JP2004020718A - Optical switch module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save space of a device in relation to an optical switch module by downsizing the optical switch module. <P>SOLUTION: In the optical switch module, a collimator part 1 to individually collimate each of a plurality of the optical signals 6, an optical deflection element part 2 to deflect a propagation direction of each optical signal 6 having passed through the collimator part 1 by using an electrooptical effect and a common waveguide part 3 which has a slab shaped optical waveguide structure and through which the deflected optical signal 6 propagates are at least integrated on a substrate. A structure to bend an optical path 7 along which the deflected optical signal 6 propagates is provided on the common waveguide part 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical switch module, and more particularly to an optical switch for switching an optical signal transmission destination between a plurality of input ports and a plurality of output ports in an optical communication system for transmitting a high-speed and large-capacity signal. The present invention relates to an optical switch module characterized by a configuration for miniaturizing an optical switch module including an element.
[0002]
[Prior art]
With the dramatic increase in communication demand in recent years, a high-speed and large-capacity system is coupled with a wavelength division multiplexing (WDM) technology in which a plurality of signal lights having different wavelengths are multiplexed and transmitted through one optical fiber. However, in order to construct an optical fiber network hardware infrastructure in a backbone communication network, development of an optical switch that switches propagation light at high speed is required.
[0003]
As such an optical switch, an optical switch having a structure in which the optical path is switched by deflecting the collimated propagating light by an electro-optic effect or an electro-acoustic effect is used. To form an optical switch module.
[0004]
Here, a conventional optical switch module will be described with reference to FIG.
FIG. 7 is a schematic plan view of a conventional optical switch module, in which an optical input side and an optical output side are configured symmetrically.
First, as the light deflecting elements 51 and 55, prism-shaped electrodes 52, 53, 56 and 57 are configured in multiple stages. In the drawing, the light deflection elements 51 and 55 have a two-stage configuration. The deflection direction of the deflection angle is made arbitrary by combining the points 56 and 57 point-symmetrically.
[0005]
The light deflecting element 51 on the light input side and the light deflecting element 55 on the light output side are opposed to each other via a common waveguide 54 having a slab waveguide structure. A side optical fiber 60, an individual waveguide 59, and a two-dimensional lens 58 are provided, while an output side optical fiber 63, an individual waveguide 62, and a two-dimensional The configuration is such that the lens 61 is disposed.
[0006]
[Problems to be solved by the invention]
However, in the light deflection element using the electro-optic effect, since the light deflection angle due to the electro-optic effect is small, the common waveguide 54 is used when an optical deflection element array having a large number of channels such as 64 channels or more is constructed. The waveguide length of the slab waveguide must be 100 mm or more, which causes a problem that the optical switch module becomes large.
[0007]
For example, in the conventional optical deflecting element, even when the driving voltage of the optical deflecting element is set to 600 V, the deflection angle θ is only about 0.5 °, and a long optical path is required to obtain a large displacement. You will need it.
[0008]
Therefore, an object of the present invention is to reduce the size of the optical switch module and save the space of the device.
[0009]
[Means for Solving the Problems]
FIG. 1 is a diagram showing the basic configuration of the present invention. Means for solving the problems in the present invention will be described with reference to FIG.
Referring to FIG. 1, in order to solve the above-mentioned problem, the present invention provides a collimating unit 1 for individually collimating a plurality of optical signals 6 and a propagation direction of each optical signal 6 passing through the collimating unit 1 by an electro-optical effect. An optical deflecting element unit 2 that deflects using the light and a common waveguide unit 3 having a slab-type optical waveguide structure through which the deflected optical signal 6 propagates, at least on a substrate. The waveguide section 3 has a structure that bends an optical path 7 through which the deflected optical signal 6 propagates.
[0010]
As described above, by providing a structure for bending the optical path 7 through which the deflected optical signal 6 propagates in the common waveguide section 3 and bending the optical signal 6, it is possible to reduce the waveguide area as compared with the linear slab waveguide. Therefore, the size of the optical switch module can be reduced.
Further, even when an optical fiber is used to extract the optical signal 6 to the outside, the optical signal 6 can be extracted from one direction, so that the space in the device can be saved.
[0011]
In this case, the structure for bending the optical path 7 may be one that bends the optical path 7 of the optical signal 6 in a plane parallel to the main surface of the substrate by using the end surface of the substrate, or that is perpendicular to the main surface of the substrate. The optical path 7 of the optical signal 6 may be bent in the plane.
However, from the viewpoint of easiness of manufacturing by the current manufacturing technology, a structure in which the optical path 7 of the optical signal 6 is bent in a plane parallel to the main surface of the substrate is desirable.
[0012]
When bending the optical path 7, the optical path 7 may be bent by total reflection on the end face, or the metal reflective film 5 may be provided on the end face, and the optical path 7 may be bent by metal reflection.
[0013]
In addition, it is desirable to insert the half-wave plate 4 in the optical path 7, so that the intensity difference due to the polarization direction caused by the difference in the reflectance between the TE mode and the TM mode on the reflection surface can be compensated.
This is particularly effective when the optical path 7 is bent by the metal reflection film 5.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Here, an optical switch module according to the first embodiment of the present invention will be described with reference to FIGS.
2 (a) and 2 (b) are shown. FIG. 2 (a) is a schematic plan view of the optical switch module according to the first embodiment of the present invention, and FIG. 2 (b) is a schematic sectional view. FIG.
The optical switch module 10 according to the first embodiment of the present invention has a slab-type waveguide structure including a lower clad layer 12, a core layer 13, and an upper clad layer 14 on a quartz substrate 11. 15 and the collimator 16 are formed monolithically, and the optical deflection element array 34 is integrated in a hybrid manner between the common waveguide 15 and the collimator 16.
[0015]
In this case, a bent portion formed of a right-angled isosceles triangle is provided at one end of the common waveguide portion 15, and two end surfaces of the right-angled isosceles triangle serve as the reflection surface 17.
In addition, the collimator 16 includes a two-dimensional lens having the same slab waveguide structure as the common waveguide 15 and an individual waveguide.
[0016]
The light deflection element array 34 is formed, for example, on a Nb-doped SrTiO ₃ substrate (not shown) by using a pulse laser deposition method (Pb _0.91 La _0.09 ) (Zr _0.65 Ti _{0. 35)} PLZT lower cladding layer 31 made of _{O 3 and,,} PZT core layer 32 made of _{Pb (Zr 0.52 Ti 0.48) O} 3, _{and, (Pb 0.91 La 0.09) (} Zr 0. After sequentially depositing a PLZT upper cladding layer 33 of ₆₅ Ti _0.35 ) O ₃ , a plurality of prismatic electrodes 35 are provided on the PLZT upper cladding layer 33.
In the figure, for simplicity of illustration, only one prism-shaped electrode 35 is provided, but a multi-stage configuration may be used.
[0017]
In this optical switch module 10, an optical signal is input to the collimator 16 via an optical fiber (not shown), and a predetermined voltage is applied to each prismatic electrode 35 in the input-side optical deflection element array 34. Causes the optical signal to be polarized according to the applied voltage.
[0018]
The polarized optical signal propagates through the common waveguide section 15, is reflected twice by the total reflection on the reflection surface 17, is input to the output side optical deflection element array 34, and is collimated by each prismatic electrode 35. The light is re-deflected so as to be incident on the optical fiber 16 at right angles, and is output to an optical fiber (not shown) via the collimator 16.
[0019]
Next, a manufacturing process of the optical switch module according to the first embodiment of the present invention will be described with reference to FIGS.
3 (a) and 3 (b) are shown. FIG. 3 (a) is a plan view, and FIG. 3 (b) is a cross-sectional view of a main part taken along a dashed line connecting AA 'in FIG. 3 (a). .
It is to be noted that the pentagonal optical switch module 10 in FIG. 3A is not actually formed, but is a view showing the imposition of the finally formed optical switch module.
[0020]
First, a lower cladding layer 12 made of SiO ₂ having a thickness of, for example, 15 μm, a core layer 13 made of Ge-doped SiO ₂ having a thickness of, for example, 7 μm on a quartz substrate 11 by using a CVD method, and The slab waveguide is formed by sequentially laminating an upper cladding layer 14 having a thickness of, for example, 8 μm of SiO ₂ .
[0021]
Referring to FIG. 4C, a resist is applied to the entire surface, and then exposed and developed to form a pentagonal common waveguide portion 15 and a collimating portion 16 composed of a two-dimensional lens and individual waveguides shown in FIG. 2A. Is formed.
[0022]
Next, referring to FIG. 4D, the upper cladding layer 14 to the lower cladding layer 12 are etched by RIE (reactive ion etching) using CF ₄ + O ₂ or C ₃ H ₈ as a source gas using the resist pattern 18 as a mask. Thereby, the common waveguide section 15 and the collimating section 16 are formed.
Reference numeral 19 in the drawing represents an end face of two adjacent common waveguide portions 15.
[0023]
4E, the resist pattern 18 is removed, a resist is applied again on the entire surface, and then exposed and developed to obtain a pentagonal resist pattern corresponding to the optical switch module 10 shown in FIG. 20 are formed.
[0024]
Referring to FIG. 4F, wet etching is performed again using hydrofluoric acid using the resist pattern 20 as a mask, and the exposed portion of the quartz substrate 11 is etched to form a separation groove 21. Divide into modules 10.
[0025]
Thereafter, after the resist pattern 20 is removed, the above-described optical deflection element array 34 is mounted in a concave portion provided between the common waveguide portion 15 and the collimator portion 16 to complete the basic configuration of the optical switch module 10. I do.
[0026]
As described above, in the optical switch module according to the first embodiment of the present invention, since the bent portion is provided in the common waveguide portion 15, the waveguide area is reduced as compared with the case where the straight waveguide portion is used. Accordingly, the size of the optical switch module 10 can be reduced.
In addition, since the optical fiber group for inputting and outputting optical signals only needs to be provided on one end face side of the optical switch module 10, space in the device can be saved.
[0027]
Next, an optical switch module according to a second embodiment of the present invention will be described with reference to FIG. 5, but since the basic waveguide configuration is completely the same as that of the first embodiment, The explanation will be simple.
5 (a) and 5 (b) Reference FIG. 5 (a) is a schematic plan view of an optical switch module according to a second embodiment of the present invention, and FIG. 5 (b) is a schematic cross section. FIG.
[0028]
In the optical switch module according to the second embodiment of the present invention, the lower clad layer 12, the core layer 13, and the upper clad 13 are divided after the substrate is divided by the process of FIG. A dicing saw is used to form an insertion groove 22 in a portion including the apex angle of an isosceles triangle of the common waveguide portion 15 of the slab type waveguide structure composed of the layer 14, and a λ / 2 wavelength plate is formed in the insertion groove 23. 23 is inserted and fixed with an adhesive, and a metal reflection film 24 made of Cu is provided on the end face of the bent portion of the common waveguide portion 15.
[0029]
When the λ / 2 wavelength plate 23 receives polarized light having a polarization axis inclined by θ with respect to the polarization axis of the λ / 2 wavelength plate 23, the λ / 2 wavelength plate 23 has a polarization axis with respect to the polarization axis of the λ / 2 wavelength plate 23. In this case, the λ / 2 wavelength plate 23 is rotated so that its polarization axis is inclined by 45 ° with respect to the polarization axis of the optical signal incident on the collimator 16. insert.
Therefore, the light transmitted through the λ / 2 wavelength plate 23 has its polarization axis rotated by 2θ = 90 °.
[0030]
In the optical switch module according to the second embodiment of the present invention, an optical signal incident via an optical fiber (not shown) is deflected by a predetermined angle by an optical deflecting element array 34, 24 reflected.
[0031]
At this time, the polarization axis of the optical signal is rotated by 90 ° at the time of reflection by the metal reflection film 24. However, since the reflectance of the metal reflection film 24 is different between the TE mode and the TM mode, the polarization axis of the other metal reflection surface 24 is not reflected for the second time. When the light is reflected, the higher-reflectance mode is rotated by 90 ° and becomes the lower-reflectance mode, so that the light intensity difference increases depending on the mode.
[0032]
However, in the optical switch module of the second embodiment, since the λ / 2 wavelength plate 23 is provided in the optical path, the reflected light is further rotated by 90 °, and the other metal reflecting surface 24 Since the light is incident in the mode with the higher reflectivity, the difference in light intensity between the modes can be compensated, and a decrease in efficiency can be suppressed.
[0033]
Note that the allowable incident angle of the λ / 2 wavelength plate 23 is 2.5 to 4.5 ° for the crystal quartz wavelength plate, and about 9 ° for the polymer wavelength plate, and the polarization angle θ Therefore, even when the light enters the λ / 2 wavelength plate 23 at a predetermined deflection angle, it functions sufficiently as a λ / 2 wavelength plate.
[0034]
Next, an optical switch module according to a third embodiment of the present invention will be described with reference to FIG. 6, but since the basic waveguide configuration is exactly the same as that of the first embodiment, The explanation will be simple.
6 (a) and 6 (b). FIG. 6 (a) is a schematic plan view of an optical switch module according to a third embodiment of the present invention, and FIG. 6 (b) is a schematic cross section. FIG.
[0035]
In the optical switch module according to the third embodiment of the present invention, the quartz substrates 11 of the two optical switch modules 10 are opposed to each other after the substrate is divided by the process of FIG. After the λ / 2 wavelength plate 25 is inserted into the facing surface and bonded with an adhesive, the dicing blade is used to grind the end face of the common waveguide section 15 to an angle of 45 °, and then, the reflection is performed by polishing. The surface 26 is formed as a bent portion.
[0036]
Also in this case, by providing the λ / 2 wavelength plate 25, it is possible to compensate for a decrease in output due to a difference in the reflectance between the TE mode and the TM mode on the reflection surface 26.
[0037]
In the optical switch module according to the third embodiment of the present invention, since the input side port and the output side port have a laminated structure, the entire area of the optical switch module can be reduced to almost half. Thereby, further space saving becomes possible.
[0038]
The embodiments of the present invention have been described above. However, the present invention is not limited to the configurations described in the embodiments, and various modifications are possible.
For example, in the description of each of the above-described embodiments, (Pb _0.91 La _0.09 ) (Zr _0.65 Ti _0.35 ) O ₃ (PLZT) and Pb Although (Zr _0.52 Ti _0.48 ) O ₃ (PZT) is used, PLZT and PZT having other composition ratios may be used as the composition ratio. Further, SBT (SrBi ₂ Ta) Other known ferroelectrics such as ₂ O ₉ ) may be used.
[0039]
Further, in each of the above embodiments, the slab type waveguide forming the common waveguide is formed of SiO ₂ / Ge doped SiO ₂ / SiO ₂ , but may be formed by combining other dielectrics. Further, as in the case of the optical deflecting element array, a ferroelectric material may be used.
[0040]
Although the λ / 2 wavelength plate is not provided in the first embodiment, the λ / 2 wavelength plate may be used even when the metal reflection film is not provided as in the second embodiment. It may be provided.
[0041]
Further, in the third embodiment, the metal reflection film is not provided on the reflection surface, but a metal reflection film may be provided similarly to the second embodiment.
[0042]
Further, in the third embodiment, since the total reflection on the reflection surface is used, the difference between the reflectances in the TE mode and the TM mode is small, so that λ is equal to that in the first embodiment. The / 2 wavelength plate may be omitted.
[0043]
Further, in the second embodiment, Cu having a high reflectance to infrared rays used for optical communication is used as the metal reflection film. However, the present invention is not limited to Cu, and other metal such as Al or Au may be used. A metal reflective film may be used. In particular, when Au is used, a decrease in reflectance due to oxidation can be prevented.
[0044]
Here, referring to FIG. 1 again, the detailed features of the present invention will be described again.
1 again (Appendix 1) A collimator 1 for individually collimating a plurality of optical signals, and an optical deflecting element for deflecting the propagation direction of each optical signal 6 passing through the collimator 1 using an electro-optic effect. 2. In an optical switch module in which a common waveguide section 3 of a slab type optical waveguide structure through which the deflected optical signal 6 propagates is at least integrated on a substrate, the common waveguide section 3 is deflected. An optical switch module having a structure for bending an optical path 7 through which an optical signal 6 propagates.
(Supplementary note 2) The optical switch according to Supplementary note 1, wherein the optical path 7 of the optical signal 6 is bent in a plane parallel to the main surface of the substrate by using an end surface of the substrate by a structure that bends the optical path 7. module.
(Supplementary Note 3) The optical switch according to Supplementary Note 1, wherein the optical path 7 of the optical signal 6 is bent in a plane perpendicular to a main surface of the substrate by using an end surface of the substrate by a structure that bends the optical path 7. module.
(Supplementary Note 4) The optical switch module according to Supplementary note 2 or 3, wherein the optical path 7 is bent by total reflection at the end face.
(Supplementary Note 5) The optical switch module according to Supplementary note 2 or 3, wherein a metal reflective film 5 is provided on the end surface, and the optical path 7 is bent by metal reflection.
(Supplementary note 6) The optical switch module according to Supplementary note 4 or 5, wherein a half-wave plate 4 is inserted into an optical path 7 through which the deflected optical signal 6 propagates.
[0045]
【The invention's effect】
According to the present invention, since a structure for bending an optical path for propagating an optical signal is provided in the common waveguide section, the waveguide area can be reduced as compared with the linear slab type waveguide, thereby reducing the size of the optical switch module. In addition, when an optical fiber group is used to extract an optical signal to the outside, the optical signal can be extracted from one direction, and the space in the device can be saved.
[0046]
In addition, by providing a λ / 2 wavelength plate in the optical path, the influence due to the difference in the reflectance between the TE mode and the TM mode in the reflection when the optical path is bent can be reduced. It greatly contributes to the spread and development of multiplexed optical communication.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a basic configuration of the present invention.
FIG. 2 is a schematic configuration diagram of the optical switch module according to the first embodiment of the present invention.
FIG. 3 is an explanatory diagram of a manufacturing process of the optical switch module according to the first embodiment of the present invention halfway;
FIG. 4 is an explanatory diagram of manufacturing processes of the optical switch module according to the first embodiment of the present invention after FIG.
FIG. 5 is a schematic configuration diagram of an optical switch module according to a second embodiment of the present invention.
FIG. 6 is a schematic configuration diagram of an optical switch module according to a third embodiment of the present invention.
FIG. 7 is a schematic plan view of a conventional optical switch module.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Collimating part 2 Optical deflection element part 3 Common waveguide part 4 1/2 wavelength plate 5 Metal reflection film 6 Optical signal 7 Optical path 10 Optical switch module 11 Quartz substrate 12 Lower cladding layer 13 Core layer 14 Upper cladding layer 15 Common waveguide Part 16 collimating part 17 reflecting surface 18 resist pattern 19 end face 20 resist pattern 21 separation groove 22 insertion groove 23 λ / 2 wavelength plate 24 metal reflection film 25 λ / 2 wavelength plate 26 reflection surface 31 PLZT lower cladding layer 32 PZT core layer 33 PLZT upper cladding layer 34 Optical deflection element array 35 Prism electrode 51 Optical deflection element 52 Prism electrode 53 Prism electrode 54 Common waveguide 55 Optical deflection element 56 Prism electrode 57 Prism electrode 58 Two-dimensional lens 59 Individual waveguide 60 Input side optical fiber 61 Two-dimensional lens 62 Individual waveguide 63 Output side Optical fiber

Claims (5)

A collimator for individually collimating a plurality of optical signals, an optical deflecting element for deflecting a propagation direction of each optical signal passing through the collimator using an electro-optic effect, and a propagation of the deflected optical signal An optical switch module in which a common waveguide portion of a slab type optical waveguide structure is integrated at least on a substrate, wherein the common waveguide portion has a structure that bends an optical path through which the deflected optical signal propagates. Optical switch module. 2. The optical switch module according to claim 1, wherein the optical path bending structure bends an optical path of an optical signal in a plane parallel to a main surface of the substrate by using an end surface of the substrate. The optical switch module according to claim 2, wherein the optical path is bent by total reflection at the end face. The optical switch module according to claim 2, wherein a metal reflection film is provided on the end face, and the optical path is bent by metal reflection. The optical switch module according to claim 3 or 4, wherein a half-wave plate is inserted in an optical path in which the deflected optical signal propagates.

Images