JP2008286950A - Optical waveguide connection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide connection device that can connect, at a low cost and with simple machining, between multimode planar optical waveguides or between a multimode planar optical waveguide and a multimode optical fiber. <P>SOLUTION: A waveguide core 1-4 is imbedded in a groove formed in a lower substrate 1-3, and a substrate 1-2 is stuck to the substrate 1-3 so as to be in contact with one side of the waveguide core 1-4. The substrates 1-2, 1-3 around both ends of the waveguide core 1-4 are cut off to make into a projected shape, and a connection part 1-5 is formed. For the formation of the projected shape of the connection part 1-5, the entire thickness of the substrates 1-2, 1-3 is merely cut off, so that a wire saw capable of cutting several substrates simultaneously can be used as a machining device. In the projected part of the connection 1-5, a split sleeve 1-6 is installed as shown in Fig.1(c). This split sleeve 1-6 is fixed to the connection part 1-5 by allowing the projected part of the connection 1-5 to come in internal contact with the split sleeve 1-6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical waveguide connecting device, and more particularly to an optical waveguide connecting device used for connecting a multimode optical fiber and an optical line and connecting optical lines.

  The multimode optical fiber and the multimode optical line are characterized by a large misalignment tolerance at the time of connection because the core size is larger than that of the single mode fiber and the single mode optical line. The plastic optical fiber (POF) used for wiring in automobiles, wiring around AV equipment and PC equipment has a large diameter, so it is easy to handle such as cutting and joining, connectors for connecting to various equipment, etc. There are many (see Non-Patent Document 1).

Yasuhiro Koike, 10 others, “Optical Fiber The POF in the Broadband Era”, NTS, January 2004, p92-129

  However, on the other hand, since the connection technology between the optical line and the optical fiber has been developed based on the single mode, a method capable of precise alignment has been adopted, and a method considering a large tolerance has not been studied. It has become an obstacle to cost reduction.

  For example, it is a common technique to attach a pigtail to a waveguide and connect it to a fiber using an FC connector or SC connector. This is a technique using a single mode technique as it is, and an axis of 1 μm or more. A technique for compensating for the deviation error is used. However, in the case of a GI glass fiber having a 50 μm core diameter, which is a general multimode optical fiber, and a 120 μm core diameter POF having a larger diameter, the loss is almost increased at an axial misalignment of 5 μm and 12 μm which is 1/10 of the core diameter Absent. That is, the guarantee of an axis deviation of 1 μm or less corresponding to the conventional single mode is over-spec.

  Further, optical communication by multimode has many connection points because it is mainly used for communication in a relatively short distance, for example, high-speed communication within a device or an optical network in a building or home. Therefore, an inexpensive connection method is desirable for multimode optical communication. For this reason, establishment of an inexpensive connection method specialized for multimode optical communication in consideration of a high misalignment tolerance of a multimode planar optical waveguide such as a multimode optical fiber is strongly desired.

  The present invention has been made in view of such problems, and its object is to reduce the connection between multimode planar optical waveguides or between a multimode planar optical waveguide and a multimode optical fiber by simple processing. An object of the present invention is to provide an optical waveguide connecting device which can be realized at a low cost.

  In order to achieve such an object, according to the first aspect of the present invention, there is provided an optical waveguide connecting device that is a planar optical circuit including a multimode optical waveguide, wherein an optical input portion and an optical output portion of the multimode optical waveguide include: A convex is formed in the waveguide direction, and the core of the multimode optical waveguide is provided at the center of the circumscribed circle of the convex.

  The invention according to claim 2 further includes a split sleeve attached to the convex portion, and another multimode optical waveguide is fixed by the split sleeve and optically connected to the fixed multimode optical waveguide. Features.

  According to a third aspect of the present invention, in the optical waveguide connecting device according to the first or second aspect, the diameter of the circumscribed circle of the convex portion is 1.23 mm or more and 1.27 mm or less, or 2.48 mm or more and 2.52 mm or less. It is characterized by being.

  The invention according to claim 4 is the optical waveguide connecting device according to claim 2 or 3, wherein the core positional deviation with respect to the multimode optical waveguide fixed by the sleeve is 20 μm or less. It is characterized by that.

  According to the present invention, it is possible to connect multimode planar optical waveguides or between multimode planar optical waveguides and a multimode optical fiber with simple processing, and as a result, it is possible to construct a short-distance optical communication system at low cost. It becomes possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows the structure of an optical waveguide connecting device according to an embodiment of the present invention. 1A shows an optical waveguide chip before processing, FIG. 1B shows a waveguide chip after processing, and FIG. 1C shows an optical waveguide connecting device. The waveguide core 1-4 is embedded in a groove formed in the lower substrate 1-3, and the substrate 1-2 is bonded to the substrate 1-3 so as to be in contact with one side of the waveguide core 1-4. The substrates 1-2 and 1-3 around both ends of the waveguide core 1-4 are cut out and shaped into a convex shape, thereby forming a connecting portion 1-5. In order to form the convex shape of the connecting portion 1-5, the entire thickness of the substrates 1-2 and 1-3 may be cut off. Therefore, a wire saw capable of simultaneous cutting can be used as the processing apparatus.

  A wire saw is a mechanical reference if there are no scratches or dust between the work table and the workpiece (work), as is the case with precision processing equipment that performs cutting with respect to the external reference, such as a machining center, water jet, and dicing saw. It is easy to make the positional deviation between the position and the cutting position 5 μm or less, and furthermore, since a large number of connecting portions can be manufactured at the same time, the cost can be kept low.

  As shown in FIG.1 (c), the split sleeve 1-6 is attached to the convex part of the connection part 1-5. The split sleeve 1-6 is fixed to the connecting portion 1-5 by inscribed in the convex portion of the connecting portion 1-5. Since the split sleeve 1-6 has a 1.25 mm inner diameter and a 2.5 mm inner diameter widely circulated, the convex shape of the connecting portion 1-5 has a circumscribed circle diameter of 1.25 mm or 2.5 mm. It is desirable to be designed. Further, in the case of a GI plastic fiber having a 120 μm core diameter, when the core misalignment is 20 μm or less, the excess loss due to the misalignment is 0.5 dB or less and is an allowable size in many cases, so 20 μm is a tolerance.

  FIG. 2 shows a connection method using the optical waveguide connection device according to one embodiment of the present invention. A multi-mode optical fiber having a ferrule 2-3 attached to the tip thereof is connected to the split sleeves 2-4 and 2-5 attached to the convex portion of the connection portion of the waveguide chip 2-1. Further, the waveguide chips can be connected to each other by inserting the convex portions of the connection portions into the split sleeves 2-8 and 2-9 like the waveguide chips 2-6 and 2-7.

  Here, the position of the core center of the substrate and the shape of the convex portion of the connecting portion 1-5 will be described. 3A to 3E illustrate the cutting positions at the time of producing the convex portions of the connection portions. The ease of processing of the substrate varies depending on whether the core center is at the center of thickness.

  FIG. 3A shows a case where the core center coincides with the waveguide chip thickness center. There are only two cutting positions, X and Y, and the entire thickness of the waveguide chip can be cut off. Therefore, a processing machine such as a wire saw or a water jet can be used. In particular, the cost can be kept low by using a wire saw capable of simultaneous machining.

  On the other hand, as shown in FIGS. 3B to 3E, when the upper substrate and the lower substrate to be bonded have the same thickness and a waveguide core is formed on the lower substrate, the core center is the waveguide chip. It does not match the thickness center. In such a case, in order to align the center of the core with the cylindrical axis of the split sleeve, in addition to the cutting at the positions X and Y, the cutting at the depth W is required at the positions p and q. In FIG. 3B, only the upper substrate is cut at positions p and q so as to be inscribed in the split sleeve at four points.

  However, in order to fix the split sleeve to the convex portion, it is only necessary to inscribe the three points of the convex portion to the split sleeve, and either one of the positions p and q may not be precisely positioned. Therefore, in FIGS. 3C to 3E, only p is positioned so as to be inscribed in the split sleeve, and q is closer to p than in the case of FIG. In other words, the positioning of q does not have to be accurate to perform the positioning of p.

  Cutting of the positions p and q at the depth W is performed in FIGS. 3B and 3C with the entire thickness of the upper substrate, in FIG. 3D with a part of the thickness of the upper substrate, and in FIG. 3E with the upper substrate. For the entire thickness and part of the thickness of the lower substrate. 3 (b) to 3 (e) must be cut at two places more than (a), and the entire thickness of the upper substrate and the lower substrate is not allowed to be cut off, so that a dicing saw, a machining center, etc. A processing machine is required. Since these processing machines are not suitable for a plurality of simultaneous processing, they are disadvantageous for cost reduction.

  From the above, it is desirable that the core center coincide with the waveguide chip thickness center because the number of cuttings is small and the cost can be suppressed.

(Embodiment 1)
FIG. 4 shows a manufacturing process of an optical waveguide connecting device according to an embodiment of the present invention. (A) The surface of the PMMA substrate 4-1 having a thickness of 1 mm is cut into a groove 4-3 with a width of 90 μm and a depth of 90 μm by processing with an end mill 4-2 using a machining center. A plurality of grooves 4-3 are cut in parallel, and the groove pitch is 4 mm. (B) An ultraviolet curable epoxy resin 4-4 having a refractive index larger than that of PMMA is poured into the formed groove 4-3. Next, (c) a Teflon (registered trademark) tape 4-5 is put on and an extra UV-curable epoxy resin is extruded. (D) Ultraviolet rays are irradiated by the ultraviolet irradiator 4-6 to cure the ultraviolet curable epoxy resin accumulated in the grooves 4-3. (E) After the ultraviolet curing epoxy resin is cured, the Teflon (registered trademark) tape 4-5 is peeled off. Next, (f) an ultraviolet curable epoxy resin 4-7 having a refractive index comparable to that of the PMMA substrate is spin-coated with a thickness of 10 μm. (G) A PMMA substrate 4-8 having a thickness of 0.99 mm is affixed on an ultraviolet curable epoxy resin 4-7 so that air is not mixed in, and is irradiated with ultraviolet rays by an ultraviolet irradiator 4-6. -7 is cured. (H) A wire saw using a wire saw 4-10 having a thickness of 0.05 mm is cut so that the convex portion is inscribed in a circle 4-9 having a diameter of 2.5 mm. The distance between the wire saws is 4 mm, and it is cut out in a U shape so as to leave 776 μm on both sides from the center of the core. That is, the center of the wire saw starts at 802 μm (cutting distance: 776 μm + half of the wire saw thickness: 25 μm + abrasive grain size: 1 μm) at the left of the core center, and cuts by 5 mm in the waveguide direction. .. Cut 346 mm, cut 5 mm in the waveguide direction, contrary to the previous one. Thus, (i) the shaded portion 4-11 is cut off, and the convex portion 4-12 remains as a connection portion. By attaching a split sleeve having an inner diameter of 2.5 mm to this convex portion 4-12, an optical waveguide connecting device of the present invention can be obtained, and it can be connected to a planar optical waveguide or a multimode optical fiber by the method shown in FIG.

It is a figure which shows the structure of the optical waveguide connection apparatus which concerns on one Embodiment of this invention. It is a figure which shows the connection method using the optical waveguide connection apparatus which concerns on one Embodiment of this invention. (A) is a figure which shows a connection part in case a core center and a waveguide chip thickness center correspond, (b)-(e) is a case where a core center and a waveguide chip thickness center do not correspond. It is a figure which shows a connection part. It is a figure which shows the manufacturing process of the optical waveguide connection apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

1-1 Waveguide Chip Before Processing 1-2 Upper Substrate 1-3 Lower Substrate 1-4 Waveguide Core 1-5 Connection 1-6, 2-4, 2-5, 2-8, 2-9% Sleeve 1-7 Cross-sectional shape of connecting portion 2-1, 2-6, 2-7 Waveguide chip 2-2 Multimode optical fiber 2-3 Ferrule 4-1, 4-8 PMMA substrate 4-2 End mill 4-3 Groove 4-4, 4-7 UV curable epoxy resin 4-5 Teflon (registered trademark) tape 4-6 UV irradiator 4-9 circumscribed circle 4-10 wire saw 4-11 cutting part 4-12 convex part

Claims (4)

  In an optical waveguide connecting device which is a planar optical circuit including a multimode optical waveguide, the light input portion and the light output portion of the multimode optical waveguide form a convex portion in the waveguide direction, and a central portion of a circumscribed circle of the convex portion And an optical waveguide connecting device comprising a core of the multimode optical waveguide.   The split sleeve attached to the convex portion is further provided, another multimode optical waveguide is fixed by the split sleeve, and optically connected to the fixed multimode optical waveguide. Optical waveguide connection device.   3. The optical waveguide connection device according to claim 1, wherein the circumscribed circle of the convex portion has a diameter of 1.23 mm to 1.27 mm, or 2.48 mm to 2.52 mm.   4. The optical waveguide connecting device according to claim 2, wherein the core position deviation with respect to the multimode optical waveguide fixed by the sleeve is 20 μm or less. 5.

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