JPH05100122A - Waveguide type optical device and production thereof and method for connecting optical device and other optical element - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a waveguide type optical device, a method for manufacturing the same, and a method for connecting the optical device to another optical element,
The purpose is to make this connection easy and accurate. [Structure] A thin film layer 28 made of, for example, Si is formed in the same process as a mask for forming a core 24A by etching
Is formed on the core layer 24, and the outer clad 30
After forming, the reference surface 28A is exposed on the thin film layer 28 by etching. The reference surface 28A is the core 24
Since it always has a predetermined positional relationship with A, it can be used for positioning an optical fiber or the like to be connected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type optical device, a method of manufacturing the same, and a method of connecting the optical device to other optical elements.

In the field of optical communication or optical transmission, in addition to optical transmitters, optical receivers and transmission lines, various optical devices such as optical switches and optical couplers are used. One form of optical device is a waveguide type. The waveguide type optical device is configured so that an optical waveguide is formed on a waveguide substrate and a light beam is confined in the optical waveguide to be controlled. In addition to the advantage that it can be used for mass production, it has the advantage that an electric field or magnetic field can be effectively applied.

In this type of waveguide type optical device,
Optical and mechanical connections to other optical elements such as optical fibers are often required, and it is desirable to be able to make such connections accurately and easily.

[0004]

2. Description of the Related Art Conventionally, in the case of connecting a waveguide type optical device and an optical fiber, the position of the optical fiber is individually adjusted with respect to the input / output end of the waveguide type optical device to obtain an optical fiber having a predetermined refractive index. A matching adhesive or the like is used to fix the input and output ends of the waveguide type optical device and the optical fiber.

It has also been attempted to form a groove or a pair of protrusions on a substrate of a waveguide type optical device and mount an optical fiber in the groove or the pair of protrusions, thereby eliminating the need for position adjustment during connection. There is.

[0006]

According to the former prior art, it takes a lot of time to adjust the position of the optical fiber, and complicated work is required to connect the waveguide type optical device and the optical fiber. There was a problem.

Further, in the latter prior art, the thickness of the waveguide layer in which the grooves and protrusions are formed varies due to problems in the manufacturing technology, which makes it difficult to accurately connect the waveguide type optical device and the optical fiber. There was a problem.

In particular, when connecting a single mode fiber having a core diameter of 5 to 10 μm and a silica optical waveguide,
Since positioning accuracy of 1 μm or less is required, it is difficult to set the thickness of the waveguide layer with accuracy of 1 μm or less, so that adjustment of position adjustment in the waveguide layer thickness direction is virtually achieved. Can not do it. If the waveguide type optical device and the optical fiber are not correctly connected, the connection loss increases.

The above problems occur not only when connecting an optical fiber to a waveguide type optical device, but also when connecting optical elements such as a light emitting element and a light receiving element to a waveguide type optical device.

The present invention has been made in view of such technical excessiveness, and an object thereof is to make it possible to easily and accurately connect a waveguide type optical device and an optical element such as an optical fiber. There is.

[0011]

The waveguide optical device of the present invention comprises an underclad having a relatively low refractive index, a core having a relatively high refractive index formed on the underclad, and an outer surface of the core. Of the outer clad having a relatively low refractive index formed on the under clad so as to cover the surface of the plane including the lower surface of the core or a plane parallel to the plane and separated from the plane by a predetermined distance. And a thin film layer formed in a region near the core, the upper surface of the thin film layer being exposed as a reference plane.

The method of manufacturing a waveguide type optical device of the present invention is applied to the waveguide type optical device of the present invention in which the thin film layer is formed on a plane including the upper surface of the core. Then, this method comprises the step of uniformly forming a core layer having a relatively high refractive index on the underclad having a relatively low refractive index, and the step of forming the core layer in the core layer and the region in the vicinity of the region in the core forming region. Forming a core forming thin film layer and a reference surface thin film layer made of a material having an etching rate sufficiently smaller than the etching rate of the core layer, and etching the core layer using these thin film layers as a mask, A step of removing the thin film layer on the core obtained by etching, and a relatively low refractive index outer clad made of a material having an etching rate sufficiently higher than the etching rate of the thin film layer so as to cover the outer surface of the core. And a step of partially etching the outer cladding to expose at least a part of the thin film layer as a reference surface. And a step.

The connection method of the present invention is applied to the connection of the waveguide type optical device according to the present invention and another optical element, and this method uses the reference surface of the guide member supporting the other optical element. The optical axis of the other optical element and the optical axis of the waveguide type optical device are positioned at the same position in the thickness direction of the optical device when they are brought into close contact with the reference surface of the waveguide type optical device. The shape of the guide member is determined, and the waveguide type optical device and the other optical element are fixed to each other in a state where the two reference surfaces are in close contact with each other.

[0014]

In the waveguide type optical device of the present invention, a thin film layer is formed at a predetermined position with respect to the core, and the upper surface of the thin film layer is exposed as a reference plane. When connecting the device to an optical element such as an optical fiber, the connection can be made accurately and easily using the reference plane.

When the thin film layer is formed on a plane including the upper surface of the core, the thin film layer for the reference plane is formed by the method of the present invention.
Since it can be easily formed in the same step as the mask thin film layer for forming the core by etching, forming the thin film layer for the reference plane does not hinder the manufacturing workability.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a glass soot deposition apparatus that can be used for carrying out the method of the present invention. Reference numeral 2 is a burner to which source gas and O ₂ and H ₂ for combustion are supplied. The burner 2 is reciprocally scanned by the X-axis drive device 4 in the left-right direction at a constant speed (for example, 100 mm / sec). It

Reference numeral 6 denotes a stage on which the substrate 8 is placed. The stage 6 is driven by the Y-axis drive device 10 at a constant speed in a direction from the front surface side to the back surface side of the paper or the opposite direction. It reciprocates at (for example, 1 mm / sec). The substrate 8 is for forming an optical waveguide on it,
Silicon wafers commonly used for semiconductor manufacturing can be used.

Reference numeral 12 is a combustion control device, which includes O ₂ and H ₂
Are mixed at a predetermined mixing ratio and supplied to the burner 2 at a predetermined flow rate. 14A, 14B and 14C are fuel gas supply devices, respectively, and gas flow meters 16A, 16B and 16C.
The raw material gas is sent out according to the flow rate of the carrier gas such as O ₂ sent from each of the above. In this example, the source gas supply devices 14A, 14B, and 14C are each made of SiC.
A raw material gas such as l ₄ and POCl ₃ is filled in a liquid phase. The raw material gas in the vapor phase may be used, and the flow rate may be directly adjusted by the gas flow meter. Reference numeral 18 denotes a gas flow meter for controlling the total flow rate of the mixed raw material gas.

The raw material gas blown from the burner 2 burns.
SiO due to flame hydrolysis due to baking ₂Such as oxides
This oxide is a white powdery oxide glass soot 20
Are deposited on the substrate 8.

By operating the burner 2 and moving the stage 6, the glass soot 20 is deposited on the substrate 8 with a uniform thickness. The glass soot deposited on the substrate 8 is vitrified by heating in an electric furnace or the like, so that a transparent film for an optical waveguide can be obtained. In the present specification, the "flame deposition method" is a method of heating the oxide glass soot deposited on the substrate by flame hydrolysis to vitrify it.

FIG. 2 is a process explanatory view of a method of manufacturing a waveguide type optical device showing an embodiment of the present invention. First, FIG.
As shown in (A), on the waveguide substrate 8 made of Si,
Applying the flame deposition method using the apparatus of FIG.
A low-refractive-index underclad 22 made of iO ₂ and a high-refractive-index core layer 24 mainly made of SiO ₂ are laminated in this order. Underclad 22 and core layer 24
The relative refractive index difference of is, for example, 1%. Under clad 2
2 and the core layer 24 each have a thickness of about 20 μm,
It is about 6 μm.

Next, as shown in FIG. 2B, a core forming thin film layer 26 and a reference surface thin film layer 2 are formed on the core layer 24.
8 and 8 are formed. The material of the thin film layers 26 and 28 is Si, and the thickness of about 0.5 μm is sufficient.

A plan view of the waveguide substrate at this time is shown in FIG. In this embodiment, the core thin film layer 26 extends to the end of the waveguide substrate 8, and two reference plane thin film layers 28 are formed in a rectangular shape on both sides of the end of the core thin film layer 26. To do. The dimensional accuracy of the thin film layers 26 and 28 on the plane can be sufficiently enhanced by a normal patterning technique.

After that, as shown in FIG. 2C, the core layer 24 is etched by using the thin film layers 26 and 28 as masks. Since the etching rate of the core layer 24 made of SiO _{2 as a} main component is sufficiently higher than the etching rates of the thin film layers 26 and 28 made of Si, this etching removes unnecessary portions of the core layer 24 and the thin film layer 26. The core 24A remains under the thin film layer 28, and a part of the core layer 24B similarly remains under the thin film layer 28.

After the thin film layer 26 on the core 24A is removed, as shown in FIG. 2D, SiO _{2 is} mainly formed on the underclad 22 by the flame deposition method so as to cover the outer peripheral surface of the core 24A. The outer cladding 30 having a low refractive index is formed. The components of the outer clad 30 are adjusted so that the refractive index of the outer clad 30 becomes equal to the refractive index of the under clad 22. The thickness of the outer clad 30 is about 20 μm.

Finally, as shown in FIG. 2E, the outer clad 30 is partially etched away using an appropriate mask to expose the upper surface of the thin film layer 28 as a reference surface 28A. A plan view of the waveguide substrate at this time is shown in FIG. By this etching, the grooves 32 are formed symmetrically on both sides of the core 24A.

The accuracy of determining the position of the groove 32 thus formed in the planar direction can be obtained on the order of submicrons by a normal patterning technique, and the waveguide of the reference surface 28A, which is the bottom surface of the groove 32, can be obtained. The position in the layer thickness direction substantially coincides with the upper surface of the core 24A.

The positional deviation between the reference surface 28A and the upper surface of the core 24A in the thickness direction of the waveguide layer corresponds to the thickness of the thin film layer 28, and the variation in the thickness of the thin film layer 28 is 0.1 μm or less. The relative positional relationship between the core 28A and the core 24A can be easily set to a preset positional relationship.

A method of connecting the waveguide type optical device thus manufactured and the optical fiber will be described. An exploded perspective view of the connection structure in this case is shown in FIG. 5, and a side view of the connection structure is shown in FIG.

Reference numeral 38 is a guide member for supporting the optical fiber 34. The guide member 38 is a rectangular parallelepiped block in which a groove 36 into which the optical fiber 34 is fitted is formed. In this guide member 38, the surface on which the optical fiber 34 is mounted serves as the reference surface 40. Optical fiber 34 is groove 3
6, the guide member 38 is inserted up to the approximate center.
The optical fiber 34 and the optical fiber 34 are fixed to each other with an adhesive.

When the optical fiber 34 and the waveguide type optical device are connected to each other, the core 42 of the optical fiber 34 and the core 24A of the waveguide type optical device are positioned coaxially in order to obtain high optical coupling efficiency. Required.

In this embodiment, the reference surface 40 of the guide member is
Is in close contact with the reference surface 28A of the waveguide type optical device, and the groove 32 and the core 24A and the core 42 are positioned so as to be coaxial with each other when the convex portion of the guide member 38 is just fitted into the groove 32. The shape of the guide member 38 is set.

As a result, the optical fiber 34 and its guide member 38 are attached to the end of the waveguide type optical device, and a pressing force is applied to both ends of the optical fiber 34 so that the end face of the optical fiber 34 comes into close contact with the end face of the core 24A. By mechanically fixing each other in this state with, for example, an adhesive, mechanical and optical connection can be easily performed.

According to the present embodiment, when the reference plane is set on the waveguide substrate 8 or the outer surface of the outer cladding 30 in the conventional method, the thickness of the waveguide layer is caused by the manufacturing error of the thickness of the core layer or the cladding layer. As compared with the case where the positional deviation in the direction was extremely large, it is possible to position the optical fiber accurately without adjustment.

Although the reference surface thin film layer 28 is formed on the plane including the upper surface of the core 24A in the above embodiments, the reference surface thin film layer may be formed on the plane including the lower surface of the core 24A. Good. In this case, in the process of FIG. 2A, the glass soot of the underclad 22 and the core layer 24 is not deposited in the same step, but first, the glass soot for underclad is deposited on the waveguide substrate. Then, after vitrifying this to form an underclad, a thin film layer for a reference surface is formed on the underclad, and then the core layer is formed.

Further, in the embodiments described above, the optical element to be connected to the waveguide type optical device is an optical fiber, but a light emitting element such as a laser diode or a light emitting diode, a light receiving element such as an APD or an active / active element. The present invention can also be applied when connecting a passive optical device to a waveguide optical device.

[0037]

As described above, according to the present invention,
The waveguide type optical device and other optical elements can be easily and accurately connected.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a glass soot deposition apparatus applicable to a method of manufacturing a waveguide type optical device of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process of a waveguide type optical device showing a preferred embodiment of the present invention.

FIG. 3 is a plan view of a thin film layer according to a preferred embodiment of the present invention.

FIG. 4 is a plan view of a reference plane according to a preferred embodiment of the present invention.

5 is an exploded perspective view of a connection structure between a waveguide type optical device and an optical fiber manufactured by the manufacturing process of FIG.

FIG. 6 is a side view of the connection structure of FIG.

[Explanation of symbols]

 8 Waveguide Substrate 22 Underclad 24 Core Layer 24A Core 26, 28 Thin Film Layer 28A Reference Plane 30 Outer Clad 34 Optical Fiber 38 Guide Member

Claims (6)

[Claims] 1. An underclad (22) having a relatively low refractive index
A core (24A) having a relatively high refractive index formed on the underclad, and the underclad (22) so as to cover the outer surface of the core.
Relatively low-index outer cladding formed on top (30)
And a thin film layer (28) formed on a plane including the lower surface of the core or in a plane parallel to the plane and separated from the plane by a predetermined distance in the vicinity of the core. A waveguide type optical device, wherein the upper surface of the layer is exposed as a reference surface (28A). 2. The waveguide type optical device according to claim 1, wherein the thin film layer (28) is formed on a plane including an upper surface of the core (24A). 3. The method of manufacturing a waveguide type optical device according to claim 2, wherein a core layer (24) having a relatively high refractive index is uniformly formed on the underclad (22) having a relatively low refractive index. And a thin film layer (26) for forming a core and a reference surface for forming a core in the core forming region of the core layer and a region in the vicinity of the region, each of which has an etching rate sufficiently smaller than the etching rate of the core layer. Forming the thin film layer (28) of the core layer (24) and using these thin film layers (26, 28) as a mask.
And a thin film layer (26) on the core (24A) obtained by the etching.
And a step of forming a relatively low refractive index outer clad (30) made of a material having an etching rate sufficiently higher than the etching rate of the thin film layer so as to cover the outer surface of the core (24A), Partially etching the outer clad to expose at least a part of the thin film layer (28) as a reference plane (28A), the method for producing a waveguide type optical device. 4. The manufacture of a waveguide type optical device according to claim 3, wherein the main component of the core layer (24) is SiO ₂ , and the thin film layers (26, 28) are composed of Si. Method. 5. A method for connecting a waveguide type optical device according to claim 1 or 2 to another optical element, the reference surface (4) of a guide member (38) supporting the other optical element.
(0) is brought into close contact with the reference surface (28A) of the waveguide type optical device, the optical axes of the other optical elements and the optical axis of the waveguide type optical device are at the same position in the thickness direction of the optical device. The shape of the guide member (38) is determined so as to be located at, and the waveguide type optical device and the other optical element are mutually fixed in a state where the reference surfaces (40, 28A) are in close contact with each other. A method for connecting a waveguide type optical device and another optical element, which does not require position adjustment in the thickness direction. 6. The method of connecting a waveguide type optical device to another optical element according to claim 5, wherein the other optical element is an optical fiber.