JPS63311212A - Optical waveguide device and method for packaging optical waveguide - Google Patents

Abstract

PURPOSE:To realize optical axis alignment only by fitting a waveguide chip into a recessed part and arranging an optical fiber in a groove part and to realize optical coupling, by forming the groove part in which an optical waveguide and the optical axis of the optical fiber coincide in a state where the waveguide chip is fitted on a substrate. CONSTITUTION:The titled device includes the waveguide chip 1 on which the optical waveguide 3 is formed and the substrate 2 having the recessed part 4 in which the waveguide chip 1 is fitted, and the groove parts 5A-5C are formed on the substrate 2. In other words, the groove parts 5A-5C are provided with width in which the cores of the optical fibers 6A-6C coincide with the end face of the optical waveguide 3 when the optical fibers 6A-6C are arranged at the position of a pattern including a line in which the optical waveguide 3 is extended virtually to the substrate 2 side in its center part at the state where the waveguide chip 1 is fitted in the recessed part 4. In such a way, only by fitting the waveguide chip 1 in the recessed part 4 of the substrate 2 and arranging the optical fibers 6a-6C on the groove parts 5A-5C, it is possible to perform the optical axis alignment inevitably based on the function of the depth of the groove parts 5A-5C and the existence of the optical waveguide 3 in a longitudinal direction.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical waveguide device used in fields such as optical communication,
This article concerns a method for mounting optical waveguides.

[Conventional technology]

As a conventional technology for connecting optical waveguides and optical fibers, the 1986 IEICE General National Conference Journal (10-301
> are known. This technology is
It is characterized by creating three-part optical waveguide modules and fixing these modules by metal welding using a laser.

[Problem that the invention seeks to solve]

However, since the above-mentioned conventional technology consists of three modules, a special jig is required for optical axis alignment during fixation, and moreover, there are problems in that it takes a long time.

In addition, when fixing an optical fiber to a metal tube, it is necessary to use resin, and there is a large difference in coefficient of thermal expansion and thermal contraction between this resin and the materials that make up the metal tube. Mechanical distortion may occur in the parts.

Therefore, the present invention provides an optical waveguide device that can couple an optical fiber and an optical waveguide with low loss, and that can be easily assembled and fixed without taking time for optical axis alignment, and a method for mounting the same. The purpose is to provide.

[Means for solving problems]

The optical waveguide device according to the present invention includes a waveguide chip on which an optical waveguide is formed, and a substrate having a recessed portion large enough to fit the waveguide chip, and this substrate has a groove portion as described below formed therein. It is characterized by In other words, when the optical fiber is placed in the groove, with the waveguide chip fitted into the recess, the optical fiber is placed at the position of a line pattern whose central portion includes a line that is a virtual extension of the optical waveguide toward the substrate.
The depth is such that the core of this optical fiber and the end face of the optical waveguide coincide.

Further, the method for mounting an optical waveguide according to the present invention includes a first step of placing a waveguide chip on the top surface of a substrate, and forming a first mask pattern matching the waveguide chip on the top surface of the substrate; A second step of etching the substrate from the top surface through the first mask pattern to form a recess large enough to fit the waveguide chip in a self-aligned manner; , a third step of forming a second mask pattern having an opening at the position of the line pattern including a line in the center of which the optical waveguide is virtually extended toward the substrate; A fourth step of etching the substrate from the top surface to form a groove with a depth that matches the core of the optical fiber and the end surface of the optical waveguide when the optical fiber is placed, and fitting the waveguide chip into the recess. The present invention is characterized in that it also includes a fifth step of arranging and fixing the optical fiber in the groove.

[Effect]

Since the optical waveguide device according to the present invention is configured as described above, by simply fitting the waveguide chip into the recess of the substrate and arranging the optical fiber in the groove, the effect of the depth of the groove can be adjusted. Due to the presence of the optical waveguide in the longitudinal direction, optical axis alignment is inevitably achieved.

Further, since the optical waveguide mounting method according to the present invention is configured as described above, the recess into which the waveguide chip is inserted is formed in the substrate in a self-aligned manner, and therefore the optical axis alignment with the optical fiber can be easily performed. act to do so.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4 of the accompanying drawings.In the explanation of the drawings, the same elements are denoted by the same reference numerals, and Omit the explanation.

FIG. 1 is an assembled perspective view of an optical waveguide device according to an embodiment of the present invention. In the figure, an optical waveguide 3 is formed in a waveguide chip 1, and here it is an optical waveguide capable of producing two outputs per person. Although the waveguide chip 1 is a rectangular parallelepiped, the substrate 2 is also a rectangular parallelepiped, and its thickness is larger than that of the waveguide chip 1. A recess 4 is formed in the center of the substrate 2 and is large enough for the waveguide chip 1 to fit and be buried therein. Further, in the substrate 2, with the waveguide chip 1 fitted in the recess 4, the cross section is approximately at the position of a line pattern including a line in the center that is a virtual extension of the optical waveguide 3 toward the substrate 2 side. The V-shaped grooves 5A to 5C are formed, for example, through a phosphorography process.

The depth of the grooves 5A to 5C is such that the waveguide chip 1 is
The optical fibers 6 are inserted into these grooves 5A to 5C while
When A to 6C are arranged, these optical fibers 6A to 6C
The center portion (core) of the optical waveguide 3 is formed so as to coincide with the end face of the optical waveguide 3. Then, the waveguide chip 1 is fitted into the recess 4 of the substrate 2, and the optical fiber 6A is inserted into the grooves 5A to 5C of the substrate 2.
6C, and by fixing the end faces of the optical fibers 6A to 6C and the end face of the optical waveguide 3 using bond, resin, solder, etc., the optical waveguide 3 and the optical fibers 6A to 6C are connected.
It is possible to achieve optical coupling with

Next, the manufacturing process of the optical waveguide device according to the above embodiment will be explained with reference to FIGS. 2 to 4.

First, when forming the recess 4 in the substrate 1, the following procedure is performed. For example, it is made of LiNbO3 and has a size of 110 mm.
Chromium (Cr) and gold (Au
) consisting of Cr/Au (20OA/200OA>
20 is vacuum-deposited (see FIG. 2 (a)).

Next, it is made of silicon (Si) and has a size of 15×3.
On the substrate 2, which is 5 m thick and thicker than the waveguide chip 1, aluminum (AN) 21 is vacuum-deposited to a thickness of 1 μm, and then a negative resist 22 is spin-coded (as shown in FIG. 2(b)). . Therefore, the waveguide chip 1 is placed at a desired position on the substrate 2 with the optical waveguide 3 side facing upward, and is exposed to ultraviolet rays 23 using the waveguide chip 1 as a mask (see Fig. 2 (C> ) At this time, the optical axis of the optical waveguide 3 is set in the <110> direction of the 3i substrate 2.Next, by removing the waveguide chip 1 and developing it, the waveguide in the negative resist 22 is The portion 22A on which the chip 1 was placed is removed (FIG. 2(d))
(Illustrated). As a result, a first mask pattern formed in a self-aligned manner by the waveguide chip 1 is obtained.

Next, using a reactive ion etching device, CBr F3 was used as an etching gas at 1105 CC, and the gas pressure was set at 1.
Under conditions of 5 Pa and IKW power, using the negative resist 22 as a mask, the substrate 2 consisting of 3i (A, l!
Including 21. ), and the etching is stopped when the depth of the recess 4 becomes equal to the thickness of the waveguide chip 1. Finally, using phosphoric acid or the like, the remaining negative resist 22 and AI! 21 is removed. As a result, the second
As shown in Figure (e), it is possible to obtain a substrate 2 in which a recess 4 large enough to fit the waveguide chip 1 is formed.

Grooves 5 (5A to 6C) for fixing optical fibers 6A to 6C
5C) in the <110> direction of the 3i substrate 2, proceed as follows.

First, the waveguide chip 1 is fitted into the recess 4 of the substrate 2. At this time, the error between the size of the recess 4 and the size of the waveguide chip 1 is suppressed to about 0.1 μm. Next, silicon dioxide (
Si 02 >30 is deposited to a thickness of 1 μm, and a positive resist 31 is further spin-coded to a thickness of 1.5 μm. A photomask 32 as shown in FIG. 4 is placed over this and exposed (as shown in FIG. 3(a)). Here, as shown in FIG. 4, the photomask 32 includes the line pattern (shown as a mesh pattern) of the optical waveguide 3 of the waveguide chip 1 in the center, and exposes the extended line pattern. It has a line pattern 33, and the hatched portions are grooves that do not allow ultraviolet rays to pass through. Exposure line pattern 3
The line width of 3 is related to the outer diameter of the optical fibers 6A to 6C,
prescribed.

After performing exposure using such a photomask 32,
The waveguide chip 1 is taken out, the recess 4 is filled with the same positive type resist 31A as the above resist, and using these positive type resists 31 and 31A as a mask, S! Etching 0230 using a reactive ion etching device (
(Illustrated in FIG. 3(b)). As a result, the positive resist 31
S! at the position corresponding to the exposure line pattern 33 of 0230 is removed (as shown in FIG. 3(C)).

Thereafter, using this Si0230 as a mask, the substrate 2 made of 3i is etched with an etching solution (for example, CH3CO0H).
, NHO3, HF system). As a result, the surface of the substrate 2 corresponding to the exposure line pattern 33 is etched, and a groove 5 whose wall surface is inclined at 54.7 degrees is formed. Etching is stopped when the depth of the groove 5 reaches 67 μm. Then, the positive resist 33 is removed (FIG. 3 (d> shown). The positive resist 31A of the waveguide chip 1 is also removed.

In this way, a waveguide chip 1 and a substrate 2 as shown in FIG. 1 are completed. Therefore, as already described using FIG. 1, the waveguide chip 1 is fitted into the recess 4 of the substrate 2, and the groove 5A is
Optical fibers 6A to 6C are arranged at ~5C, and optical fiber 6
A to 6C are pressed against the waveguide chip 1 side, and the optical fiber 6
The end faces of A to 6C and the end face of the optical waveguide 3 are fixed in contact with each other. Then, the depth of grooves 5A to 5G is 67μ.
m, so the outer diameter of the optical fibers 6A to 6C is 12
When a layer having a thickness of 5 μm is used, when considering the depth of the layer of the optical waveguide 3, the centers (cores) of the optical fibers 6A to 6C match the center of the layer of the optical waveguide 3 (the optical axes match).

In this case, even if the above-mentioned fixation is performed with resin, the optical fiber is not fixed to the metal tube as in the past, so the difference in thermal expansion coefficient and thermal contraction coefficient does not differ greatly between the fixing members. Therefore, distortion is less likely to occur, and light propagation can be carried out with low loss. Since the recesses 4 and grooves 5 are formed in a self-aligned manner through a lithography process, and the recessed grooves 5 are formed with high precision according to the crystal orientation, optical axis alignment can be performed without adjustment. possible, and the assembly work can be done easily and in a short time.

The present invention is not limited to the above embodiments, and various modifications are possible.

For example, the cross-sectional shape of the groove portion does not necessarily have to be approximately V-shaped or inverted trapezoidal, and it is sufficient that it is concave. Furthermore, the number of grooves can be changed as appropriate depending on the number of inputs and the number of outputs of the optical waveguide. In addition, the substrate is made of gallium arsenide (GaAs) or indium phosphide (
InP> etc.

Furthermore, we made sure that the waveguide chip was just buried in the recess of the substrate, but the point is that the center of the optical fiber and the end face of the optical waveguide only need to match, so the waveguide chip is lower than the surface of the substrate. Even if the waveguide chip is protruding, or conversely, even if the waveguide chip is depressed from the substrate surface, it can be handled by forming a groove portion with a depth corresponding to the protrusion.

Further, the groove and the optical fiber may be fixed by metalizing and alloying them with Cr/Au, Al1, etc., or the optical fiber may be fixed using solder.

This allows for more stable and reliable fixation than with resin.

〔Effect of the invention〕

As explained in detail above, in the optical waveguide device of the present invention,
A groove in which the optical axes of the optical waveguide and the optical fiber coincide with each other when the waveguide chip is inserted is formed in the substrate, for example, through a Sogerahuie process, so the waveguide chip is inserted into the recess and the groove is Optical axes can be aligned simply by arranging optical fibers, and low-loss optical coupling can be achieved.

In addition, in the mounting method of the present invention, since the recess into which the waveguide depth is inserted is formed in a self-aligned manner, accurate positioning is possible, and no special jig is required, making assembly work easier and shorter. It can be done with

[Brief explanation of the drawing]

FIG. 1 is an assembled perspective view showing the configuration of an optical waveguide device according to an embodiment of the present invention, FIGS. 2 and 3 are cross-sectional views of the manufacturing process of the optical waveguide device shown in FIG. FIG. 3 is a plan view of a photomask used to form a groove in a substrate. DESCRIPTION OF SYMBOLS 1... Waveguide chip, 2... Substrate, 3... Optical waveguide, 4... Recessed part, 5,5A-5C... Groove part, 6.6
A~6C...Optical fiber. Patent Applicant: Sumitomo Electric Industries, Ltd. Representative Patent Attorney Yoshiki Hase 2nd Figure 7jFJ'3

Claims (1)

[Claims] 1. A waveguide chip having an optical waveguide formed thereon, and a substrate having a recessed portion large enough to fit the waveguide chip;
When an optical fiber is placed on this substrate at a line pattern position including a line in the center of which the optical waveguide is virtually extended toward the substrate side with the waveguide chip fitted into the recess, An optical waveguide device characterized in that a groove portion having a depth that matches the core of the optical fiber and the end face of the optical waveguide is formed at the position of the line pattern. 2. Claims characterized in that the recess is made by etching using a mask pattern formed by placing the waveguide chip on the substrate before the recess is formed. The optical waveguide device according to item 1. 3. The optical waveguide device according to claim 1 or 2, wherein the groove portion is metalized with Cr/Au. 4. The optical waveguide device according to any one of claims 1 to 3, wherein the substrate is made of silicon. 5. A first step of placing a waveguide chip on the top surface of the substrate and forming a first mask pattern on the top surface of the substrate that matches the waveguide chip; a second step of etching the substrate from the top surface to form a recess large enough to fit the waveguide chip;
With the waveguide chip fitted into the recess, a second mask pattern is formed that has openings at the position of a line pattern whose center part includes a line that is a virtual extension of the optical waveguide toward the substrate. a third step, etching the substrate from the top surface through the second mask pattern to form a groove portion having a depth such that when an optical fiber is placed, the core of the optical fiber and the end surface of the optical waveguide coincide with each other; and a fifth step of fitting the waveguide chip into the recess and arranging and fixing the optical fiber in the groove.