JP2008046185A - Method of manufacturing lens-attached optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance efficiency in manufacturing and testing a lens-attached optical fiber such as an optical fiber collimator. <P>SOLUTION: The lens-attached optical fiber is manufactured by a process of cutting a lens, a process of polishing the end face of the cut lens, and a process of welding the polished lens to the end face of an optical fiber. The inspection of the lens can be inspected before the lens is welded to the optical fiber, thereby preventing a defective lens from being welded to the optical fiber, and enhancing the efficiency of manufacturing the lens-attached optical fiber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an optical fiber with a lens by fusing a rod-shaped gradient index lens to an optical fiber.

  An optical fiber having a gradient index lens fused to the end is used as an optical fiber collimator. Also, an optical fiber capacitor in which two gradient index lenses having different numerical apertures are fused to the end of an optical fiber is used. The gradient index lens is a rod-like lens whose refractive index in the cross-sectional direction changes continuously in a square curve, and a lens action is generated by this refractive index distribution. Gradient index lenses are roughly classified into so-called GI fibers and GRIN lenses. A GI fiber has a clad around the core, and a GRIN lens has no clad, so that a larger cross-sectional area can be obtained for collimation than a GI fiber. An optical fiber collimator and an optical fiber condenser in which a GRIN lens is fused to the end of an optical fiber are disclosed in, for example, Patent Document 1 below, and an optical fiber collimator in which an GI fiber is fused to an end of an optical fiber is disclosed in, for example, Patent Document 2 below. Has been.

In the conventional method of manufacturing an optical fiber collimator, a lens having a long length is fused to an optical fiber, and then the lens is cut into a predetermined length (desired length + polishing length), and then the lens end face is polished. To do. Further, in the conventional method of manufacturing an optical fiber capacitor, a first lens having a long length is fused to an optical fiber, the first lens is cut to a desired length, and a long length is formed on the first lens. The second lens having the above is fused, the second lens is cut into a predetermined length (desired length + polishing length), and then the end surface of the second lens is polished. Such a conventional method of manufacturing an optical fiber collimator / optical fiber capacitor is disclosed in Patent Document 3 below.
Japanese Patent Laid-Open No. 2005-115097 Japanese Patent No. 3285166 Japanese Patent No. 3095622

  According to the conventional manufacturing method, whether or not the lens performance satisfies the required quality can be inspected only when it is a final product (an optical fiber collimator or an optical fiber capacitor). There's a problem. In addition, for the purpose of reducing reflected return light on the lens end surface, an antireflection film (AR coating) may be applied to the lens end surface. However, in the case of an optical fiber collimator manufactured by a conventional method, the lens is exposed. In addition, the anti-reflection coating process is performed with an optical fiber of about 1 m connected, so not only the handling is very complicated, but also tens to hundreds of batches are fixed to a bundle or dedicated jig and processed again. As a result, the lens portion may be damaged.

  The present invention eliminates the waste of fusing a defective lens to an optical fiber by enabling performance inspection of the lens before fusing to the optical fiber, and manufacturing efficiency and inspection efficiency of the optical fiber collimator and the like. In addition, when the antireflection film treatment is performed on the lens end face, it is an object to make the lens difficult to break and to improve the processing efficiency.

(Configuration 1)
The present invention includes a method of manufacturing an optical fiber with a lens, comprising: a step of cutting a lens; a step of polishing an end surface of the cut lens; and a step of fusing the polished lens to an end surface of an optical fiber. It is. In the step of cutting the lens, the cutting length of the lens is a length obtained by adding a polishing length to a desired length. Polishing of the end face of the cut lens includes both the case where only one end face is polished and the case where both end faces are polished.

(Configuration 2)
According to the present invention, in the manufacturing method according to Configuration 1, the step of polishing the end face of the lens is performed by temporarily fixing a plurality of lenses to a holder and polishing the lens. Is the method.

(Configuration 3)
Further, the present invention is the method for manufacturing an optical fiber with a lens, characterized in that in the manufacturing method of the configuration 1 or 2, the lens is inspected after the step of polishing the end face of the lens.

(Configuration 4)
Further, the present invention is the method for manufacturing an optical fiber with a lens, wherein in the manufacturing method of the configuration 3, the step of inspecting the lens is performed in a state where a plurality of lenses are temporarily fixed to a holder.

(Configuration 5)
Moreover, this invention has the process of forming an anti-reflective film in the end surface of the said lens before the process of fuse | melting the said lens in the said optical fiber end surface in the manufacturing method in any one of the said structures 1-4. It is a manufacturing method of the optical fiber with a lens characterized. The reflection film is formed on the end surface of the lens that is not fused to the optical fiber.

(Configuration 6)
The present invention also includes a step of fusing end faces of the first lens and the second lens, a step of cutting the fused first lens and the second lens to separate a coupling lens, and the coupling A method of manufacturing an optical fiber with a lens, comprising: a step of polishing an end surface of a lens; and a step of fusing the polished connecting lens to an end surface of an optical fiber. In the step of separating the connecting lens, the cutting length of the lens is set to a desired length plus a polishing length. Polishing of the end face of the separated connecting lens includes both the case of polishing only one end face and the case of polishing both end faces.

(Configuration 7)
According to the present invention, in the manufacturing method according to Configuration 6, the step of polishing the end surface of the connecting lens is performed by temporarily fixing and polishing a plurality of connecting lenses on a holder. It is a manufacturing method.

(Configuration 8)
Further, the present invention provides the method for manufacturing an optical fiber with a lens, characterized in that, in the manufacturing method of the configuration 6 or 7, the step of inspecting the connecting lens is provided after the step of polishing the end surface of the connecting lens. is there.

(Configuration 9)
Further, the present invention is the method of manufacturing an optical fiber with a lens according to the manufacturing method of the configuration 8, wherein the step of inspecting the connecting lens is performed in a state where a plurality of connecting lenses are temporarily fixed to a holder. .

(Configuration 10)
Moreover, this invention has the process of forming an anti-reflective film in the end surface of the said connection lens in the manufacturing method in any one of the said structures 6-9 before the process of fuse | melting the said connection lens to the said optical fiber end surface. This is a method for producing an optical fiber with a lens. The reflective film is formed on the end surface of the connecting lens that is not fused to the optical fiber.

  In the present invention, the lens or the coupling lens is first cut and polished before being fused to the optical fiber, so that the lens can be inspected before being fused to the optical fiber. Therefore, waste of fusing the defective lens to the optical fiber is eliminated, and the manufacturing efficiency of the optical fiber with a lens such as an optical fiber collimator and an optical fiber capacitor is improved. Further, by polishing and inspecting a plurality of lenses or connecting lenses temporarily fixed to the holder, the lens can be efficiently polished and inspected. When the antireflection film treatment is performed, the treatment can be easily and efficiently performed without damaging the lens by performing the treatment before the lens or the coupling lens is fused to the optical fiber.

  When manufacturing an optical fiber collimator, a lens (GI fiber, GRIN lens, etc.) manufactured in the shape of a long bar is first cut into a predetermined length. The cutting length of the lens at this time is a length obtained by adding a length (polishing length) lost by polishing to a desired length required for the lens.

  Next, the plurality of cut lenses are temporarily fixed to the holder. FIG. 1 shows an example of the holder. The holder 4 in FIG. 1 is made of a suitable material such as glass, plastic, metal, or the like formed into a plate shape, and a plurality of (in this case, five) grooves 5 are formed in parallel. The shape of the groove is V-shaped in this case, but is not limited to the V-shape, and may be a U-shape, a semicircle, or the like. The cut lens 2 is fitted into the groove 5 and temporarily fixed with an adhesive 6 and a cover plate 7 as shown in FIGS. As the adhesive, a thermoplastic adhesive, a hot water soluble UV adhesive, or the like is used so that the lens can be removed from the holder after polishing. The holder 4 is suitable for polishing both end faces of the lens. FIG. 4 shows another example of the holder. The holder 8 shown in FIG. 4 has a plurality of grooves 9 into which the lens is fitted in the same manner as the holder 4 described above, but is different in that a holding portion 10 is formed for convenience of handling and holding by a polishing machine. A lens is fitted into the groove 9, and the lens is temporarily fixed in the same manner as in FIG. The holder 8 is suitable for polishing one end surface of the lens. FIG. 5 further shows another example of the holder. The holder 10 of FIG. 5 has a plurality of (in this case, five) through holes 12 formed in a box-shaped main body. One lens is inserted into each through-hole 12 with its end exposed to the outside from the main body of the holder 10, and temporarily fixed with an adhesive. As described above, the holder only needs to be capable of temporarily fixing a plurality of lenses and simultaneously polishing and inspecting the plurality of lenses.

  Next, the plurality of lenses temporarily fixed to the holder are polished. A general polishing machine may be used for polishing. For example, as shown in FIG. 6, the plurality of lenses 2 temporarily fixed to the holder 4 with the grindstone 13 rotated by the grinder are polished together with the holder. By polishing the lens together with the holder, it is possible to prevent the lens from being damaged during polishing.

  After the polishing is completed, the lens is inspected with the plurality of lenses 2 temporarily fixed to the holder 4. Inspection is possible simply by observing the image point position with an optical microscope. In other words, the rear image is formed on the lens end surface or in the lens due to the lens effect (where the image is formed depends on the lens length setting), but the inspection is performed by measuring the distance of the image point from the lens end surface. It becomes possible. Further, the superiority or inferiority of the lens can also be determined by entering parallel light having a measurement wavelength (for example, 1550 nm) and measuring the intensity ratio of the emitted light with respect to the incident light and the beam divergence angle. Since the lens is inspected with a plurality of lenses temporarily fixed to the holder, the inspection can be performed efficiently.

  After the inspection of the lens is completed, an antireflection film (AR coating) is applied to the lens end face as necessary. This process is also performed with a plurality of lenses temporarily fixed to the holder. Conventionally, since the antireflection film was applied after the lens was fused to the optical fiber, the work was not only complicated, but there was a risk of damaging the lens. By temporarily fixing the lens to the lens, it is possible to easily and efficiently work without damaging the lens.

  Next, the lens is removed from the holder and collected. When a thermoplastic adhesive is used for temporary fixation, the holder is heated to melt the adhesive and the lens is taken out of the holder, then washed with an organic solvent such as alcohol, and filtered to collect the lens. When hot water-soluble UV adhesive is used, the holder is immersed in hot water to dissolve the adhesive, and the lens is taken out of the holder and then filtered to collect the lens.

  After collecting the lens from the holder, the lens is fused to the tip of the optical fiber. In this case, it is generally necessary to handle a lens having a diameter of about 0.125 mm and a length of about 0.3 to 2 mm. In this regard, if a metal thin tube (for example, copper outer diameter φ0.16 mm, inner diameter φ0.07 mm) and a suction pump are used under a microscope, the lens end face can be held and handled at the time of fusing. Further, if a micromanipulator technique generally used in the biological field is used, the lens can be recovered and handled more efficiently. As shown in FIG. 7, the lens 2 is fused to the tip of the optical fiber 1 to complete the optical fiber collimator. In addition, a higher quality collimator is completed by fusing the optical fiber and the lens while fusing.

  When manufacturing an optical fiber capacitor, first, as shown in FIG. 8, after the end surfaces of the first lens 3a and the second lens 3b manufactured in the shape of a long bar are fused, the first lens is cut. The lens is cut by the part A and the cutting part B of the second lens, and the connecting lens 3 in which the first lens and the second lens are connected by fusion is cut off. The first lens 3a is a lens fused to the optical fiber, the second lens is a tip lens, and the second lens has a larger numerical aperture than the first lens. The cutting length of the first and second lenses at this time is a length obtained by adding a length (polishing length) lost by polishing to a desired length required for the lens. Note that the first lens may not be polished.

  The separated connecting lens 3 is temporarily fixed to the holder in the same manner as the lens 2 of the above-described embodiment, polished, inspected, and subjected to an antireflection film treatment if necessary, and similarly removed from the holder and collected. . As shown in FIG. 9, the connecting lens 3 is fused to the tip of the optical fiber 1 to complete the optical fiber capacitor.

4 is a perspective view of a holder 4. FIG. It is a side view of the holder 4 which fixed the lens 2 temporarily. It is a top view of the holder 4 which fixed the lens 2 temporarily. 7 is a perspective view of a holder 8. FIG. 3 is a perspective view of a holder 10. FIG. It is explanatory drawing of the process of grind | polishing the end surface of a lens. It is a side view of an optical fiber collimator. It is explanatory drawing of the process of fuse | melting the 1st lens 3a and the 2nd lens 3b, and cut | disconnecting the connection lens 3. FIG. It is a side view of an optical fiber capacitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Lens 3 Connection lens 3a 1st lens 3b 2nd lens 4 Holder 5 Groove 6 Adhesive 7 Cover plate 8 Holder 9 Groove 10 Hold part 11 Holder 12 Through-hole 13 Grinding stone

Claims (10)

  A method of manufacturing an optical fiber with a lens, comprising: a step of cutting a lens; a step of polishing an end surface of the cut lens; and a step of fusing the polished lens to an end surface of an optical fiber.   2. The method of manufacturing an optical fiber with a lens according to claim 1, wherein the step of polishing the end face of the lens is performed by temporarily fixing a plurality of lenses to a holder and polishing.   3. The method of manufacturing an optical fiber with a lens according to claim 1, further comprising a step of inspecting the lens after the step of polishing the end face of the lens.   4. The method of manufacturing an optical fiber with a lens according to claim 3, wherein the step of inspecting the lens is performed with a plurality of lenses temporarily fixed to a holder.   5. The method according to claim 1, further comprising a step of forming an antireflection film on the end face of the lens before the step of fusing the lens to the end face of the optical fiber. An optical fiber manufacturing method.   A step of fusing the end surfaces of the first lens and the second lens, a step of cutting the fused first lens and the second lens to separate the coupling lens, and polishing the end surface of the coupling lens And a process for fusing the polished connecting lens to the end face of the optical fiber.   7. The method of manufacturing an optical fiber with a lens according to claim 6, wherein the step of polishing the end face of the connecting lens is performed by temporarily fixing and polishing a plurality of connecting lenses on a holder.   8. The method of manufacturing an optical fiber with a lens according to claim 6, further comprising a step of inspecting the connecting lens after the step of polishing an end face of the connecting lens.   9. The method of manufacturing an optical fiber with a lens according to claim 8, wherein the step of inspecting the connecting lens is performed in a state where a plurality of connecting lenses are temporarily fixed to a holder.   The manufacturing method according to claim 6, further comprising a step of forming an antireflection film on an end surface of the connection lens before the step of fusing the connection lens to the end surface of the optical fiber. Manufacturing method of optical fiber with lens.

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