JPH01159614A - Waveguide type optical switch - Google Patents

Abstract

PURPOSE:To reduce leak light outputted from the port of the waveguide type optical switch and to improve crosstalk by guiding leak light which is generated when signal light passes through a 1st control optical switch into a substrate by a 2nd control optical switch. CONSTITUTION:Waveguides 22, 24, and 28 are waveguides for guiding light signals from ports 22a and 24a to ports 22b and 24b, or waveguides for guiding light signals from the ports 22b and 24b to the ports 22a and 24a. Further, control optical switches 30a-30d are used as 1st control optical switches for selecting a waveguide for guiding signal light or as the 2nd control optical switches for guiding the leak light into the substrate 20. Consequently, the leak light is prevented from being outputted from the output ports 22a, 22b, 24a, and 24b of the waveguide optical switches 18 to light circuit elements of a following stage.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a polarization-independent waveguide optical switch that can select an output port from which an input signal light is output, and in particular can reduce crosstalk. This invention relates to an optical switch whose operation is easy to control.

(Prior Art) In an electro-optic crystal material such as LiNbO2 used as a substrate material for an optical switch, the electro-optic effect differs depending on the direction of polarization. For this reason, common optical switches often have polarization dependence such that switching can only be performed for a specific linearly polarized light.
In devices such as optical switching equipment, high-speed optical LAN notebooks, and optical measuring instruments that normally use single-mode optical fiber as a transmission path, it is important to eliminate the polarization dependence of the optical switches that are the components of these devices. It has become a challenge.

For example, as an optical switch that eliminates polarization dependence, there is a
Physis, Lett, ), 35 (10),
15November 1979. p748-75
There is a directional coupler type optical switch disclosed in 0J.

FIG. 8 is a diagram schematically showing the configuration of a conventional optical switch without polarization dependence disclosed in Document I.

The conventional optical switch shown in the figure has a T
The first waveguide 10 and the second waveguide 12 are formed by diffusing i, the first waveguide 10 having a constant width and a linear stripe shape, and the second waveguide 12 having a constant width. It is a curved striped waveguide with a large and constant curvature.

Further, a first electrode 14 used as a ground electrode is provided on the first waveguide 10, and a second electrode 16 used as a control electrode is provided on the second waveguide 12.

The second electrode 16 consists of electrode members 16a and +6b and is divided into two parts.

In the diagram, the direction from the upper edge of the first electrode 14 to the lower edge is defined as the wave guiding direction, and the wave guiding distance from this upper edge is 2, and the direction from the upper edge of the first electrode 14 to the lower edge of the first electrode 14 is assumed to be 2. The waveguide distance is the length of the element. In addition, the first waveguide 10 and the second waveguide 1
2 is the distance between the electrode members 16a and 16a.
and +6b, and changes sequentially according to the distance 2 so that the minimum value is reached between the distance 2 and +6b.

A conventional optical switch having the above-mentioned configuration is manufactured so that the coupling length for ordinary light and the coupling length for extraordinary light are each equal to the element length.

In the conventional optical switch created in this way, the electrode member 16a has a positive (+) polarity, and the electrode member +6b has a negative (-) polarity.
) A cross state can be obtained by performing so-called inversion β drive by applying a polarity voltage and finely adjusting the applied voltage. In the cross state, light input from the input port (2=0) of one waveguide 10 or 12 is output from the output port (z=L) of the other waveguide 12 or 10.

Furthermore, in order to obtain a bar state in this conventional optical switch, so-called uniform β drive is performed in which the same voltage is uniformly applied to the electrode members 16aJ6b.

When LiNbO2 is used as the substrate material, the electro-optic effect for extraordinary light is about three times larger than that for ordinary light, and therefore the equivalent refractive index difference for extraordinary light is about three times that for ordinary light. growing. Therefore, by applying a voltage capable of obtaining a bar state for ordinary light, a bar state with a high extinction ratio can be obtained for extraordinary light.

In the bar state, signal light input from the input port of one of the waveguides 10 or 12 travels straight and is output from the output port of the same waveguide 10 or 12 to which it was input.

In this conventional optical switch, when equal voltages are variably applied to the electrode members 16a and 16b on the second waveguide 12, it is possible to obtain a bar state with a high extinction ratio over a wide range above a certain threshold value. I can do it.

(Problem to be solved by the invention) However, in the conventional optical switch without polarization dependence described above, by adjusting the voltage value and polarity of the voltage applied to the electrodes, it is possible to cross the abnormal light in the cross state. Although the talk can be improved to a practically satisfactory level, there is a problem in that it is difficult to improve the crosstalk of ordinary light in the cross state to a practically satisfactory level.

Moreover, in order to improve crosstalk, it is necessary to change the voltage value and polarity of the voltage applied to the electrodes.
There was a problem in that the operation control was complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a waveguide optical switch which can further reduce crosstalk and whose operation can be easily controlled, in order to solve the above-mentioned conventional problems.

(Means for solving the problem) In order to achieve this object, the waveguide type optical switch of the present invention includes a first controlled optical switch that selects a waveguide that guides signal light from an input port to an output port. , and a second control optical switch that allows leakage light leaked from the first control optical switch to a waveguide different from the waveguide into the substrate in the same operating state as the first control optical switch, in series. It has an arranged configuration.

In carrying out the present invention, it is preferable that the first and second control optical switches are optical switches without polarization dependence.

(Function) According to the waveguide type optical switch configured as described above, leakage light leaking from the first control optical switch is released into the substrate via the second control optical switch. It is possible to prevent output from the output port of the optical switch to the next stage optical circuit element.

Moreover, since the operating states of the first and second control switches are the same, operation control is easy.

(Example) Hereinafter, the configuration of an example of the present invention will be described with reference to the drawings. It should be noted that the drawings are only schematic representations to the extent that the invention can be understood, and therefore the dimensions of each component,
The shape and arrangement are not limited to the illustrated example.

Schematic description of the configuration of the first embodiment> FIG. 1 is a plan view schematically showing the configuration of the first embodiment. In the figure, reference numeral 18 indicates a waveguide type optical switch, and the waveguide type optical switch 18 of the first embodiment includes a substrate 20, input/output waveguides 22 and 24 provided on this substrate 20, and a connecting waveguide. 26.28 and control light switches 30a, 30b,
30c and 30d, and an input/output waveguide 22.2.
Ports 22a, 24a are provided at the upper end of the 4, and ports 22b, 24b are provided at the lower end, respectively.

Port 22 is the input port of the waveguide optical switch 18.
a, 24a or port 22b, 24b @, or as an output port, port 22b, 24b or port 22a
, 24a are used.

Waveguides 22.24.26.28 are connected to ports 22a, 24
for guiding the signal light from a to the ports 22b and 24b,
Or, the signal light from ports 22b and 24b is transferred to port 22a.
, 24a. Further, the control optical switches 30a130b, 30c, and 30d are used as a first control optical switch that selects a waveguide for guiding signal light, and/or as a second control optical switch that releases leaked light into the substrate 18.

As shown in FIG. 1, in this embodiment, the input and output waveguides 22, 24 are spaced apart from each other by M and run parallel to each other. The upper end side of the connecting waveguide 26 is connected to the port 22a side of the input/output waveguide 22 via the control optical switch 30a IFr, and the lower end side is connected to the port 22a of the input/output waveguide 24. Furthermore, the upper end side of the connection waveguide 28 is connected to the port 24a side of the input/output waveguide 24 via the control optical switch 30b, and the lower end side is connected to the port 24a side of the input/output waveguide 24 via the control optical switch 30b. Input/output waveguide 22
is connected to the port 22b side of the control optical switch 30c via the control optical switch 30c.

As the substrate 20, for example, a substrate made of a material having an electro-optic effect (for example, a 2-cut LiNb3 substrate) is used, and the control optical switches 30a, 30b, 30c.

30 du, for example, a directional coupling type 2x2 optical switch. In this case, 2×2 optical switches are replaced by 1×
A 2 or 2×1 optical switch is used, and the unused port (input or output port) is used as an output port for leaked light.

In this embodiment, the control optical switches 30a, 3
0b, 30c, and 30d, for example, optical switches without polarization dependence are used.

<Description of configuration and operation> Figures 2 (A) to (8) show control optical switches 30a and 30c.
, 30d is a diagram showing how signal light and leakage light propagate. Below, Figures 1 and 2 (A) to (B)
8, the configuration and operation of the waveguide optical switch 18 of this embodiment will be explained. In addition, Fig. 2 (A) - (
In B), signal light is indicated by a solid line arrow and leakage light is indicated by a broken line arrow.

(2) First, consider the case where signal light is input from ports 22a and 24a and signal light is output from ports 22b and 24b.

(I-a) Control light switches 30a, 30b, 30c, 3
When all 0d are operated in the bar state, the waveguide type optical switch 18 is controlled by the control optical switch 30a330 on the port 22a, 24a side to which the signal light is input.
b becomes the first control light switch, and the control light switch 30a
The control optical switch 30d and the control optical switch 30c are arranged in series as a second control optical switch.

The control optical switches 30a and 30c have the signal light connected to the port 22.
The waveguide 22 is selected so that the signal light passes from port 24a to port 22b, and the control optical switches 30b and 30d select the waveguide 24 so that the signal light passes from port 24a to port 24b.

As also shown in FIG. 2(A), the control optical switch 30d directs leaked light leaked from the control optical switch 30a to a waveguide 26 different from the selected waveguide 22.
It escapes into the board 20 from the remaining port d.

Similarly, the controlled optical switch 30c uses a waveguide 28 different from the waveguide 24 selected from the controlled optical switch 30b.
The leaked light is released into the board 20 from the remaining port of this switch 30c.

(I-b) Double optical switch 30a, 30b, 30c, 30
d are all operated in a crossed state. At this time, the waveguide type optical switch 18 is controlled by the control optical switch 30a130 on the port 22a, 24a side to which the signal light is input.
b becomes the first control light switch, and the control light switch 30a
The control optical switch 30c is arranged in series with the control optical switch 30c, and the control optical switch 30d is arranged in series with the control optical switch 30b as a second control optical switch.

The control optical switch 30a connects the connecting waveguide 2 so that the signal light input from the port 22a is output from the port 24b.
6 and the control optical switch 30d select the input/output waveguide 24, and the control optical switch 30b selects the connection waveguide 28 and the control optical switch 30c so that the signal light input from the port 24a is output from the port 22b. selects the input/output waveguide 22.

As shown in FIG. 2(B), the control optical switch 30c directs the leaked light leaked from the control optical switch 30a to a waveguide 22 different from the selected waveguide 26 from the remaining port of the switch 30c to the substrate. Missed into the 20s.

Similarly, the control light switch 30d is the control light switch 3
The leaked light leaking into a waveguide 24 different from the waveguide 28 selected from 0b is released into the substrate 20 from the remaining port of the switch 30d.

(2) Next, consider the case where signal light is input from ports 22b and 24b and signal light is output from port 22a%24a.

(II-a) Controlled optical switches 30a, 30b, 30c
, 30d are all operated in the bar state. At this time, the waveguide type optical switch 18 is the control optical switch 30c130 on the port 22b, 24b side to which the signal light is input.
d is the first control light switch, and control light switch 30c
control light switch 30b and control light switch 30
The control optical switch 30a is arranged in series with respect to the control optical switch 30a as a second control optical switch.

The control optical switches 30c and 30a have the signal light connected to the port 22b.
The waveguide 22 is selected so that the signal light passes from the port 24b to the port 22a, and the control optical switches 30d and 30b select the waveguide 24 so that the signal light passes from the port 24b to the port 24a.

The control light switch 30a is the control light switch 30d.
The control optical switch 30b transfers the leakage light leaking from the control optical switch 30c to the connection waveguide 26 from the remaining port of the switch 30a to the connection waveguide 26, and the control optical switch 30b transfers the leakage light leaking from the control optical switch 30c to the connection waveguide 28 from the remaining port of the switch 30b. Escape inside.

(n-8) Control light switches 30a, 30b, 30c, 3
When all 0d are operated in a crossed state, the waveguide type optical switch 18 is controlled by the control optical switch 30c130 on the port 22b, 24b side where the signal light is input.
d is the first control light switch, and control light switch 30c
control light switch 30a and control light switch 30
d, the control light switch 30b switches the second control light switch 30b to
The configuration is such that they are arranged in series as a single inch.

The control optical switch 30c connects the connecting waveguide 2 so that the signal light input from the port 22b is output from the port 24a.
The control optical switch 30d selects the connection waveguide 26 and the control optical switch 30a so that the signal light input from the port 24b is output from the port 22a. selects the input/output waveguide 22.

The control light switch 30a is the control light switch 30c.
The leakage light leaked from the input/output waveguide 22 to the switch 30a
The control optical switch 30b releases the leaked light leaked from the control optical switch 30d to the input/output waveguide 24 into the substrate 20 from the remaining port of the switch 30b.

According to the waveguide optical switch 18 configured as described above, leakage light generated when the signal light passes through the first control optical switch can be caused to escape into the substrate by the second control optical switch. Therefore, the port 22a of the waveguide optical switch 18
, 24a or the ports 22b, 24b can be reduced, and crosstalk can therefore be improved.

Therefore, since the leakage light output from the waveguide type optical switch 18 can be reduced, the control optical switches 30a and 30b.

For example, the control optical switch 30 can have a more relaxed tolerance range for manufacturing errors for 30c and 30d than before.
a, 30b, 30c, 30d @ When operated in the cross state, the crosstalk of the waveguide optical switch 18 is 120
In order to create a crosstalk of dB or less, the required tolerance for creation error is set such that when a conventional optical switch is operated in a cross state, the crosstalk of a conventional optical switch is 120 dB or less. Therefore, it is possible to make the production error tolerance approximately twice as loose as the required tolerance range.

Configuration of Controlled Optical Switch> FIGS. 3A and 3B are diagrams showing an example of the configuration of an optical switch suitable for use as the controlled optical switch of this embodiment.

In Fig. 3(A), 32 is a directional coupler type 2×2
An optical switch 32 is shown, which includes linear striped waveguides 34 and 36 arranged in parallel, and an electrode 38.
．． 40 and 42 on a substrate, the waveguides 34, 36 are shown with dots and the electrodes 38, 40, 42 are shown with hatching.

The electrode 38 is provided so as to extend from the right side edge of the waveguide 34 to the left side edge side, and the portion extending toward the left side edge side extends to the outer region of the waveguide 34 . electrode 40
extends from the right side edge of the waveguide 36 to the left side edge side, and furthermore, the part extending to the left side edge side is an area outside the waveguide 36 and extends to the area between the waveguides 34 and 36. It is set up to do so. The electrode 42 is arranged so that the waveguide 36 is sandwiched between the electrode 42 and the waveguide 34, and is arranged in a difficult manner with the waveguide 36.

The optical switch 32 transmits two orthogonal polarized C76 waves and T
It is designed so that the coupling length for the closed TE wave (M wave) matches the element length (interaction length) L, and the coupling length for the TM wave matches the element length, and is created based on these design conditions.

The optical switch 32 created in this way has electrodes 38.4
It can be operated in the cross state when no voltage is applied to the electrodes 38, 40, and 42, and in the bar state by applying voltages of any suitable polarity and any suitable voltage value to the electrodes 38, 40, and 42, respectively.

Here, the upper end of the waveguide 34 is a port 34a and the lower end is a port 34b, and the upper end of the waveguide 36 is a port 36a and a lower end! 36b, when the optical switch 32 is used as the control optical switch 30a, the input/output waveguide 22 is connected to the ports h34a and 34b, and the connection waveguide 26 is connected to the port 36b, and the port 36a'IJ is used as an output port for leakage light. .

Furthermore, when used as the control optical switch 30c, the ports 34a and 34b are connected to the input/output waveguide 22 and the port 3.
The connection waveguide 28 is connected to the port 6a, and the port 36b is used as an output port for leakage light. When used as the control optical switch 30b, the input/output waveguide 24 is connected to the ports 36a and 36b, and the connection waveguide 2 is connected to the port 34b. When the port 34a is used as a leakage light output port, and the control optical switch 30d is used, the port 3-6a is used as an output port for leakage light.
, 36b are connected to the input/output waveguide 24 and the connection waveguide 26 is connected to the port 34a, and the port 34b is used as an output port for leaked light.

When the optical switch 32 is used as the control optical switch 30a, 30b, 30c, 30d in the connection state as described above,
For example, control light switches 30a, 30b, 30c,
The respective electrodes 38.42 of 30d may be commonly connected to serve as a ground electrode, and the respective electrodes 40 may be commonly connected to serve as a control electrode.
If you connect 40.42, the control light switches 30a, 30
The operating states of optical waveguide switches 18b, 30c, and 30d can be controlled simultaneously and kept in the same operating state, and therefore the operation of the waveguide optical switch 18 can be easily controlled.

The optical switch 32 shown in FIG. 3A has an operating voltage approximately 20 to 30% lower than a conventional optical switch, and therefore has the advantage that the operating voltage of the waveguide optical switch 18 can be reduced.

Next, the optical switch shown in FIG. 3(B) will be explained.

In FIG. 3 CB), reference numeral 44 indicates a directional coupler type 2×2 optical switch proposed by the inventors of this application. wave path 46.48 and electrodes 50.52 and 54
and on the substrate. In the figure, the waveguides 46, 48 are shown with dots, and the electrodes 50, 52, 54 are shown with hatching. Further, 46a and 46b are an upper end port and a lower end port of the waveguide 46, and 48a and 48b
indicate the upper end port and the lower end port of the waveguide 48, respectively.

The waveguide 46 is convex to the side opposite to the waveguide 48.
The waveguide 48 is curved in the shape of a "<" so as to be convex on the side opposite to the waveguide 46, and the waveguide 46.4
8 has a curved shape that is symmetrically bent at the midpoint of the element length.

The electrode 50 is provided so as to extend from the right side edge of the waveguide 46 to the left side edge side, and the portion extending toward the right side edge side extends to the outer region of the waveguide 46 . The electrode 52 extends from the right side edge of the waveguide 48 to the left side edge, and the portion extending to the right side edge is an area outside the waveguide 48 and extends to the area between the waveguides 46 and 48. It is set up so that it exists. The left side edge of the electrode 52 between the waveguides 46 and 48 has a convex shape that matches the right side constraint of the waveguide 460. The electrode 54 is provided apart from the waveguide 48 so that the waveguide 48 is sandwiched between the electrode 54 and the waveguide 46, and the left side edge of the electrode 54 matches the right side edge of the waveguide 48. It has a concave shape.

The optical switch 44 is designed so that the coupling lengths for TE waves and TM waves match the respective element lengths, and is created based on this design condition. The optical switch 44 made in this way can be operated in a crossed state when no voltage is applied to the electrodes 50.52.54, and by applying a voltage of any suitable polarity and voltage value to the electrodes 50.52.54, respectively. It can be operated in bar state.

A light switch 3 that controls the light switch 44 shown in FIG. 3 (8)
0a, 30b, 30c, and 30d, the waveguides 22.24.26.28 and the optical switch 44 can be connected in the same way as the optical switch 32 shown in FIG. 3(A). The explanation will be omitted. Also, the light switches 30a, 30b, 30c, 3 control the light switch 44.
Control optical switch 30a130b when used as 0d
Electrode 48.50.52 which becomes the electrode of s 30cm30d
The connection can be made in the same manner as the optical switch 32 described above, for example, so the explanation thereof will be omitted.

This optical switch 44 has the advantage that the operating voltage can be lowered by about 20 to 30% than the optical switch 32 shown in FIG. 3(A), and therefore the operating voltage of the waveguide type optical switch 18 can be reduced.

Furthermore, the above-mentioned optical switches 32 and 44 are very easy to control, and therefore, for example, the switch 3, which is easy to control,
By using 2 or 44 as a control optical switch, the operation control of the waveguide type optical switch 18 can be made simpler than in the past.

4 is a plan view schematically showing the configuration of a modification of the first embodiment. Note that constituent components corresponding to those of the first embodiment are designated with the same reference numerals.

This modification example includes control optical switches 30a, 30b, 30c.
.

30d and a waveguide 22.2 connected to these switches.
The configuration is the same as that of the first embodiment except for the connection state with 4.26.28.

(2) First, consider the case where signal light is input from ports 22a and 24a and signal light is output from ports 22b and 24b.

(III-a) Controlled optical switches 30a, 30b, 30c
, 30d are all operated in the bar state, the waveguide type optical switch 18 at this time
The control optical switches 30a and 30b on the a side are the first control optical switches, and the control optical switch 30c is connected to the control optical switch 30a, and the control optical switch 30d is connected to the control optical switch 30b as a second control optical switch. has a configuration.

In order for the signal light to reach port 22a to port 24b,
The control optical switch 30a selects the connection waveguide 26, and the control optical switch 30d selects the input/output waveguide 24. Furthermore, the control optical switch 30b selects the connection waveguide 28 and the control optical switch 30c selects the input/output waveguide 22 so that the signal light reaches port 22b from port 24a.

The control light switch 30c is a control light switch.

Waveguide 22 different from waveguide 26 selected from 30a
The leaked light is released into the board 20 from the remaining port of the switch 30c.

Similarly, the control optical switch 30d selects a waveguide 2 different from the waveguide 2B selected from the control optical switch 30b.
The leaked light leaked to the switch 30d is released into the board 20 from the remaining port of the switch 30d.

(III-1)) Control light switch, 30a, 30b
, 30c, and 30d are all operated in a crossed state. At this time, the waveguide type optical switch 18 is connected to the port 22a.

The control light switches 30a and 30b on the 24a side serve as the first control light switch, the control light switch 30d serves as the control light switch 30a, and the control light switch 30c serves as the second control light switch for the control light switch 30b. They are arranged in series.

The control optical switches 30a and 30c select the input/output waveguide 22 so that the signal light is input from the port 22a and output from the port 22b. Also, the signal light is at port 24.
so that it is input from a and output from port 24b,
The control optical switches 30b and 30d select the input/output waveguide 24.

The control light switch 30d is the control light switch 30
The leaked light leaking into a waveguide 26 different from the waveguide 22 selected from a is transferred from the remaining port of the switch 30d to the substrate 2.
Missed into 0.

Similarly, the control light switch 30c is the control light switch 3
The leaked light from the waveguide 0b to the waveguide 28 different from the selected waveguide 24 is released into the substrate 20 from the remaining port of the switch 30c.

(2)0 Next, consider the case where signal light is input from the ports 22b and 24b and signal light is output from the ports 22a and 24a.

(■-a) Control light switches 30a, 30b, 30c, 3
When all 0d are operated in the bar state, the waveguide type optical switch 18 is connected to the port 22b.

The control light switches 30c and 30d on the side of 24b serve as the first control light switch, and the control light switch 30a serves as the control light switch 30c, and the control light switch 30b serves as the second control light switch for the control light switch 30d. They are arranged in series.

The control optical switch 30c selects the connection waveguide 2 and the control optical switch 30b selects the input/output waveguide 24 so that the signal light passes from the port 22b to the port 22a. Further, the control optical switch 30d selects the connection waveguide 26 and the control optical switch 30a selects the input/output waveguide 22 so that the signal light reaches the port 22a from the port 24b.

The control light switch 30a is the control light switch 30c.
The control optical switch 30b transfers the leakage light leaked into the waveguide 22 from the remaining port to the control optical switch 30d.
The leaked light leaking into the waveguide 24 is released into the substrate 20 from the remaining port.

(rV-B) control optical switches 30a, 30b, 30c,
When all 30d are operated in a crossed state, the waveguide type optical switch 18 is connected to the port 22b124.
The control light switches 30c and 30d on the b side become the first control light switches, and the control light switch 30a is connected in series to the control light switch 30c as a control light switch 30b and to the control light switch 30d as a second control light switch. It has an arranged configuration.

The control optical switches 30c and 30a select the waveguide 22 so that the signal light is input from the port 22b and output from the port 22a. Furthermore, the control optical switches 30d and 30b select the waveguide 24 so that the signal light is input from the port 24b and output from the port 24a.

The control light switch 30a is the control light switch 30d.
The control optical switch 30b transfers the leakage light leaked to the connection waveguide 26 from the remaining port to the control optical switch 30b.
The leaked light leaked from 0c to the connection waveguide 28 is released into the substrate 20 from the remaining port.

Even in this modification configured as described above, the same effects as in the first embodiment can be obtained.

No.: General description of the overall structure of the J1 giant system> FIG. 5 is a plan view schematically showing the structure of a second embodiment of the present invention. Note that constituent components corresponding to those of the first embodiment are designated with the same reference numerals.

In FIG. 5, 56 indicates a waveguide type optical switch, and the waveguide type optical switch 56 of this second embodiment includes a substrate 20, input/output waveguides 58 and 60 provided on this substrate 20, and a connecting waveguide. 62 and a control optical switch 64a164b, ports 58a and 60a are provided at the upper end of the input/output waveguide 58.60, and ports 58a and 60a are provided at the lower end of the input/output waveguide 58.
b, 60b are provided.

As shown in FIG. 5, in this embodiment, the input and output waveguides 58.60 are curved waveguides having a "<" shape, and are separated from each other by M and H waveguides. A connecting waveguide 62 is provided between them. The upper end side of the connection waveguide 62 is connected to the port 60a side of the input/output waveguide 60 via the control optical switch 64a, and the lower end side is connected to the port 58b side of the input/output waveguide 58 via the control optical switch. 64b
Connect via.

As the control optical switches 64a and 64b, for example, a directional coupling type 2x2 optical switch is used as a 1x2 optical switch, as in the first embodiment.
Or use it as a 2X1 optical switch.

In this case as well, the remaining ports are used as output ports for leaked light.

<Description of Configuration and Operation> Next, the configuration and operation of the waveguide optical switch 56 will be explained with reference to FIG. 5.

(2) First, consider the case where signal light is input through ports 58a and 60a and output through ports 58b and 60b.

(V-a) When the control optical switches 64a and 64b are all operated in the bar state, the waveguide type optical switch 56 at this time is On the other hand, the control optical switch 64b is arranged in series as a second control optical switch.

The control optical switch 64a selects the input/output waveguide 6o so that the signal light passes from the port 60a to the port 60b, and the control optical switch 64b selects the input/output waveguide 58 so that the signal light passes from the port 58a to the port 58b. Select.

The control light switch 64b is the control light switch 64b.
The leaked light leaking from a to the waveguide 62 is released into the substrate 20 from the remaining port.

(V-b) When operating the control optical switches 64a, 64b in a crossed state, the control optical switch 60a connects the connection waveguide 62 and the control optical switch 64b connects the connection waveguide 62 so that the signal light travels from the port 60a to the port 58b. The input/output waveguide 58 is selected.

(6) Next, consider the case where signal light is inputted through ports 58b and 60b and outputted from ports 58a and 60a.

(VI-a) When the control optical switches 64a and 64b are operated with all the rv bar states At this time, the waveguide type optical switch 56 sets the control optical switch 64b on the port 58b side as the first control optical switch, and this switch 64b The control optical switch 64a is arranged in series as a second control optical switch.

The control optical switch 64b selects the input/output waveguide 58 so that the signal light passes from the port 58b to the port 58a, and the control optical switch 64a selects the input/output waveguide 6° so that the signal light passes from the port 60b to the port 60a. Select.

The control light switch 64a is the control light switch 64b.
The leaked light leaking from the connecting waveguide 62 to the connecting waveguide 62 is released into the substrate 20 from the remaining port.

(Vl-b) When the control optical switches 64a and 64b are all operated in a crossed state, the control optical switch 64b connects the connection waveguide 62 and the control optical switch so that the signal light travels from the port 58b to the port 60a. The switch 64a selects the input/output waveguide 6o. Then, the control optical switch 64a releases the leaked light from the remaining port into the board 20 so that the leaked light from the preceding optical circuit element inputted from the port 60b is not outputted from the port 60a.

Even in the waveguide type optical switch 56 of the second embodiment configured as described above, the same effects as in the first embodiment can be expected.

The waveguide type optical switch 56 of this second embodiment is preferably used as a node used in an optical LAN.

2. Figure 6 is a plan view schematically showing the configuration of a modification of the third embodiment. Note that constituent components corresponding to those of the third embodiment are designated with the same reference numerals.

This modification has the same configuration as the second embodiment except for the connection state between the control optical switches 64a, 64b and the waveguides 58, 60, and 62 connected to these switches.

(2) Consider the case where signal light is input from ports 58a and 60a and signal light is output from ports 58b and 60b.

(■-a) When the control optical switches 64a and 64b are all operated in the bar state, the control optical switch 60a connects the connection waveguide 62 and the control optical switch 64b so that the signal light reaches the port 58b from the port 60a. selects the input/output waveguide 58.

(Vll-1)) When the control optical switches 64a, 64b @all are operated in a crossed state, the waveguide type optical switch 56 has the control optical switch 64a on the port 60a side as the first control optical switch, A control optical switch 64b is arranged in series with this switch 64a as a second control optical switch.

The control optical switch 64a selects the input/output waveguide 60 so that the signal light passes from the port 60a to the port 60b, and the control optical switch 64b selects the input/output waveguide 58 so that the signal light passes from the port 58a to the port 58b. Select.

The control light switch 64b is the control light switch 64b.
The leaked light leaking from a to the waveguide 62 is released into the substrate 20 from the remaining port.

(2) Consider the case where signal light is input from ports 58b and 60b and output from ports 58a and 60a.

(■-a) When all of the control optical switches 64a and 64b are operated in the bar state At this time, the control optical switch 64b connects the connection waveguide 62 and the control light so that the signal light travels from the port 58b to the port 60a. The switch 64a selects the input/output waveguide 601Fr.

(■-b) When the control optical switches 64a and 64b are all operated in a crossed state.At this time, the waveguide type optical switch 56 uses the control optical switch 64b on the port 58b side as the first control optical switch, and this switch edge 64b (On the other hand, the control light switch 64a is arranged in series as a second control light switch.

The control optical switch 64b selects the input/output waveguide 58 so that the signal light passes from port 58b to port 58a, and the control optical switch 64a selects the input/output waveguide 60 so that the signal light passes from port 60b to port 60a. select.

The control light switch 64a is the control light switch 64b.
The leaked light leaking from the connecting waveguide 62 to the connecting waveguide 62 is released into the substrate 20 from the remaining port.

Even in this modification configured as described above, the same effects as in the second embodiment can be obtained.

Figure 7 is a plan view schematically showing the configuration of a third embodiment of the present invention. It should be noted that constituent components corresponding to those in the third embodiment are denoted by the same reference numerals.

In FIG. 7, 66 indicates a waveguide type optical switch. The waveguide type optical switch 611r of this embodiment includes a control optical switch 64c in the input/output waveguide 58 between the port 58a and the control optical switch 64b, and roughly the input/output guide between the port 60b and the control optical switch 64a. The configuration is similar to that of the third embodiment except that a control optical switch 64d is provided in the wave path 60. The control optical switches 64c and 64d have the same configuration as the control optical switches 64a and 64b.

Hereinafter, the structure of this embodiment will be explained in terms of its operation and good fortune. Note that descriptions of the same configurations and operations as in the second embodiment will be omitted.

(2) Consider the case where signal light is input from ports 58a and 60a and output from ports 58b and 60b.

(IX-a) Control light switches 64a, 64b, 64c,
When all the optical switches 64d are operated in the bar state, the control optical switches 64a and 64d are such that the signal light is connected to the port 60.
The input/output waveguide 60 is selected so that the signal light travels from port 58a to port 60b, and the control optical switches 64b and 64c select the input/output waveguide 58 so that the signal light travels from port 58a to port 58b. The control switch 64a becomes a first control light switch, and the control light switch 64b becomes a second control light switch with respect to this switch 64a.

(IX-b) Control light switches 64a, 64b, 64c,
64d are all operated in a crossed state.At this time, the waveguide type optical switch 66 is the control optical switch 64a18 on the port 60a side, and the control optical switch 64d is the second control optical switch for this switch 64a. It has a configuration in which the switches are arranged in series.

The control optical switch 64d allows leakage light leaked from the control optical switch 64a to the waveguide 60 to escape into the substrate 20 from the remaining ports.

Further, the control optical switch 64c allows the leaked light to escape from the remaining port into the board 20 so that the leaked light from the optical circuit element in the previous stage inputted from the port 58a is not outputted from the port 58b.

X3 Next, consider the case where signal light is input from ports 58b and 60b and output from ports 58a and 60a.

(X-a) Control light switches 64a, 64b, 64c, 6
At this time, the control optical switches 64b and 64c select the input/output waveguide 5 so that the signal light passes from the port 58b to the port 58a, and the control optical switches 64d and 64a , the input/output waveguide 60 is selected so that the signal light travels from the port 60b to the port 60a. The control light switch 64b becomes a first control light switch, and the control light switch 64a becomes a second control switch with respect to this switch 64b.

(X-b) Control light switches 64a, 64b, 64c, 6
4d are all operated in a crossed state. At this time, in the waveguide type optical switch 66, the control optical switch 64b on the side of the port 58b is the first control optical switch, and the control optical switch 64c is the second control optical switch for this switch 64b. It has a configuration in which the switches are arranged in series.

The control optical switch 64c allows leakage light from the control optical switch 64b to escape into the board 20 through the remaining ports.

Then, the control optical switch 64d releases the leaked light from the remaining port into the board 20 so that the leaked light from the preceding optical circuit element inputted from the port 60b is not outputted from the port 60a.

In this embodiment as well, the same effects as in the first embodiment can be obtained.

The present invention is not limited to the above-described embodiments, and therefore, the distribution positions, connection relationships, configurations, and other design conditions of each component can be changed as desired.

As the control optical switch, various conventional optical switches such as a directional coupling type optical switch, a total reflection type optical switch, and others may be used. Furthermore, materials having an electro-optic effect and others can be used as the substrate material. Further, the design conditions of the control optical switch can be changed arbitrarily and suitably.

Note that the connection state between each port of the controlled optical switch and each waveguide can be changed arbitrarily and suitably, and therefore is not necessarily limited to the state described below. Supplementary explanation will be provided below with more specific examples.

In a modification of the first embodiment, for example, when the optical switch 32 and the control optical switch 30a are used, the port 34a is an output port for the leaked light, and the ports 36a and 34b are used as the waveguide 2.
2 and port 36b are connected to the waveguide 26 and used as a control optical switch 30c. Ports 34a and 36b are connected to the waveguide 22 and port 36a to the waveguide 28, and port 34b is used as an output port for leakage light, and the control optical switch 30c is used. optical switch 30
In the case of b, the ports: 34a and 36b are connected to the waveguide 24, and the port 34b is connected to the waveguide 28, and the port 36a is used as the output port for leakage light.If the control optical switch 30d is used, the ports 36a and 34b are connected to the waveguide. 24 and the port 34a may be connected to the waveguide 26, and the port 36b may be used as an output port for leaked light.

In the second embodiment, for example, when the optical switch 32 is used as a control optical switch 84a, the port 36a136b is connected to the waveguide 60 and the port 34b is connected to the waveguide 62, and the port 34a @leakage light output port is used for rough control. In the case of an optical switch 64b, the waveguide 58P8 may be connected to the ports 34a and 34b, and the waveguide 62 may be connected to the port 36a, so that the port 36b8 can be used as an output port for the leaked light.

Further, in a modification of the second embodiment, for example, the optical switch 3
2. If the control optical switch 64a is used, the port 34a,
In the case where a waveguide 60 is connected to port 36b and a waveguide 62 is connected to port 36b, port 36a is used as an output port for leakage light, and roughly used as a control optical switch 64b, ports 34a and 36b are connected.
% waveguide 58 and port 36a to waveguide 62 and port 34b! It may be used as an output port for leaked light.

In the third embodiment, for example, when the optical switch 32 is used as control optical switches 64a and 64b, they are connected in the same manner as in the second embodiment, and when it is used as a control optical switch 64c, the ports 36a and 36b are connected to the waveguide 58. port 34a,
34b When used as an output port for IFr leakage light and as a rough control optical switch 64d, ports 34a and 34b 7
The ports 36a and 36b may be connected to the JR waveguide 60 and used as output ports for leaked light.

(Effects of the Invention) As is clear from the above description, according to the waveguide optical switch of the present invention, when the signal light passes through the first control optical switch, the main leakage light is absorbed by the second control light. Since the switch allows the light to escape into the board, leakage light output from the port of the waveguide type optical switch can be reduced, and crosstalk can therefore be improved.

Therefore, since the leakage light output from the waveguide optical switch can be reduced, the allowable range of error in manufacturing the control optical switch can be made more relaxed than in the past.

Alternatively, since the leakage light output from a waveguide optical switch can be reduced, it is possible to replace an optical switch that does not have sufficient losstalk for practical purposes when operating without polarization dependence with a waveguide optical switch. Therefore, the degree of freedom in selecting an optical switch to be used as a control optical switch can be increased. This is because even if an optical switch does not provide sufficient losstalk for practical purposes by itself, leakage light can be reduced when this optical switch is used as a control optical switch for a waveguide type optical switch. This is because the crosstalk of the optical switch can be made practically sufficient. As a result, it has become possible to use an optical switch that does not provide sufficient losstalk for practical purposes, but has a low operating voltage, as a control optical switch for a waveguide optical switch, which increases the degree of freedom of selection. This also leads to the advantage that the operating voltage of the waveguide optical switch can be easily reduced.

Furthermore, even if an optical switch that has polarization dependence when used alone is used as a control optical switch, according to the waveguide optical switch of the present invention, the waveguide optical switch can be used as a control optical switch. Since the output leakage light can be reduced, the waveguide type optical switch of the present invention can also be used as an optical switch without polarization dependence. Since polarization dependence is eliminated, for example, it is possible to reduce the crosstalk for each of the TE wave and TM wave to -20 dB or less even in the operating state of the bar and cross state chairs.

In general, in the waveguide type optical switch of the present invention, since the operation of the waveguide type optical switch is controlled by making the operating states of the first and second control optical switches the same, the operation control is simple.
Therefore, it is possible to avoid complicating operation control.

[Brief explanation of the drawing]

Fig. 1 is a plan view schematically showing the configuration of a first embodiment of the present invention, Fig. 2 is a diagram showing the propagation state of signal light and leakage light in the first embodiment, and Fig. 3 is a diagram showing a control optical switch. FIG. 4 is a plan view schematically showing the structure of a modification of the first embodiment, and FIG. 5 is a schematic diagram showing the structure of a second embodiment of the present invention. 6 is a plan view schematically showing the structure of a modification of the second embodiment, FIG. 7 is a plan view schematically showing the structure of the third embodiment of the present invention, and FIG. 8 is a plan view schematically showing the structure of the third embodiment of the present invention. FIG. 2 is a plan view illustrating the configuration of a conventional optical switch. 18.56.66... Waveguide optical switch, 20...
Substrate, 22.24.26.28.58.60.62--Waveguide, 30a, 30b, 30c, 30d. 64a, 64b, 64c, 64d... Control light switches. Patent applicant Oki Electric Industry Co., Ltd. 18: Waveguide optical switch 20: Substrate 22.24.26.28 Waveguides 22a, 22b, 24a, 24b: Ports 30a, 3
0b, 30c, 30d: Explanatory diagram of the first embodiment of the control optical switch Fig. 1 Propagation states of signal light and leakage light Fig. 2 (A) (B) Explanatory diagram of the control optical switch Fig. 3 221> 24b No. - Modified example of the embodiment Fig. 4

Claims (2)

[Claims] (1) A first controlled optical switch that selects a waveguide that guides signal light from an input port to an output port; and a first controlled optical switch that selects a waveguide that guides signal light from an input port to an output port; What is claimed is: 1. A waveguide type optical switch comprising a second control optical switch that releases light into a substrate in the same operating state as the first control optical switch, and a second control optical switch arranged in series. (2) The waveguide type optical switch according to claim 1, wherein the first and second control optical switches are polarization-independent optical switches.