JP2005189564A - Three-dimensional plate-shaped optical waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-dimensional plate-shaped optical waveguide in which even when an optical waveguide is a high-density and multi branching plate-shaped optical waveguide, it can be miniaturized and moreover strength, such as impact resistance is also improved. <P>SOLUTION: In the three-dimensional optical waveguide, a plate-shaped optical waveguide block 2 is constituted by stacking plate-shaped optical waveguides 1a to 1d, another plate-shape optical waveguide 3 is coupled to the plate-shaped optical waveguide 2 by being made to intersect the bolck 2 at 90 degrees, coupling end faces of respective plate-shaped optical waveguides 1a to 1d constituting the block 2 are ground while being slanted by a prescribed angle and a distance among cores of respective plate-shaped optical waveguides 1a to 1d and a distance among cores of the plate-shaped optical waveguide 3 are made to become an equal distance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a planar optical waveguide capable of reducing the size and improving the strength of a waveguide.

  In recent years, the introduction of FTTH (Fiber To The Home) has begun, and the use of the high-speed Internet in each home has been rapidly spreading. Under such circumstances, there is an increasing need to enhance the communication network, and there is a demand for a highly reliable, low-cost and small-sized optical waveguide.

  Among the optical waveguides, the planar optical waveguide has a structure in which a core having a high refractive index is covered with a clad having a refractive index lower than that of the core. A multi-branch planar optical waveguide is constituted by a large number of core branches in a tree shape.

  Such a planar optical waveguide is produced on a substrate such as glass using a photoengraving technique, and the core is branched in two dimensions. Therefore, as the number of branches increases, the core has a planar spread (see, for example, Patent Document 1 and Patent Document 2).

FIG. 5 shows a conventional planar optical waveguide 41, in which one core 42 is branched in a tree shape and divided into 16 cores. That is, this figure shows an example of a 1 × 16 branching waveguide. The 1 × 16 branch means a configuration in which a branch is finally made from one core to 16 cores. Here, coordinate axes are displayed such that the width direction of the waveguide is the X axis, the thickness direction is the Y axis, and the longitudinal direction is the Z axis.
JP-A-4-289803 JP 2003-29067 A

  By the way, the conventional techniques as described above have the following problems to be solved.

  With the recent development of communication networks, planar optical waveguides are also required to have higher density. The increase in the density of the planar optical waveguide means that the number of core branches increases. As the number of branches of the core increases, the core tends to expand in the direction parallel to the upper surface of the substrate, that is, in the X-axis direction and the Z-axis direction, and the substrate tends to increase in size.

  On the other hand, miniaturization of various devices is desired in the market, and planar optical waveguides are no exception. Therefore, realization of a compact planar optical waveguide with high density has been desired.

  In addition, since the conventional planar optical waveguide is two-dimensionally branched in a direction parallel to the upper surface of the substrate as described above, the area of the substrate must be increased when the number of branches increases. However, since the thickness of the substrate is usually constant, there is a problem that the bending strength is lowered and the impact resistance is deteriorated.

  The present invention has been made paying attention to the above points, and it is an object of the present invention to provide a planar optical waveguide that can be reduced in size even if the density is increased and that has excellent impact resistance. It is what.

  The present invention adopts the following configuration in order to solve the above points.

<Configuration 1>
A planar optical waveguide block formed by laminating a plurality of planar optical waveguides so that their upper surfaces are parallel to each other, and another planar optical light having an output end face coupled to an input end face of the planar optical waveguide block Each of the plurality of planar optical waveguides and the other planar optical waveguides has a configuration in which a core having a predetermined refractive index is covered with a clad having a refractive index lower than that of the core. Each of the cores forms a branching path that branches into a plurality from the input end face toward the output end face, and the upper surface of each planar optical waveguide constituting the planar optical waveguide block and another plane The input end face of the planar optical waveguide block and the output end face of the other planar optical waveguide are coupled to each other at a predetermined crossing angle with the upper surface of the planar optical waveguide, and the other plane Of the output end face of the optical waveguide A total of N cores of the N cores in each of the branch paths and the input end faces of each of the N planar optical waveguides constituting the planar optical waveguide block are coupled to each other. A three-dimensional planar optical waveguide.

  With such a configuration, since the planar optical waveguide block is three-dimensionally coupled to another planar optical waveguide, it is possible to reduce the size and realize a planar optical waveguide with excellent impact resistance. be able to.

<Configuration 2>
When the above planar optical waveguides are laminated and integrated, a total of N core ends of the input end faces of the respective planar optical waveguides are arranged on a predetermined straight line that intersects the upper surfaces of all the planar optical waveguides. The three-dimensional structure according to Configuration 1, wherein the three cores are arranged so as to maintain the arrangement interval of the N core ends in the N branch paths on the output end face of the other planar optical waveguide. Planar optical waveguide.

  By adjusting the positional relationship between the cores in this way, planar optical waveguides having an arbitrary configuration can be coupled to each other at an arbitrary crossing angle.

<Configuration 3>
3. The three-dimensional planar optical waveguide according to Configuration 1, wherein the crossing angle between the upper surface of each planar optical waveguide constituting the planar optical waveguide block and the upper surface of another planar optical waveguide is 90 degrees. .

  When the crossing angle is set to 90 degrees in this way, the planar optical waveguide that is usually produced most often can be miniaturized to form a three-dimensional planar optical waveguide.

<Configuration 4>
When a plane perpendicular to the optical axis of the transmitted light is used as a reference plane, the input end face of each of the planar optical waveguides and the output end face of the other planar optical waveguide are set at a predetermined angle with respect to the reference plane. The three-dimensional planar optical waveguide according to Configuration 1, wherein the input end face or the output end face is polished so as to be inclined.

  By obliquely polishing the coupling surface in this manner, transmission light can be prevented from being reflected, so that the coupling efficiency between the planar optical waveguide block and another planar optical waveguide is improved.

<Configuration 5>
The three-dimensional planar light guide according to Configuration 4, wherein each input end face of each planar optical waveguide is collectively polished so as to be inclined by the predetermined angle within a plane including the upper surface of the planar optical waveguide. Waveguide.

  As described above, when the end surfaces of the respective planar optical waveguides constituting the planar optical waveguide block are formed at a predetermined angle in the longitudinal direction, there is an influence due to the reflection of light at the coupling surface with the other planar optical waveguide. It is reduced.

  Hereinafter, embodiments of the present invention will be described using specific examples.

FIG. 1 is a perspective view showing a three-dimensionally coupled state of planar optical waveguides of the present invention.
In FIG. 1, four planar optical waveguides 1a to 1d having exactly the same configuration, each having a 1 × 4 branch, are laminated to form one planar optical waveguide block 2 surrounded by a broken line. In the example of this figure, a gap having a certain width is formed between the planar optical waveguides 1a to 1d. Each of the planar optical waveguides 1a to 1d may be laminated, for example, with an appropriate spacer interposed therebetween, or may be integrated by closely contacting without any gap. Separately, a 1 × 4 branched planar optical waveguide 3 having the same configuration as that of the planar optical waveguides 1a to 1d is prepared. This planar optical waveguide 3 will be referred to as another planar optical waveguide 3. Further, as shown in the figure, the end face T on the light input side of the substrate constituting the planar optical waveguide 3 is called the input end face, and the end face on the light branching output side is called the output end face. Each of the planar optical waveguides has a configuration in which a core having a predetermined refractive index is covered with a clad having a refractive index lower than that of the core.

  In the present invention, the planar optical waveguide block 2 and one other planar optical waveguide 3 are three-dimensionally coupled. That is, the upper surfaces of the planar optical waveguides 1a to 1d constituting the planar optical waveguide block 2 and the upper surfaces of the other planar optical waveguides 3 are coupled so as to intersect each other by 90 degrees. The top surface is the substrate surface on which the waveguide is formed. As a result, a total of four cores 5 consisting of the four branched cores 4 on the output end face of the planar optical waveguide 3 and the input end faces of the planar optical waveguides 1a to 1d constituting the planar optical waveguide block 2 are obtained. Are coupled to each other. The planar optical waveguide 3 has 1 × 4 branches, and the planar optical waveguides 1a to 1d also have 1 × 4 branches. Therefore, a 1 × 16 branched planar optical waveguide can be formed as a whole. Compared with the whole shown in FIG. 4, the width in the X-axis direction can be sufficiently narrowed, so that downsizing can be realized.

FIG. 2A is a perspective view of a completed planar optical waveguide in which the planar optical waveguides 1a to 1d and another planar optical waveguide 3 are coupled.
The planar optical waveguide after completion of what is shown in FIG. 1 is as shown in this figure. Generally, the breaking strength of a material having a rectangular cross section is proportional to the section modulus. Here, the section modulus is the width of the cross-section (the size of the X-axis direction) w, when the thickness of the (Y-axis direction size) t, can be expressed as wt ^2/6. That is, the strength is improved as the width w is reduced and the thickness t is increased. Since the planar optical waveguide having the configuration as in the present invention can suppress the spread in the width direction (X-axis direction in FIG. 1), not only can the size be reduced, but also the strength such as impact resistance can be obtained. Will also be excellent. Further, since the four planar optical waveguides 1a to 1d are laminated, the thickness t is increased and the strength is improved.

FIGS. 2B and 2C are explanatory diagrams for explaining the crossing angle between the planar optical waveguide block 2 and another planar optical waveguide 3.
In the first embodiment, the upper surfaces of the planar optical waveguides 1a to 1d constituting the planar optical waveguide block 2 and the upper surfaces of the other planar optical waveguides 3 are not necessarily in a state where they intersect each other exactly 90 degrees. There is no need to combine them. The configuration of each planar optical waveguide need not be the same. For example, one of the planar optical waveguides 1a to 1d may be a 1 × 8 branch. That is, any planar optical waveguide forms a branch path of 1 × N (N is a positive arbitrary integer of 2 or more) branching into a plurality of branches from the input end face toward the output end face. The core 4 is in a branch path of another planar optical waveguide 3. The number of stacked planar optical waveguide blocks 2 may be the same as the number of branches of other planar optical waveguides 3, and a plurality of arbitrary number of planar optical waveguides may be parallel to each other. A planar optical waveguide block formed by stacking may be manufactured.

  The position of the core 5 on the input end face of each of the planar optical waveguides 1a to 1d may be arbitrary. However, when the planar optical waveguides 1a to 1d are laminated and integrated, the ends of the cores 5 of these input end faces intersect with all the planar optical waveguides 1a to 1d as shown in FIG. They are arranged on a predetermined straight line 8. At the same time, it must be arranged accurately so as to maintain the arrangement interval of the ends of the four cores 4 in the four branch paths on the output end face of the planar optical waveguide 3. As long as this relationship is maintained, the crossing angle α between the upper surfaces of the respective planar optical waveguides 1a to 1d constituting the planar optical waveguide block 2 and the upper surfaces of the other planar optical waveguides 3 is as shown in FIGS. ), An angle less than 90 degrees may be used.

  By the way, when the end faces of the laminated planar optical waveguides 1a to 1d and the end faces of the planar optical waveguide 3 are coupled, the input end face and the output end face are brought into close contact with the optical axis in the longitudinal direction of the optical waveguide. Then, light is reflected on the end face, resulting in a large coupling loss. Therefore, normally, both input and output end faces are polished obliquely so as to reduce light reflection. Therefore, in the present invention, when the plane perpendicular to the optical axis of the transmitted light is used as the reference plane, the input end face and the output end face of the planar optical waveguide are inclined by a predetermined angle with respect to the reference plane.

FIG. 3 shows a planar optical waveguide of Example 3, FIG. 3 (a) is a side view of one example, and FIG. 3 (b) is a side view of another example.
For example, as shown in FIG. 3A, when the input end faces of the laminated planar optical waveguides 1a to 1d and the output end face of the planar optical waveguide 3 are polished so as to be inclined by an angle β, the planar optical waveguide 3 Light from the end face is not reflected and returned to the planar optical waveguide 3 again. In the embodiment shown in FIG. 5B, the input end faces of the respective planar optical waveguides 1a to 1d are polished individually and the output end face of the planar optical waveguide 3 is polished by an angle β. That is, the Z-axis direction in the figure is the optical axis direction of the transmission light, and the plane including the X axis and the Y axis is a plane perpendicular to the optical axis of the transmission light. The input end faces of the respective planar optical waveguides 1a to 1d and the output end faces of the other planar optical waveguides 3 are inclined by a predetermined angle. Thus, the light from the other planar optical waveguide 3 is not reflected and returned to the planar optical waveguide 3 again.

FIG. 4 shows a planar optical waveguide of Example 4, FIG. 4 (a) is a perspective view thereof, and FIG. 4 (b) is an input end face of the planar optical waveguides 1a to 1d and a planar optical waveguide. 3 is a plan view showing a relationship with an output end face of a waveguide 3. FIG.
As shown in FIG. 5B, the input end faces of the planar optical waveguides 1a to 1d and the output end face of the planar optical waveguide 3 are inclined by an angle θ within a plane including the upper surfaces of the planar optical waveguides 1a to 1d. Lump-polishing to allow When the input end faces of the planar optical waveguides 1a to 1d are polished in this way, the cores 5 of the input end faces of all the planar optical waveguides 1a to 1d and the cores 4 of the output end faces of the planar optical waveguides 3 As in the third embodiment, the coupling loss can be reduced and the influence of the reflected light is eliminated.

  As described above, the planar optical waveguide of the present invention is small in size because the other planar optical waveguide is three-dimensionally coupled to the planar optical waveguide block constituted by a plurality of laminated planar optical waveguides. It has become possible to make it possible to improve the strength such as impact resistance.

It is a perspective view showing one embodiment of the present invention. (A) is the perspective view of the planar optical waveguide after completion, (b) and (c) are explanatory drawings explaining the crossing angle. The planar optical waveguide of Example 3 is shown, (a) is a side view of a comparative example, (b) is a side view of an Example. FIG. 7 shows a planar optical waveguide of Example 4, where (a) is a perspective view and (b) is a plan view showing the relationship between an input end face and an output end face. It is a perspective view showing the conventional planar optical waveguide.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Planar optical waveguide 2 Planar optical waveguide block 3 Other planar optical waveguide 4 Core of other planar optical waveguide 5 Core of planar optical waveguide

Claims (5)

A planar optical waveguide block formed by laminating a plurality of planar optical waveguides such that their upper surfaces are parallel;
Another planar optical waveguide having an output end face coupled to the input end face of the planar optical waveguide block;
The plurality of planar optical waveguides and the other planar optical waveguides each have a configuration in which a core having a predetermined refractive index is covered with a clad having a refractive index lower than that of the core, , Each of which forms a branching path that branches into a plurality from the input end face toward the output end face,
The input end face of the planar optical waveguide block, with the upper surface of each planar optical waveguide constituting the planar optical waveguide block and the upper surface of another planar optical waveguide intersecting each other at a predetermined intersection angle The output end face of the other planar optical waveguide is coupled,
In addition, a total of N cores including N cores in N branch paths on the output end face of the other planar optical waveguide and input end faces of each of the N planar optical waveguides constituting the planar optical waveguide block The three-dimensional planar optical waveguides are characterized in that the cores are coupled to each other.   When the planar optical waveguides are laminated and integrated, a total of N core ends of the input end faces of the planar optical waveguides are arranged on a predetermined straight line that intersects the upper surfaces of all the planar optical waveguides. 3. At the same time, the other planar optical waveguides are arranged so as to maintain an arrangement interval of N core ends in N branch paths on an output end face of the other planar optical waveguide. Dimensional planar optical waveguide.   2. The three-dimensional planar shape according to claim 1, wherein the crossing angle between the upper surface of each planar optical waveguide constituting the planar optical waveguide block and the upper surface of another planar optical waveguide is 90 degrees. Optical waveguide.   When a plane perpendicular to the optical axis of the transmitted light is used as a reference plane, the input end face of each planar optical waveguide and the output end face of the other planar optical waveguide are set at a predetermined angle with respect to the reference plane. The three-dimensional planar optical waveguide according to claim 1, wherein the input end face or the output end face is polished so as to be inclined.   5. The three-dimensional planar shape according to claim 4, wherein each input end face of each planar optical waveguide is collectively polished so as to be inclined by the predetermined angle within a plane including the upper surface of the planar optical waveguide. Optical waveguide.

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