JPH0921912A - Multilayered dielectric film filter and its production and structure for insertion of multilayered dielectric film filter into optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered dielectric film filter insertable into an optical waveguide in such a manner that its filter surface is made perpendicular to this waveguide, a process for producing such filter and a structure for insertion of the multilayered dielectric film filter into the optical waveguide. SOLUTION: The multilayered dielectric films 3 broader than a substrate 2 of a (1, 1, 1) Si wafer are formed on the front surface 24 of this substrate 2 so as to overhang from the sides of the substrate 2. The end faces 21, 22 of the substrate 2 on the overhanging side of the multilayered dielectric films 3 are formed perpendicular to the film plane of the multilayered dielectric film 3. A filter insertion groove 20 having the thickness of the multilayered dielectric films 3 is formed in the optical waveguide when the multilayered dielectric film filter 1 is inserted into the optical waveguide 25. The multilayered dielectric film filter 1 is then direction lateral in such a manner that the end face 22 of the substrate 2 faces downward. The end face 22 is pressed to the front surface of the optical waveguide 25 and the overhanging part of the multilayered dielectric films 3 is inserted into the filter insertion groove 20, by which the filter surface is held perpendicular to the optical waveguide 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a dielectric multi-layer film filter which is inserted into an optical waveguide and is used for wavelength demultiplexing of light propagating through the optical waveguide, a method for producing the same, and a dielectric multi-layer film. The present invention relates to a structure for inserting a filter into an optical waveguide.

[0002]

2. Description of the Related Art For example, a dielectric multi-layer film filter having a dielectric multi-layer film is used when wavelength-demultiplexing a signal light having a plurality of wavelengths propagating through an optical waveguide.
1 shows a cross-sectional view of the structure of the conventional dielectric multilayer filter 1. As shown in the figure, the dielectric multilayer filter 1 is formed by forming the dielectric multilayer 3 on the upper surface 24 of the substrate 2 made of silicon or the like. Its thickness is almost constant throughout the year. In addition, as shown in (a) and (b) of FIG.
Generally, a warp is caused due to a difference in linear expansion coefficient between the dielectric multilayer film 3 and the dielectric multilayer film 3.

When such a dielectric multilayer filter 1 is manufactured, it is manufactured by forming a plurality of dielectric thin films on the substrate 2 by a vapor deposition method or the like and then cutting them into a predetermined size. When the dielectric multilayer filter 1 is inserted into the optical waveguide, for example, as shown in FIG. 7A, the optical waveguide 25 having the core 4 and the clad 13 is provided with a thickness of the dielectric multilayer filter 1. A filter insertion groove 20 having a width corresponding to is formed substantially perpendicular to the optical waveguide, and the dielectric multilayer filter 1 is inserted into this filter insertion groove 20.

[0004]

By the way, when the dielectric multilayer filter 1 is inserted and fixed in the optical waveguide to form an optical component, the filter insertion groove is mainly formed by cutting the optical waveguide with the filter insertion groove 20. The optical loss due to the gap of 20 itself, and the optical loss due to the light spreading laterally in the optical waveguide near the optical waveguide intersection when the filter insertion groove 20 is provided near the optical waveguide intersection, Loss due to groove surface roughness, filter insertion groove
20 may be displaced from the set position, a loss may be caused by displacement of the optical axis due to a displacement between the filter insertion groove 20 and the dielectric multilayer filter 1, a loss may be caused by tilting of the dielectric multilayer filter 1, and the like. Is being considered.

The loss () caused by the gap of the optical waveguide and the loss () caused by the roughness of the groove surface of the filter insertion groove 20 are the transmitted light transmitted through the dielectric multilayer filter 1 and the dielectric multilayer filter. 1 affects both the reflected light that reflects the light 1 and the loss () associated with the positional deviation of the dielectric multilayer filter 1 and the loss () associated with the inclination mainly affect the reflected light.

From the above, the dielectric multilayer filter 1
When inserting and fixing in the optical waveguide 25, the filter insertion groove 20 formed in the optical waveguide 25 is formed substantially perpendicular to the optical waveguide 25 and its width is made as small as possible to minimize the gap due to the filter insertion groove 20. In addition, the dielectric multilayer filter 1 can be inserted and fixed substantially perpendicularly to the optical waveguide 25 without displacement so that the optical loss due to the displacement or inclination of the dielectric multilayer filter 1 can be minimized. Is desired.

However, it is difficult to form the filter insertion groove 20 substantially perpendicular to the optical waveguide 25, and in practice,
As shown in (b) to (f) of FIG. 7, the filter insertion groove
In most cases, 20 is formed obliquely with respect to the optical waveguide 25, and it was difficult to suppress the inclination of the oblique angle to about 0.1 degree, which hardly affects the increase of optical loss.
In addition, the dielectric multilayer filter 1 generally has a thickness variation of about several μm, and even if there is no thickness variation, a warp occurs as shown in FIG. In many cases, the filter insertion groove 20 for inserting such a dielectric multilayer filter 1 has to be a groove wider than the thickness of the dielectric multilayer filter 1.

Further, the state when the dielectric multilayer filter 1 is inserted and fixed in the optical waveguide 25 happens by chance depending on the inserted state of the dielectric multilayer filter 1 and the state when the adhesive 5 is put in or solidified. Even if the dielectric multilayer filter 1 can be inserted substantially perpendicularly to the optical waveguide because it is determined, it cannot always be fixed to the optical waveguide 25 in that state.

From the above, the state of inserting and fixing the conventional dielectric multilayer filter 1 into the optical waveguide 25 is shown in FIG.
From (f) to (f), the dielectric multilayer filter 1 may be inserted and fixed substantially perpendicular to the optical waveguide 25 as shown in (d) of FIG.
As shown in (b), (c), (e), and (f) of FIG.
In most cases, the dielectric multilayer filter 1 was inserted and fixed with a large inclination with respect to the optical waveguide 25.

Therefore, of the optical loss that occurs when the dielectric multilayer filter 1 is inserted into the optical waveguide 25 to form an optical component, the loss due to the tilting of the dielectric multilayer filter 1 becomes extremely large. As a result, the optical loss of the fixed component inserted into the optical waveguide 25 of the dielectric multilayer filter 1 is greatly increased.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to reduce loss due to tilting of a dielectric multilayer filter when the filter is inserted into an optical waveguide. The present invention provides a dielectric multilayer filter that can be easily inserted almost perpendicularly to an optical waveguide, a method of manufacturing the same, and a structure for inserting the dielectric multilayer filter into the optical waveguide.

[0012]

In order to achieve the above-mentioned object, the present invention has means for solving the problem by the following constitution. That is, in the dielectric multilayer filter of the present invention, a dielectric multilayer film wider than the width of the substrate is formed on the upper surface of the substrate by projecting the width of the substrate to at least one side, and at least the dielectric multilayer film. The end surface of the substrate on the protruding side is formed so as to be substantially perpendicular to the film surface of the dielectric multilayer film, and the filter has a L-shaped or T-shaped cross section.

In the method for manufacturing a dielectric multilayer filter according to the present invention, after the dielectric multilayer is formed on the substrate, at least one side of the substrate is a filter surface formed by the film surface of the dielectric multilayer. It is removed so as to be substantially perpendicular to, and thereby the filter cross section is formed into an L shape or a T shape.

Further, in the method for producing a dielectric multilayer filter of the present invention, after the dielectric multilayer is formed on the substrate, at least one side of the substrate is a filter surface formed by the film surface of the dielectric multilayer. It is also characterized in that the substrate material is removed by anisotropic etching so as to be substantially perpendicular to, and thereby the filter cross section is formed into an L shape or a T shape.

Further, the insertion structure of the dielectric multilayer filter of the present invention into the optical waveguide is an insertion structure of the dielectric multilayer filter into the optical waveguide, in which the dielectric multilayer filter is inserted into the optical waveguide. A filter insertion groove having a width corresponding to the film thickness of the dielectric multilayer film of the dielectric multilayer film filter according to claim 1 is formed in a direction crossing the optical waveguide. The protruding portion of the dielectric multilayer film is inserted into the filter insertion groove in a state where one end of the substrate is in contact with the surface of the optical waveguide, and the filter surface of the dielectric multilayer filter is substantially perpendicular to the optical waveguide. It is characterized by what it does.

In the present invention having the above structure, the dielectric multilayer film forming the dielectric multilayer film filter is formed to be wider than the width of the substrate by projecting the width of the substrate to at least one side. Unlike the dielectric multilayer filter in which the substrate is formed over the entire area of, at least at the protruding portion of the dielectric multilayer film, the stress due to the difference in linear expansion coefficient between the dielectric multilayer film and the substrate is released, and At least the projecting portion of the dielectric multilayer film does not warp, and the warpage of the dielectric multilayer film filter is almost suppressed.

Further, according to the present invention, the film surface of the dielectric multilayer film and the end surface of the substrate on the projecting side of the dielectric multilayer film are substantially vertical (the term “substantially vertical” in this specification includes vertical). Therefore, when the dielectric multilayer filter is inserted into an optical waveguide in which a filter insertion groove having a width corresponding to the thickness of the dielectric multilayer film is formed,
The projecting portion of the dielectric multilayer film is inserted into the filter insertion groove with one end of the substrate on the projecting side of the dielectric multilayer film in contact with the optical waveguide surface. Even if it is formed obliquely, the filter surface of the dielectric multilayer filter is surely inserted substantially perpendicular to the optical waveguide and fixed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings using embodiments. In the description of the present embodiment, the same reference numerals are given to the same parts as those in the conventional example, and the overlapping description will be omitted. FIG. 1 is a sectional view showing an example of an embodiment of a dielectric multilayer filter according to the present invention. In the figure, a dielectric multilayer film 3 having a width wider than the width of the substrate 2 is formed on the upper surface of the substrate 2 formed by the (1,1,1) Si wafer 7 so as to project the width of the substrate 2 to both sides. The end faces 21 and 22 of the substrate 2 on the protruding side of the dielectric multilayer film are formed so as to be substantially perpendicular to the film surface of the dielectric multilayer film 3 to form the dielectric multilayer film filter 1.

As shown in the figure, the filter cross section of this dielectric multilayer filter 1 is T-shaped, and in this embodiment, the thickness of the substrate 2 (the length in the vertical direction in the figure) is used. ) Is formed sufficiently larger than the thickness of the dielectric multilayer film 3. In addition, the end face 21 of the substrate 2 is (1, -1,0)
The end face 22 is formed of the (-1, 1, 0) face, and the bottom face 23 of the substrate 2 is formed of (-1,-).
1, -1) plane.

The example of the present embodiment is configured as described above. Next, a method of manufacturing the dielectric multilayer filter 1 of the example of the embodiment will be described with reference to FIG. First, (a) of the figure
As shown in, a dielectric multilayer film 3 functioning as a filter is formed on the upper surface of a (1,1,1) Si wafer 7 as a substrate by a vacuum deposition method, and a Si wafer 6 with a dielectric multilayer film is manufactured. . Next, as shown in the figure, the Si wafer 6 with the dielectric multi-layer film is processed with the vector <1, 1, -2.
>, <-1, -1, 2>, and cut into a direction parallel to that, and processed into an elongated rod shape having a cross-sectional shape shown in FIG.

Next, the bar-shaped Si wafer 6a with a dielectric multilayer film is dipped in an aqueous potassium hydroxide solution heated to about 70 to 100 ° C. to form (1, 1, 1) as a substrate material.
1) By anisotropically etching the Si wafer 7, both end sides of the substrate 2 are removed in the directions of arrows A and A ', and the filter surface formed by the film surface of the dielectric multilayer film 3 is removed. It is removed so as to be substantially vertical, whereby the dielectric multilayer filter 1 having a T-shaped cross section is formed.

The anisotropic etching of the (1,1,1) Si wafer 7 hardly etches the (-1, -1, -1) plane 10 corresponding to the bottom surface (back surface) 23 of the substrate 2, (1, -1,0) surface 11 that corresponds to the end surfaces 21 and 22 of the substrate 2
And the arrows A, A'in the figure from the (-1, 1, 0) plane 12 direction
Etching is performed in the direction indicated by, and at this time, (1,
Since the etching is performed perpendicularly to the (1, 1) surface 9 and the (-1, -1, -1) surface 10, the end surfaces 21 and 22 on both sides of the substrate 2 are formed by the film surfaces of the dielectric multilayer film 3. It is substantially perpendicular to the formed filter surface.

Further, the etching amount by anisotropic etching is appropriately set within a range of several tens to several thousands μm,
The anisotropic etching is performed. Although the surface of the dielectric multilayer film is also slightly etched by this potassium hydroxide aqueous solution, the multilayer film is formed in consideration of this etching amount in advance.
There is no problem if a protective film is formed on the surface.

The dielectric multilayer filter 1 of the present embodiment is manufactured as described above. Next, the operation of inserting the dielectric multilayer filter 1 into the optical waveguide will be described with reference to FIG.
It will be described based on. Also in this embodiment, the optical waveguide 25 into which the dielectric multilayer filter 1 is inserted has a filter insertion groove.
20 is formed, in the present embodiment example, unlike the conventional example,
A filter insertion groove 20 having a width corresponding to the film thickness of the dielectric multilayer film 3 is formed in a direction crossing the optical waveguide 25. In addition,
This filter insertion groove 20 is, as shown in FIG.
Although it is desirable that the filter insertion groove 20 is formed substantially perpendicular to the optical waveguide 25, in the present embodiment, the filter insertion groove 20 is formed slightly obliquely with respect to the optical waveguide 25, as shown in FIG. It doesn't matter.

When inserting the dielectric multilayer filter 1 into the filter inserting groove 20, for example, holding the substrate 2 and tilting the dielectric multilayer filter 1 sideways as shown in FIG. Board end face 22 on one side of the protruding side of
Is directed toward the lower side of the drawing, and the projecting portion of the dielectric multilayer film 3 is inserted into the filter insertion groove 20 with the end face 22 being in contact with the surface of the optical waveguide 25.

Then, in this embodiment, the end faces 22,
Since 21 is formed so as to be substantially perpendicular to the film surface of the dielectric multilayer film 3, the filter surface of the dielectric multilayer film filter 1 is necessarily substantially perpendicular to the optical waveguide 25. Then, in this state, the dielectric multilayer filter 1 operates as an optical waveguide.
Since the dielectric multilayer filter 1 is fixed to the optical waveguide 25 with the adhesive 5 in this state because the insertion state is stable with no rattling with respect to 25, the dielectric 5 is inserted when the adhesive 5 is injected and when it is solidified. The multilayer filter 1 does not tilt, and is fixed while the filter surface is perpendicular to the optical waveguide 25.

From the above, in the insertion structure of the dielectric multilayer filter 1 of this embodiment, the substrate end surface 22 on one side of the protruding side of the dielectric multilayer film 3 is in contact with the surface of the optical waveguide 25. Then, the projecting portion of the dielectric multilayer film 3 is inserted into the filter insertion groove 20, so that the filter surface of the dielectric multilayer film filter 1 is surely perpendicular to the optical waveguide 25.

According to this embodiment, as described above, the dielectric multilayer film 3 is formed wider than the substrate 2, and the end faces 21 and 22 of the substrate 2 on the projecting side are formed into the film of the dielectric multilayer film 3. Since the substrate is formed so as to be substantially perpendicular to the surface, the protruding portion of the dielectric multilayer film 3 is inserted into the filter insertion groove 20 with the substrate end surface 22 in contact with the surface of the optical waveguide 25, and The membrane filter 1 can be surely made substantially vertical to the optical waveguide 25. Therefore, the present embodiment differs from the conventional dielectric multilayer filter in that even the filter insertion groove is
Even if 20 is formed obliquely, the filter surface of the dielectric multilayer filter 1 does not tilt obliquely, and it is possible to suppress the optical loss caused by the filter surface being displaced or tilted. The optical loss of the optical component formed by inserting the dielectric multilayer filter 1 into the optical waveguide 25 can be reduced.

Further, in the dielectric multilayer filter 1 of the present embodiment, the thickness of the substrate 2 is formed to be sufficiently larger than the thickness of the dielectric multilayer film 3. For example, holding the substrate 2 and holding the filter insertion groove. It becomes easy to perform an operation such as inserting the dielectric multi-layer film filter 20 into the film 20, and the dielectric multilayer filter 1 can be easily handled.

Moreover, according to the present embodiment, the dielectric multilayer filter 1 is formed by the dielectric multilayer 3 protruding from both ends of the substrate 2, and the entire dielectric bottom film 3 on the lower side. Unlike the conventional example in which the substrate 2 is formed over the region, at least in the protruding portion of the dielectric multilayer film 3, the stress due to the difference in linear expansion coefficient between the substrate 2 and the dielectric multilayer film 3 can be released. As a result, it is possible to substantially eliminate at least the warpage of the protruding portion of the dielectric multilayer film 3, and it is also possible to almost eliminate the entire warpage of the dielectric multilayer film filter 1. Therefore, in this embodiment, it is possible to prevent an increase in optical loss due to the warp of the dielectric multilayer filter 1.

Further, by eliminating the warp of the dielectric multilayer film filter 1 as described above, when the filter insertion groove 20 is formed in the optical waveguide 25, a wide filter is inserted in consideration of the warp. It is not necessary to form a groove, and since the substrate 2 is not inserted into the filter insertion groove 20 and only the protruding portion of the dielectric multilayer film 3 is inserted, the width of the filter insertion groove 20 can be reduced. It will be possible. Therefore, the loss due to the gap of the optical waveguide for forming the filter insertion groove 20 can be reduced, and the optical loss of the optical component formed by inserting the dielectric multilayer filter 1 into the optical waveguide 5 can be further reduced. can do.

FIG. 4 shows a dielectric multilayer filter according to the present invention together with a method for manufacturing the same, and the dielectric multilayer filter 1 of the present embodiment has a cross-sectional shape shown in FIG. Is configured. The first embodiment is the first embodiment described above.
Of the substrate 2 (1,
1,0) Si wafer 14 and the bottom surface of this substrate 2
The glass mask 15 is provided on 23 (in the figure, the upper surface 24 side of the substrate 2 is shown to be located on the lower side of the figure). In addition, in this embodiment, the substrate 2 is set to (1, 1,
0) The substrate 2 is formed by forming the Si wafer 14.
The upper surface 24 of the becomes the (1,1,0) surface 16, and the bottom surface 23 becomes (-
The (1, -1,0) surface 17 and the end surfaces 21, 22 are respectively (-1 ,, 0)
It is formed by a (1,1) surface 18 and a (1, -1, -1,) surface 19.

The dielectric multilayer filter 1 of the present embodiment is constructed as described above, and a method of manufacturing the same will be described next. First, as shown in FIG. 4A, a dielectric multilayer film 3 functioning as a filter is formed on the upper surface 24 of a (1,1,0) Si wafer 14 as a substrate by a vacuum evaporation method,
A glass film is formed on the bottom surface 23 side of the (1,1,0) Si wafer 14 (on the side opposite to the dielectric multilayer film 3) by a sputtering method and functions as an etching mask by photolithography and glass etching. The glass mask 15 is formed with a space. In addition, this glass mask
The pattern shape of 15 is formed to have a width of several tens to several thousands μm, and its interval is set to several tens to several thousands μm, thereby forming a stripe shape as shown in FIG. Also, this glass mask 15
The transfer direction of the pattern is vector <1, -1,2>,
The longitudinal direction of the stripe is formed parallel to the <-1,1, -2> direction.

Next, cleavage is performed at a portion without the glass mask 15 in a direction parallel to the vector <1, -1, 2,>, <-1, 1, -2> direction which is the same as the transfer direction of this pattern, and the same. An elongated rod-shaped Si wafer 6a with a dielectric multilayer film having a cross-sectional shape as shown in FIG. Then, the rod-shaped Si wafer 6a with a dielectric multilayer film is
Similarly to the above embodiment, by immersing in an aqueous potassium hydroxide solution heated to about 70 to 100 ° C., (1, 1,
0) Anisotropic etching is performed on the Si wafer 14 to form the bottom surface 23 of the substrate 2 as shown by arrows B and B'in the figure (-1,
The (1,1,0) Si wafer 14 in the portion without the glass mask 15 is removed from the (-1,0) plane 17 direction, whereby the dielectric multilayer filter 1 having a T-shaped cross section is formed.

Depending on the anisotropic etching,
The (1,1,0) Si wafer 14 is hardly etched from the (1, -1, -1,) plane 19 and the (-1,1,1) plane 18 side corresponding to the cleavage plane, and (-1,-). By etching from the (1,0) plane direction, the (1, -1, -1) plane 19 and the (-1,1,1) plane 18 are exposed, and the end surface 22,
It becomes 21. Also, the (1, -1, -1,) plane 19 and (-
The (1,1,1) surface 18 corresponds to the bottom surface 23 of the substrate 2 (-1,
Since the (1,0) plane 17 and the (1,1,0) plane 16 that is the upper surface 14 (front surface) of the substrate 2 are perpendicular to each other, the end face 21 is also formed in this embodiment as in the above-described embodiment. , 22 are substantially perpendicular to the filter surface formed by the film surface of the dielectric multilayer film 3. Although the surface of the dielectric multilayer film is slightly etched by this potassium hydroxide aqueous solution, there is no problem if the multilayer film is formed in advance in consideration of the etching amount and a protective film is formed on the surface.

The dielectric multilayer filter 1 of this embodiment is manufactured as described above, and this embodiment also has the same substrate 2 as the dielectric multilayer filter 1 of the first embodiment.
Since both end surfaces 21 and 22 of the dielectric multilayer film 3 are formed to be substantially perpendicular to the film surface (filter surface) of the dielectric multilayer film 3, when the dielectric multilayer film filter 1 is inserted into the optical waveguide, It is inserted in the same manner as in the first embodiment and is fixed so that the filter surface of the dielectric multilayer filter 1 is substantially perpendicular to the optical waveguide 25, and the same effect as that of the first embodiment is obtained. You can

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can take various modes. For example, in the second embodiment described above, by cleaving the Si wafer 6 with the dielectric multilayer film having the shape shown in FIG.
S with a rod-shaped dielectric multilayer film as shown in FIG.
Although the i-wafer 6 is formed, the rod-shaped Si wafer 6a with a dielectric multilayer film may be formed by cutting with a cutting tool such as a dicing saw instead of cleaving.

Further, in the second embodiment, as shown in FIG. 4B, Si with a rod-shaped dielectric multilayer film is used.
After forming the wafer 6a, a (1,1,0) Si wafer
Dielectric multilayer filter 1 by anisotropically etching 14
However, when anisotropic etching is performed using a mask such as the glass mask 15 as in the second embodiment, the anisotropic etching is performed in the state shown in FIG. 4A, for example. After that, the dielectric multilayer film 3 may be cleaved or cut to produce the dielectric multilayer filter 1.

Furthermore, in each of the above embodiments,
Anisotropic wet etching was performed using a potassium hydroxide aqueous solution heated to 70 to 100 ° C., but the etching solution used for this anisotropic wet etching is not necessarily a potassium hydroxide aqueous solution, and the above embodiment Any etching liquid may be used as long as it can perform etching so that at least one side of the substrate 2 is substantially perpendicular to the film surface of the dielectric multilayer film 3 by the same anisotropic etching effect as described above.

Further, instead of using such an etching solution, dry anisotropic etching is performed so that at least one side of the substrate 2 is placed on the film surface of the dielectric multilayer film 3 as in the above embodiment. Alternatively, anisotropic etching may be performed so as to be substantially vertical.

Further, in the first embodiment, the Si wafer 6 with the dielectric multilayer film is cut in the vector <1,1, -2>, <-1, -1, -2> directions, and the second wafer is used. In the example embodiment, the vectors <1, -1,2>, <-1,1,-
The Si wafer 6 with a dielectric multilayer film was cleaved in the 2> direction to form a rod-shaped Si wafer 6a with a dielectric multilayer film. However, if the cutting direction and the cleavage direction are not necessarily parallel to the above vector. However, in the first embodiment, the vector <1, -2, 1
>, <-1, 2, -1> parallel to the direction (end face is (1,
(0, -1) plane or (-1, 0, 1) plane) or a direction parallel to the vectors <-2, 1, 1,>, <2, -1, -1> (end face is (0, 1) , -1) plane or (0, -1,
It may be cut into 1) plane. In the second embodiment, for example, the vector <1, -1, -2>
, <-1, 1, 2> parallel to the end face ((1,-
It may be cleaved or cut to the (1,1) plane or the (-1,1, -1) plane).

Further, in the first embodiment, the (1,1,1) Si wafer 7 is used as the substrate material for forming the substrate 2, and in the second embodiment, the substrate material (1 , 1, 0) Si wafer 14 was used, but the substrate material for forming the substrate 2 is not always (1, 1, 1) Si wafer 7
Not limited to (1,1,0) Si wafer 14,
By using the anisotropic etching as in the above embodiment, the anisotropic etching can be performed so that at least one side of the substrate 2 is substantially perpendicular to the film surface of the dielectric multilayer film 3. Good.

Further, in the above-mentioned embodiments, the dielectric multilayer film 3 is formed by the vacuum deposition method, but the method for forming the dielectric multilayer film 3 is not particularly limited and may be set appropriately. Is.

Further, in the second embodiment, the glass mask 15 is formed by the sputtering method. However, the glass mask 15 is not necessarily formed by the sputtering method, but may be formed by an appropriate method. It is what is formed. Further, instead of the glass mask 15, an etching mask formed of a material other than glass may be formed, and the substrate material in the portion without the etching mask may be anisotropically etched.

Furthermore, in each of the above embodiments,
By anisotropically etching a Si wafer as a substrate material, both sides of the substrate 2 were removed so as to be substantially perpendicular to the filter surface formed by the film surface of the dielectric multilayer film 3. Is not necessarily performed by anisotropic etching, and if the end face of the substrate can be removed substantially perpendicularly to the film surface of the dielectric multilayer film 3 without damaging the dielectric multilayer film 3 side, for example, cutting, etc. The substrate 2 may be removed by.

Further, in the above embodiment, when the dielectric multilayer filter 1 is inserted into the filter insertion groove 20 of the optical waveguide 25, the end face 22 of the substrate 2 is brought into contact with the surface of the optical waveguide 25. Conversely, the end face 21 may be brought into contact with the surface of the optical waveguide 25, and the projecting portion of the dielectric multilayer film 3 formed on the end face 21 side may be inserted into the filter insertion groove 20.

Further, in each of the above embodiments,
Both sides of the substrate 2 are removed so that both end surfaces of the substrate are the dielectric multilayer film 3
The cross section of the dielectric multi-layer film filter 1 is T-shaped so as to be substantially vertical to the film surface of the dielectric multi-layer film 1. Both sides of the substrate 2 may be removed so as to be vertical, and, for example, as shown in FIG. 5, one side of the substrate 2 may be opposed to the filter surface formed by the film surface of the dielectric multilayer film 3. It may be removed so as to be substantially vertical, whereby the filter cross section may be L-shaped. Further, the T shape may be cut at the center to be divided into two L shapes.

[0048]

According to the present invention, the dielectric multi-layer film filter forms a dielectric multi-layer film wider than the width of the substrate by projecting the width of the substrate on at least one side on the upper surface of the substrate. Since the end face of the substrate on the projecting side of the dielectric multilayer film is formed so as to be substantially perpendicular to the film surface of the dielectric multilayer film, this dielectric multilayer film filter is inserted into the filter insertion groove formed in the optical waveguide. At this time, if the protruding portion of the dielectric multilayer film is inserted into the filter insertion groove while the substrate end surface on one side of the extension of the dielectric multilayer film is in contact with the optical waveguide surface, even if the filter insertion groove is formed diagonally. Even if it is done, the filter surface of the dielectric multilayer filter can be made substantially vertical to the optical waveguide. Therefore, of the optical loss that occurs when the dielectric multilayer filter is inserted into the optical waveguide, the optical loss that accompanies the inclination of the filter can be almost completely suppressed.

Further, according to the dielectric multilayer film filter of the present invention, the dielectric multilayer film having a width wider than that of the substrate is formed on the upper surface of the substrate, and the lower part of the entire dielectric multilayer film forming region is formed as in the conventional case. Unlike the dielectric multilayer filter in which the substrate is provided on the substrate, the warpage of the dielectric multilayer filter caused by the stress due to the difference in linear expansion coefficient between the substrate and the dielectric multilayer film is suppressed at least in the protruding portion of the dielectric multilayer film. Therefore, at least the warpage of the projecting portion of the dielectric multilayer film can be almost eliminated. When the dielectric multilayer filter is inserted into the optical waveguide, it is formed in the optical waveguide so that only the projecting portion of the dielectric multilayer film is inserted into the filter insertion groove with the substrate end face abutting the optical waveguide surface. It is not necessary to consider the warp of the dielectric multi-layered film filter as the filter insertion groove, and at least the groove should have a width corresponding to the thickness of the dielectric multi-layered film. Therefore, it is possible to reduce the optical loss due to the gap caused by the optical waveguide being cut by the groove.

From the above, according to the dielectric multilayer filter of this embodiment and the insertion structure of the dielectric multilayer filter into the optical waveguide, the optical formed by inserting the dielectric multilayer filter into the optical waveguide is described. Of the optical loss that occurs in the components, it is possible to suppress both the loss due to the gap of the optical waveguide, the loss due to the displacement of the dielectric multilayer filter, and the loss due to the inclination of the dielectric multilayer filter,
It is possible to form an optical component with extremely small light loss.

Further, after forming the dielectric multilayer film on the substrate, the substrate material is changed so that at least one side of the substrate is substantially perpendicular to the filter surface formed by the film surface of the dielectric multilayer film. According to the method for producing a dielectric multilayer filter of the present invention in which the cross section of the filter is L-shaped or T-shaped by removing it by performing anisotropic etching, anisotropic etching is performed on the substrate material. Thus, it is possible to easily and surely remove at least one side of the substrate on which the dielectric multilayer film is formed so as to be substantially perpendicular to the film surface of the dielectric multilayer film. A dielectric multilayer filter having an L-shaped or T-shaped cross section can be easily formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram showing a first embodiment of a dielectric multilayer filter according to the present invention.

FIG. 2 is an explanatory diagram showing a method for manufacturing the dielectric multilayer filter of the first embodiment.

FIG. 3 is an explanatory diagram showing an example of a structure for inserting a dielectric multilayer filter according to the present invention into an optical waveguide.

FIG. 4 is an explanatory view showing the second embodiment of the dielectric multilayer filter according to the present invention together with its manufacturing method.

FIG. 5 is a cross-sectional explanatory view showing another embodiment example of the dielectric multilayer filter according to the present invention.

FIG. 6 is a cross-sectional explanatory view showing a conventional dielectric multilayer filter.

FIG. 7 is an explanatory diagram showing an example of an insertion structure of a conventional dielectric multilayer filter.

[Explanation of symbols]

 1 Dielectric Multilayer Filter 2 Substrate 3 Dielectric Multilayer 7 (1,1,1) Si Wafer 14 (1,1,0) Si Wafer 20 Filter Insertion Groove 21,22 End Face

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shiro Nakamura 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Nobuhiro Nanzato 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (4)

[Claims] 1. A dielectric multilayer film wider than the width of the substrate is formed on the upper surface of the substrate by projecting the width of the substrate to at least one side, and at least the end face of the substrate on the projecting side of the dielectric multilayer film. Is formed so as to be substantially vertical to the film surface of the dielectric multilayer film, and has a filter cross section of an L shape or a T shape. 2. After forming a dielectric multilayer film on a substrate, at least one side of the substrate is removed so as to be substantially perpendicular to the filter surface formed by the film surface of the dielectric multilayer film, The method for producing a dielectric multilayer filter according to claim 1, wherein the cross section of the filter is L-shaped or T-shaped. 3. After forming a dielectric multilayer film on a substrate, at least one side of the substrate is made of a different substrate material so as to be substantially perpendicular to a filter surface formed by the film surface of the dielectric multilayer film. A method for producing a dielectric multilayer filter, which comprises removing by performing isotropic etching, thereby forming a filter cross section into an L shape or a T shape. 4. A structure for inserting a dielectric multilayer filter into an optical waveguide, wherein the dielectric multilayer filter is inserted into the optical waveguide, wherein the optical waveguide has a dielectric multilayer of the dielectric multilayer filter according to claim 1. A filter insertion groove having a width corresponding to the thickness of the film is formed in a direction crossing the optical waveguide, and one end of the substrate on the projecting side of the dielectric multilayer film is in contact with the surface of the optical waveguide. An optical waveguide of a dielectric multi-layer film filter, wherein an overhanging portion of the dielectric multi-layer film is inserted into the filter insertion groove, and a filter surface of the dielectric multi-layer film filter is substantially perpendicular to the optical waveguide. Insertion structure.