JPH04109205A - Structure for coupling waveguide type optical element and optical fiber - Google Patents

Abstract

PURPOSE:To facilitate the discrimination of superposition by registering the marks of both of a waveguide type optical element and an optical fiber holder and coupling an optical waveguide and an optical fiber. CONSTITUTION:The optical waveguide 23 of the waveguide type optical element 21 is partly exposed and is formed as a coupling part. The marks 24 for positioning are formed around the optical waveguide 23 and the optical fiber 26 is fixed to the optical fiber holder 25 formed with the marks mating with the marks 24 of the waveguide type optical element 21. A core 30 is partly exposed and formed as a coupling member. The optical waveguide 23 and the optical fiber 26 are coupled by registering the marks of both of the waveguide type optical element 21 and the optical fiber holder 25 each other. Either of the waveguide type optical element 21 or the optical fiber holder 25 is shifted and moved to register the marks of both until the marks mate each other. The axial alignment stage is easily executed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a coupling structure between a waveguide type optical element and an optical core inode, and particularly relates to a waveguide type optical element having an optical waveguide and a coupling structure fixed to an optical fiber holder. It concerns the bonding structure of the optical core ino.

[Conventional technology] Optoelectronics technology has made remarkable progress in recent years, and audio equipment, communication equipment, etc.
Optical wiring between devices and coupling between optical waveguides formed in waveguide type optical devices, optical functional devices, etc. and optical fibers are required, and since the process has already reached the prototype stage, various attempts and proposals have been made. Many have been done.

For example, well-known methods for coupling an optical waveguide and an optical fiber include an end face direct coupling (butt joint) method, a lens coupling method, a prism coupling method, and the like.

In particular, when the fields of the optical waveguide and the optical fiber are relatively coincident, for example, the optical waveguide is formed on a glass substrate such as a fused silica (SiOt) substrate using an ion exchange method such as electric field ion exchange or thermal ion exchange. When coupling an optical fiber to an ion exchange waveguide or a lithium niobate (LiNbo3) optical waveguide, which is most commonly used for high-performance optical control devices, etc., an end-face direct coupling method is generally used.

Figure 5 shows an example of a coupling structure between an optical waveguide and an optical fiber using the end-face direct coupling method. The end face of the optical waveguide 2 formed above and the end face of the core 4 of the single mode optical fiber 3 are combined by adjusting their positions.

This method achieves a high efficiency of about -2 dB by matching the distribution of the incident wave and the waveguide mode and optimizing the parameters, and reduces Fresnel reflection loss by using anti-reflection coatings, etc., and the structure is Because it has various features such as simplicity, it is considered to be the most effective method, especially in the field of optical ICs.

Further, FIG. 6 shows an example of a coupling structure between an optical waveguide and an optical fiber by coupling light from the side, in which an optical fiber 13 embedded in a U groove 12 of an optical fiber holder 11,
The optical waveguide 15 formed on the substrate 14 is coupled to the optical waveguide 15 formed on the substrate 14.

To couple the optical fiber I3 and the optical waveguide 15, first, the optical fiber 13 is embedded in the groove 12 formed in the optical fiber holder 11, and the optical fiber 13 and one side 16 of the optical fiber holder 11 are mirror polished. do. Next, the above optical fiber holder II is placed on the S r 02 substrate 14 on which the optical waveguide 15 is formed, and a part of the field of the core 17 of the optical fiber 13 is radiated, and the radiated field and the optical waveguide 15 are Combine both fields.

In this method, there is no need to polish the end face of the optical waveguide 15, and it is only necessary to align the axes of the tip fiber 13 and the optical waveguide 15, and align the two translation axes and the tilt l axis in micron units. The alignment work can be considerably simplified compared to the end face direct bonding method.

[Problems to be Solved by the Invention] Although the conventional end face direct bonding method certainly has the many advantages mentioned above, at the same time various problems and drawbacks have been pointed out as follows.

That is, in the structure in which the end faces are coupled to each other as described above, there is a problem in creating the end faces that the input and output end faces of the optical waveguide 2 need to be polished at a submicron level.
When bonding and fixing the end face of the core 4 of the single mode optical fiber 3 to the end face of the core 4 of the single mode optical fiber 3 by adjusting their positions, the bonding force is extremely weak because the cross-sectional area of the joint is very small (
When aligning the end face of the optical waveguide 2 and the end face of the core 4 of the single mode optical fiber 3, three translational axes and two tilting axes (with multiple optical waveguides 2 and When coupling the single mode optical fibers 3, it is necessary to adjust the three axes, and this adjustment work becomes extremely complicated, which is a drawback in terms of axis alignment.

In addition, in the structure of coupling the optical fiber 13 embedded in the optical fiber holder 11 and the optical waveguide 15, although the alignment work can be considerably simplified compared to the conventional end face direct coupling method, There was a drawback that only one axis remained for alignment, and the alignment process itself could not be eliminated.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a coupling structure for a waveguide type optical element and an optical fiber, which allows the alignment process to be performed simply and with high precision.

[Means for Solving the Problems] In order to solve the above problems, the present invention employs the following coupling structure between a waveguide type optical element and an optical fiber. That is,
A structure for coupling an optical waveguide of a waveguide type optical element and a part of the core of an optical fiber, wherein a part of the optical waveguide of the waveguide type optical element is exposed and formed as a coupling part, and the optical waveguide A positioning mark is formed around the optical fiber, and the optical fiber is fixed to an optical fiber holder on which a mark matching the mark of the waveguide type optical element is formed, and a part of the core of the optical fiber is exposed. It is characterized in that it is formed as a coupling member, and the optical waveguide and the optical fiber are coupled by matching marks on both the waveguide type optical element and the optical fiber holder.

[Function] According to the coupling structure of a waveguide type optical element and an optical fiber according to the present invention, a positioning mark is formed around the optical waveguide of the waveguide type optical element, and the positioning mark is aligned with the mark on the optical fiber holder. By forming a mark, when coupling the optical waveguide and the optical fiber, by moving either the waveguide type optical element or the optical fiber holder,
Positioning is performed so that the marks on both the waveguide type optical element and the optical fiber holder coincide with each other.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of a waveguide type optical device according to the present invention, and is an electric field ion exchange linear optical waveguide (waveguide type optical device).
21 (hereinafter abbreviated as glass waveguide).

The glass waveguide 21 is a linear optical waveguide 23 formed on a glass substrate 22 by electric field ion exchange.

As the glass substrate 22, for example, a soda glass substrate such as Corning 7059 glass or Schott BK-7 glass, a fused silica (SiOl) substrate, or the like is suitably used.

The above-mentioned optical waveguide 23 is an optical waveguide having a step-like refractive index distribution and a constant ion concentration, and is a single mode optical waveguide having a width of 10 μm. Around this optical waveguide 23, a metal aluminum (A
A plurality of cross-shaped marks 24.24 consisting of ρ),
- are formed so as to sandwich the optical waveguide 23 with an interval of 300 μm, and to be lined up in a line along the optical waveguide 23 at equal intervals of 500 μm. Mark 2 above
The material constituting 424, . . . is an ultraviolet curing adhesive (
In addition to the above-mentioned AC, for example, titanium (T), chromium (
Metals such as Cr), gold (Au), colored glass, etc. are preferably used.

Further, FIG. 2 is a diagram showing an example of the optical fiber according to the present invention, and is a diagram showing an optical fiber 26 fixed to an optical fiber holder 25. As shown in FIG.

The optical fiber holder 25 is made of mirror-polished fused silica (Si).
n.) A linear U-groove 28 for inserting an optical fiber 26 is formed on a substrate 27 by photolithography.

The optical fiber 26 is a single mode optical fiber with a core diameter of 1.3 μm, and after being inserted into the U groove 28, the upper side surface 29 of the optical fiber 26 is mirror polished to expose a part of the core 30. It is something.

A plurality of cross-shaped marks 31.3+ are formed on the optical fiber holder 25 by photolithography.

are formed parallel to the optical fiber 26 at intervals of 500 μm along the optical fiber 26 so as to sandwich the optical fiber 26 at intervals of 300 μm. The positions of these marks 31.3+, . . .
They are formed to match the positions of the corresponding marks 24, 24, .I, respectively.

Next, a method for coupling the glass waveguide 21 and the optical fiber 26 will be explained with reference to FIG.

■ [See Figure 3 (a)] "Creation of optical fiber holder 25" A plurality of linear U grooves 42 for inserting optical fibers 26 are formed at intervals of 500 μm on the 5iot board 41 by photolithography, and these Insert the optical fibers 26 into each of the U grooves 42° 42, and connect these optical fibers 26.
, 26. The tip 43 of... is SiO! It is aligned and fixed so that it is flush with the side surface 44 of the substrate 41. Next, the upper surface 45 of the 5iOy substrate 41 and the upper side surface portion 46 of the optical fiber 26 are mirror-polished to a range of 11 μm from the center of the core 30 of the optical fiber 26 .

■[See Figure 3(b)] On the upper surface 45 of the Sin board 4X, a plurality of cross-shaped marks 3 with a size of 10 x 30 μ■ are formed by photolithography.
1.31. ..., optical fibers 26 with a spacing of 300 μm
500 along this optical fiber 26 so as to sandwich the
They are formed parallel to the optical fiber 26 at intervals of μm.

■ [See Figure 3 (C)] Using the machining process, Sin! By cutting the substrate 41 into a plurality of pieces, marks 3 to which the optical fibers 26 are fixed are formed.
One fiber optic holder 25 can be created.

``Creation of glass waveguide 21'' See FIG. 3(d) A linear optical waveguide 23 with a radius of 10 μm is formed on the glass substrate 22 by electric field ion exchange. This optical waveguide 23 is a single mode optical waveguide with a constant ion concentration and a step-like refractive index distribution.

Next, around this optical waveguide 23, a plurality of cross-shaped marks 24, 24 .・The optical waveguide 23 is spaced at a distance of 300 μm.
500μ along this optical waveguide 23 so as to sandwich the
They are formed so as to be arranged parallel to the optical waveguide 23 at regular intervals of m. The positions of these marks 2424, . . . are the same as those of the corresponding marks 31, 31 .
are consistent with their respective positions. Mark 24, 24
．． ,... In addition to the above-mentioned lift-off method, methods such as etching are also fully applicable.

Through the above steps, the glass waveguide 21 containing the marks 24 can be created.

■ "Refer to FIG. 3(e)" Coupling of the glass waveguide 21 and the optical fiber 26 -: The optical fiber 26 is placed on the optical waveguide 23 on the glass waveguide 21.

■ "See Figure 3 (J) Σ Observe both the marks 24 and the marks 31 from vertically above the optical fiber holder 25 using an optical microscope, move the end fiber holder 25 on the upper surface, and remove these marks 24.
and mark 31 completely overlap. It is determined that the alignment is complete when the marks 24 and 31 completely overlap each other and can be seen as one shape. After completing the alignment, the glass waveguide 21 and the optical fiber boulder 25
Temporarily fasten.

(See FIG. 3(g)) The glass waveguide 21 and the optical fiber boulder 25 are bonded and integrated using TJV adhesive.

The coupling loss between the glass waveguide 21 and the optical fiber 26 coupled in this manner is about 2 dB as an actual value per coupling, and it can be seen that the coupling state between the two is very good.

As described above in detail, according to the coupling structure of the glass waveguide 21 and the optical fiber 26, the glass waveguide 21
An optical fiber holder 2 in which marks 24, 24, . . . are formed around the optical waveguide 23 and an optical fiber 26 is fixed thereto.
Mark 24.24 of glass waveguide 2I on 5,...
Since the marks 31 and 31 that match are formed, when coupling the optical fiber 26 and the optical waveguide 23, both the mark 24 and the mark 31 are observed from the top of the optical fiber holder 25 using an optical microscope, and the optical fiber Holder 25 flat
It is only necessary to move the marks 24 and 31 by moving the marks 24 and 31 completely, making it very easy to determine the overlap.
The positioning of both the optical fiber and the optical waveguide 23 can be performed easily and with high precision, and there is no need to perform complicated axis alignment of the optical fiber and the optical waveguide in micron units as in the conventional method. Additionally, this alignment can easily be automated using image recognition.

Also, mark 24. ... and mark 31. - When coupling the optical fiber 26 and the optical waveguide 23, it is easier to distinguish the shape of the mark 24 and the mark 31 and to judge and evaluate the degree of overlapping of the mark 24 and the mark 31 compared to a simple dot-like mark. become. Therefore, mark 24 and mark 3
1 becomes easier, and the alignment process itself becomes easier.

Note that in the above embodiment, the mark 24 and the mark 31 . Although the shape of .
- As shown in (d), there is a circle with a crosshair ((a) in the same figure)
), 17-shape ((b) in the same figure), diamond shape ((C) in the same figure), or glove shape ((d) in the same figure).

[Effects of the Invention] As described in detail above, according to the present invention, there is provided a structure for coupling an optical waveguide of a waveguide type optical element and a part of the core of an optical fiber, A part of the optical waveguide of the element is exposed and formed as a coupling part, a positioning mark is formed around the optical waveguide, and the optical fiber forms a mark that matches the mark of the waveguide type optical element. A part of the core of the optical fiber is exposed to form a coupling member, and by aligning the marks on both the waveguide type optical element and the optical fiber holder, the optical waveguide can be connected to the optical fiber holder. Since it was decided to couple the optical fiber, when coupling the optical waveguide and the optical fiber, it is only necessary to completely overlap the marks on both sides, which makes it very easy to judge the overlap. Therefore, alignment of both the optical fiber and the optical waveguide can be performed easily and with high precision, and there is no need to perform complicated axis alignment of the optical fiber and the optical waveguide in micron units as in the conventional method. Furthermore, this alignment can be very easily observed and judged using an optical microscope or the like, and can easily be automated using image recognition.

In addition, the marks formed around the optical waveguide of the waveguide type optical element and on the optical fiber holder are used to determine the shape of these marks and the degree of overlapping of the marks when coupling the optical fiber and the optical waveguide. Judgment evaluation is facilitated and therefore the alignment process becomes extremely simple and easy.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an embodiment of the present invention, in which FIG. 1 is a perspective view of an electric field ion exchange linear optical waveguide, which is an example of a waveguide type optical device, and FIG. A perspective view of the holder, Figures 3 (a) to (g) are process diagrams explaining the method of coupling the glass waveguide and optical fiber, and Figures 4 (a) to (d)
5 and 6 are diagrams showing conventional examples, and FIG. 5 is a perspective view of a coupling structure of an optical waveguide and an optical fiber by the end-face direct coupling method. FIG. 6 is a perspective view of a coupling structure between an optical waveguide and an optical fiber by coupling light from the side. 27.4.1 Electric field ion exchange linear optical waveguide, glass substrate, optical waveguide, 24... Mark, optical fiber holder, ... optical fiber, fused silica substrate, ... -- U groove, core, 3 I... Mark. Figure 1

Claims (1)

[Claims] A structure for coupling an optical waveguide of a waveguide type optical element with a part of the core of an optical fiber, wherein a part of the optical waveguide of the waveguide type optical element is exposed and serves as a coupling part. a positioning mark is formed around the optical waveguide, the optical fiber is fixed to an optical fiber holder having a mark that matches the mark of the waveguide type optical element, and a positioning mark is formed around the optical waveguide; A waveguide is formed as a coupling member with a part exposed, and the optical waveguide and the optical fiber are coupled by matching marks on both the waveguide type optical element and the optical fiber holder. Coupling structure of type optical element and optical fiber.