JPH10160981A - Optical waveguide module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To package an optical semiconductor element and an optical waveguide varying in working polarization planes without alignment by disposing an optical element in the upper step part of a base plate formed with a difference in level, fixing the flank of an optical waveguide substrate formed with the optical waveguide on one main surface to the lower step part and optically coupling the optical element and the optical waveguide of the optical waveguide substrate. SOLUTION: The difference in level is formed on the base plate 1. An electrode pattern 4 is mounted at its upper step part and the optical element 2 is mounted on this electrode pattern 4. The lower step part is formed as a groove 6 formed to a straight shape from the light emitting section of the optical element 2 toward the light emitting direction. The optical waveguide substrate 3 formed with the optical waveguide 3a on its one main surface is fixed with its flank 3b faced downward to the groove 6 via an adhesive 5, such as epoxy resin, by which the optical element 2 and the optical waveguide 3a of the optical waveguide substrate 3 are exactly optically coupled. In such a case, the electrode pattern 4 is positioned to the flank 6a of the groove 6 extending to the straight shape with relatively high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide module used in the field of optical communication and optical information processing, and more particularly to an optical element such as a light emitting element or a light receiving element and an optical waveguide element such as an SHG element on a base. The present invention relates to an optical waveguide module integrated with an optical element, in which are integratedly mounted.

[0002] The present invention also relates to an optical waveguide module integrated with an optical semiconductor element, in which an optical semiconductor element and an optical waveguide element whose operating polarization directions are different from each other by 90 degrees can be easily mounted on a base.

[0003]

2. Description of the Related Art Conventionally, an optical semiconductor element such as a light emitting element or a light receiving element such as a semiconductor laser and an optical waveguide element are connected to each other through a lens system by connecting separately constructed modules. there were.

For this connection, the optical semiconductor element is actually made to emit light, coupled to one end of the waveguide of the optical waveguide element by a lens system, and the alignment is performed while monitoring the output light from the other end of the waveguide. A method (active alignment method) has been adopted.

On the other hand, there has been proposed a method of hybrid mounting an optical semiconductor element and an optical waveguide element on the same substrate with reference to positioning markers, stoppers and the like (for example, Japanese Patent Laid-Open No. 6-214129). Reference).

According to this method, the optical semiconductor element and the optical waveguide element are aligned without causing the optical semiconductor element to emit light.
This method is called passive alignment, and only requires high-precision patterning of positioning markers and stoppers on the substrate, compared to the active alignment method described above.
Since the connection between the optical semiconductor element and the optical waveguide can be performed very easily, it is excellent in mass productivity, and is attracting attention as a low cost technology for an optical transmission / reception module for optical communication and a commercial SHG blue laser module.

[0007]

However, when the optical waveguide element has an operation polarization dependence, not only the optical semiconductor element is aligned with the optical semiconductor element but also the polarization planes of the optical semiconductor element and the optical waveguide element are made to coincide with each other. It becomes necessary. In particular, when the optical waveguide device operates in the TM mode, the optical semiconductor element such as a semiconductor laser generally operates in the TE mode.
Both cannot be combined on the same plane. Also,
There is also a method of coupling by rotating the polarization plane by 90 degrees using a half-wave plate or the like. However, in general, direct connection results in a large loss due to an increase in the number of components and the thickness of the wave plate. This necessitates the use of a lens system,
There are problems that not only the number of parts further increases but also the configuration becomes complicated.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide an optical waveguide module in which an optical semiconductor element and an optical waveguide having different operation polarization planes can be mounted without adjustment.

[0009]

According to an optical waveguide module for solving the above-mentioned problems, an optical element for emitting and / or receiving light is disposed on an upper portion of a base having a step, and a lower portion of the base is provided. Wherein the side face of an optical waveguide substrate having an optical waveguide formed on one principal surface is fixed, and the optical element is optically coupled to the optical waveguide of the optical waveguide substrate.

[0010] Further, the upper surface of the base is a (110) silicon substrate, and the steps of the base are formed by anisotropic etching. In this case, the base may be configured so that a plurality of substrates are stacked.

Thus, a step for mounting the optical waveguide perpendicular to the substrate is formed in a part of the base, and the electrode is positioned and manufactured with high precision with respect to the end face of the step. The optical semiconductor element is mounted on the optical waveguide, and the optical waveguide is mounted along the end face of the stepped portion, so that the optical semiconductor element and the optical waveguide can be automatically positioned and the polarization plane can be aligned.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an optical waveguide module integrated with an optical semiconductor device according to the present invention will be described below with reference to the drawings. Optical waveguide module S shown in FIG.
Is a substrate having a single crystal silicon substrate, a semiconductor laser as an optical semiconductor element as the optical element 2, and an optical waveguide substrate 3 having a periodic polarization inversion structure as an optical waveguide element.
A so-called SHG blue laser module is configured using each of the PM-SHG (quasi phase matching second harmonic generation element) elements.

Here, the base 1 is formed with a step,
The electrode pattern 4 and the electrode pattern 4 are provided on the upper portion 1a.
The optical element 2 is mounted thereon. The lower part is a groove 6 formed linearly from the light emitting part of the optical element 2 in the light emitting direction, and the optical waveguide substrate 3 having the optical waveguide 3a formed on one main surface is disposed on the side surface 3b. The optical element 2 and the optical waveguide 3a of the optical waveguide substrate 3 are accurately optically coupled to each other by being fixed to the groove 6 via an adhesive 5 such as an epoxy resin.

That is, the electrode pattern 4 is positioned with high precision relative to the side surface 6a of the linearly extending groove 6, and the optical element 2 is mounted on the electrode pattern 4, while The waveguide substrate 3 is fixed to the bottom 6c of the groove with an adhesive 5 in close contact therewith. The positioning in the horizontal (X) direction is performed with the positional accuracy between the side surface 6a of the groove 6 and the electrode pattern 4, and in the height (Y) direction, the depth of the groove 6 is controlled (the degree of etching described later). By making the corners of the optical waveguide substrate 3 coincide with the corners 6b of the groove 6, passive alignment between the light emitting portion of the optical element 2 and the end of the optical waveguide 3a of the optical waveguide substrate 3 is easily and accurately realized. Things.

Next, a specific method of manufacturing the base 1 will be described. First, as a material for forming the base 1, a single crystal silicon substrate having a (110) main surface of the base 1 is prepared. The surface of the silicon substrate is thermally oxidized (heat-treated in an oxygen atmosphere at about 1050 ° C.) to about 1 μm.
A thermal oxide film of a degree is formed.

Furthermore, in order to provide a step (including a concave shape, etc.) of a predetermined shape with respect to the base 1, a known opening is formed so that an opening of a predetermined shape is formed except for a mounting portion of the optical element 2. Patterning is performed using photolithography and anisotropic etching. At this time, (11)
1) It is important to pattern so that the surface comes. However, the end face on the optical element 2 side and the bottom face 6c of the groove 6 are not flat because a crystal plane equivalent to the (111) plane is generally exposed. For this reason, in the vicinity of the mounting portion of the optical element 2, the crystal face is removed by cutting with a dicing device or the like to form the groove 7.

The base 1 may be made of a material other than single crystal silicon, and desirably has a desired hardness, toughness, or cleavage so as to be suitable for microfabrication.

Next, another method of manufacturing the base will be described. As shown in FIG. 2A, first, a silicon substrate 11 whose main surface is a (110) plane for patterning and a base substrate 12 similar to this are prepared. And FIG.
As shown in (b), the silicon substrate 11 and the base substrate 12 are bonded by a known surface activated bonding method. Thereby, an amorphous layer is formed at the joint 13. Next, in order to form a groove for mounting the optical waveguide substrate in a partial region of the main surface of the silicon substrate 11, a mask pattern 1 having an opening 15 and having resistance to an etching solution described later.
4 is formed. Thereafter, potassium hydroxide (KO)
H), sodium hydroxide (NaOH), EPW (ethylenediamine + pyrocaterol + water), hydrazine, TM
By dipping in an etchant such as AH (tetramethylammonium hydroxide), the opening 15 without the mask pattern 14 is etched to form a predetermined angle (11).
1) A groove 16 having an inner inclined surface 11a is formed. At this time, the joint 13 serves as an etching stopper, and a flat step bottom can be obtained.

The base substrate 12 is made of a single crystal material such as lithium niobate, lithium tantalate, lithium tetraborate or the like, a glass material such as BK7 (trade name of Hoya Corporation), quartz, silicon, gallium arsenide, etc. The semiconductor material described above can be suitably used, but any material having good bonding properties with the silicon substrate 11 and a thermal expansion coefficient close to that of silicon can be suitably used.

In the above example, a light emitting element is used as an optical element. However, a light receiving element may be used, and the optical waveguide substrate is not limited to the SHG element. It can be changed as appropriate and implemented.

[0021]

According to the optical waveguide module of the present invention,
Extremely productive optical waveguides that can easily align the optical element and optical waveguide substrate and align the polarization plane without the use of a half-wave plate or lens as in the past and with passive alignment. Modules can be provided.

[Brief description of the drawings]

FIG. 1 is a view for explaining an embodiment of an optical waveguide module according to the present invention, wherein (a) is a plan view, (b) is a front view, and (c) is a side view.

FIGS. 2A to 2D are cross-sectional process diagrams illustrating a method of manufacturing a base of an optical waveguide module according to the present invention.

[Explanation of symbols]

 1: Base 2: Optical element 3: Optical waveguide substrate 4: Electrode pattern 5: Adhesive 6: Groove 11: Silicon substrate 12: Base substrate S: Optical waveguide module

Claims (2)

[Claims] An optical waveguide in which an optical element for emitting and / or receiving light is disposed on an upper portion of a base having a step, and an optical waveguide is formed on one main surface of a lower portion of the base. An optical waveguide module, wherein a side surface of a substrate is fixed, and the optical element and the optical waveguide of the optical waveguide substrate are optically coupled. 2. The optical waveguide module according to claim 1, wherein an upper surface of the base is a silicon substrate having a (110) plane, and a step of the base is formed by anisotropic etching.