JP2000089048A - Wavelength dividing multiple module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the loss of an optical signal by enhancing the attaching accuracy of a filter easily and making the optical signal so as to be made vertically incident on the filter. SOLUTION: The wavelength dividing multiple module is constituted so that a multiplexed optical signal of wavelengths of 1.3 μm and 1.55 μm is made incident on a core 110 from an optical fiber 104 to reach a interference filter 107 via a core 110, a total reflection film 106 and a core 111 and only an optical wave having wavelength of 1.55 μm passes the filter 107 to be outputted to an optical fiber 105. Thus, the loss of the optical signal is eliminated by making the optical signal to be made vertically incident on this module always while making the side face 101a of a silicon substrate 101 vertical with respect to a core forming surface and also forming the interference filter 107 by a vacuum vapor deposition on the side face 101a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexing module used for transmitting and receiving optical signals.

[0002]

2. Description of the Related Art Conventionally, a transmitting / receiving module used in an optical access network, for example, has a wavelength of 1.3 μm and a wavelength of 1.3 μm.
Wavelength division multiplexing (WD) for demultiplexing / combining with a wavelength of 55 μm
M; a device having a Wavelength Division Multiplex (M) function is known. In a transmission / reception module having a wavelength division multiplexing function, for example, a silica-based waveguide is provided on a silicon substrate. As a module having a silica-based waveguide, a Mach-Zehnder module and a filter module have been proposed. The filter type wavelength division multiplexing module is disclosed in the following document, for example.

Japanese Patent Application Laid-Open No. Hei 8-190026 Publication of the IEICE Electronics Society Conference 1996, 1-p168 (Institute of Electronics, Information and Communication Engineers Electronics Society Press)

[0004]

FIG. 3 is a diagram schematically showing a configuration of a wavelength division multiplexing module disclosed in the above-mentioned document. 3A is a plan view, FIG. 3B is a sectional view taken along line AA of FIG. 3A, and FIG. 3C is a sectional view taken along line BB of FIG.

[0005] As shown in FIG.
Above, the core 302 as a single mode optical waveguide,
303 and 304 are formed so as to be covered by the clad 305. A groove 306 is provided between the cores 302 and 303 and the core 304, and a dielectric film filter 307 is inserted into the groove 306 and fixed with an adhesive 308.

The cores 302 and 303 are optically coupled to the optical fibers 310 and 311 by a glass block 309. On the other hand, the core 304 includes the Y branch 31
2 are coupled to the laser diode 313 and the photodiode 314.

In the wavelength division multiplexing module having such a configuration, an optical signal obtained by wavelength multiplexing a light wave having a wavelength of 1.3 μm and a light wave having a wavelength of 1.55 μm from the optical fiber 310 enters. Of this optical signal, a wavelength of 1.3
The μm light wave passes through the dielectric film filter 307, propagates in the core 304 and the Y branch 312, and reaches the laser diode 313 and the photodiode 314.
On the other hand, a light wave having a wavelength of 1.55 μm passes through the dielectric film filter 3.
07, propagates through the core 303, and
11 is output.

The filter-type wavelength division multiplexing module as shown in FIG. 3 has features such as easy downsizing, wide wavelength band characteristics, and small crosstalk.

On the other hand, such a filter type wavelength division multiplexing module is required to have a high mounting accuracy of the dielectric film filter 307. In particular, a silica-based waveguide (core 30
2,303,304)
Of the light wave (wavelength 1.3 μm) passing through the dielectric film filter 307 and the reflected light wave (wavelength 1.55 μm).
m) (see the above document).

However, as described above, the conventional filter-type wavelength division multiplexing module employs a structure in which the dielectric film filter 307 is inserted into the groove 306, so that the mounting accuracy of the dielectric film filter 307 can be improved. Was difficult.

That is, the dielectric film filter 3 is
07, the width of the groove 306 must be larger than the thickness of the dielectric film filter 307, so that the dielectric film filter 307 is
Perpendicular to (so cores 302, 303,
(Perpendicular to 304) is difficult.

As shown in FIG. 4A, the depth of the groove 306 is a, the width is b, and the thickness of the dielectric film filter 307 is w.
Then, the maximum value θ of the tilt angle is given by {tan ^-1 } (bw) / a}. From this equation, it can be seen that the gap bw between the groove 306 and the dielectric film 307 may be reduced and the depth a of the groove 306 may be increased in order to reduce the maximum value 傾 き of the tilt angle.

However, when the gap bw is reduced, it becomes difficult to insert the dielectric film 307 into the groove 306. Also,
When the depth a is increased, as shown in FIG. 4B, it becomes difficult to form the groove 306 itself vertically, and it is rather difficult to eliminate the inclination of the dielectric film filter 307.

[0014] For these reasons, the appearance of a wavelength division multiplexing module that can easily improve the mounting accuracy of the filter has been desired.

[0015]

SUMMARY OF THE INVENTION A wavelength division multiplexing module according to the present invention relates to a wavelength division multiplexing module for performing wavelength division and wavelength multiplexing of an optical signal.

Then, a first waveguide for guiding an optical signal incident from the first side surface of the substrate to the second side surface of the substrate, and an optical signal reaching the second side surface via the first waveguide are reflected. A light reflecting means provided on the second foot surface, a second waveguide for guiding an optical signal reflected by the light reflecting means to the third side face, and an optical signal reaching the third side face via the second waveguide A filter provided on the third side surface for transmitting only light of a predetermined wavelength and reflecting light of another wavelength, and a third waveguide for transmitting light between the filter and the optical element. Is provided.

According to such a configuration, since the filter means can be arranged on the side surface of the substrate, it is easy to improve the mounting accuracy of the filter means.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the size, shape, and arrangement of each component are only schematically shown to an extent that the present invention can be understood, and numerical conditions described below are merely examples. Please understand that.

First Embodiment First, a first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a plan view schematically showing the configuration of a wavelength division multiplexing module according to this embodiment.

In FIG. 1, as the substrate 101, for example, a silicon substrate having a thickness of 1 mm is used. Substrate 101
The cladding 102 is formed in a layer on the upper surface.

Further, the side surfaces 101a, 1 of the substrate 101
01b are each perpendicular to the upper surface (the surface on which the clad 102 is formed). Here, when the total reflection film 106 and the interference film filter 107 are formed by vapor deposition as described later, it is desirable that the side surfaces 101a and 101b are polished in advance.

On the side surface 101a of the silicon substrate 101,
A glass block 103 is arranged. The glass block 103 is used for fixing the input single optical fiber 104 and the output optical fiber 105. These optical fibers 104 and 105 are optically coupled to cores 110 and 111 (described later) in the cladding 102.

A total reflection film 106 is formed on the side surface 101b of the substrate 101. This total reflection film 106 can be formed, for example, by depositing a metal thin film.

An interference filter 107 is formed on the side surface 101 a of the substrate 101 so as to face the optical fiber 105. The interference film filter 107 has a wavelength of 1.3.
One that reflects a light wave of μm and transmits a light wave of a wavelength of 1.55 μm is used. Such an interference film filter 10
As 7, for example, a dielectric film having a multilayer structure composed of SiO ₂ , TiO ₂ , TaO ₅ or the like can be used, and can be formed by, for example, vacuum evaporation.

A photodiode 108 and a laser diode 109 are arranged on the side surface 101b of the substrate 101.

In the cladding 102, a core 11 as a single mode optical waveguide is provided in parallel with the upper surface of the substrate 101.
0, 111 and 112 are formed. The core 110 is formed so as to guide an optical signal incident from the optical fiber 104 to the total reflection film 106. The core 111 has a total reflection film 106
The optical signal reflected by the optical waveguide is guided to the interference film filter 107. The core 112 has a Y-branch 113, and the interference film filter 107 and the photodiode 10
8 and the laser diode 109 are propagated.

In the wavelength division multiplexing module having such a configuration, an optical signal (wavelength: 1.3 μm) is transmitted from the optical fiber 104.
m) and an optical signal having a wavelength of 1.55 μm (wavelength multiplexed), the optical signal
The light propagates through the inside and is reflected by the total reflection film 106. The optical signal after the reflection propagates in the core 111 and is
Reach seven. Then, of the two types of light waves that form the optical signal, the light wave having a wavelength of 1.3 μm is transmitted through the interference film filter 107.
And propagates through the core 112 and branches at the Y-branch 113, where the photodiode 108 and the laser diode 1
09 is reached. On the other hand, a light wave having a wavelength of 1.55 μm passes through the interference film filter 107 and is output to the optical fiber 105.

As described above, in the wavelength division multiplexing module according to this embodiment, the side surface 101 is perpendicular to the substrate 101.
a, and the interference film filter 107 is formed on the side surface 101a by vacuum evaporation. This allows
Interference film filter 107 for optical waveguide (core 111)
Can be made substantially zero, and thus loss of the optical signal can be eliminated.

Also, by polishing the side surface 101a, the surface smoothness of the interference film filter 107 can be improved, so that light loss due to the unevenness of the filter can be suppressed, and therefore, the actual filter characteristics can be reduced. And the design value can be reduced. It should be noted that the filter is not formed by vacuum evaporation, but by the side surface 101a.
If the filter is attached to the filter, it is possible to prevent the warping of the filter, so that the error between the actual filter characteristic and the design value is reduced.

Further, since a step of forming a groove in the substrate 101 becomes unnecessary, the manufacturing cost can be reduced.

In addition, since there is no step of inserting the filter into the groove, there is no possibility of causing mechanical damage to the filter. For example, there is no problem that the surface of the filter is rubbed and broken on the side surface of the groove, and the filter is broken by the pressing force when inserting the filter to the depth of the groove. Therefore, the yield and reliability of the module can be improved.

Second Embodiment First, a second embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a plan view schematically showing the configuration of the wavelength division multiplexing module according to this embodiment. In the figure, the components denoted by the same reference numerals as those in FIG. 1 indicate the same components as those in FIG.

As shown in FIG. 2, in this embodiment, a laser diode 202 is disposed on a side surface 101b of a substrate 101 via a semi-transmissive film 201. The semi-transmissive film 201 transmits a part of the incident optical signal and reflects the rest.

On the other hand, a photodiode 203 is arranged on the side surface 101a of the substrate 101.

In this embodiment, a core 204 having no Y branch is provided as a single mode optical waveguide for transmitting light between the interference film filter 107 and the laser diode 202. Further, the laser diode 20
A core 205 is provided as a single-mode optical waveguide for transmitting light between the photodiode 2 and the photodiode 203.

In the wavelength division multiplexing module having such a configuration, an optical signal (wavelength: 1.3 μm) is transmitted from the optical fiber 104.
m) and an optical signal having a wavelength of 1.55 μm (wavelength multiplexed), the optical signal
The light propagates through the inside and is reflected by the total reflection film 106. The optical signal after the reflection propagates in the core 111 and is
Reach seven. Then, of the two types of light waves forming the optical signal, the light wave having a wavelength of 1.55 μm
7 and output to the optical fiber 105. on the other hand,
The 1.3 μm wavelength light wave is reflected by the interference film filter 107, propagates through the core 204, and reaches the semi-transmissive film 201. A part of the light wave (wavelength: 1.3 μm) transmits through the semi-transmissive film 201, but the remaining light wave is reflected by the semi-transmissive film 201, propagates through the core 205, and reaches the photodiode 203.

In the wavelength division multiplexing module according to this embodiment, as in the above-described first embodiment, the substrate 101
The side surface 101a is formed perpendicularly to the optical waveguide and the interference film filter 107 is formed on the side surface 101a by vacuum deposition.
07 can be made substantially zero, so that loss of the optical signal can be eliminated.

Further, the point that the unevenness or warpage of the filter can be corrected and the error between the actual filter characteristic and the design value can be reduced is the same as in the first embodiment.

Further, since there is no step of forming a groove in the substrate 101 or a step of inserting a filter into the groove, it is possible to reduce the manufacturing cost and the mechanical damage of the filter. This is the same as in the first embodiment.

[0042]

As described in detail above, according to the wavelength division multiplexing module of the present invention, it is possible to easily improve the mounting accuracy of the filter.
Optical signal loss can be eliminated.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a configuration of a wavelength division multiplexing module according to a first embodiment.

FIG. 2 is a plan view schematically showing a configuration of a wavelength division multiplexing module according to a second embodiment.

3A and 3B are diagrams schematically showing a configuration of a conventional wavelength division multiplexing module, where FIG. 3A is a plan view and FIG. 3B is a diagram A of FIG.
FIG. 2C is a cross-sectional view of FIG.

4A and 4B are partially enlarged views of FIG. 3;

[Explanation of symbols]

 Reference Signs List 101 substrate 101a, 101b side surface of substrate 102 clad 103 glass block 104, 105 optical fiber 106 total reflection film 107 interference film filter 108 photodiode 109 laser diode 110, 111, 112 core 113 branch of core

Claims (9)

[Claims] 1. A wavelength division multiplexing module for performing wavelength division and wavelength multiplexing of an optical signal, comprising: a first waveguide for guiding the optical signal incident from a first side surface of a substrate to a second side surface of the substrate; In order to reflect the optical signal that has reached the second side surface via one waveguide, a light reflecting means disposed on the second side surface, and the optical signal reflected by the light reflecting means is reflected on a third side surface. A second waveguide for guiding; and a third side surface for transmitting only light of a predetermined wavelength and reflecting light of another wavelength from the optical signal reaching the third side surface via the second waveguide. And a third means for transmitting light between the filter means and the optical element.
A wavelength division multiplexing module comprising: a waveguide; 2. The wavelength division multiplexing module according to claim 1, wherein the second side surface is a surface facing the first side surface, and the third side surface is the same surface as the first side surface. . 3. The wavelength division multiplexing module according to claim 1, wherein the first side surface, the second side surface, and the third side surface are surfaces perpendicular to a surface of the substrate. 4. The wavelength division multiplexing module according to claim 1, wherein said light reflecting means is a total reflection film deposited on said second side surface. 5. The filter according to claim 1, wherein the wavelength is 1.55 μm.
The wavelength division multiplexing module according to any one of claims 1 to 4, wherein the filter is an interference film filter deposited so as to transmit light having a wavelength of 1.3 μm and reflect light having a wavelength of 1.3 μm. 6. The apparatus according to claim 1, wherein the third waveguide has a branch for performing light propagation between the filter means and the plurality of optical elements. Wavelength division multiplex module. 7. The wavelength division multiplexing module according to claim 6, wherein said optical element is a photodiode and a laser diode. 8. A semi-transmissive film provided between an end of the third waveguide and the optical element, and a fourth waveguide for transmitting light between the semi-transmissive film and another optical element. The wavelength division multiplexing module according to any one of claims 1 to 5, further comprising: 9. The wavelength division multiplexing apparatus according to claim 8, wherein the optical element is one of a photodiode and a laser diode, and the other optical element is the other of the photodiode and the laser diode. module.