator to a mixture of acetal glycol diacrylate and urethane acrylate. For example, one selected from acetophenone-based, benzoin-based, thioxane-based, and acylphosphine oxide-based photopolymerization initiators may be used, or two or more may be used in combination.

The optical component according to the present invention is manufactured by electroforming a first mold by using a glass product produced by, for example, an ion exchange method, a photothermal method, an ion beam etching method or a reactive ion etching method as a master. And drop this resin on the mold and press a glass plate or glass mold formed by ion exchange, photothermal, ion beam or reactive ion etching from above. And by irradiating ultraviolet rays through a glass flat plate or mold to cure the resin.

By using this manufacturing method, a molded product having a thickness of several mm can be manufactured. In this method, once the mold is formed, the processing only requires a short time after molding. That is, it is possible to provide an inexpensive product as compared with a complicated process using a conventional photoresist.

In optical communication, high transmittance in the near infrared region is required. As described above, the resin composed of acetal glycol diacrylate and urethane acrylate has a high internal transmittance from the visible light region to the near infrared region, and is therefore particularly suitable for use as an optical element for optical communication.

[0030] A second means for solving the above-mentioned problem is as follows.
A resin obtained by polymerizing acetal glycol diacrylate and at least one urethane acrylate is formed on one or both surfaces of a flat substrate made of an inorganic material,
An optical component for optical communication characterized by being used exclusively in a wavelength range of 800 nm or more (claim 2).

In the case of the optical component of the first means, it is necessary to prepare a mold in consideration of the molding shrinkage of the resin in advance. The molding shrinkage of this resin is 2-10 depending on the molding method.
Change by a few percent. This means is to solve such a problem, and in order to reduce the molding shrinkage, an optical component is made of a composite of a flat substrate made of an inorganic material and a resin. is there. That is, a portion providing optical characteristics for changing the traveling direction of light is made of the resin, and a portion giving thickness and strength is made of a flat substrate made of an inorganic material.

Therefore, since the substrate made of the inorganic material may be a flat plate, no complicated processing is required. Also, since the thickness of the resin can be reduced, the molding shrinkage can be almost ignored. Therefore, a product almost in conformity with a model can be stably manufactured, and the manufacturing is facilitated. Note that glass is most preferably used as the inorganic material. In this case, it is preferable that the surface of the glass be treated with silane to improve the adhesion to the resin.

The urethane acrylate used in this means may be the same as that used in the first means, and it is preferable to add an appropriate amount of a photopolymerization initiator. This is the same as the first means.

In order to manufacture the optical component according to the present invention, for example, a glass product produced by an ion exchange method, a photothermal method, an ion beam etching method, a reactive ion etching method or the like is used as a master by electroforming. Make the first mold, drop this resin on the mold,
The resin layer is pressed down from above with a flat plate of glass to make the thickness of the resin layer at most 100 μm, and then cured by irradiating ultraviolet rays through the glass. In the case of an optical component having a flat surface on one side, a product is obtained by separating the optical component from the first mold as it is. In the case of an optical component having both curved surfaces, after curing one surface, the optical component is turned upside down without being separated from the first mold. Then, the resin is dropped on a glass mold (second mold) made by an ion exchange method, a photothermal method, an ion beam etching method, a reactive ion etching method, or the like, and the glass is turned upside down. Hold down to increase the thickness of the resin layer
After the thickness is reduced to 100 μm, the mixture is cured by irradiating ultraviolet rays through a glass mold. Finally, the two molds are peeled off.

The results of a solder heat resistance test performed on a replica of a fine concavo-convex pattern using this method are shown below. That is, a resin is dropped on a glass mold having a plurality of grooves having a predetermined depth and a predetermined width at a predetermined track pitch on the surface, and is held down by a flat glass substrate having a thickness of 1.1 mm. Was formed and irradiated with ultraviolet light through a glass substrate to be cured. Then, the glass mold was peeled off. Thereby, a composite optical member (diffraction grating) of glass and resin having a plurality of grooves on the surface was formed.
This was used as a sample.

Using a laboratory reflow furnace manufactured by Malcolm Co., Ltd., a thermocouple was attached to the sample surface, and heating was performed according to the temperature rise curve shown in FIG. The groove shape before and after heating was measured with diffracted light to examine the change, and the results shown in Table 1 were obtained. Heating was performed by exposing to an atmosphere of 260 ° C. for 1 minute. (Table 1)

[0037]

[Table 1]

From Table 1, it can be seen that the dimensional change after the first heating and the second heating is within the measurement error and is substantially zero. In other words, no change in the shape of the resin was observed even after passing through the atmosphere at 260 ° C. for 1 minute twice, and it was found that the resin could sufficiently withstand the high temperature during soldering.

A third means for solving the above-mentioned problem is as follows.
What is claimed is: 1. A method for manufacturing an optical component for optical communication, comprising forming a resin layer on a transparent substrate at a wavelength used, the optical component having an inverted shape to one surface shape of the manufactured optical component, and further having an alignment mark. When forming the resin layer on the substrate using a first mold and a second mold having an inverted shape with respect to the other surface shape of the manufactured optical component and further having an alignment mark, Forming the resin layer on the surface of the substrate by aligning the alignment marks of the first type and the alignment marks of the second type with each other. (Claim 3).

In this means, since the alignment mark is provided on the first mold and the alignment mark is provided by making the second mold transparent, the alignment mark of the first mold and the alignment mark of the second mold are combined. This makes it possible to easily align the resin molds formed on the front and back surfaces of the substrate. Therefore, the optical axes of the optical surfaces formed on both surfaces of the substrate can be easily matched, and the accuracy of the shape of the optical component for optical communication can be improved.

[0041]

(Example 1) A lens array was prepared by polymerizing a mixture of the acetal glycol diacrylate represented by the aforementioned chemical formula 1 and the urethane acrylate represented by the aforementioned chemical formulas 2 and 3. Was manufactured by the method as shown in FIG. Using eight lens arrays (two rows) 1 made of quartz glass having a diameter of 30 mm as shown in (a) as a master, a mold 2 was manufactured from this by electroforming Ni (b).

This mold 2 is composed of 70 parts by weight of acetal glycol diacrylate and 30 parts by weight of urethane acrylate, and is an ultraviolet curable resin 3 containing an appropriate amount of a photopolymerization initiator.
(C), and the resin layer was slowly pressed down from above with a flat glass 4 so as to have a thickness of 1 mm. When the resin layer was uniformly stretched, it was cured by irradiating ultraviolet rays through four flat glass. After curing, it was released from the mold 2 and cut into 4.2 mm x 2 mm. As a result, the lens shape has a radius of curvature of 0.3103 mm,
The collimator lens array 5 with an effective diameter of 0.270 mm was completed.

In this embodiment, the photopolymerization initiator is
1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184; manufactured by Ciba-Geigy Corporation) was used.

This lens array has a working distance of 10 mm with respect to an optical fiber light source of λ = 1550 nm.
The sertion loss was 0.6-0.8 dB. In addition, endurance test for 30 days at a temperature of 80 ° -85% humidity according to the old Delcore standard,
Temperature -40 ℃ ~ 70 ℃, Humidity 10 ~ 80% RH 42cycles (14
Sun) There were no problems with the results of the two types of environmental test, the environmental change test. (Example 2) A lens group composed of a convex lens having one aspheric surface and a spherical lens having the opposite surface was manufactured by a method as shown in FIG. In this lens group, an aspheric convex lens is formed on one surface side and a spherical lens is formed on the other surface side with a flat quartz glass having a thickness of 1.0 mm as a core. The resin layer forming the surface shape of this lens group is formed of an ultraviolet curable resin 7 comprising 70 parts by weight of acetal glycol diacrylate and 30 parts by weight of urethane acrylate.

First, a resin 6 containing an appropriate amount of the same photopolymerization initiator as in Example 1 was dropped on a mold 6 having an inverted shape of an aspherical convex lens formed on the surface of quartz glass (a). The surface of the resin 7 is slowly pressed down to a thickness of 0.1 mm with a 1 mm-thick plate-like quartz glass 8 whose surface has been treated with silane to improve the adhesion to the quartz glass 7. The resin 7 was cured by irradiating ultraviolet rays through the substrate to form a resin layer on one surface of the substrate (b).

Subsequently, on a mold 9 having an inverted shape of a spherical lens shape formed on the quartz glass surface in the same manner as described above,
Resin 1 to which the same photopolymerization initiator as in Example 1 was added in an appropriate amount
0, the combined body of the quartz glass 8 and the resin 7 is inverted (c), the surface of the quartz glass 8 is subjected to silane treatment, the resin 10 is pressed with the quartz glass 8, and ultraviolet rays are irradiated through the mold 9. Thus, the resin 10 was cured to form a spherical lens on the resin 10 (d). At this time, an alignment mark for alignment of the optical axis was prepared on both the molds 6 and 9 in advance, and the alignment of the alignment mark was performed so that the optical axis of the previously formed aspherical surface was aligned with the optical axis of the spherical surface.

After curing, the substrate 8 to which the resins 7 and 10 were bonded was released from the dies 6 and 9 (e) and cut into 3.2 mm × 2 mm (f). The lens array 11 is composed of 12 lenses (3 shown in the figure for simplicity), and is used for an optical interconnect for condensing light emitted from a surface emitting laser on a fiber.

This lens array 11 was mounted on an optoelectronic printed circuit board, and was passed through a reflow furnace at a maximum temperature of 260 ° C. for about 30 seconds for soldering. There were no problems with the characteristic measurement results after the module was completed. Some of them were re-flowed once again after correction, that is, twice in total, due to defective soldering, but this also had no problem.

[0049]

As described above, according to the present invention,
An optical element having the necessary performance for use in optical communication can be efficiently and inexpensively manufactured by a simple method.

[Brief description of the drawings]

FIG. 1 is a view showing the internal transmittance characteristics of a resin made of a polymer of acetal glycol diacrylate and urethane acrylate at a thickness of 0.1 mm.

FIG. 2 is a diagram illustrating a temperature rise curve during a heat resistance test using a reflow furnace.

FIG. 3 is a diagram illustrating a method of manufacturing the optical element according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a method for manufacturing an optical element according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Master 2 ... Mold 3 ... Resin 4 ... Flat glass 5 ... Collimator lens array 6 ... Mold 7 ... Resin 8 ... Quartz glass 9 ... Mold 10 ... Resin 11 ... Lens array

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Claims (3)

[Claims] 1. An optical component for optical communication, comprising a resin obtained by polymerizing acetal glycol diacrylate and at least one urethane acrylate, and used exclusively in a wavelength range of 800 nm or more. 2. A resin layer obtained by polymerizing acetal glycol diacrylate and at least one urethane acrylate is formed on one or both sides of a flat substrate made of an inorganic material, and is used exclusively in a wavelength range of 800 nm or more. An optical component for optical communication characterized by being performed. 3. A method for manufacturing an optical component for optical communication, comprising forming a resin layer on a transparent substrate at a wavelength used, wherein the optical component has an inverted shape with respect to one surface shape of the manufactured optical component, Further, using a first mold having an alignment mark and a second mold having an inverted shape with respect to the other surface shape of the manufactured optical component and further having an alignment mark, the resin layer is formed on the substrate. When forming, the alignment mark of the first type and the alignment mark of the second type are aligned to form the resin layer on the surface of the substrate. Manufacturing method of optical parts.