JPS60177326A - Matrix switch and its driving method - Google Patents

Abstract

PURPOSE:To obtain a small-sized matrix switch which is suitable for miniaturization and formation of IC and capable of high-speed switching by arranging one optical control element for each of MXN light emitting element and one photodetector for every M optical control elements, and turning on and off the light emitting elements according to an input signal. CONSTITUTION:Signals inputted to input terminals 10a and 10b are passed through amplifiers 18a and 18b and applied to light emitting elements 11a and 11b, and 12a and 12b of a 2X2 matrix switch. Their modulated light beams are incident on optical control elements 13a and 13b, and 14a and 14b. Those four optical control elements are controlled by a controller 19 so that incident light is transmitted or cut off. Light beams transmitted through the optical control elements 13a and 14a, and 13b and 14b are detected by photodetectors 17a and 17b respectively and transmitted to output terminals 20a and 20b. Consequently, the small-sized matrix switch which is integrated suitably and capable of high- speed switching is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a matrix switch that arbitrarily switches and connects a plurality of input signal paths and output signal paths, and a driving method thereof.

(Prior art and its problems) With the rapid development of optical communication systems, efforts are being made to increase the capacity of transmission lines, and the development of increasingly sophisticated systems is proceeding. In order to expand the functions of communication systems, clear functions such as exchanging various signals and high-speed switching of transmission line networks are becoming required, and there is a growing need for optical switching networks that make these functions possible. Methods for exchanging optical signals and switching transmission paths include (1) switching by changing the optical path in the optical state, and (2) converting the optical signal into a commercial signal and converting it into a commercial signal. (3) A method of switching the input optical signal and converting it back into an optical signal in the state of A method has been proposed in which all the data are selected and connected to the output terminal.

First, regarding the optical path switching type switch in (1), is there a waveguide type optical switch that is composed of a mechanical optical switch that uses mechanical movement of brism or mirror elements using electricity, magnets, etc., and an optical waveguide provided on a substrate? However, the latter is superior in terms of high speed and multi-channel possibilities. Waveguide optical switches have the advantage of being able to switch optical signals as they are at high speed, but generally it is difficult to obtain normal operation unless the incident light is linearly polarized, so they can be applied directly to normal single-mode optical fibers or multi-mode optical fiber systems. However, there are drawbacks such as the fact that it is difficult to obtain adequate loss talk characteristics and rejection characteristics, and that the size becomes large when multi-channeling is used. In the method (2) using a wealth switch/da circuit,
Since it is a regenerative amplification system, there is no need to consider insertion loss, and it has the advantage of not depending on the optical fiber structure. Therefore, there is a drawback that it is difficult to obtain sufficient losstalk characteristics for wideband signals.

The method (3) has the advantage that losstalk can be relatively low for broadband signals and the electrical circuit is not so complicated. FIG. 1 is a diagram for explaining method (3). Input optical transmission line 1a, Ib deviation 7 *i
□The light is received by the diodes 3a, 3b, 4a, and 4b. Here, by switching the bias applied to the photodiode 1' in accordance with the control signal and operating only the desired photodiode A, it is possible to suppress the electrical signals output to the output branches 5a and 5b.

This chisel method has the advantages mentioned above, but on the other hand,
A major drawback is that it requires an optical branch circuit as shown in FIG. Currently, optical branch circuits are mainly manufactured by bundling multiple optical fibers and connecting them to 1B, but in general, when there are multiple branches, the loss or thickness becomes large. is difficult to obtain. Ma/ko, (3)
The disadvantage of this method is that the diode switch is large and difficult to switch at high speed.

(Objective of the Invention) The object of the present invention is to eliminate the drawbacks of conventional optical switches as described above, to be small and suitable for integration, and to switch multi-channel wideband signals at high speed with low crosstalk. The object of the present invention is to provide a possible matrix switch and its driving method.

(Structure of the Invention) The matrix switch of the present invention has IVI and N divided by M and 1.
．． When N is an integer of 1, the origin of MX N is J
゛A light element, a total of M x N light control elements optically coupled to each of the light emitting elements, and one light control element optically coupled to each of the M light control elements. It has a configuration with M input and N output terminals consisting of a total of N photodetectors, and its driving method is to use the above matrix switch,
Each of the light emitting elements is modulated by an input signal, and the light control cable passes the modulated light generated by each of the light emitting elements depending on the connection state of the input/output terminals.
The driving method is such that the light control element is controlled to turn off or off, and the light control element is modulated by an input signal, and the light emitting element turns on or off light emission depending on the connection state of the input/output terminal.
This is a driving method that is controlled to achieve F.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 2 is a diagram showing a 2×2 matrix switch, which is an embodiment of the matrix switch according to the present invention, and a method of driving the same. In FIG. 2, four luminescent cords 11a, 1
A light control element 13 is provided for each of 2a, llb, and 12b.
a, 14a, 13b, 14b are optical transmission lines 15a, 16
a, 15b, and 16b, respectively, and the light control elements 13a and 14a are optically coupled to the photodetector 17a, and the light control elements 13b and 14b are optically coupled to the photodetector 17b, respectively, by optical transmission paths similar to those described above. ing. Here, the light emitting elements include semiconductor lasers, light emitting diodes,
As a photodetector, a 7-balance photodiode (A
PD), PIN photodiode, etc. can be used. In addition, as a light control element, a waveguide-shaped optical switch or optical modulator formed by an optical waveguide on the main plate, or an element that controls transmitted light to switch the injection current of a semiconductor laser (hereinafter abbreviated as LD switch) can be used. FIG. 3 is a plan view showing an example of the above-mentioned waveguide type optical switch. Optical waveguides 21 and 22 are formed on a dielectric or semiconductor substrate exhibiting an electro-optic effect, such as a lithium niobate or InP substrate, by metal diffusion or crystal growth. close,
A control electrode 23 is installed on the optical waveguide adjacent to the optical waveguide, and the amount of transmitted light or the optical path of the transmitted light is controlled by applying a voltage to the control electrode 23. When the voltage applied to the control electrode 23 is O, the incident light 24 to the optical waveguide 21 is coupled to the optical waveguide 22 and becomes the output light 27. At an appropriate applied voltage, the incident light 24 is coupled to the optical waveguide 21 again and becomes the output light 25. becomes. In addition, applying a modulation voltage to the control electrode 23
can be modulated.

FIG. 4 is a sectional view showing an example of an LD switch.

In FIG. 4, when the current injected into a semiconductor laser 30 having a normal Pn junction is reversed, the semiconductor laser 30 functions as an optical amplifier, and incident light 31 is amplified and emitted.

In the injection type, when m is set to OF'F, the incident light 31 is absorbed and the output light 32 becomes 0. That is, in this LD switch, the incident light can be transmitted or blocked by turning the injection W flow ON or OF'F, and the sound of transmitted light can be modulated by modulating the injection current.

The embodiment of FIG. 2 has two input terminals 10a, 10b and 2.
The signal input to the input terminal Oa is amplified by the amplifier 18a and applied to the light emitting elements 11a and llb, and the signal input to the input terminal 1fJb is amplified by the amplifier 18b. Light emitting element 1
2a112b. As a result, the light emitting element 11a
, llb are determined by the signal input to the input terminal 10a,
The light-emitting cables 12a and 12b are each modulated by a signal input to the input terminal 10b, and the modulated light is sent to the light control element 13a113b, respectively.

14a and 14b. Here, all of the above four light control elements are connected to the controller 19, and
- They are controlled to transmit or block incident light independently depending on the control voltage or control current generated by the laser beam 19. Controller] 9 is a device for driving four light control elements based on commands from a central control device (omitted in FIG. 2). For example, when using a light control element that transmits or rapidly cuts incident light depending on the magnitude of the applied voltage as shown in Fig. 3, each of the four light control elements is independently Generates pressure.

As the simplest example, one light control element has one
It can be configured with a circuit using two transistors. For example, the transistor is constructed by connecting the collector of the transistor to a power source with high voltage vI through a resistor R, grounding the emitter, using the base as an input terminal for a control signal, and outputting an output voltage terminal from the collector. In this circuit, when the control signal voltage is 00, the output voltage ■! Therefore, when the control signal pressure is positive, the output voltage becomes ciO. Furthermore, when using a light control element that transmits or blocks incident light depending on the angle of the injected current as shown in FIG. A binary current, that is, a current 0, generates an arbitrary current 1 for each light control element independently. 1
The simplest configuration for one optical control element is a circuit using one transistor. For example, the n side of a PTI junction of an LD switch, which is a light control element, is connected to the collector side of the transistor via a resistor R, and the p side thereof is grounded. Further, the emitter 1t (II) of the transistor is connected to a negative power supply of voltage -V+, and the base is used as an input terminal for a control signal.

When the base potential of the transistor is 0, the transistor is turned on, so the LD switch has a current L”V1/(R
1+ r1+ rxn flows. Here, rl is the resistance of the LD switch, and r2 is the resistance of the transistor. Ten thousand,
When a negative voltage of sufficient magnitude is applied to the base of a transistor, the transistor turns off, causing lightning.

The flow becomes 0. The optical signals that have passed through the light control elements 13a and 14a are detected by the photodetector 17a and transmitted to the output terminal 20a, and the light that has passed through the light control elements 13b and 14b is detected by the photodetector 17b and transmitted to the output terminal 20b. communicated. For example, if the light control elements 1.4a and 13b are turned off and the others are set to the transparent state, the input terminal 10a becomes the output terminal 20a, and the input terminal 10b becomes the output terminal. Connected to terminal 20b. In addition, if the light control elements 13a and 13b are transmitted and the others are set to the blocked state, the input terminals 1. A so-called broadcast mode connection in which Oa is connected to both output terminals 20a and 20b is also possible.

The IJ optical switch in this embodiment is made of GaAs,
'If constructed using a semiconductor material such as InP, an amplifier,
A light emitting element, a light control element, a photodetector, etc. can all be monolithically integrated on the same substrate, the size can be made compact, and multi-channels can be achieved. In addition, since the input signal transmission system and the control circuit section that controls the switch are configured independently, it is much easier to control broadband signals compared to switching elements using ordinary electric circuits, and it can be used as an optical control element for quenching. By using elements with a high ratio, switching with low crosstalk can be achieved. In addition, the light control elements shown in FIGS. 3 and 4 are generally /
Switching speeds of n5ec or less can be obtained relatively easily.

FIG. 5 is a diagram showing a 2×2 matrix switch, which is another embodiment of the matrix switch according to the present invention, and a method of driving the same. The embodiment shown in FIG. 5 has four light emitting elements 11a.
%12a, llb, 12b, 4 light control elements 13a
, 14a, 13b, 14b, the two photodetectors 17a, 17b, and the arrangement and configuration of each element of the optical transmission line connecting them are completely the same as in the embodiment shown in FIG. However, in this embodiment, the signal manually input from the input terminal lOa is amplified by the amplifier 40a and sent to the light control element 13a.
, 13b and input from the input terminal 10b is amplified by the amplifier 40b and sent to the light control element 14a.
, 14b. Also, light emitting element], 1a, 1
2a, llb, and 12b are all connected to the controller 41, and the control 111Mt generated by the controller 410
The light emission is controlled to be turned on or off independently by each of the first and second lights. The configuration of the controller 41 is the same as that in the embodiment shown in FIG. 2 in which an LD switch is used as a light control element, and it supplies current to each of the four light emitting elements independently based on commands from the central controller. Turn on, turn off. The 2.times.2 matrix switch of this embodiment also allows arbitrary connections between input and output terminals, similar to the embodiment of FIG. For example, if the light emitting element 12aJ1b is turned on and the other light emitting elements are turned off, the input terminal LOa is connected to the output terminal 20b, and the input terminal 10b is connected to the output terminal 20a.

Similar to the example shown in FIG. 2, the matrix switch of this embodiment is also smaller and more suitable for integration than conventional matrix switches, and is capable of high-speed switching of multi-channel wideband signals with low crosstalk. Moreover, when this embodiment is compared with the embodiment shown in FIG.
Since a higher extinction ratio can be obtained by performing the light transmission and fast-actuation control of the light control element, it can be said that this embodiment is more advantageous in terms of crosstalk characteristics.

FIG. 6 is a diagram showing a 2×2 optical matrix switch which is another embodiment of the present invention. In this embodiment, a matrix switch with two optical inputs and two optical outputs is constructed by combining the 2×2 matrix switch shown in FIG. 2 or FIG. 5 with a light weight converter. In this embodiment, an input optical signal 60a transmitted through an input optical fiber 51a is detected by a photodetector 52a and inputted to a 2×2 matrix switch 500A power terminal 10a shown in FIG. 2 or FIG. 5. In addition, the input optical signal 60b transmitted through the input fiber 51b is transmitted to the photodetector 52.
b is detected and input to the 2×2 matrix switch 500 Å power terminal 10b. 2x2 Matrix Suinochi 50
An amplifier 53 is connected to the output terminals 20a and 20b of the
a, 53b1 light emitting elements 54a, 54b are connected,
Output optical signals 70a and 70b generated in the light emitting elements 54a and 54b, respectively, are transmitted to output optical fibers 55a and 55.
b respectively. That is, in this embodiment, the input source signal transmitted through the input source fiber 51a151b is regenerated, amplified, and coupled to any one of the output optical fibers 55a and 55b. 2×2 in this example
It goes without saying that the optical matrix switch also has the features of the embodiments shown in FIGS. yg2 and 5, as described above.

As described above, the present invention provides a matrix switch that is small, suitable for integration, and capable of high-speed switching of multi-channel wideband signals with low p-stoke, and a method for driving the same.

Note that the present invention is not limited to the above-described embodiments. For example, the number of input/output terminals may be provided independently for 4X4 and 8X. It is also possible to separately install the photodetector 17a117b so as to face each light control element and electrically connect them so that they function in the same way as the embodiment shown in FIG. 2 or 5. be. In the present invention, the electrically connected photodetectors as described above are treated as the same photodetector.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a conventional matrix switch, FIGS. 2, 5, and 6 are diagrams showing an embodiment of a matrix switch according to the present invention, and FIGS. 3 and 4 are diagrams showing an example of a matrix switch used in the present invention. It is a figure showing an example of a light control element. Oite in the figure, Ila
, llb, 12a, 12b are light emitting elements, 13a
, 13 b, 14 a, 14 b are light control elements,
17a, 17b are photodetectors, 18a, 18b,
40 a, 40 b are m111M equipment, 19.41
+i core) q -ra, 10a, 10bb 4b 2 Figure 1/a /2a /3a FDA T7a procedure/amendment (voluntary) 1. Indication of the case 1980 Patent Application No. 33466 2
, Title of the invention M) IJ switch and its driving method 3, Relationship with the amended case Applicant No. 1, No. 33, 33, 51, Shiba, Minato-ku, Tokyo (423) NEC Co., Ltd. Representative: Sekimoto Tadahiro 4, Attorney No. 8, 37 Shiba 5-chogetsu, Minato-ku, East 108 Sumitomo 31
1] Billing contact information: NEC Corporation Patent Department) 5. Claims column of the specification subject to amendment Column 6. Detailed explanation of the invention in the specification column 6. Contents of the amendment 1) Claims attached. Correct as shown below. 2) Insert the following sentence after the 6th line of page 16 of the specification. ``Furthermore, in the embodiments shown in FIGS. 2 and 5, the light wave is coupled to the hanger, or after being emitted from the light combiner, the light wave is transmitted through the optical transmission line, and then coupled to the photodetector. (Attachment) Claim (1) When M and N are integers such as M≧1 and N≧1, M
XN light emitting elements, a total of MXN light control elements optically coupled to each of the light emitting elements, and one light control element optically coupled to each of the M light control elements; A matrix switch with M input and N output terminals consisting of N photodetectors. Itch. (41M, when N is an integer with M≧1 and N>1, M
XN light emitting elements, a total of MXN light control elements optically coupled to each of the light emitting elements, and one light control element optically coupled to each of the M light control elements. In a matrix switch having M input and N output terminals consisting of N photodetectors, each of the light emitting elements is modulated by an input signal, and each of the light control elements inputs modulated light generated by the light emitting element. A method for driving a matrix switch, characterized in that the matrix switch is controlled to pass or block depending on the connection state of an output terminal. (51M, when N is an integer with M≧1 and N>1, M
XN light emitting elements, a total of MXN light control elements optically coupled to each of the light emitting elements, and a total of N light control elements optically coupled to each of the M light control elements;
In a matrix switch having M input and N output terminals, each of which is made up of a plurality of photodetectors, each of the light control elements is modulated by an input signal, and the light emitting element turns on or off light emission depending on the connection state of the input and output terminals. A method for driving a matrix switch, characterized in that the matrix switch is controlled to

Claims (1)

[Claims] (1) When M and N are integers such that M≧1 and Nuni,
MXN light emitting elements, one light control element optically coupled to each of the light emitting elements, a total of MXN light control elements, and one light control element optically coupled to each M light control element; A matrix switch with M power consisting of N photodetectors and N output terminals. (21M, when N is an integer of M x 1 and N uni,
MXN light emitting elements, a total of MxN light control elements optically coupled to each of the light emitting elements, and one light control element optically coupled to each of the M light control elements. In a matrix switch that has M input and N output terminals and is composed of N coupled photodetectors, each of the light emitting elements is modulated by an input signal, and each of the light control elements modulated light generated by the light emitting element. A method for driving a matrix switch, characterized in that the matrix switch is controlled to pass or block depending on the connection state of input/output terminals. (3) When M and N are integers M41 and N uni, M
A total of MXN light control elements, each of which is optically coupled to each of the XN light emitting elements and the emitting t-element, and one light control element is optically coupled to each of the M light control elements. In a matrix switch having M input and N output terminals and consisting of a total of N coupled photodetectors, each of the light control elements is modulated by an input signal, and the light emitting element is modulated according to the connection state of the input and output terminals. A method for driving a matrix switch, characterized in that the matrix switch is controlled to turn on or turn off light emission.