JPH0348203A - Formation of optical waveguide device - Google Patents

Abstract

PURPOSE:To improve the mass-productivity and productivity by forming grooves crossing optical waveguides on the optical waveguide formation surface of a waveguide substrate and then adhering films on the internal wall surfaces of the grooves. CONSTITUTION:The grooves 5a which are deep enough to cut the optical waveguides 6 are formed with a blade saw at right angles to the optical waveguides 6 on the optical waveguide formation surface of the wafer type waveguide substrate 5 and then the films of, for example, silicon oxide (SiO2) are adhered by CVD, etc., on the surface of the waveguide substrate 6 to give the same effect with an AR coat film to the end surfaces of the optical waveguides 6. Therefore, a next process can be entered without cutting the wafer type waveguide substrate 6 individual parts. Consequently, the optical waveguide device which is rich in mass-productivity is obtained.

Description

[Detailed Description of the Invention] [Summary] To improve productivity by improving mass production and reducing the number of single-function components in a method of forming a guided waveguide device as an optical circuit structure or component of an optical communication system, etc. For the purpose of this, a groove is formed at least deep enough to cut the optical waveguide in the direction across the leading waveguide on the optical waveguide forming surface of the waveguide substrate, and then a film is deposited on the inner wall surface of the groove. to override.

Further, a groove having a depth sufficient to cut at least the optical waveguide is formed in the direction across the optical waveguide on the optical waveguide forming surface of the waveguide substrate, and a film is deposited on the inner wall surface of the groove, and then the groove is formed. The waveguide substrate is cut on the center line of the waveguide substrate.

[Industrial application field]

The present invention relates to optical circuit structures or components for optical communication systems, and more particularly to a method for forming an optical waveguide device that improves productivity by improving mass productivity and reducing the number of single-function components.

As optical communication technology advances, optical devices with various functions are required, but these devices are usually constructed by combining single-function parts, and this assembly requires highly precise adjustment work. Therefore, the price is high and it is hindering productivity improvement.

Therefore, there is a strong desire to put optical devices into practical use that can be easily mass-produced.

[Conventional technology]

Generally, when connecting an optical waveguide as an optical device with an optical fiber, or when transmitting an optical signal to the outside via a lens, etc., the guide waveguide is The end face must be machined.

FIG. 4 is a diagram showing an example of a conventional method for forming an end face of a guided waveguide device.

In Figure 4 (1), l is, for example, lithium niobate (
It is a wafer-shaped waveguide substrate made of LiNb03) or the like, and a plurality of, for example, modulators 2 are formed on the surface of the waveguide substrate l along with optical waveguides 3 connected to both sides thereof.

Normally, a bathophage layer is further formed on the entire surface of the waveguide substrate l on the side where the modulator 2 and optical waveguide 3 are formed, but this is not shown in this figure for ease of understanding. Not yet.

Therefore, when connecting each of the above-mentioned optical waveguides 3 to an optical fiber or other device, first cut the above-mentioned waveguide substrate 1 into individual pieces for each modulator along broken lines A and A'' using a diamond cutter, etc. The end face 3a of the optical waveguide 3 is exposed on the cut plane la perpendicular to the optical waveguide 3, resulting in the state shown in FIG.

In this case, the cut surface 1 by the above-mentioned diamond cutter etc.
There are minute irregularities in a, and especially the waveguide substrate l is made of lithium niobate (LiNbO:+) as mentioned above.
When the crystal substrate is made of a crystal substrate such as the one shown in FIG.
The reflection loss of the optical signal increases.

Therefore, usually, the surface of the cut surface 1a is optically polished using an abrasive such as alumina powder to make it almost mirror-like, and then an AR coating film (anti-reflection film) 4 is deposited on the entire surface of the cut surface 1a. I try to do that.

Figure (3) is a diagram showing this state.

However, when such an end face formation method is used, there is a greater risk of damaging the waveguide substrate l during the polishing step, and it is also necessary to polish each element individually, and to apply an AR coating film (anti-reflection film).
Since it is necessary to form 4, there is a drawback that it takes a lot of man-hours.

On the other hand, there are reactive ion etching techniques and ion ξ ring techniques (not shown) that form grooves in the waveguide substrate that expose almost mirror-like cross sections of the optical waveguides, but these methods do not require processing of the grooves. It takes a long time to process, and the depth of the groove formed is at most about 10 μm or less.Furthermore, since the waveguide substrate is a crystal substrate, anisotropy occurs during etching, and the sides of the groove are not vertical. Therefore, the field of application is restricted and it is not common.

[Problem to be solved by the invention]

In conventional methods for forming optical waveguide devices, there is a problem in that there is a risk of damaging the waveguide substrate at the stage of polishing the end face of the optical waveguide, which is the connection surface with other optical devices. Since it is necessary to form an AR coating film, there is a problem in that mass productivity is suppressed and no improvement in productivity can be expected.

[Means to solve the problem]

The above problem is solved by forming a groove with a depth sufficient to cut at least the optical waveguide in the direction across the optical waveguide on the optical waveguide forming surface of the waveguide substrate, and then forming a film on the inner wall surface of the groove. The problem is solved by a method of forming an optical waveguide device.

Further, after forming a groove at least deep enough to cut the optical waveguide in the direction across the optical waveguide on the optical waveguide forming surface of the waveguide substrate and depositing a film on the inner wall surface of the groove, This problem is solved by a method of forming an optical waveguide device in which the waveguide substrate is cut on the center line of the groove with a cutter that is thinner than the width.

[Operation] When a groove for cutting the optical waveguide is formed on the surface of the waveguide substrate using a blade saw with a fineness of about #2000, the cross section of the optical waveguide exposed on the wall of the groove becomes an optically polished surface. It exhibits almost the same smooth surface.

In addition, for example, CVD is applied to the surface of the waveguide substrate in which grooves are formed.
When a thin film is formed using technology such as sputtering technology or sputtering technology, the thin film adheres to the inner wall surface of the groove with a substantially uniform thickness, but at this time, minute irregularities on the inner wall surface are buried in the thin film and become even smoother. form a surface.

In the present invention, a groove with a depth sufficient to cut at least a leading waveguide is formed using a blade saw in a direction orthogonal to the optical waveguide on the optical waveguide forming surface of a wafer-shaped waveguide substrate on which a plurality of optical waveguides are formed. After the formation, a silicon oxide (SiO2) film, for example, is deposited on the surface of the waveguide substrate using a technique such as CVD, thereby providing the same effect as an AR coating film on the end face of the optical waveguide.

Therefore, it is possible to proceed to the next process without cutting the wafer-shaped waveguide substrate into individual pieces, and it is possible to obtain an optical waveguide device that is highly mass-producible.

? Example] Figure 1 is a diagram explaining the present invention, and Figures 2 and 3 are diagrams for explaining the present invention.
The figure shows another embodiment.

In Figure 1 (A), 5 is, for example, lithium niobe} (
This is a wafer-shaped waveguide substrate made of LiNbOs, etc., and a plurality of modulators 2 are formed on the surface of the waveguide substrate 5, as in FIG. 4, along with optical waveguides 6 connected to both sides thereof.

Further, a bathophage layer 7 made of silicon dioxide (SiO) or the like having a thickness of about 0.5 μm is adhered to the entire surface of the waveguide substrate 5 on the side where the modulator 2 and the optical waveguide 6 are formed. .

Therefore, using a blade saw with a fineness of, for example, #2000, the width a is 10 to 2 otts along the line A in the diagram.
m rank. A groove 5a having a depth d of about 100 μm is formed as shown in FIG.
The state shown in B) is established.

At this point, the end surfaces of the optical waveguide 6 exposed on the wall surfaces 5b on both sides of the groove 5a have approximately the same smoothness as an optically polished surface.

Figure (C) shows the optical waveguide 6 of the waveguide substrate 5 in the state shown in Figure (B), cut vertically along its elongated direction, and 6a shows the end surface of the optical waveguide 6. There is.

Next, a silicon oxide (Sing) film 8 with a thickness of about 1000 nm is deposited on the entire surface of the waveguide substrate 5 by CVD technology, and as shown in FIG.
h) The film 8 is also formed to have approximately the same thickness on each wall surface inside the groove 5a.

In particular, minute irregularities on the inner wall surface of the groove 5a are buried in the silicon oxide (Si02) film 8, so that a smoother surface is formed.

In this case, since the refractive index n of the silicon oxide (Stow) film 8 is approximately 1.45, the reflection loss of the optical signal at the end face 6a of the optical fiber 6 is small, and as a result, it can be used as an AR coating film (anti-reflection film). It will be effective.

After that, when connecting another device such as an optical fiber to the end surface 6a of the optical waveguide 6, the Y! Diamond thinner than the width of I#5a.
By cutting the waveguide substrate 5 using a cutting method using a cuff or a rotary thin blade to expose the end face 6a to the outside, it is possible to connect other devices.

In this method of manufacturing an optical waveguide device, an AR coating film that reduces the reflection loss of optical signals can be simultaneously formed on each end face of a plurality of optical waveguides without cutting and separating each chip. A leading waveway device can be obtained.

FIG. 2 illustrating another embodiment shows an enlarged view of the leading waveguide.

In the figure, 10 is a wafer-shaped waveguide substrate made of lithium niobate as in FIG.
As shown by the broken line in the figure, there are optical waveguides 11a. 1 lb is formed.

Furthermore, the buffer FJ12 explained in FIG. 1 is formed on the surface of the optical waveguides 11a and 11b.

Therefore, after forming a groove 10a by the method explained in FIG. As explained in FIG. 1, the silicon oxide film 13 as an AR coating film is deposited and formed on the entire surface including the inner wall surface by a technique such as CVD.

Next, on the silicon oxide film 13, gold (Au) or copper (Cu), which has a high reflectance particularly for optical signals in the infrared region, is applied.
) A reflective film 14 having a thickness of about 0.1 μm is deposited using sputtering technology.

In such an optical waveguide device, for example, an optical signal L incident from point P of the optical waveguide 11a is transmitted through the silicon oxide film 13 as an AR coating film on the wall surface of the groove 10a, and is totally reflected by the reflective film 14 near the point S. , is transmitted as an optical signal L° to an optical waveguide 1lb connected to the same wall surface of the groove 10a.

On the other hand, on the other side of the groove 10a, the optical signal L1 transmitted through the optical waveguide 11a is completely absorbed by the reflective film 14. After being irradiated, it becomes an optical signal L1'' and is transmitted through the optical waveguide 1lb.

This means that the optical waveguides that cross each other, lla, 1l
Since it has the same effect as arranging a total reflection mirror at the intersection S of b, the total reflection ξ mirror and the man-hours for its installation become unnecessary, making it possible to form an optical waveguide device with high productivity.

FIG. 3 showing still another embodiment is a reflection film I in FIG.
Instead of 4, a dielectric multilayer film 15 is formed by alternately laminating more than 20 layers of silicon oxide (SiO2) and silicon (Si), each with a thickness of several angstroms, by, for example, CVD technology.

In such an optical waveguide device, when an optical signal e having two wavelengths λ, λ2 is inputted from point P of the leading waveguide 11a, the optical signal e is transmitted through the silicon oxide film 13 on the wall surface of the groove 10a and is transmitted to a point near point S. After being separated by the dielectric multilayer film 15, the optical signal with a wavelength λ1, for example, is reflected and transmitted as an optical signal C to an optical waveguide 1lb connected to the same wall surface of the groove lOa, and is transmitted with a wavelength λ1.
The optical signal No. 2 passes through the dielectric multilayer film l5 and enters the groove 10a.
The optical signal 12 is transmitted as is to the optical waveguide 11a connected to another wall surface. It should be noted that the optical waveguides 11a and 11b on the opposite side of the groove 10a also exhibit the same effect as in the case explained in FIG. 2.

Furthermore, by utilizing the reversibility of light, two
It is possible to separate and combine individual optical signals.

This means that the mutually intersecting optical waveguides, 11a. 1l
Since it has the same effect as placing a filter, optical splitter, and optical coupler at the intersection S of b, these single-function components and their installation man-hours are no longer required, resulting in a highly productive optical waveguide. Debye. can form a space.

〔Effect of the invention〕

As described above, the present invention can provide a method for forming an optical waveguide device that improves productivity by improving mass productivity and reducing the number of single-function parts.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the present invention, FIGS. 2 and 3 are diagrams showing other embodiments, and FIG. 4 is a diagram illustrating an example of a conventional method for forming an end face of an optical waveguide device. In the figure, 2 is a modulator; 5. 10 is a temporary waveguide base, 5a,
10a is a groove, 5b is a wall surface, 6, lla
, llb are leading waveguides, 6a is an end face, 7 and 12 are buffer layers, and 8 and 13 are silicon oxide films, respectively. (C) Plan 9i! 5F + 21 of the illustrations and explanations of illustrations and explanations! ] Jise's 4J! Ubai 1ki Higeaki 11 figures mocking 1'21'! 7l

Claims (2)

[Claims] (1) Optical waveguide (
After forming a groove (5a) deep enough to cut at least the optical waveguide (6) in the direction across the optical waveguide (6), the groove (5a)
) A method for forming an optical waveguide device, characterized by forming a film (8) on the inner wall surface of the device. (2) Optical waveguide (
After forming a groove (5a) at least deep enough to cut the optical waveguide (6) in the direction across the optical waveguide (6) and depositing a film (8) on the inner wall surface of the groove (5a), A method for forming an optical waveguide device, comprising cutting the waveguide substrate (5) on the center line of the groove (5a).