JPH03196004A - Waveguide type optical device - Google Patents

Abstract

PURPOSE:To facilitate the coupling of a plane optical waveguide with optical fibers and to satisfactorily reduce loss due to coupling by forming the surface of a base stand supporting a substrate and connectors with silicon or ceramics having <=+ or -1 mum flatness. CONSTITUTION:Only the part 21 of a base stand 1 directly supporting a substrate 24 including a plane optical waveguide and connectors 25 holding optical fibers 26 is formed with a silicon wafer or a hard ceramic sheet. In this case, the surface flatness of a support member 2 is regulated to <=+ or -1 mum and the member 2 is integrated with a support frame 3 by fixing in the frame 3. When the connectors are slid on the base stand, the optical axes of the optical fibers held by the connectors can be aligned in a direction parallel to the base stand without moving in a direction perpendicular to the base stand. The plane optical waveguide can efficiently and easily be coupled with the optical fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to waveguide type optical devices. More specifically, the present invention relates to a waveguide-type optical device including a planar optical waveguide, and particularly to a novel device configuration that allows easy and low-loss coupling with an optical fiber.

BACKGROUND OF THE INVENTION Planar optical waveguides are sometimes used to construct various optical control elements, optical passive elements, and the like. In such cases, the planar optical waveguide is often used in conjunction with an optical fiber, which is the most popular optical waveguide medium.

FIG. 3(a) is an enlarged view showing the coupling portion between the optical fiber and the planar optical waveguide as described above.

As shown in the figure, a planar optical waveguide 32 and an optical fiber 33 formed on a base 31 are generally bonded to a resin-based adhesive 3.
4, but at this time, in order to suppress coupling loss, it is necessary to align the optical axes of the guided light beams. Therefore, in reality, the optical axis is adjusted for each optical fiber 33 and each optical fiber 33 is directly coupled to the planar optical waveguide 32. Such a complicated method can only be applied at an experimental level or in cases where there are a small number of bonding points.

FIG. 3(b) is a diagram showing a connector member used when coupling a plurality of optical fibers to a planar optical waveguide.

That is, when coupling a plurality of optical fibers 33 to a plurality of planar optical waveguides 32 formed on the surface of the base 310, it is too complicated to adjust the optical axis of each optical fiber. Therefore, as shown in FIG. 3(5), optical fibers 33 are arranged at intervals equal to the intervals of the planar optical waveguides 32 on the base 31.
By using the connector member 35 that holds the optical fibers 33, it is possible to handle a plurality of optical fibers 33 at once.

However, in the method shown in FIG. 3(b), it is still possible to connect a plurality of optical fibers at positions in two directions that are perpendicular to the optical axis direction of the optical fibers and mutually perpendicular to each other, and with respect to the mutual angles of the optical axes. 33 and the planar optical waveguide 32 must be adjusted. Therefore, Patent Application No. 3107 of 1988
No. 39 proposes a configuration of an optical device including a coupling auxiliary device that facilitates optical axis adjustment during coupling.

FIG. 4(a) is a diagram showing the constituent members of the above-mentioned coupling auxiliary device.

As shown in the figure, this auxiliary device is a base having a mounting surface with a groove 41a formed in the center for mounting a connector and a hole 41b corresponding to a bolt 43 for fixing a holder 42, which will be described later. A base 41, a holder 42 for fixing the optical waveguide base 44 on the mounting surface of the base 41, and an optical fiber 46.
It is mainly composed of a connector member 45 that holds the end portion of the connector member 45.

Here, the connector 45 is composed of an upper member 45a and a lower member 45b, and is configured to sandwich and hold the end of the optical fiber 46 between the pair of members. More specifically, grooves each having a V-shaped cross section are formed in the lower surface of the upper member 45a and the upper surface of the lower member 45b, and light is emitted into the tube defined by the grooves having the V-shaped cross section facing each other. A fiber 46 is clamped. The grooves having a V-shaped cross section are arranged at equal intervals to the pair of planar optical waveguides 44a on the base 44, and the optical axis of the optical fiber 46 is located at the upper member 4.
It is formed so as to be located on the surface where the groove 12 of 5a is formed. Therefore, after housing the optical fiber 46 in the groove of the upper member 45a, the lower member 45b is inserted into the upper member 45.
By fixing the upper member 45a to the position a, the positional relationship between the upper member 45a and the optical fiber 46 is determined regardless of the accuracy of assembly with the lower member 45b. The width of the lower member 45b matches or is narrower than the width of the groove of the base 41, while the width of the upper member 45a is wider than the width of the lower member 45b.

FIG. 4(b) is a diagram showing a state in which the optical fiber 46 and the planar optical waveguide 44a are coupled using the above-mentioned members.

As shown in the figure, the guiding waveguide base 44 is mounted on the base 41 so that the surface on which the planar optical waveguide 44a is formed is in contact with the surface of the base 41, and the holder 42 and the base 41 are connected by bolts. 43 or by using an adhesive. Therefore, the planar optical waveguide 44a is connected to the base 4.
1 and is fixed in direct contact with the top surface of the device.

On the other hand, in the connector member 45, a lower member 45b having the same width as the groove 41a is housed inside the groove 41a, and an upper member 45a wider than this is in contact with the upper surface of the base 41. As described above, by fixing the optical fiber 46 from the upper member 45a side, the upper member 45a and the optical fiber 46 are connected.
The positional relationship with is fixed. Since the upper member 45a and the base 41 are in direct contact with each other, the positional relationship between the optical fiber 46 and the upper surface of the base 41 is also fixed thereby.

In this way, by using the auxiliary member shown in FIG. 4(c), the optical axis of the optical fiber 46 and the planar optical waveguide 44a are fixed to each other with the upper surface of the base 41 as a reference. Further, since the width of the lower member 45b of the connector 45 matches the groove 41a of the base 41, the width of the lower member 45b of the connector 45 matches the groove 41a of the base 41, so that
The horizontal position of is also fixed by this.

Problems to be Solved by the Invention As described above, vertical alignment of the optical axes of the planar optical waveguide and the optical fiber is performed by fixing them to a planar holder.

FIG. 5(a) is a graph showing the relationship between the amount of axial misalignment in the connection between the planar optical waveguide and the optical fiber and the loss caused by it. Note that the amount of axis deviation in the graph shown in FIG. 5(a) refers to the vertical displacement of the optical axis of the optical fiber with respect to the optical axis of the planar optical waveguide, as shown in FIG. 5(b). It is.

As shown in the figure, in order to suppress the coupling loss due to axial misalignment between the planar optical waveguide and the optical fiber to within 1 dB, the amount of axial misalignment needs to be within 2 μm.

Therefore, the surface accuracy of the flat holder needs to be within 2 μm of flatness.

However, in reality, it is difficult to achieve a flatness of 2 μm or less, and when using the conventional waveguide optical device described above, there is a large variation in coupling loss due to axis misalignment, and it is difficult to achieve a flatness of 2 μm or less. The yield of products that achieve this is extremely low.

Therefore, the present invention solves the problems of the prior art described above, allows easy coupling of a planar optical waveguide and an optical fiber, and
The purpose of this invention is to provide a novel waveguide type optical device that can sufficiently reduce the coupling loss between the two.

According to the present invention, a base body including a plurality of planar optical waveguides whose end faces are arranged in a row on the same plane is mounted, and the ends of a plurality of optical fibers are connected to each other. A waveguide-type optical waveguide comprising a base having a shape to support and guide a connector member held at the same interval as the planar optical waveguide so that the optical fiber and the planar optical waveguide are optically coupled. Provided is a waveguide type optical device, wherein at least a surface of the base supporting the base and the connector member is formed of silicon or ceramics with a flatness within ±IAtm. be done.

Function: In the waveguide type optical device as described above, the base supporting the connector member has conventionally been made of metal such as stainless steel. However, when the base is made using metal materials, due to surface sagging during processing, etc.
It is extremely difficult to achieve the following smoothness. Therefore, when bases were made from various materials and the flatness was compared, it was found that a flatness of 2 μm or less can be achieved when hard ceramics or silicon wafers are used. Furthermore, it has been found that when mounting holes or the like are formed on a base made of these materials, the flatness deteriorates, and conversely, the flatness improves as the dimensions are smaller.

Therefore, according to a preferred embodiment of the present invention, among the bases,
In particular, only the base portion that directly supports the substrate including the planar optical waveguide and the connector holding the optical fiber is formed from a silicon wafer or a hard ceramic plate. In addition, the processing of the support member made of silicon wafer or hard ceramic plate is kept to a minimum, and the mounting holes are formed in a separately processed metal support frame, and the support frame and support member are integrated. Use it as a base. Here, the flatness of the surface of the support member is within 2 μm (±1 μm), and by fitting the support member into the support frame, both can be integrated.

When a base with a flat support surface as described above is used, by sliding the connector member on this base, the optical axis of the optical fiber held by the connector member can be displaced in a direction perpendicular to the base. It is possible to perform axis alignment in the direction parallel to the base. Therefore, in the waveguide type optical device according to the present invention, precise axis alignment can be easily performed.

In this waveguide type optical device, the connector member for holding and positioning the end of the optical fiber is made of a material such as Si, and has a groove formed in a smooth surface to accommodate the optical fiber. It can be configured as follows. Here, the groove for accommodating the optical fiber has, for example, a figure 7-shaped cross section, and is formed so that the end of the optical fiber is arranged on the same plane at the same predetermined interval as the planar optical waveguide to be coupled. be done. Further, the optical axis of each optical fiber is arranged on the same plane as the surface of the upper member of the connector member.

Hereinafter, the present invention will be described in more detail with reference to the drawings, but the following disclosure is only one embodiment of the present invention, and does not limit the technical scope of the present invention in any way.

Embodiment FIG. 1 is a diagram showing an example of the configuration of a base used in a waveguide type optical device according to the present invention.

Incidentally, this base is a member corresponding to the base 41 of the conventional waveguide type optical device shown in FIG.

As shown in the figure, this base 1 is composed of a support member 2 and a support frame 3. The support member 2 is a rectangular plate-like member, and is provided with a wide groove 2a extending from a pair of opposing sides toward the center for accommodating a portion of a connector member to be described later.

Here, the support member 2 is made of hard ceramics, and is finished to have a surface smoothness of 2 μm (±1 μm) or less. The support frame 3 is made of metal and has a recess 3a in the center for accommodating the support member 2 described above, and furthermore, holders, which will also be described later, are fixed to both sides of the recess 3a. A bolt hole 3b is provided for this purpose.

FIG. 2 is a diagram showing a specific example of the configuration of a waveguide type optical device using the base configured as described above.

In the figure, the objects to be coupled are a base body 24 having a pair of planar optical waveguides on its lower surface, and a pair of optical fibers 26 each having an end portion held by a connector member 25. The connector member 25 includes an upper member 25a and a lower member 2.
5b, and each optical fiber 26 is constructed by bonding and integrating the upper member 25a and the lower member 25b.
5b. Also,
The upper member 25a and the lower member 25b have grooves each having a V-shaped cross section formed on their opposing surfaces, and each optical fiber 26 is partially housed in the V-shaped groove. The optical axis of the upper member 25a is arranged on the same plane as the lower surface of the upper member 25a.

On the other hand, the base 21 has the same configuration as the base 1 shown in FIG. 1, and is composed of a support member 21a and a support frame 21b. The support member 21a is made of hard ceramics, and the upper support surface is finished to have a flatness of 2 μm or less. Further, a pair of wide grooves are formed in the support member to accommodate the lower member 25b of the connector member 25 and allow the connector member 25 to freely slide on the support member 21a within a predetermined range. However, as described above, if the supporting member 21a is highly processed, its flatness will be reduced, so the processing is kept to a minimum. Instead, bolt holes are formed on both sides of the support frame 21b for fixing holders (not shown) for fixing the base body 24 on which the planar optical waveguide is mounted.

A planar optical waveguide and an optical fiber are actually coupled using the members configured as above, and the coupling loss is calculated by subtracting the waveguide loss of the optical waveguide itself and the mode mismatch between the waveguide and the optical fiber from the total loss. was 0.3 dB, which FIi confirmed was significantly lower than 1 dB. In this manner, the waveguide type optical device according to the present invention can easily realize low-loss coupling.

Effects of the Invention As detailed above, in the waveguide type optical device according to the present invention, the base of the planar optical waveguide and the support member on which the connector member holding the end portion of the optical fiber to be coupled is mounted are smooth and smooth. Since it is made of ceramic or silicon wafer formed in the same manner, precise axis alignment can be easily achieved. Therefore, it becomes possible to easily couple the planar optical waveguide and the optical fiber with high efficiency.

In this method, the mounting surface of the base is used as a reference surface, and the base is mounted on the reference surface so that the surface on which the planar optical waveguide is formed is in contact with the optical axis of the optical fiber. This is due to the unique structure of this optical device, in which the connector is mounted on a certain surface, and in addition, at least the part where the planar optical waveguide and connector are mounted on the base used is made of silicon or ceramics with a flatness of 2 μm. This is due to the configuration of a highly accurate flat surface within

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a base used in the waveguide type optical device according to the present invention, and FIG. 2 is a diagram showing the configuration of the waveguide type optical device according to the present invention, FIG. 3 is a diagram showing the configuration of a conventional waveguide type optical device, and FIGS. 4(a) and (b) are diagrams showing the general configuration of an improved waveguide type optical device. , FIGS. 5(a) and 5(b) are graphs for explaining the coupling loss due to axis misalignment between the optical fiber and the planar optical waveguide, and a graph for explaining the definition of the amount of axis misalignment in this graph. It is a diagram. 33.46...Optical fiber, 41...Base, 42...Holder, 45...Connector member

Claims (1)

[Claims] A base body including a plurality of planar optical waveguides whose end faces are arranged in a line on the same plane is mounted, and the ends of the plurality of optical fibers are arranged at the same intervals as the planar optical waveguides. A waveguide type optical device comprising a base having a shape to support and guide a connector member to be held so that the optical fiber and the planar optical waveguide are optically coupled, the base comprising: at least the base; A waveguide type optical device characterized in that a surface of the base supporting the connector member and the connector member is formed of silicon or ceramics with a flatness of within ±1 μm.