KR100198427B1 - Optical switching system device - Google Patents

Abstract

The present invention provides an optical signal exchange for transmitting M × N optical signals having several wavelengths and several (N) input terminals to a destination without colliding with each other in wavelength division multiplexing (WDM) optical communication. The present invention relates to a device, in which optical signals are interchanged in a conventional optical communication system, in which an optical signal is converted into an electrical signal and then electrically switched, and then converted into an optical signal and transmitted to a destination, because the electrical switching speed is slow, and thus, high speed In the case of an optical communication signal, a problem arises that the volume of the electronic exchanger becomes large and practically useless, such as the signal itself is decompressed into several slow signals, and then switched again and then compressed again. Is an optical wavelength decomposition section for decomposing the input light for each wavelength and An N × N spatial optical switch unit having only the same wavelengths of the separated optical signals and having N switching input terminals, a wavelength conversion distribution unit for collecting the converted optical signals for each wavelength, converting them into required wavelengths, and decomposing them again; It consists of an N × N spatial optical switching unit and an optical wavelength combiner having N switching input terminals connected only to the same wavelength connected behind, and can exchange N × M optical signals. It is a new concept designed to enable the exchange of optical signals, which is impossible with an electronic exchanger.

Description

Optical exchange system device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for switching optical signals in optical communication. Optical communication is essential for large-capacity information transmission or exchange, and optical communication of 2.5 gigabits per second is used.

In addition, to increase the transmission capacity of optical communication, we are researching and developing a communication method called Wavelength Divider on Multiplexing (WDM), which transmits several optical signals of different wavelengths to one strand of optical fiber and transmits them at the receiving end. The optical signal of wavelength is separated by wavelength band and the optical signal of each wavelength is reproduced as an electric signal.

For example, four wavelengths of λ1 = 1.540 μm (channel 1), λ2 = 1.545 μm (channel 2), λ3 = 1.550 μm (channel 3) and λ4 = 1.555 μm (channel 4) were used for wavelength division multiple optical communication. Each channel has a transmission speed of the conventional optical communication method and includes different signals.

If four channels are separated at the receiving end, one fiber can transmit four times as much information as conventional optical communication.

Although the above-described transmission schemes are erupted with various ideas, the exchange of optical signals is very complicated, and thus there is no specific implementation yet.

That is, since the exchanger that exchanges optical signals has not been put into practical use yet, when exchanging optical signals of currently used optical communication, the optical signals are converted into electrical signals and then electrically switched, and the signals are converted back into optical signals. Complex systems are being used to deliver to their destinations.

However, in this case, since the electrical switching is slow, in the case of the ultra-high speed optical communication signal, the volume of the electronic exchanger becomes very large and practically useless, such as unpacking the signal itself into several slow signals, switching them, and then compressing them again. The practical use is essential.

1 is a schematic diagram of a conventional general optical exchange device.

The symbol S of the optical exchange device means a signal.

That is, the signal S ₁ ... S _N is input to signal S ' ₁ ... S ' _N is output.

The signal S ₁ is a signal S ' ₁ ... According to the exchange information. It can also be switched to any of the S _'N, and the rep and optical switching systems, such as the first 10 degrees to set the return path as described above.

The optical exchange system shown in FIG. 1 is a device for exchanging signals of a single optical wavelength.

2 is a schematic diagram of an optical switching device of a wavelength multiple optical communication (WDM) having several wavelength signals and input terminals.

The input terminal i of FIG. 2 has S _i1 . , S i _iM this is input from the ik subscript stands for i- th input terminals, and k is the k- th mean wavelength.

That is, each input terminal is λ ₁ ,... , M-wavelength signals of λ _M.

In FIG. 2, the output terminals have respective terminals λ ₁ ,. , M-wavelength signals of λ _M.

In the optical switching device as described above, the internal configuration of the paths in which each signal can go to a desired output signal must be set without collision, and the present invention provides a system capable of providing these paths.

In order to solve the above problems, the present invention, in particular in the case of the wavelength division multiplexing (WDM) optical communication, the use of an optical exchange is essential, while the light of several wavelengths in one strand of the optical fiber to set the exchange path for each wavelength This should be well constructed and ensure that light of the same wavelength does not enter the same path where wavelength separation occurs.

1 is a schematic diagram of a conventional general optical exchange device.

2 is a schematic diagram of a conventional optical switching device for wavelength multiple optical communication (WDM) having several wavelength signals and input terminals.

Figure 3a is a block diagram of an optical switching device of the wavelength multiplex optical communication (WDM) proposed in the present invention.

3b is a schematic diagram of a distribution device for wavelength multiplexed optical signals according to the present invention;

Figure 3c is a spatial switch, a wavelength conversion divider and an optical signal connection diagram according to the present invention.

3d is a conceptual diagram of a wavelength conversion distributor according to the present invention.

Figure 3e is a schematic diagram of the output section consisting of a space switch and a wavelength multiplexer according to the present invention.

4A to 4D are flowcharts showing the construction of the optical wavelength conversion distribution apparatus of the present invention.

5A is a schematic diagram of an embodiment of an optical path configuration of an optical exchange apparatus having two input terminals and four wavelength channels applied to the present invention.

Figure 5b is a schematic diagram of an embodiment of the optical path configuration of an optical exchange apparatus having four input terminals and two wavelength channels applied to the present invention.

Figure 5c is a schematic diagram of an embodiment of the optical path configuration of an optical switching device having four input terminals and four wavelength channels applied to the present invention.

* Explanation of symbols for main parts of the drawings

10: A device for exchanging optical signals of a single optical wavelength

20: Optical exchange device for exchanging multiple input light wavelengths

31,51: Optical Wavelength Decomposer (DMUX) 32,52,54: Space Optical Switch

33,53: WCDS 34,55: Multiplexer

41: light receiving element (PD) 42: wavelength variable semiconductor laser (TLD)

43: optical wavelength combiner (MC) 44: optical wavelength divider (Demultiplexer)

45 optical wavelength converter 46 spatial optical switch element or device

In order to achieve the above object, the present invention provides an optical wavelength separation unit (W-DMUX part) consisting of N pieces for decomposing input light for each wavelength in an optical exchange device for exchanging N input ports and M wavelength channels. (31) and the N × N spatial optical switch unit 32 having N switching input terminals in which only the same wavelength is input among the optical signals separated by each optical wavelength decomposition unit, and the switched optical signals are collected for each wavelength and then, A wavelength conversion distribution unit 33 for converting and redistributing, and an N × N spatial optical switch unit 32 and an optical wavelength combining unit (W-MUX) having N switching nodes inputted with only the same wavelength connected thereto. And exchange N × M optical signals.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Figure 3a is a block diagram of a wavelength multiple optical communication (WDM) optical switching device proposed in the present invention.

In the above configuration, the input unit and the output unit each have N-terminals, and each terminal includes M-wavelength signals.

In addition, a demultiplexer (DMUX) 31 which separates an optical signal of multiple wavelengths input through a single fiber into each wavelength, and N × N spatial switch when the number of input terminals is N, has M wavelengths. number of spatial light signal exchange switch 32 and the device, the input optical signal as needed, and converts these signals are input signals each having a different wavelength M- of the part to distribute the array by each wavelength glows wavelengths λ _1, ... , an optical wavelength conversion divider (part) 33 arranged in the order of λ _M and input to the space switch 32.

In addition, the signals found in the path of the space switch 32 are input to the optical wavelength combiner 34, and M-wavelength signals for each channel are mixed to form a new signal array.

Before explaining the function of each part of the system configured as described above with reference to Figure 5 as a specific embodiment as follows.

5A is a schematic diagram of an embodiment of an optical path configuration of an optical exchange apparatus having two input terminals and four wavelength channels applied to the present invention.

In the above configuration, the input signal is S ₁₁ ,. , S ₂₄ and output signal S _'11 ,. , Exchange of the signals illustrated in FIG. 5a when S _'24 d corresponds to the following:

S ₁₁ → S _'24 , S ₁₂ → S' ₂₁ , S ₁₃ → S _'23 , S ₁₄ → S' ₁₃ ,

S ₂₁ → S _'11 , S ₂₂ → S' ₁₂ , S ₂₃ → S _'22 , S ₂₄ → S' ₁₄ ,

If the destination of the input signal is to be changed, the path may be changed as much as the switching unit and the wavelength conversion unit are adjusted.

Looking at the principle that the signals are exchanged as described above, S ₁₁ is input to the first input terminal of the first space switch 52a in the optical wavelength splitter 15 because the wavelength is λ ₁ .

When the spatial switch 52a is operated to cross the S ₁₁ to the S ′ ₂₄ , the S ₁₁ signal is output to the lower output terminal of the switch output and the wavelength is still λ ₁ .

The signal is input to the first input terminal of the second wavelength conversion distributor.

That is, it can be seen that the signal output from the second output terminal of the space switch is incident to 53b.

Thus, signal S ₁₁ is to the wavelength to S 'in order to be connected to ₂₄ and then past the wavelength conversion distributor there is incident on any element of the respective switching elements 54 to the second input terminal of which S' changing to ₂₄ be replaced with λ ₄ .

Therefore, the write wavelength of the light wavelength conversion cracker (DMUX) device, such as an array waveguide grating (Arrayed Waveguide Grating, AWG) after changing a wavelength of λ ₁ to λ ₄ in the distributor is distributed to the space switch of the bottom automatically.

At this time, the signal of S ₁₁ is converted into a wavelength of λ ₄ .

S _11, as shown in the signal output by collecting the signal is sent to the desired destination then placed in the S 'signal _24.

If the remaining signals are also tracked in the same manner, the above signal conversion occurs.

At this time, the most important is the wavelength conversion distribution unit 33 (53).

In the signal exchange, S ₁₁ , S ₂₁ , S _'11 , and S' ₂₁ have a wavelength of λ _1, and S ₁₂ , S ₂₂ , S _'12 , and S' ₂₂ have a wavelength of λ ₂ and S ₁₃ , S ₂₃ , S Since _'13 and S _'23 are λ ₃ and S ₁₄ , S ₂₄ , S' ₁₄ and S _'24 have a wavelength λ ₄ , it is well understood how the wavelength of each signal is changed.

That is, it can be seen that the signal S ₁₁ has a wavelength converted from the initial λ ₁ to λ ₄ .

Therefore, in the optical signal exchange as described above, the path switching and the optical wavelength conversion of the space switch should be simultaneously performed.

5B is a schematic diagram of an embodiment of an optical path configuration of an optical exchange apparatus having four input terminals and two wavelength channels applied to the present invention.

By tracking the respective paths, the signals of the input / output units correspond as follows.

S ₁₁ → S _'32 , S ₂₁ → S' ₄₂ , S ₃₁ → S _'22 , S ₄₁ → S' ₁₁ ,

S ₁₂ → S _'41 , S ₂₂ → S' ₃₁ , S ₃₂ → S _'12 , S ₄₂ → S' ₂₁

The signals mean that the arrangement of the spatial switches can be performed as shown in FIG.

In the signal exchange as described above in FIG. 5A, S ₁₁ , S ₂₁ , S ₃₁ , S ₄₁ , S _'11 , S' _21, S _'31 , and S' ₄₁ have a wavelength of λ ₁ , S ₁₂ , Since S ₂₂ , S ₃₂ , S ₄₂ , S _'12 , S' _22, S _'32 , and S' ₄₂ have a wavelength of λ ₂ , it is well understood how the wavelength of each signal is changed.

In this case, it can be seen that the signal S ₁₁ has been converted from the initial lambda ₁ to lambda ₂ .

5C is a schematic diagram of an embodiment of an optical path configuration of an optical exchange apparatus having four input terminals and four wavelength channels according to the present invention.

In the above configuration, when the signals are to be exchanged as follows, the configuration of the space switch is configured as shown in the figure.

S ₁₁ → S _'33 , S ₁₂ → S' ₁₄ , S ₁₃ → S _'24 , S ₁₄ → S' ₄₁ ,

S ₂₁ → S _'12 , S ₂₂ → S' ₃₁ , S ₂₃ → S _'43 , S ₂₄ → S' ₄₄ ,

S ₃₁ → S _'32 , S ₃₂ → S' ₁₃ , S ₃₃ → S _'42 , S ₃₄ → S' ₂₃ ,

S ₄₁ → S _'11 , S ₄₂ → S' ₂₁ , S ₄₃ → S _'34 , S ₄₄ → S' ₂₂ ,

As described above, the signals exchanged as described above are also converted in wavelength.

5A, 5B, and 5C, the optical exchange device proposed in the present invention is scalable to wavelength and input terminals and is governed by a very simple rule.

The function and requirements of each part constituting the above will be described in detail as follows.

The function of each part of the system shown in FIG. 3a is described in detail as follows.

3b is a schematic diagram of an apparatus for distributing wavelength multiplexed optical signals according to the present invention.

As shown in FIG. 3B, the optical wavelength splitter 31 of FIG. 3A distributes M wavelength signals to the spatial switches by wavelength, and the k-th wavelength signal of the i-th input terminal is the k-th spatial switch element. It is connected to be incident to the i-th terminal (Port).

Accordingly, the optical wavelength splitter 31 of FIG. 3b serves to separate each wavelength signal, and the device having such a function is a wavelength variable filter, and an optical wavelength called an arrayed waveguide grating (AWG) or a phased array (Phased Array). A decomposer (DMUX).

Looking at the block of the space switch 32 of FIG. 3a in detail, it can be seen that an optical signal having the same wavelength is incident on each space switch.

That is, only the optical signal having a wavelength of λ ₁ is incident on the first space switch 32a.

The switch has N input terminals for each switch, λ ₁ is input to the first switch, λ ₂ is input to the second switch, and λ _M is input to the M-th switch.

The switch is routed to enable optical exchange and primarily selects the path.

The optical signal whose path is changed is incident to the wavelength conversion divider 33 along a predetermined path as shown in FIGS. 3A and 3C. The wavelength conversion divider converts the incident light wavelength according to each path and then outputs the output terminal. It has a function to arrange in the order of the wavelength at.

For example, in FIG. 3D, four optical wavelengths are considered, and the signals are transmitted as λ ₁ → λ ' ₂ , λ ₂ → λ' ₄ , λ ₃ → λ ' ₃ , λ ₄ → λ' _1, etc. on the optical path. When the path of the whole signal is correct when is changed, there are several ways to change each signal.

4A to 4D are flowcharts showing the construction of the optical wavelength conversion distribution apparatus of the present invention.

First, as shown in FIG. 4A, a photoelectric (OE) converter (Photodetector, PD) is used to convert an electric signal and then a wavelength-tunable semiconductor laser (tunable LD) is used to change the wavelength.

After changing the wavelength as described above, after integrating light of various wavelengths into 43 (W-MUX or a combiner) of FIG. 4A, the wavelength may be separated by a wavelength splitter (W-DMUX) to arrange the wavelength.

In this case, the combiner is simply a device for collecting the optical signal in one place and the wavelength splitter is a device for separating the light by wavelength.

As described above, the wavelength splitter may use a phased array or an arrayed waveguide grating (AWG) device.

Alternatively, as shown in FIG. 4B, a wavelength converter may be used instead of using the light receiving element PD and the tunable LD of FIG. 4A.

The wavelength converter is an element or device for changing the wavelength of an input light wave.

The method shown in FIG. 4C is a method of using a space switch, and the number of input terminals is required as many as the wavelength of the signal light wave.

That is, when M-light wavelengths are used, M × M spatial switches should be used.

In this case, the wavelength converter may always output a constant wavelength regardless of the wavelength of the input signal.

4d is the same principle as in FIG. 4c. Instead of the wavelength converter, the light receiving element PD and the wavelength tunable semiconductor laser LD are used.

In this case, since the wavelength mask semiconductor laser LD may not be a wavelength mask, it may have an advantageous configuration.

However, there are disadvantages in that it is difficult to implement the space switch because the number of input / output terminals of the space switch increases when the optical wavelength is several channels.

As described above, the wavelength converting and arranging unit that can be implemented in various ways requires as many input terminals as shown in FIG. 3A.

In the form shown in Figure 3a above, N- will be needed.

As described above, when each signal is separated and entered into the space switch, signals are exchanged by selecting an optical path from the space switch, and the signals are combined in the combiner or the optical wavelength combiner 34 in FIG. 3a and the optical wavelength combiner 34 in FIG. 3e. It is then sent to a new optical exchange or destination.

Configuring the system as described above has the following features or advantages.

First, in the combined optical paths (W-MUX, W-DMUX and wavelength conversion divider), the M-optical signals wavelength-multiplexed at each of the N-I / O terminals are interconnected point-to-point without blocking inside the switch. It can be said to be a very advantageous technology to implement a large capacity optical switch.

Second, in setting the optical path, if only the path of the optical space switch and the path of the wavelength converter are set, the path for the optical signals of the entire system is determined.

The path setting of the space switch may have various paths in each case, and these paths can be set through the central controller by detecting an input signal.

Third, the optical exchanger configured as described above can be expanded by increasing or decreasing the number of optical wavelength channels.

For example, if the number of optical wavelengths is increased from M to P, the number of spatial optical switches may be increased from M to P and the input / output terminals of the wavelength conversion distributor may be increased from M to P.

Fourth, since the system configuration is composed of elements that can be implemented although the current performance is still poor, it is possible to realize the optical exchanger with a slight development of the current device technology.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switching device or an optical switch device capable of exchanging optical signals used in wavelength division multiplexing (WDM) optical communication. have.

Claims (6)

An optical exchange device for exchanging N input ports and M wavelength channels, comprising: N optical wavelength decomposition parts 31 for decomposing input light for each wavelength, and optical signals separated in the optical wavelength separation parts. An N × N spatial optical switch unit 32 having N switching nodes input only the same wavelength, an optical wavelength conversion distribution unit 33 which collects the switched optical signals by wavelength, converts them into necessary wavelengths, and redistributes them; And an N × N spatial optical switch and an optical wavelength combiner (MW-MUX) having N switching nodes connected only to the same wavelength connected thereafter, to exchange N × M optical signals. The apparatus of claim 1, wherein the optical wavelength decomposition unit (31) separates optical signals having a plurality of wavelengths inputted through a single optical fiber for each wavelength. The optical wavelength conversion distribution unit 33 converts the optical signal into an electrical signal using the light receiving element 41 and then converts the wavelength using a wavelength tunable semiconductor laser, and then converts the wavelength into several wavelengths using a combiner (W-MUX). Integrating the optical signal of the optical exchange system device, characterized in that separated by the optical wave splitter. The wavelength conversion splitter 33 converts the wavelength of the optical signal using a wavelength converter as an element and combines the optical signals of various wavelengths with a combiner (W-MUX), and then the wavelength splitter. Optical exchange system device, characterized in that separated by. The optical switching system apparatus according to claim 1, wherein the optical wavelength conversion distribution unit (33) uses a spatial switch using input terminals as many as the number of wavelengths of the signal light waves. The apparatus of claim 1, wherein the optical wavelength conversion distributor (33) uses a light emitting element (PD) and a semiconductor laser (LD) and a spatial light switch which can be used without changing the wavelength.