JPS5897994A - Switch for exchange - Google Patents

Abstract

PURPOSE:To obtain a switch for exchange without using any special devices an optical switch with a switching function and a photodetector with an photoelectric converting function, by separating the switching function and photoelectric converting function. CONSTITUTION:An electric signal inputted to an input terminal 11 is converted by an electrooptic converting element 21 into an optical signal, which is inputted to optical switch elements 811, 812, and 813 through an optical demulplexing circuit 31 at the same time. The optical switch elements 811-813 are closed normally and the optical signal is sent to none of optical multiplexing circuits 91, 92, and 93, but once the optical switch 812 is opened, the optical signal reaches a photodetector 102 through the optical multiplexing circuit 92 to be converted into an electric signal, which is amplified to a prescribed voltage by an amplifier 62 and sent to an output terminal 72. Thus, the input terminal 11 and output terminal 72 are connected together and other input terminals and other output terminals are connected similarly.

Description

TECHNICAL FIELD This invention relates to broadband switching switches in telecommunications.

(Background Art) A wideband replacement switch that combines an optical circuit and an electronic circuit as shown in FIG. 1 has been reported. (E, H,
Hara, S., Machida, M., and Ike.
da, H, Kanbeand T, Kimura
, Electronics Letters, vo
117. pp150-151 (1981)) Figure 1 shows an example of the configuration of a 3x3 switch, in which 11 to 13 are input terminals, 21 to 23 are electrical/optical conversion elements, and 31 to 33 have a light input end of 1 and a light input terminal. (IX3) optical branch circuit with 3 output ends, 4
1. ~433 is a photodetector, 531 is a photodetector drive circuit (
51,~5.3,5□1~52. .

(The photodetector drive circuit corresponding to 532 y ss is omitted in the figure), 6. ~63 is an amplifier; 7. ~7s is an output terminal.

Input terminal 1. The operation when connecting the output terminal 72 and the output terminal 72 will be explained. Input terminal 1. The electrical signal input to
The light is converted into an optical signal by the optical conversion element and input to the light input end of the optical branch port 3I. Optical branch circuit 3. The optical signal is branched and sent from three light output ends to photodetectors 411 + 412
+413 is input at the same time. Photodetector 4+1 +
The photodetector drive circuits 511+51□ and 513 connected to 412+4+s are always off and waiting, and the photodetectors 41H412+413 are not operating, but only the photodetector drive circuit 5.2 is on. When the state is set, the photodetector 412 operates to convert the optical signal into an electrical signal, and the electrical signal is amplified to a predetermined voltage by the amplifier 62 and sent to the output terminal 7□. In this way, the input terminal 11 and the output terminal 72 are connected, but the other input terminal 1° (l=
1 to 3) and output terminal 7. (Cores 1 to 3) can also be connected in the same manner.

In this replacement switch, since the photodetectors 411 to 433 perform the switching function and the optical/electrical conversion function, there is a drawback that a special photodetector with excellent threshold characteristics is required.

In addition, a switch with N input terminals and N output terminals requires a large number of N2 photodetectors (for example, 1 (100 for a lxin switch)), which has the disadvantage of being difficult and expensive to manufacture. be.

(Disclosure of the Invention) In order to eliminate these drawbacks, the present invention provides a broadband replacement switch using an optical interlocking switch. N electrical/optical conversion elements connected, N IXM optical branch circuits connected to their respective outputs, and M (M
is a natural number), and has an M x N optical closing switch matrix having N optical closing switching elements in the row direction, and each of the N optical branch circuits corresponds to an N column of optical closing switching elements. , for each optical branch circuit, M light emitting ends are input to each of the M rows of optical inter-closing switch elements, and furthermore, M light emitting ends are input to each of the M rows of optical inter-closing switch elements, and each of the N columns is provided corresponding to each row of the M rows of optical inter-closing switch elements. M N×1 optical merging circuits connected to the outputs of the open/close switch elements, and M electrical/optical conversion elements connected to the outputs of the respective merging circuits and coupled to the M output terminals, A replacement switch that connects each input terminal to a desired output terminal by selectively driving each component of the optically closed switch matrix.

It's on it.

(BEST MODE FOR CARRYING OUT THE INVENTION) FIG. 2 shows an embodiment of the present invention, and is a configuration example of a 3×3 switch. 8 is a 3x3 optical open/close switch (811-833
is an optical switching element arranged in a matrix), 91
-93 are 3x1 light combining circuits, and 101-1()3 are photodetectors. The optical multiplexing circuits 97, 9□, and 93 function to guide the light input to the three light input ends to the output end.

The electric/optical conversion element 2k (k=1 to 3) is coupled to the optical branch circuit. The three light output ends of the optical branch circuit 3 are connected to the optical closing switch element 8k118 of the 3×3 optical opening/closing switch 8 (21).
Combine 8 with 3. The three light input ends of the optical multiplexing circuit 91 (A'=1 to 3) are connected to the optical closing switch element 8+J T821
F8sl, and the light emitting end is connected to the photodetector 10J.

Input terminal 1. The operation when connecting the output terminal 72 and the output terminal 72 will be explained. Input terminal 1. The electrical signal input to the electrical/optical conversion element 2. is converted into an optical signal and passed through the optical branch circuit 31 to the optical switching element 811 + 812 + sts
are input simultaneously. Optical close switch elements 811-8,
3 is always closed and waiting, and the optical multiplexing circuit 91, 9□
.

Although no optical signal is sent to 9, when the optical closing switch element 8□2 is opened, the optical signal reaches the photodetector 102 via the optical multiplexing circuit 92 and is converted into an electrical signal. The voltage is amplified to a predetermined voltage by the amplifier 62 and sent to the output terminal 72. In this way, input terminal 1 and output terminal 72 are connected, but in the same way, other input terminals 1□ (i=1 to 3)
and output terminal 7j (j=1 to 3) can also be connected.

The configuration of the 3x3 replacement switch has been explained above, and in the same way, an NxN optical opening/closing switch consisting of N electrical/optical conversion elements, N IXN optical branch circuits, and NxN optical inter-optical switching elements has been described. Nxl light combining circuits, N photodetectors,
N×N switching switches can be fabricated using N amplifiers.

FIGS. 3(a) to 3(C) show examples of a 3×3 optical on/off switch 8 that utilizes the electro-optic effect.

(a) is a front view, (bl is a side view, and (C) is a perspective view. 11 is an electro-optic crystal plate such as LiNbO3, KDP, (3aAs), 12 is a polarizer, 13 is an analyzer, 14
2. -1433 are transparent electrodes on the surface of the electro-optic crystal plate 11 provided at the positions of the optical opening/closing switch elements 811-833;
Reference numeral 5 denotes a transparent electrode provided on the entire back surface of the electro-optic crystal plate 1.

Transparent electrode 144. 1433 and the transparent electrode 150, the main axis of the crystal is set in the y-axis direction, the polarization direction of the polarizer 12 is set at 145 degrees from the y-axis, and the analyzer 12
The polarization direction of is set at +45 degrees from the y-axis. In this way, the transmitted light becomes zero when no voltage is applied, and the light switching element 81. ~833 is in a closed state. -The amount of transmitted light I when an actual voltage is applied is expressed by the following formula.

1-I, 5in2 (πΔnd/λ) where ■. is the amount of light immediately after passing through the polarizer 12, Δn is the difference in refractive index between the y-axis direction and the x-axis direction when voltage is applied, d is the thickness of the electro-optic crystal plate, and λ is the wavelength of the light.

By setting πΔnd/λ=π/2, transmitted light with the best extinction ratio can be obtained. In this manner, the optical switching element is in an open state when a voltage is applied. Desired transparent electrode 141. When a voltage is applied to 1433, a desired optical switching element is brought into an open state.

FIGS. 4(a) and 4(bl) show another embodiment of the 3×3 optical on/off switch 8, which uses a liquid crystal.(a) is a front view, and (b) is a side view.16 17 is a transparent electrode provided on the entire surface of the glass plate 16; 18 is a glass plate for encapsulating a skeleton crystal; 1911-1933
20 is a liquid crystal, 21 is a polarizer, and 22 is an analyzer. A nematic liquid crystal is used for the liquid crystal 20. Transparent electrode 170 surface and transparent electrode 195
．． The surface of the glass plate 18 including .about.1933 is subjected to parallel alignment treatment to define the alignment of liquid crystal molecules.

As the parallel alignment treatment method, a vertical evaporation method or an oblique evaporation method, which is commonly used in the manufacture of liquid crystal displays, can be used. The long axes of liquid crystal molecules are oriented in the X-axis direction on the surface of the transparent electrode 17, and in the y-axis direction on the surface of the glass plate 180. The polarization directions of the polarizer 21 and the analyzer 22 are set in the X-axis direction.

When no rhombic voltage is applied between the transparent electrode 17 and 1911 to 19330, the long axis direction of the liquid crystal molecules is rotated by 90° from the y-axis to the y-axis between the transparent electrode 17 and the glass plate 180, so that the incident light is The polarization direction of is also rotated by 90°. Therefore, the polarization direction of the light that has passed through the polarizer 21 and the liquid crystal 20 is perpendicular to the polarization direction of the analyzer 22, so that no light is transmitted. On the other hand, when a voltage is applied, all the liquid crystal molecules are aligned in the Z-axis direction, so the incident light passes through without being affected by the polarization direction. Therefore, the light that has passed through the polarizer 21 and the liquid crystal 20 passes through the analyzer 22 as is. Therefore, transparent electrode】9,1~1
'The optical switching switch can be opened or closed depending on whether or not a voltage is applied to J33.

The present invention has been described in detail above. Electrical/optical conversion elements include
For example, A I (jaA s or 1nQaAsP
It is possible to use semiconductor lasers and light emitting diodes that emit light from visible light to near-infrared light. The photodetector is composed of (ie, Si, 1nGaAsP) depending on the wavelength of the electrical/optical conversion element.
An avalanche photodiode, a photodiode, etc. can be used. In addition to the above-mentioned optical switching elements, absorption edge shift of ZnS film due to ultraviolet irradiation (T, Matsui and K, 'l'oyoda)
, Japan Journal of Applic
d Pr+ysics, vol, 12pp625-
626 (1973)) Absorption edge shift due to the Franz-Keldichko effect in Beno semiconductors (e.g. L', K
, Re1nhart, Appl 1ed Physics
Letters, vol 22+ pp372-3
74 (1973)) is also available. Note that since there is no factor that limits the pass band in the optical switching element, it can easily have a band of 500 MHz or more.

(Effects of the Invention) As explained above, the present invention separates the switch function and the optical/electrical conversion function, thereby providing a special optical opening/closing switch with the switching function and a photodetector with the optical/electrical conversion function. It has the advantage of not being necessary and easy to manufacture. In other words, parts used for normal optical modulation can be used for the optical switch, and a photodetector that does not have a threshold characteristic or has poor threshold characteristics can be used. Furthermore, the number of expensive photodetectors, which occupy a large proportion of the broadband exchange switch, can be reduced from N2 to N, which has the advantage of being extremely economical. Furthermore, since the exchange is performed using light, there is no stray capacitance that limits the band of conventional electromagnetic switches (easily 500M), and a wide band of z or more can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional replacement switch, FIG. 2 is a configuration example of an optical switch according to an embodiment of the present invention, and FIGS. 3 and 4 are configurations of an optical inter-closing switch for explaining the present invention. This is an example. 11-1. ... Input terminal, 2I-23... Electrical/optical conversion element, 3, -33... 1x3 optical branch circuit, 411-43. ... photodetector, 53, ... photodetector drive circuit, 6. ~63... Amplifier, 7, ~73... Output terminal, 8... 3x3 optical open/close switch, 81, ~833... Optical close switch element,
9, ~93...3x1 light combining circuit, ■01~103... Photodetector, 11... Electro-optic crystal plate, 12... Polarizer, 13... Analyzer, 1411... ■3. ...Transparent electrode, 15...Transparent electrode, 16...Glass plate, 17...Transparent electrode,
18...Glass plate, 1911-1p33...Transparent electrode, 20...Liquid crystal, 21...Polarizer, 22
...Analyzer. Patent Applicant Nippon Telegraph and Telephone Public Corporation Patent Application Agent Patent Attorney Megumi Yamamoto -Table 3 Figure (at (1)) (() Ice 4 Figure

Claims (1)

[Claims] N electrical/optical conversion elements connected to each of N input terminals (N is a natural number), and N electrical/optical conversion elements connected to each output.
1xM optical branch circuits and M in the column direction (M is a natural number)
has an MxN optical opening/closing switch matrix having N optical opening/closing switch elements in the row direction, and each of the N optical branch circuits corresponds to the N columns of optical opening/closing switch elements. M light emitting ends are inputted to each of the Pv1 row of optical switch elements, and are further provided corresponding to each row of the M row of optical switch elements and connected to the output of each party switch element of N columns. M NXI optical merging circuits and M circuits connected to the outputs of each optical merging route and coupled to M output terminals.
What is claimed is: 1. A replacement switch characterized in that the switch is equipped with several electrical/optical conversion elements, and connects each input terminal to a desired output terminal by selectively driving each component of the IJ.