JPS6331158B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switching matrix for switching input and output of optical signals as they are in optical communication systems that use optical fibers as transmission paths. recent years,
There are great expectations for optical communications because the attenuation characteristics of optical fibers have been significantly improved and the possibility of extending the lifespan of semiconductor lasers has emerged. In other words, when transmitting high-speed PCM signals, compared to transmitting electrical signals through cables, using optical signals is expected to offer numerous advantages in terms of characteristics such as attenuation, waveform distortion, and crosstalk, as well as communication capacity. can. Naturally, in this case, a switch that switches the high-speed PCM signal becomes necessary, but currently the switch that switches the optical signal as it is is as simple as 2 inputs and 1 output, and has a large capacity. There is no suitable switch for the switching matrix.

For example, at current TV broadcasting stations, studios,
A large-capacity video switching matrix of 320 inputs x 320 outputs is used to interconnect VTRs, telecines, external lines, etc. A mercury relay is used as this switching element. If all these video signals are converted to PCM, high-speed PCM of 100Mb/s
A large-capacity switching matrix is required to switch the signals. If this were to be done using electrical signals as they were, problems such as transmission path problems and crosstalk in the switching matrix itself would arise, but these problems can be solved by replacing these with optical communications. What is needed in this case is an optical communications switch that performs switching using optical signals as they are.

The purpose of the present invention is to provide switching necessary for configuring an optical communications exchange that can switch optical signals as they are when exchanging optically modulated high-speed PCM signals or analog video signals transmitted using optical fibers. The purpose is to provide a matrix.

According to the present invention, for example, eight input optical signals are branched into eight channels at the input side, and the optical fibers of each branched channel are concentrated one by one into eight optical beam selection switching elements provided at the output side. , this selection switching element selects one of the eight input fibers by electromagnetically moving the movable piece to which the photoelectric conversion element is attached to a predetermined position, and receives this optical signal. An optical switching matrix of input x 8 outputs is obtained.

Next, embodiments of the invention will be described in detail with reference to the drawings. In Fig. 1a, D ₁ to _{D 8} are optical signal distributors installed on the input side of the matrix, which branch optical signals input from the outside through optical fiber 1 and connect them to eight optical fibers. Outputs the same optical signal to both. This optical signal splitter is usually
The input signal is first converted into an electrical signal, then shaped and amplified, converted back into an optical signal, and outputted to eight fibers.It is an application of an optical communication repeater and cannot be achieved using existing technology. be.

Outputs from the optical signal distributors D ₁ to _{D 8} are input to eight optical beam selection switching elements R ₁ to _{R 8} one by one. That is, one optical signal from the distributors D ₁ to _{D 8} is input to each of the selection switching elements,
The selection switching element selectively receives one optical signal among the eight inputs and sends the signal to the outside as an output.

This corresponds to a switching matrix of 8 inputs x 8 outputs in the case of the electrical signal shown in FIG. 1b.

FIGS. 2a and 2b show the structure of this light beam selection switching element. A shows a side surface and b shows a cross section. In Fig. a, 1 is an optical fiber for input signals. The eight input fibers are housed in the positions indicated by dotted circles in Figure b. A photoelectric conversion element 2 is mounted on a movable piece 3 made of a magnetic material. The movable piece 3 is supported by a flexible metal support 4. As shown in Figure b, electromagnets 7 are attached to the four outer sides of the movable piece.

Further, a lead wire 5 is drawn out from the light receiving element 2, and this lead wire guides the signal converted into an electric signal in the photoelectric conversion element to the amplification conversion section 6. The amplification conversion unit amplifies and shapes the minute electrical signal input from the photoelectric conversion element, converts it into an optical signal again, and outputs it to the outside through the output side optical fiber 9.

By applying a driving current to the coil terminal 8 of the electromagnet 7, the driven electromagnet attracts the movable piece 3 supported by the flexible column in its own direction. For example, in figure b, if electromagnets M ₁ and M ₂ are driven, the movable piece moves to the upper left corner position, and the photoelectric conversion element 2
can receive the light of the optical fiber housed in this position. When the electromagnet's current is cut off, the movable piece returns to its central position and the matrix is turned off. In this way, by driving one or a combination of two electromagnets, one of the eight optical fiber inputs can be arbitrarily selected.

Returning to FIG. 2, the selection switching elements R ₁ to _{R 8} in the diagram
By configuring the device with elements having functions as described above, an 8-input x 8-output switching matrix for optical communication can be constructed.

The 8-input x 8-output switching matrix described in detail above is used as a unit block, and this unit block is used to configure a multi-stage switching matrix using the same method as the switcher configuration method for a telephone exchange. A switching matrix can be constructed.

[Brief explanation of the drawing]

Figure 1a is a system diagram showing the structure of this invention;
Figure b is a system diagram of a conventional electric signal matrix corresponding to this, Figure 2 a is a side view showing the structure of the light beam selection switching element shown in Figure 1 a, and Figure 2 b is a cross-sectional view of this. . 1...Optical fiber, _D1 to _D8 ...Optical signal distributor, _R1 to _R8 ...Light beam selection switching element, 2...
Photoelectric conversion element, 3... Movable piece, 4... Support column, 5...
...Lead wire of the light receiving element, 6...Width amplification conversion section, 7...
... Electromagnet (positions are indicated by M ₁ to _{M 4} ), 8 ... Coil terminal of electromagnet, 9 ... Output side optical fiber.

Claims (1)

[Claims] 1 The input optical signals of n systems are each branched into m branches at the input side, and the optical fibers of each branched system are connected to 1
Each light beam is concentrated into m light beam selection switching elements provided on the output side, and in this selection switching element,
By electromagnetically moving the movable piece to which the photoelectric conversion element is attached to a predetermined position, one of the m input fibers is selected, and this optical signal is received, electrically amplified and shaped, and then converted into a light beam again. A switching matrix for optical communications that switches n input x m output optical signals by outputting as follows.