JPH01288802A - Light guide and its production - Google Patents

Abstract

PURPOSE:To connect two optical parts at a low loss by continuously changing the mode field on the inside surface of a light guide so that the shape of both end faces coincide with the shape of the mode field of the parts at both ends to be connected. CONSTITUTION:The quartz light guide 2 is disposed between an optical fiber 1 which is the passive optical part and a light emitting diode 3 as the active optical part. Both end faces of the light guide 2 have the end faces coincident with the shape of the mode field of the two parts to be connected and are so constituted that the mode field changes continuously on the inside surface of the light guide. In addition, the deposition patterns of fine particles of SiO2 are so changed as to eliminate the mismatch of the mode field between the optical fiber 1 and the light guide 2 and between the guide 2 and the light emitting diode 3 to gradually change the concn. and quantity so that the core diameter and the refractive indices coincide.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for coupling an optical waveguide between an active optical component such as a light source or a light receiving element and a passive optical component such as an optical fiber.

(Prior Art) Generally, an optical communication system uses an optical fiber that guides light.
It consists of passive optical components such as optical waveguides and active optical components such as light sources, light receiving elements, and optical switches. Therefore,
Technology for connecting passive optical components and active optical components is essential for constructing optical communication systems. Here, a semiconductor device is generally used as the active optical component, and has the ability to mutually convert electrical signals and optical signals. Passive optical components are made of quartz glass, plastic, multi-component glass, etc., and it is important to guide light with low loss.

Furthermore, there are currently three techniques for connecting these active optical components and passive optical components, as described below. That is, to explain an example of connection between a light source and an optical fiber, as shown in FIG. 9, there is a direct coupling method in which the optical fiber 20 and the light source 21 are butted together without changing their shape, etc., and as shown in FIG. As shown in FIG. This is a fiber-lens coupling method in which the shape of the end face of the fiber is processed to connect it to the light source 21 as a tipped optical fiber 23 that has a lens-like focusing ability.

(Problem to be Solved by the Invention) However, in the conventional optical waveguide coupling method, the conventional direct coupling method has a connection loss of about 10% due to the following reasons.
There is a problem that it is as large as dB.

That is, in passive optical components such as optical fibers and optical waveguides, the distribution of propagating optical power is Gaussian, and the mode field diameter is a circle with a diameter of about 10II11. On the other hand, active optical components have an elliptical mode field with a short axis of about 1 μm and a long axis of about 5 μm, as shown in Figure 12, due to semiconductor manufacturing and the properties of the drive circuit. Due to the difference in mode field (shape, size) of the parts, the connection loss between the two ends up being about 10 dB. In addition, the method of combining individual lenses via lenses has problems in terms of assembly workability and cost because the optical system becomes complicated.Furthermore, in the fiber lens combining method, the lens diameter is limited when processing the lens on the end face of the fiber. There are problems in that it cannot be freely selected because it is limited by the outer diameter of the fiber, and it cannot support an elliptical mode field.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical waveguide that connects a passive optical component and an active optical component with low connection loss, and a method for manufacturing the same.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, each end face has a mode field shape that matches the mode field shape of an optical component coupled to both end faces thereof, An optical waveguide is provided in which the mode field changes continuously within the optical waveguide so that the mode fields at both end faces are continuous, and
An optical waveguide is inserted between a passive optical component that guides light and an active optical component that has a photoelectric conversion ability so that their respective cores match, and the optical waveguide is brought into close contact with the passive optical component and the active optical component. An optical waveguide assembly is provided in which the optical waveguide is formed of quartz, and the core diameter, core shape, and refractive index changes are determined by the deposition pattern, dopant type, and concentration during flame deposition. A method of manufacturing an optical waveguide configured by changing the structure is provided.

(Function) Optical components with different mode field shapes are coupled by inserting an optical waveguide between them whose mode fields at both ends match the mode field of each optical component to be connected, resulting in low connection loss. Combine optical components.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of the optical waveguide of the present invention, and FIG. 2 is a top view of the optical waveguide of FIG. By inserting an optical waveguide 2 between which has a mode field shape on both end faces that matches the mode field shape of both optical components, and whose mode field shape on both end faces is continuously changed,
The present invention provides an optical waveguide that can connect passive optical components and active optical components with low loss. FIG. 1 shows an embodiment in which the passive optical component 1 is an optical fiber, the active optical component 3 is a light emitting diode, and the optical waveguide 2 is a quartz optical waveguide. An optical waveguide 2 is interposed between the optical fiber 1 and the light emitting diode 3, and is arranged so that the core portions through which the respective lights are guided are coincident in position. In addition, the optical fiber 1, the optical waveguide 2, and the light emitting diode 3 are set on a heat sink 7 in order to avoid temperature changes in these connecting parts and the light emitting diode element 3 as much as possible.

Since the optical fiber 1 is circular, a suitable fixing jig 8 is prepared on the heat sink 7 to fix the optical fiber 1, and the optical waveguide 2 and the light emitting diode 3 are fixed on the heat sink 7 with adhesive or the like. are doing. Here, the optical fiber 1 and the light emitting diode 3 are a commonly used optical fiber and a light source element, respectively. The optical waveguide 2 has the same core diameter and refractive index value so that there is no mode field mismatch between the optical fiber 1 and the optical waveguide 2 and between the optical waveguide 2 and the light emitting diode 3. is continuously changed.

Next, a method for manufacturing an optical waveguide according to the present invention will be explained.

The outline of the flame deposition method is shown in Fig. 7, for example, using silicon St.
For example, on the board 4 of
3. Glass fine particles formed by introducing raw materials such as iCI 4 and TiCI a are deposited,
By changing the moving path of the burner 10, that is, by making the moving pitch more or less dense, the amount of deposition can be changed to achieve an arbitrary thickness, and by changing the temperature and amount of raw materials, it is possible to create an optical waveguide with an arbitrary refractive index. be. The specific steps of the manufacturing method are as follows.

(1) SiO□ fine particles are deposited on the substrate 4 in a deposition pattern as shown in FIG. The upper part of FIG. 8 is the left side of FIG. This forms the cladding 12b.

(2) On top of that, a layer doped with SiO□ and a material with a higher refractive index than SiO□, for example, TiOz, is deposited in a pattern that is upside down from the deposition pattern in Figure 8, that is, the top is dense and the bottom is coarse. deposit Also, during this deposition, the concentration and amount of the material added to StO□ are gradually increased, and the optical fiber 1
and the optical waveguide 2 and between the optical waveguide 2 and the light emitting diode 3
The refractive index and core width are determined such that mode field mismatch does not occur between the two. Thereby, the core layer 2a is formed.

(3) The material formed by the above procedure is heated at an appropriate temperature to make it transparent vitrified.

(4) The core layer 2a is etched using an etching technique used in the production of semiconductor devices to produce a core 2a having a core diameter similar to that of the optical waveguide 2 shown in FIG.

(5) On top of that, apply St.
A cladding layer 2b' is formed by depositing O□.

(6) The material thus formed is vitrified again.

In the present invention, the method of fixing the optical fiber 1, the optical waveguide 2, and the light emitting diode 3 is not limited to the method shown in FIG. A fixing jig may be attached.
In addition, an optical fiber l and a light emitting diode 3 are connected to the optical waveguide 2.
or by inserting optical fiber 1 and light emitting diode 3
The optical waveguide 2 may be inserted and fixed in the heat sink 7. The heat sink 7 may be removed if it is not necessary. The connection surface and the connection surface between the waveguide device 2 and the light emitting diode 3 may be soaked with matching oil or the like having a refractive index between the optical fibers 1 and the light emitting diode 3, if necessary. Any shape may be used as long as the mode field shapes of the optical waveguides 3 and 3 match and this mode field changes continuously within the optical waveguide 2.

In addition, in the method of manufacturing the optical waveguide 2, the method of changing the core width, that is, the thickness of the core in the height direction is not necessarily limited to the deposition pattern shown in FIG. 8, but any pattern may be used depending on the performance of the equipment used. be able to. Multiple depositions can be performed if necessary. Similarly, the method of changing the core refractive index is not necessarily limited to changing the concentration or amount of one type of dopant; for example, when lowering the refractive index, it is possible to further add materials such as Bz O, F, etc. that lower the refractive index. On the other hand, in order to increase the refractive index, materials such as P, Os, Ge0t, etc. that increase the refractive index may be added.

(Effects of the Invention) As explained above, according to the present invention, each end face has a mode field shape that matches the mode field shape of the optical component coupled to both end faces, and the mode field is continuous inside the end face. The continuous mode fields on both end faces change the optical density, and the cores of the passive optical components that guide light and the active components that have photoelectric conversion ability match. Further, the optical waveguide is formed of quartz by interposing an optical waveguide and bringing the passive optical component and the active optical component into close contact with each other.
By configuring the core diameter, core shape, and refractive index by changing the deposition pattern, dopant type, and concentration during flame deposition, it is possible to eliminate the main cause of connection loss between conventional passive and active optical components. Since mismatches in mode fields can be eliminated, it is possible to connect active optical components and passive optical components with low connection loss.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the optical waveguide of the present invention, FIG. 2 is a top view of the optical waveguide shown in FIG. 1, and FIGS. Cross section III-III in Figure 2
, IV-TV, , V-V and Vl-νI cross-sectional diagrams, FIG. 7 is a schematic explanatory diagram of the flame deposition method, FIG. 8 is a diagram showing the deposition pattern, FIGS. 9, 10, and 11. are diagrams illustrating a conventional method of coupling a light emitting diode and an optical fiber, respectively.
FIG. 12 is a perspective view illustrating a field pattern of a light emitting diode. DESCRIPTION OF SYMBOLS 1... Optical fiber, 2... Optical waveguide, 3... Light emitting diode, 4... Substrate, 7... Heat sink, 8
... Optical fiber fixing jig, 10... Burner, 11
···duct.

Claims (3)

[Claims] (1) Each end face has a mode field shape that matches the mode field shape of the optical component coupled to both end faces, and the mode field changes continuously within the end face, so that the mode field on both end faces is continuous. An optical waveguide characterized by: (2) An optical waveguide is inserted between a passive optical component that guides light and an active component that has a photoelectric conversion ability so that their respective cores are aligned, and the optical waveguide is brought into close contact with the passive optical component. An optical waveguide combination body, characterized in that it is formed by combining the above-mentioned active optical component. (3) A method for manufacturing an optical waveguide, characterized in that the optical waveguide is formed of quartz, and its core diameter, core shape, and refractive index are changed by changing the deposition pattern, dopant type, and concentration during flame deposition.