JP2003014957A - Optical fiber, method of processing the same, and optical semiconductor module using the same - Google Patents

Abstract

(57) [Summary] [Problem] Chips and cracks are easily generated at the corners of the tip of an optical fiber, and the assembling efficiency to an optical semiconductor module is low. An optical fiber (1) having a coating layer (1b) formed on the outer periphery of an optical fiber (1a), wherein the tip (2) of the optical fiber (1) has the same end face as the optical fiber (1a) and the coating layer (1b). The optical fiber 1 is inclined at a predetermined angle with respect to a perpendicular A of the core axis of the optical fiber 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber used for optical communication, a light emitting source, an optical fiber used for optical coupling with a light receiving source, a processing method thereof, and an optical semiconductor module using the same.

[0002]

2. Description of the Related Art In an optical semiconductor module for optical communication, a photodiode (hereinafter referred to as PD) is used as a light receiving element, a laser diode (hereinafter referred to as LD) is used as a light emitting element, and a light emitting diode is used. The processed optical fiber is effectively used as a connecting part for light emission and a light receiving element.

For example, in an optical fiber amplifier 20 as shown in FIG. 4, an LD is used as a pumping light source 22, and as the optical fiber amplifier 20, an optical amplifying fiber 21 doped with a rare earth element such as erbium and a pumping light source 22 are used. The optical isolator 2 is provided before and after the optical amplification fiber 21.
3, 24 and a multiplexer 25 are arranged. Excitation light source 2
The pumping light from 2 enters the multiplexer 25, and in this optical fiber amplifier 20, the pumping light and the signal light are simultaneously entered into the optical amplification fiber 21,
The energy of the excitation light is converted into the energy of the signal light, and the signal light is amplified and emitted.

The pumping light source 22 has a wavelength of 980
An LD of nm is often used, and the pattern of the light emitted from this LD is not a circular Gaussian distribution but an elliptical beam having different vertical and horizontal directions and a high aspect ratio of about 4: 1. Will have a value. In the coupling of the LD having a large aspect ratio and the optical fiber, as shown in FIG. 5, the optical fiber inserted and held so that the light emitted from the LD 39 is projected by the aspherical lens 40 from the end surface of the ferrule 41. It was done by focusing on the tip of 31.

As shown in FIG. 6 (a), the coating layer 31b of the optical fiber 31 is removed at its tip, and the tip 32 of the optical fiber 31a is perpendicular to the core axis of the optical fiber 31. It is tilted by a certain angle φ and has a lens coupling structure.

The tip 32 of the optical fiber 31 is
The optical fiber element wire 31a from which the coating layer 31b of the optical fiber 31 has been removed is scratched on the surface in a direction perpendicular to the longitudinal direction with a diamond cutter or the like, and the optical fiber element wire 31a is momentarily applied with a force to break the optical fiber element wire 31a. A method of processing so that the angle φ is inclined, or the optical fiber element wire 31a is integrally fixed to a jig for fixing an optical fiber with wax or the like, and is sandwiched by a chuck of a polishing machine and brought into contact with a polishing machine to polish an inclined surface. After processing, remove wax etc. from the tip of the optical fiber,
It is processed by a method of removing the optical fiber from the fixing jig (see Japanese Patent Laid-Open No. 2001-51127).

Further, as shown in FIG. 6B, in order to prevent chipping of the tip 32 of the optical fiber 31, the optical fiber 31
A method has also been proposed in which the chamfered portion 31c is formed by immersing and dissolving the corner portion of the tip of the sheet in hydrofluoric acid (Japanese Patent Application Laid-Open No. HEI-1).
No. 1-295534).

[0008]

However, in the case of the optical fiber 31 as shown in FIG. 6, the optical fiber 31 is integrally fixed to the fixing jig with wax or the like and the tip end surface is ground. The wax used for the optical fiber 3
Since it has a hardness lower than that of No. 1 and has a property of being easily polished, stress is applied to the tip 32 of the optical fiber 31 due to a load applied at the time of polishing the end face, and chipping or cracking is likely to occur at the edge portion of the tip 32. Was.

Further, the optical fiber 3 after end face polishing
Since the optical fiber strand 31a is exposed at the tip 32 of No. 1, chipping or the like is likely to occur due to contact with the fixing jig during the work of removing the optical fiber 31 from the fixing jig, resulting in a significant yield. It had the drawback of lowering it.

Further, when this optical fiber 31 is used in an optical semiconductor module, in the assembly process of the light receiving element and the light emitting element, chipping or cracking is likely to occur at the tip due to external stress, resulting in a large loss. Had.

Further, as shown in FIG. 6B, when the chamfered portion 31c is formed at the tip 32 of the optical fiber 31a, chipping of the tip 32 of the optical fiber 31 can be prevented, but Inclination angle φ of tip 32
When the angle is larger than 15 °, the corners become very acute and the edges cannot be sufficiently removed only by forming the chamfered portion 31c, and chipping is likely to occur.

The present invention has been devised in view of the above-mentioned drawbacks, and an object of the present invention is to provide an optical fiber having a high tensile breaking strength without causing scratches or chips on the optical fiber strand. .

[0013]

The optical fiber of the present invention comprises:
An optical fiber comprising a coating layer on the outer circumference of an optical fiber wire, wherein the tip of the optical fiber has the same end face of the optical fiber wire and the coating layer, and with respect to the perpendicular of the core axis of the optical fiber. And is inclined by a predetermined angle.

The optical fiber of the present invention is characterized in that the inclination angle of the tip of the optical fiber is 4 to 60 °.

Furthermore, the optical fiber of the present invention comprises a coating layer on the outer circumference of the optical fiber element wire, and at least one end surface of the optical fiber has the same end surface as the optical fiber element wire and the coating layer, and a wedge shape. It is characterized by making.

Furthermore, in the optical fiber of the present invention, the distal end portion is inserted and held so that the distal end of the optical fiber projects into a distal end holding member having a pore having a diameter slightly larger than the diameter of the optical fiber, and The intermediate portion of the optical fiber is sandwiched by a pressing member made of an elastic body, and the optical fiber is held so as to have a degree of freedom in the core axis direction of the optical fiber,
It is characterized in that it is processed by inclining against a polishing disk at a predetermined angle and pressing it.

Furthermore, an optical semiconductor module using the optical fiber of the present invention stores an optical semiconductor element in a package, and the tip of the optical fiber according to any one of claims 1 to 3 is used as the optical semiconductor element. The optical semiconductor device and the optical fiber are arranged to face each other and are optically connected to each other.

According to the optical fiber of the present invention, the tip of the optical fiber has the same end face with the fiber element wire and the coating layer,
Moreover, since the optical fiber is inclined at a predetermined angle with respect to the perpendicular to the core axis of the optical fiber, a light emitting element such as an LD from the tip of the optical fiber 1 when the optical fiber is used in an optical semiconductor module,
It is possible to prevent signal noise due to reflected return light to the light receiving element such as PD, and prevent damage to the LD due to reflected return light. In addition, when this optical fiber is incorporated as an optical semiconductor package, or when the tip of the optical fiber is processed, the tip surface of the optical fiber element wire can be completely protected from external stress, facilitating handling. be able to.

Further, according to the optical fiber of the present invention, since the inclination angle of the tip of the optical fiber is 4 to 60 °, signal noise due to reflected return light when this optical fiber is used in an optical semiconductor module. It is possible to prevent damage to the LD due to reflected return light.

Further, according to the optical fiber of the present invention, since the tip end of the optical fiber has the same end face as the fiber element wire and the coating layer and has a wedge shape, this optical fiber 1 is used for an optical semiconductor module. In this case, the tip of the optical fiber acts as a lens, and the light emitted from the LD having a high aspect ratio is efficiently condensed by the wedge-shaped lens provided at the tip of the optical fiber. Since it is not necessary to use, the optical semiconductor module can be downsized and the cost can be reduced.

Furthermore, according to the optical fiber of the present invention, the distal end portion is inserted and held so that the distal end of the optical fiber projects into the distal end holding member having the pore having a diameter slightly larger than the diameter of the optical fiber. , The intermediate portion of the optical fiber is sandwiched by a pressing member made of an elastic body, the optical fiber is held so as to have a degree of freedom in the core axis direction, and is pressed by inclining a predetermined angle with respect to the polishing plate. Therefore, while relaxing the load applied to the tip of the optical fiber at the time of polishing, the tip of the optical fiber simultaneously polishes the optical fiber element wire and the coating layer, and the end surface of the optical fiber element wire forms the same end surface as the coating layer. Therefore, it is possible to obtain a highly accurate optical fiber that is free from chipping or the like at the edge portion and can prevent deterioration of the tensile fracture strength of the optical fiber.

Further, according to the optical semiconductor module using the optical fiber of the present invention, the optical semiconductor element and the optical fiber are arranged to face each other in the package, and the optical semiconductor element and the optical fiber are optically connected. Therefore, it is possible to assemble with the coating layer formed on the outer circumference of the optical fiber element wire, and the optical fiber element wire does not come into contact with the ferrule to cause scratches or chipping, and to obtain a highly accurate optical semiconductor module. You can

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1A is an enlarged cross-sectional view showing an embodiment of the optical fiber of the present invention. The optical fiber 1 comprises an optical fiber element wire 1a and a coating layer 1b on the outer periphery thereof.

Here, as shown in FIG. 1A, the tip 2 of the optical fiber 1 has an optical fiber strand 1a and a coating layer 1.
It is important that b has the same end face and is inclined at a predetermined angle with respect to the perpendicular A of the core axis of the optical fiber 1. When this optical fiber 1 is used in an optical semiconductor module, the tip 2 of the optical fiber 1 is It is possible to prevent signal noise due to reflected return light from a light emitting element such as LD to a light receiving element such as PD, and to prevent damage to the LD due to reflected return light. Also,
When this optical fiber 1 is incorporated as an optical semiconductor package, or when the tip 2 of the optical fiber 1 is processed, the tip surface of the optical fiber element wire 1a can be completely protected from external stress and handling is easy. Can be

The tip 2 of the optical fiber 1 preferably has an inclination angle φ of 4 to 60 °, and prevents signal noise due to reflected return light when the optical fiber 1 is used in an optical semiconductor module. , LD, it is possible to prevent damage to the LD due to reflected return light. When the tilt angle φ is less than 4 °, LD, P
The amount of reflected light returning to D increases, while if it exceeds 60 °, the connection loss between the optical fiber 1 and the LD or PD may deteriorate.

Further, as shown in FIG. 1 (b), the tip 2 of the optical fiber 1 has an optical fiber element wire 1a and a coating layer 1b.
May have the same end face and have a wedge shape. When the optical fiber 1 is used in an optical semiconductor module, the tip 2 of the optical fiber 1 serves as a lens and has a high aspect ratio. Since the wedge-shaped lens provided at the tip 2 of the optical fiber 1 efficiently collects the light emitted from
Since it is not necessary to use an aspherical lens or a plurality of lenses, the optical semiconductor module can be downsized and the cost can be reduced.

Here, a method of processing the optical fiber 1 of the present invention will be described.

In the method of processing the tip 2 of the optical fiber 1, the optical fiber 1 is held and polished by a fixing jig as shown in FIG. The tip of the optical fiber 1 is inserted and held so that the tip 2 of the optical fiber 1 projects a predetermined length into a holding member 3 made of resin, ceramics such as alumina, or glass having pores 4 having a slightly larger diameter.

Next, 30 m from the tip 2 of the optical fiber 1.
An intermediate portion separated by m or more is sandwiched by a pressing member 5 made of an elastic material such as resin.

Then, as shown in FIG. 2B, the tip 2 of the optical fiber 1 protruding from the holding member 3 is diamond-shaped,
Processing is performed by inclining and pressing against a polishing plate 6 made of a polishing sheet such as alumina. In addition, it is preferable that the polishing board 6 starts polishing with a polishing sheet having a coarse grain size, and successively reduces the grain size of the polishing sheet to perform mirror finish.

According to this processing method, since the pores 4 of the holding member 3 are slightly larger than the outer diameter of the optical fiber 1, they can move freely in the core axis direction, and When the tip 2 of the optical fiber 1 is pressed against the polishing plate 6, the holding member 3 and the pressing member 5 are pressed as shown in FIG.
The optical fiber 1 is bent between the two, and the load applied to the tip 2 of the optical fiber 1 is relaxed. As a result, it is possible to perform processing while always maintaining an optimum load, and the tip 2 of the optical fiber 1 simultaneously polishes the optical fiber element wire 1a and the coating layer 1b to form the same end face. Therefore, even if the corner portion of the optical fiber element wire 1a is protected by the coating layer 1b and has a sharp edge portion whose inclination angle φ exceeds 15 °,
It is possible to obtain the highly accurate optical fiber 1 which is free from chipping and can prevent the deterioration of the tensile breaking strength.

The number of the optical fibers 1 held by the fixing jig is not limited to one, and a plurality of optical fibers 1 can be provided by providing a plurality of pores 4 formed in the holding member 3. It can be processed at once.

Further, by removing the coating layer 1b from the optical fiber 1 obtained by the above-mentioned processing method by treating with chemicals such as hot concentrated sulfuric acid, the optical fiber strand is damaged even when the coating layer 1b is removed. Can be obtained.

Optical fiber 1 processed as described above
Is preferably used as the optical semiconductor module 7, and is shown in FIG.
As shown in (a), the package 8 includes an LD 9 which is an optical semiconductor element, a lens 10 for condensing light emitted from the LD 9, and the optical fiber 1 held by a ferrule 11. This is a mechanism in which the tip 2 of the optical fiber 1 is arranged to face the LD 9 via the lens 10 and the LD 9 and the optical fiber 1 are optically connected.

As shown in FIG. 3 (a), the optical fiber 1 is inserted and held so that the tip of the optical fiber 1 is projected from the end face of the ferrule 11 with the coating layer 1b, and the coating layer 1b is attached. Since it is inserted and held in the ferrule 11 in the closed state, the optical fiber element wire 1a does not come into contact with the ferrule 11 to cause scratches or chips, and the yield at the time of assembly can be improved. Further, since the handling becomes easy, the number of assembling steps can be shortened, and the glass side surface of the optical fiber element wire 1a is not scratched.
The bonding strength between the ferrule 11 and the optical fiber 1 can also be improved.

The optical semiconductor module 7 is shown in FIG.
When the optical fiber 1 whose tip 2 has a wedge shape is used as shown in (b), the tip 2 of the optical fiber 1 functions as a lens, and the light emitted from the LD 9 having a high aspect ratio is directed to the tip 2 of the optical fiber 1. Since the provided wedge-shaped lens collects light efficiently, it is not necessary to use an aspherical lens or a plurality of lenses, and the optical semiconductor module 7 can be downsized and the cost can be reduced.

The fiber stub and the optical semiconductor module of the present invention are not limited to the above-mentioned embodiments, and various modifications can be made without departing from the scope of the present invention. In the form, the tip 2 of the optical fiber 1 has a slanted surface and a wedge shape. However, a shape having a pair of slanted surfaces symmetrical with respect to the core axis of the optical fiber 1, a slanted surface and a wedge shape, and a slanted surface. Having a semi-cylindrical curved surface at the apex part continuously, having an apex part consisting of a plane perpendicular to the core axis at the tip of the inclined surface, having another pair of inclined surfaces continuous to the inclined surface , And those having various shapes such as having a semi-cylindrical curved surface at the tip, and since the tip 2 of the optical fiber 1 has the same end face of the optical fiber element wire 1a and the coating layer 1b, the optical fiber 1 Chipping and cracks caused in the corner portion is to effectively prevent.

[0039]

EXAMPLES Next, examples of the present invention will be described. Example 1 First, an acrylic-coated single-mode optical fiber having a diameter of 250 μm as shown in FIG. 1 is prepared.

First, as shown in FIG. 2, the tip of the optical fiber is inserted into a holding member having a pore having a diameter of 260 μm as a fixing jig, and the tip of the optical fiber is about 0.5 mm. The optical fiber was held in a state of protruding from the end surface of the holding member.

Then, the inclination angle φ is set to 20 °, and the optical fiber element wire and the coating layer are simultaneously polished by three kinds of polishing sheets having a particle diameter of 0.5 to 1 μm to obtain an optical fiber sample. 100 pieces were produced.

Further, as a comparative example, in order to obtain a conventional optical fiber as shown in FIG. 6A, the above single mode optical fiber was prepared, and the coating layer at the tip of the optical fiber was removed. The optical fiber was inserted into a fixing jig having a hole and was integrally fixed with wax.

Next, the inclination angle φ is set to 20 °, and four kinds of polishing sheets having a grain size of 0.5 to 6 μm are sequentially polished in the polishing apparatus in order of coarse grain size. After that, the wax layer was melted and the optical fiber was pulled out from the fixing jig.

Then, the optical fibers of each sample were observed for the presence or absence of chipping and scratches on the end face under a metallurgical microscope × 400 times.

The results are shown in Table 1.

[0046]

[Table 1]

As is clear from Table 1, it was found that the optical fiber sample of the present invention is unlikely to cause chipping or cracks at its tip.

On the other hand, it was found that the conventional optical fiber sample is liable to be chipped or cracked at the tip thereof, and the processing yield is as low as 50%.

(Example 2) Further, in order to measure the tensile fracture strength of each sample, 25 optical fiber samples of the conventional and the present invention obtained in Example 1 were prepared.

Next, the tip of the optical fiber element wire of each sample is subjected to metallizing treatment, and a region of 2 mm from the tip of the optical fiber is fixed by soldering to a metal plate plated with Ni-Au, and then the rear end of the optical fiber. Was held in a measuring instrument and a tensile stress was applied to carry out a strength fracture test.

The results are shown in Table 2.

[0052]

[Table 2]

As is clear from Table 2, the tensile strength of the optical fiber sample of the present invention has an average of 20 N or more, while the conventional optical fiber sample has an average of 13 N.
It was found that N was smaller than that of the optical fiber sample of the present invention.

[0054]

According to the optical fiber of the present invention, the tip of the optical fiber has the same end face with the fiber element wire and the coating layer, and is inclined at a predetermined angle with respect to the perpendicular to the core axis of the optical fiber. Therefore, when this optical fiber is used in an optical semiconductor module, signal noise due to reflected return light from the tip of the optical fiber 1 to a light emitting element such as an LD or a light receiving element such as a PD is prevented, and the LD due to the reflected return light It can prevent damage. In addition, when this optical fiber is incorporated as an optical semiconductor package, or when the tip of the optical fiber is processed, the tip surface of the optical fiber element wire can be completely protected from external stress, facilitating handling. be able to.

Further, according to the optical fiber of the present invention, since the inclination angle of the tip of the optical fiber is 4 to 60 °, signal noise due to reflected return light when this optical fiber is used in an optical semiconductor module. It is possible to prevent damage to the LD due to reflected return light.

Further, according to the optical fiber of the present invention, since the tip end of the optical fiber has the same end face as the fiber element wire and the coating layer and has a wedge shape, this optical fiber 1 is used for an optical semiconductor module. In this case, the tip of the optical fiber acts as a lens, and the light emitted from the LD having a high aspect ratio is efficiently condensed by the wedge-shaped lens provided at the tip of the optical fiber. Since it is not necessary to use, the optical semiconductor module can be downsized and the cost can be reduced.

Furthermore, according to the optical fiber of the present invention, the distal end portion is inserted and held so that the distal end of the optical fiber projects into the distal end holding member having the pores having a diameter slightly larger than the diameter of the optical fiber. , The intermediate portion of the optical fiber is sandwiched by a pressing member made of an elastic body, the optical fiber is held so as to have a degree of freedom in the core axis direction, and is pressed by inclining a predetermined angle with respect to the polishing plate. Therefore, while relaxing the load applied to the tip of the optical fiber at the time of polishing, the tip of the optical fiber simultaneously polishes the optical fiber element wire and the coating layer, and the end surface of the optical fiber element wire forms the same end surface as the coating layer. Therefore, it is possible to obtain a highly accurate optical fiber that is free from chipping or the like at the edge portion and can prevent deterioration of the tensile fracture strength of the optical fiber.

Further, according to the optical semiconductor module using the optical fiber of the present invention, the optical semiconductor element and the optical fiber are arranged to face each other in the package, and the optical semiconductor element and the optical fiber are optically connected. Therefore, it is possible to assemble with the coating layer formed on the outer circumference of the optical fiber element wire, and the optical fiber element wire does not come into contact with the ferrule to cause scratches or chipping, and to obtain a highly accurate optical semiconductor module. You can

[Brief description of drawings]

1A and 1B are enlarged cross-sectional views showing an optical fiber of the present invention.

2A to 2C are schematic views showing a method for processing an optical fiber according to the present invention.

FIG. 3 is a cross-sectional view showing an optical semiconductor module using the optical fiber of the present invention.

FIG. 4 is a conceptual diagram showing an optical fiber amplifier.

FIG. 5 is a sectional view showing an optical semiconductor module using a conventional optical fiber.

FIG. 6 is an enlarged sectional view showing a conventional optical fiber.

[Explanation of symbols]

1: Optical fiber 1a: Optical fiber strand 1b: coating layer 2: Tip 3: Holding member 4: Pore 5: Presser member 6: Polishing machine 7: Optical semiconductor module 8: Package 9: LD 10: Lens 11: Ferrule 20: Optical fiber amplifier 21: Optical amplification fiber 22: Excitation light source 23: Optical isolator 24: Optical isolator 25: Combiner

Claims (5)

[Claims] 1. An optical fiber comprising a coating layer on the outer periphery of an optical fiber element wire, wherein the tip of the optical fiber has the same end surface of the optical fiber element wire and the coating layer, and the core of the optical fiber. An optical fiber which is inclined at a predetermined angle with respect to a perpendicular of an axis. 2. The inclination angle of the tip of the optical fiber is from 4 to 4.
The optical fiber according to claim 1, wherein the optical fiber has an angle of 60 °. 3. An optical fiber comprising a coating layer on the outer circumference of an optical fiber element wire, wherein the optical fiber element wire and the coating layer have the same end face at the tip of the optical fiber, and form a wedge shape. An optical fiber characterized by. 4. A tip end of the optical fiber is inserted and held so that the tip of the optical fiber slightly protrudes into a holding member having a pore having a diameter slightly larger than the diameter of the optical fiber, and the middle portion of the optical fiber is made elastic. The optical fiber is held so as to have a degree of freedom in its core axis direction by being sandwiched by a pressing member composed of a body, and the tip end of the optical fiber is pressed at a predetermined angle with respect to the polishing plate and processed. Item 4. A method for processing an optical fiber according to any one of Items 1 to 3. 5. An optical semiconductor element is housed in a package, and the tip of the optical fiber according to claim 1 is arranged so as to face the optical semiconductor element, so that the optical semiconductor element and the optical fiber are combined with each other. An optical semiconductor module characterized by being connected.