JPH01257921A - Optical circuit element - Google Patents

Abstract

PURPOSE:To facilitate the assembly, and to decrease the connection parts of a 1st substrate, a converting means, and a 2nd substrate and reduce the insertion loss by integrating a 1st (2nd) polarized light separating element, 1st (3rd) and 2nd (4th) waveguides, and a 1st optical function element on a 1st (2nd) substrate and connecting the 1st and 2nd substrates by the converting means. CONSTITUTION:On the 1st substrate 21, the 1st polarized light separating element 41, the 1st waveguide 51, and the 2nd waveguide are formed and in the 1st waveguide 52, the 1st optical function element, e.g. an optical matrix switch 61 is provided. On the 2nd substrate 22, on the other hand, the 2nd polarized light separating element 42, the 3rd waveguide 53, and the 4th waveguide 54 are formed and on the 4th waveguide 54, a 2nd optical function element, e.g. an optical matrix switch 62 is provided. Then the 1st and 4th waveguides 51 and 54 and the 2nd and 3rd waveguides 52 and 53 are connected through two converting means, e.g. 1st and 2nd polarized wave maintaining type optical fibers 71 and 72. Consequently, the insertion loss is small and the assembly is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical circuit element that electrically controls light traveling through a waveguide.

(Prior art) Conventionally, as a technology in this field, Japanese Patent Application Laid-Open No. 62-1
There was one described in Publication No. 70944. The configuration will be explained below using figures.

FIG. 2 is a schematic configuration diagram showing an example of the configuration of a conventional optical circuit element.

In this optical circuit element, waveguide type optical switch elements 2.3 are formed in parallel on a substrate 1 having a large electro-optic effect so as to satisfy switching conditions with a TE wave of light and a TM wave of light. has been done. A first conversion element 5 for mode converting from TE waves to TM waves is formed in the input waveguide 4 of one optical switch element 2, and a TM waveguide 6 is formed in the output waveguide 6 of the other optical switch element 3. A second conversion element 7 is formed which converts the mode from a wave to a TE wave. Between the substrate 1 and the input photometric fiber 8, a waveguide 11.13 and an optical fiber 8 are connected.
A lens 9 and a birefringent material 10 are arranged for coupling the two. In addition, the substrate 1 and the output optical fiber 11.1
A lens 13 and a birefringent material 14 are arranged between the waveguide 4.6 and the optical fiber 11.12.

TE waves and TM waves of light have different electro-optic effects, that is, different electromechanical coupling coefficients, and when the switching conditions are satisfied with the TM waves, the switching conditions are not necessarily satisfied with the TE waves. If both of these conditions are not satisfied, it means that the polarization dependence is large. In particular, since the electromechanical coefficient of engagement differs by a factor of, for example, 3 times between TE and TM waves, in optical circuit elements with large polarization dependence, the switching voltage of the optical switch element 2.3 becomes high, and as a result, it is affected by drift. Problems arise, such as the fact that the optical switch drive circuit with high-speed response becomes complicated.

Therefore, the optical circuit element shown in FIG. 2 has a structure that reduces polarization dependence. That is, the incident light from the optical fiber 8 is image-converted by the lens 9, and the birefringent material 10 transforms the image to T.
After being separated into an E wave and a TM wave, they are coupled to a waveguide 4.6. The TE wave that is not coupled to the waveguide 4 is converted into a TM wave by the first conversion element 5, and enters the optical switch element 2 that satisfies the switching conditions for the TM wave. On the other hand, the TM wave coupled to the waveguide 6 passes through the optical switch element 3 optimized for TM waves, and then is converted into a TE wave by the second conversion element 7 and output. TM output from waveguides 4 and 6
The wave and the TE wave are combined by a birefringent material 14 and then a lens 13
The image is converted into an image and coupled to an optical fiber 11 or 12. Switching between the optical fibers 8.11 and 8.12 is performed by switching control of the optical switch element 2.3. Therefore,
It has the advantage that polarization dependence is small and low voltage switching similar to that of TM waves is possible.

(Problems to be Solved by the Invention) However, in the optical circuit element having the above configuration, the lens 9.
13 and birefringent material 10.14, and the substrate 1 having optical switch elements 2.3 and the like are constructed separately, so that the optical circuit between the optical fibers 8 and 11.12 is There were problems in that the insertion loss of the element was large and assembly was difficult.

The present invention provides an optical circuit element that solves the problems of the prior art, such as high insertion loss and difficulty in assembly.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides an optical circuit element that electrically controls light traveling through a waveguide.
a first polarization separation element that separates the TE wave and the TE wave;
a first waveguide for TE wave transmission and a second waveguide for TM wave transmission, each connected to a polarization separation element of A first optical functional element such as a matrix switch is integrated and formed on a first substrate. Furthermore, a third waveguide for TE wave transmission, a fourth waveguide for TM wave transmission, and a second optical waveguide such as an optical matrix switch arranged on the fourth waveguide and operated by an electro-optic effect. a functional element, and the third
and a second polarization separation element that is connected to the fourth waveguide and combines the TE wave and the TM wave, are integrated and formed on the second substrate. Then, the first and fourth waveguides, and iij
The second and third waveguides are connected to each other.

Further, instead of the connection by the conversion element means, the first
The first and fourth waveguides and the second and third waveguides may be coupled to each other by using a second substrate whose crystal axis is rotated with respect to the crystal axis of the substrate.

Furthermore, a polarization filter that selectively passes the TE wave and TM wave may be formed on the waveguide, or an equal power divider may be provided in place of the first and second polarization separation elements. You can.

(Function) According to the present invention, since the optical circuit element is configured as described above, the polarization separation element, the waveguide, and the optical functional element are connected to the first and second
Integrating the first and second substrates on the respective substrates simplifies assembly, and furthermore, the structure in which the first and second substrates are connected by a conversion means reduces the number of connection points and reduces insertion loss.

The structure in which the first and second substrates are joined together without the conversion element means has the effect of reducing the number of parts and thereby further facilitating assembly.

Further, by using a polarizing filter, crosstalk light can be removed and polarization dependence can be reduced, and a simple-structured equal power divider can be used in place of a polarization separation element.

Therefore, the above problem can be solved.

(Example) FIG. 1 is a schematic configuration diagram of an optical circuit element showing an example of the present invention.

This optical circuit element consists of a first... a second substrate 21.22, the first substrate 21;
A plurality of input ports 31 made of waveguides formed by diffusion of Ti or the like are provided at one end of the top. Furthermore, on the first substrate 21, there is a first polarization separation element 41 connected to the input port 31 for separating TM waves and TE waves of input light, and a first polarization separation element 41 on the output side of the first polarization separation element 41. A plurality of first waveguides 51 for transmitting a plurality of TE waves and a second waveguide for transmitting a plurality of TM waves each made of a Ti diffusion etc. are connected to each other.
A waveguide 52 is formed, and a first optical functional element, such as an optical matrix switch 61, which operates by the electro-optic effect is provided in the first waveguide 52. The optical matrix switch 61 switches the optical path between input and output by applying a voltage. Second substrate 22
On the top, similar to the first substrate 21 side, there are a plurality of output ports 32 made of waveguides, and a second polarization separation element 4 connected to the output ports 32 for combining TM waves and TE waves.
2, and a plurality of third waveguides 53 for transmitting TE waves and a fourth waveguide 54 for transmitting a plurality of TM waves respectively connected to the input side of the second polarization separation element 42. At the same time, an optical matrix switch 62, for example, is provided on the fourth waveguide 54 as a second optical functional element. These first. Each element on the second substrate 21.22 is
It is formed in an integrated manner.

11 on the first substrate 21 side. The second waveguide 51°52 and the third waveguide on the second substrate 22 side. In the fourth waveguide 53.54, the first and fourth waveguides 51.54 and the second and third waveguides 52.53 each have two sets of conversion means, for example a plurality of first... Second polarization maintaining optical fiber 71.7
Connected via 2. The polarization-maintaining optical fibers 71, 72 are optical fibers that perform mutual conversion between TE waves and TM waves, and both ends of the optical fibers are connected to the waveguides 51, 52, 52, . It is connected to 53.54. In addition, input port 31 and output port 3
A plurality of optical fibers 73 and 74 are connected to the optical fibers 2 by adhesive or mechanical fixing means.

3(1) and 3(2) are enlarged cross-sectional views of the polarization-maintaining optical fibers 71 and 72 shown in FIG. ) shows a sectional view of the second substrate 22 side.

The optical fibers 71 and 72 are so-called panda-type optical fibers, and have a structure in which a core portion 80, which is an optical transmission region, and a birefringent region 81, 82 are covered with a rat portion 83. .

In this type of optical fiber 71, 72, the axes at both ends are at 90 degrees relative to each other.
By rotating it by 0°, mutual conversion between TE waves and TM waves can be performed.

Next, the operation of the optical circuit element shown in FIG. 1 will be explained.

1st. For example, LiNbO3 is used as the second substrate 21.22.
When a Z plate is used, polarized light with a large electro-optic effect is a TM wave, and a TE wave has a small electro-optic effect. optical fiber 7
The light input from the input port 31 through 3 propagates as two unique polarized waves TM and TE in the waveguide, but the TM wave and TE wave are separated by the first polarization separation element 41. The TE wave propagates to the first waveguide 51, and the TM wave propagates to the first optical matrix switch 61 through the second waveguide #I52. First waveguide I! The TE wave propagated through the optical fiber 151 is converted into a TM wave by the first polarization-maintaining optical fiber 71, and then transferred to the fourth waveguide 5.
4 to the second optical matrix switch 62 , electrically controlled by the second optical matrix switch 62 , and transmitted to the second polarization separation element 42 . On the other hand, the 'rM wave propagated in the second waveguide 52 is electrically switched and controlled by the first optical matrix switch 61, and then converted into a TE wave by the second polarization-maintaining optical fiber 72. , are transmitted to the second polarization separation element 42 through the third waveguide 53. The TM wave and TE wave transmitted to the second polarization separation element 42 are combined at the polarization separation element 42 and then transmitted from the output port 32 to the optical fiber 74. Since this optical circuit element has bidirectional properties, optical transmission from the output port 32 side to the input port 31 side is also possible.

This embodiment has the following advantages.

(a) The TM wave of the input light is left as is, and the TE wave is converted into a TM wave and then switched and controlled by the optical matrix switches 61 and 62, so that a switching operation that does not depend on polarization is possible.

(b) Polarization maintaining optical fiber 71, 72 and waveguide 5
There are 4 connection points with 1, 52, 53, and 54,
Since it is less than the conventional one, the insertion loss of the optical circuit element between the optical fibers 73 and 74 is reduced.

(c) The first polarization splitting element 41, the first . The second waveguides R51, 52 and the first optical matrix switch 61 are integrated and integrated on the first substrate 21, and the second
polarization splitting element 42, the third. Since the fourth waveguides 53 and 54 and the second optical matrix switch 62 are also integrated and integrated on the second substrate 22, both substrates
1.22 with polarization-maintaining optical fibers 71.72, assembly can be easily performed, thereby reducing costs. In addition, when a conversion means such as polarization maintaining optical fiber 71, 72 is used, the first and second substrates 21, 22
Substrates with the same crystal axis can be used as the substrates, which improves manufacturing efficiency.

FIG. 4 is a schematic configuration diagram of an optical circuit element showing another embodiment of the present invention, and the same elements as those in FIG. 1 are given the same reference numerals.

In this optical circuit element, a polarization filter 91. which passes TE waves.
92 is the new 1st. It is formed on the third waveguide 51°53. Polarization filters 91 and 92 pass TE waves, but
It has the function of blocking TM waves. Here, the first. If the separation ratio in the second polarization separation element 41, 42 cannot be large, that is, if the separation function between the TE wave and the TM wave is small, the TM wave enters the first waveguide 51 and the second A TE wave enters the waveguide 52. Since such losstalk light can be removed by the polarization filters 91 and 92, the crosstalk characteristics are improved.

Note that the present invention is not limited to the illustrated embodiment, and various other embodiments or modifications are also applicable. Examples of these include:

(i) As polarization filters 91 and 92 in Fig. 4, TE
It is also possible to use a polarization filter that passes only waves and a polarization filter that passes only TM waves. In this case, in place of the polarization separation elements 41 and 42, it is also possible to use a simple power equal distribution device (so-called 3 dB coupler) that distributes optical power into a plurality of components.

(ii) The optical matrix switches 61, 62 may be other optical functional elements such as bipolar optical switches.

(iii) The polarization maintaining optical fiber 71.72 is
Other conversion means such as an elliptical clad optical fiber may also be used.

(iv) 1st. The second substrate 21.22 is L i
It is also possible to use other substrates than NbO3Z plates.

(V) When the first and second substrates 21, 22 have crystal axes different from each other by, for example, 90 degrees, the first and second substrates 21, 22 can be By directly bonding the fourth waveguides 51, 54 and the second and third waveguides 52, 53 using an adhesive or the like, substantially the same actions and effects as in FIG. 1 can be obtained. . If such a direct joining structure is adopted, the above-mentioned conversion means can be omitted, thereby reducing the number of parts, facilitating assembly, and reducing costs.

(Effects of the Invention) As described above in detail, according to the present invention, the first polarization splitting element, the first . A second waveguide and a first optical functional element are integrated and integrated on a first substrate, and a second polarization separation element, a third . The fourth waveguide and the second optical functional element are integrated and integrated on the second substrate, and the first and second substrates are connected by the conversion means, which simplifies assembly. Since the number of connection points on the substrate, the converting means, and the second substrate is reduced, insertion loss can be reduced.

If the structure is such that the first and second substrates are joined without using a converting means, the number of parts will be reduced and assembly will be easier.

If a polarization filter that selectively passes TE waves and TM waves is formed on the waveguide, crosstalk light can be removed and polarization dependence can be significantly reduced. If such a polarization filter is used, it is also possible to use a power equalizer with a simple structure in place of the polarization separation element.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an optical circuit element showing an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a conventional optical circuit element, and FIG.
), (2) are cross-sectional views of the polarization-maintaining optical fiber in Figure 1,
FIG. 4 is a schematic diagram of an optical circuit element showing another embodiment of the present invention. 21.22...1st. second substrate, 41.42
・・・・・・First. Second polarization separation element, 51, 52° 53.54...First to fourth waveguides, 61.6
2... 1st. second optical matrix switch, 7
1゜72・・・Polarization maintaining optical fiber, 91.9
2...Polarization filter.

Claims (1)

[Claims] 1. A first polarization separation element that separates TM waves and TE waves of input light, and a first guide for TE wave transmission connected to the first polarization separation element, respectively. A second waveguide for wave and TM wave transmission, and a first optical functional element disposed on the second waveguide and operated by an electro-optic effect are integrated and formed on a first substrate. , a third waveguide for TE wave transmission and a fourth waveguide for TM wave transmission, a second optical functional element disposed on the fourth waveguide and operated by an electro-optic effect, A second polarization separation element connected to the third and fourth waveguides and combining the TE wave and the TM wave is integrated and formed on a second substrate, and the TE wave and the TM wave are mutually exchanged. The conversion means that performs
An optical circuit element characterized in that the first and fourth waveguides and the second and third waveguides are connected to each other. 2. A first polarization separation element that separates TM waves and TE waves of input light, and a first waveguide for TE wave transmission and TM wave transmission connected to the first polarization separation element, respectively. A second waveguide and a first optical functional element disposed on the second waveguide and operated by an electro-optic effect are integrated on a first substrate made of a crystal substrate having an electro-optic effect. a third waveguide for TE wave transmission, a fourth waveguide for TM wave transmission, and a second optical functional element disposed in the fourth waveguide and operated by an electro-optic effect. , a second polarization separation element that is connected to the third and fourth waveguides and that combines the TE wave and the TM wave; It is characterized in that it is integrated and formed on a second substrate made of a crystal substrate with a rotated axis, and the first and fourth waveguides and the second and third waveguides are respectively bonded. Optical circuit element.