JP2004343228A - Optical cross connect system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical cross connect system which is capable of dealing with high-speed optical cross connect switching of a millimeter second or rapid fluctuation in a wavelength such as fault, and may possibly reduce the cost of the system. <P>SOLUTION: Optical signal transmission sections of an input section transmission/reception circuit are each provided with an optical amplifier. Alternatively, reception sections of an output section transmission/reception circuit may be each provided with APD receiver. Alternatively, the reception sections of the output section transmission/reception circuit may be each provided with an optical preamplifier type receiver. With this configuration, the necessity of optically amplifying a wavelength multiplex signal is eliminated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical cross-connect device used in an optical network using a wavelength division multiplex transmission technique.
[0002]
[Prior art]
In optical communication, there is a so-called wavelength multiplexing transmission technique for simultaneously transmitting optical signals of a plurality of wavelengths and assigning different information to each wavelength in order to effectively use a transmission line. In order to efficiently operate an optical network using a wavelength multiplexing transmission technology, an optical networking technology using an optical cross-connect device is important.
[0003]
FIG. 7 shows a block diagram of a configuration of a conventional optical cross-connect device (see Patent Document 1). Here, 1-1 to 1-N are input optical fibers, 2-1 to 2-N are pre-optical amplifiers (Pre-OA), 3-1 to 3-N are wavelength demultiplexers, 4-1 to 4-1. 4-NM is a wavelength converter, 5-1 to 5-N are M-input and N-output split-mixed flow type optical switches, 6-1 to 6-N are optical couplers, and 7-1 to 7-N are post-optical amplifiers. (Post-OA), 8-1 to 8-N are output optical fibers.
[0004]
Here, it is assumed that the number of input optical fibers and output optical fibers is N, and the number of multiplexed wavelengths per optical fiber is M. The M wavelength-multiplexed optical signals are input from respective input optical fibers and amplified by a pre-amplifier. The amplified wavelength division multiplexed signal is separated into individual wavelengths by a wavelength demultiplexer. The signals separated for each wavelength are wavelength-converted by a wavelength converter as necessary and output. The output signal from the wavelength converter is input to an M-input N-output split-flow switch. This mixed flow optical switch is a combination of M 1 × N optical switches and N M × 1 optical couplers, and can realize a non-blocking M × N switch. Further, it is possible to multiplex optical signals of different wavelengths directed to the same output optical fiber. The output signal of the split-flow optical switch is connected to an optical coupler. The optical coupler multiplexes the optical signals going to the same output optical fiber at the output of another split / mixed flow type optical switch. The multiplexed optical signal is amplified to a predetermined level by a post-optical amplifier and then sent to an output optical fiber.
[0005]
FIG. 8 shows the operation principle of the split / mix flow optical switch. 11-1 to 11-N are 1 × N switches. 12-1 to 12-N are M × 1 optical couplers. The 1 × N optical switch is realized by combining a plurality of 1 × 2 optical switches. FIG. 8 shows an example of switching from input port # 1 to output port # 2 and switching from input port # 2 to output port #N.
[0006]
First, the optical signal input from the input port # 1 is set to be output to the second output port. The output signal from the switch is input to the M × 1 optical coupler, multiplexed with the optical signal from another input port to the same output port # 2, and output. In this case, it is necessary to previously set the wavelengths of the signals going to the same output port to be different from each other. Similarly, the optical signal input from the input port # 2 is set so as to be output from the N-th output of the 1 × N switch, and is input to the M × 1 optical coupler connected to the output port N. Output to output port #N.
[0007]
[Patent Document 1]
JP-A-7-67153
[Problems to be solved by the invention]
As described above, an optical amplifier is used for the output of the N × 1 optical coupler, and a wavelength multiplexed signal is input to the optical amplifier. In this case, there is a problem that the output power of the optical amplifier fluctuates when the number of input wavelengths to the optical amplifier fluctuates rapidly due to a high-speed optical cross-connect setting change in milliseconds or less, a failure, or the like. .
[0009]
Further, a wavelength division multiplexing signal optical amplifier for amplifying a wavelength division multiplexed signal light is more expensive than an optical amplifier for amplifying a signal light that is not wavelength division multiplexed, and is not suitable for reducing the apparatus cost.
[0010]
An object of the present invention is to provide an optical cross-connect device capable of responding to a high-speed change in the number of wavelengths such as high-speed optical cross-connect switching of milliseconds or a failure. It is another object of the present invention to provide an optical cross-connect device which eliminates the need for a wavelength multiplexing signal optical amplifier for amplifying a wavelength multiplexing signal light and can possibly reduce the cost of the device.
[0011]
[Means for Solving the Problems]
According to the present invention, since there is no need to perform optical amplification of a wavelength division multiplexed signal, it is possible to provide an optical cross connect device that is stable with respect to an increase or decrease in the number of channels in the optical cross connect device. In addition, an optical cross-connect device capable of reducing the cost of the device can be provided because an optical amplifier for a wavelength multiplex signal for amplifying the wavelength multiplex signal light is not required.
[0012]
That is, the present invention provides an M × N input unit including a unit for receiving an optical signal from another device, a unit for transmitting an optical signal to the inside of the device, and a unit for varying an output wavelength of the transmitting unit. N split / combined flow type optical switches comprising a transmitting / receiving circuit, means for switching an input signal input from an input port to an output port in a non-blocking manner, and means for multiplexing and outputting a plurality of signal lights of different wavelengths Unit, N M × 1 optical couplers for multiplexing the inputs from the N split / mix flow optical switch units, and N 1 × optical couplers for separating up to M wavelength-multiplexed signal lights for each wavelength. An M × N output transmission / reception circuit including an M wavelength separation unit, a unit for receiving a signal from the 1 × M wavelength separation unit, and a unit for transmitting an optical signal to another device; The output wavelength of the transmitting / receiving circuit and the output of the An optical cross-connect device for connecting between the input port and the output port by setting a power port to a predetermined value.
[0013]
Here, the feature of the present invention resides in that the optical signal transmission units of the M × N input / output transmission / reception circuits each include an optical amplifier. As described above, by performing optical amplification at the entrance of the optical cross-connect device, it is not necessary to perform optical amplification of the wavelength multiplexed signal.
[0014]
Alternatively, an APD (Avalanche Photodiode) receiver may be provided in each of the receiving units of the M × N output transmitting / receiving circuits. Alternatively, an optical preamplification receiver may be provided in each of the receiving units of the M × N output transmitting / receiving circuits. By performing optical amplification at the exit of the optical cross-connect device in this way, it is not necessary to perform optical amplification of a wavelength multiplexed signal.
[0015]
As a result, it is possible to provide an optical cross-connect device capable of responding to a high-speed change in the number of wavelengths such as high-speed optical cross-connect switching of milliseconds or less or a failure. In addition, an optical cross-connect device capable of reducing the cost of the device can be provided because an optical amplifier for a wavelength multiplex signal for amplifying the wavelength multiplex signal light is not required.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an embodiment of the present invention. Here, reference numeral 1 denotes an input transponder having an optical input interface from another device and an optical output interface in the device, and having a function of receiving an optical signal from the other device and outputting it as an optical signal after wavelength conversion. In the figure, it is described as TDR-1. Reference numeral 2 denotes a split / mix flow optical switch. By combining M 1 × N switches having 1 input and N outputs and N M × 1 couplers having M inputs and 1 output, a non-blocking M × N optical switch can be configured. It is. Here, an 8 × 8-minute compound flow type optical switch when N = M = 8 is shown. In FIG. 1, this optical switch is described as DC-SW. Reference numeral 3 denotes an optical coupler for multiplexing optical signals from a plurality of DC-SWs and an optical demultiplexing unit having a function of demultiplexing optical signals of each wavelength. In FIG. 1, the optical coupler unit and the optical demultiplexing unit are described as DMUX. Reference numeral 4 denotes an output transponder having a function of receiving an optical signal in the device and outputting an optical signal by matching an interface with another device. In FIG. 1, it is described as TDR-2.
[0017]
The principle of the optical cross-connect function using the optical cross-connect device of the present invention will be described with reference to FIG. This device uses the wavelength variable function of the input transponder TDR-1 and the wavelength multiplexing function and the switching function of the split / mix flow optical switch DC-SW. Here, an example is shown in which an input transponder TDR-1 # 01 is connected to an output transponder TDR-2 # 01 using λ1, and an example in which an input transponder TDR-1 # 08 is connected to an output transponder TDR-2 # 02 using λ2. An example is shown.
[0018]
First, a method of setting the optical cross-connect from the input transponder TDR-1 # 01 to the output transponder TDR-2 # 01 will be described. The transmission wavelength of the input transponder TDR-1 # 01 into the device is set to λ1. The output of the input transponder TDR-1 # 01 is connected to the input port # 1 of the split-flow optical switch DC-SW # 1. The signal input to the input port # 1 of the split / mix flow optical switch DC-SW # 1 is set to be output to the output port # 1.
[0019]
The output port # 1 of the split / mix flow optical switch DC-SW # 1 is connected to the input port # 1 of the DMUX # 1. The DMUX includes an 8x1 optical coupler (8x10C) and a 1x8 optical demultiplexer (AWG). The 8 × 1 optical coupler multiplexes optical signals from the other combined flow type DC-SWs # 2 to # 8. The 1 × 8 optical demultiplexer (AWG) demultiplexes a maximum of eight wavelength multiplexed signals and outputs the demultiplexed signals for each wavelength. The optical signal of λ1 input to the input port # 1 of the DMUX # 1 is multiplexed by an 8 × 1 optical coupler (8 × 10C), then demultiplexed by a 1 × 8 optical demultiplexer (AWG), and output. The signal is output from the port # 1, and is guided to the output transponder TDR-2 # 01 connected to the output port # 1.
[0020]
Next, a method of setting an optical cross-connect from the input transponder TDR-1 # 08 to the output transponder TDR-2 # 02 will be described. First, the transmission wavelength of the input transponder TDR-1 # 08 into the device is set to λ2. The output of input transponder TDR-1 # 08 is connected to input port # 8 of DC-SW # 1. The signal input to the input port # 8 of the DC-SW # 1 is set to be output to the output port # 1 of the DC-SW # 1. Here, since the DC-SW is composed of eight 1 × 8 SWs and eight 8 × 10 C, if the signal light wavelength of each input port is different, it is possible to wavelength multiplex and output to the same output port. It is possible.
[0021]
That is, the λ1 signal input to the input port # 1 and the λ8 optical signal input to the input port # 8 can be wavelength-multiplexed to the output port # 1 and output. Output port # 1 of DC-SW # 1 is connected to input port # 1 of DMUX # 1. The DMUX includes an 8x1 optical coupler (8x10C) and a 1x8 optical demultiplexer (AWG). In the 8 × 1 optical coupler (8 × 10C), optical signals from other DC-SWs # 2 to # 8 are multiplexed. An optical demultiplexer (AWG) demultiplexes the wavelength multiplexed signal and outputs the demultiplexed signal for each wavelength. The optical signal of λ8 input to the input port # 1 of the DMUX # 1 is split by an optical splitter (AWG), output from the output port # 8, and TDR-2 # 08 connected to the output port # 8. Led to.
[0022]
Here, the difference from the conventional optical cross-connect device is that the wavelength multiplexed signal is not amplified by the optical amplifier in the DMUX unit. Therefore, a stable system can be configured without receiving output fluctuation due to passing through the optical amplifier when the number of channels is rapidly increased or decreased. In the realization, since the wavelength multiplexed signal is not amplified by the optical amplifier in the DMUX unit, in this embodiment, the transmission level is increased by providing the input transponder TDR-1 with an optical amplifier of a single wavelength signal, or the output transponder TDR- 2 was realized by providing an APD type receiving circuit to increase the receiving sensitivity or by providing a receiving circuit with an optical amplifier function.
[0023]
FIG. 3 is a level diagram (example) of the optical cross-connect device of the present invention. It is assumed that the output light level of the input side transponder TDR-1 is amplified to about 10 dBm by using an optical amplifier. An optical amplifier for single-wavelength amplification having an optical output of about 10 dBm can be easily and inexpensively constituted by an erbium-doped optical amplifier using one pump laser. On the other hand, the optical input power level to the output transponder TDR-2 is about -15 dBm to -23 dBm, which is an optical level that can be sufficiently received by the current 10 Gb / s APD receiving circuit.
[0024]
Comparing the price of an APD receiving circuit and the price of an optical amplifier for wavelength multiplexing, when the number of wavelength multiplexing is small, the price of the optical amplifier per wavelength is not so much divided by the number of wavelength multiplexing. Can be realized at lower cost.
[0025]
In this embodiment, one implementation example of the optical cross-connect device having 64 input ports and 64 output ports has been described. In this case, an optical cross-connect was configured using eight 8 × 8 DC-SWs, eight 8 × 1 optical couplers, and eight 1 × 8 optical demultiplexers, but four 16 × 4 DC-SWs were used. -SW, four 4 × 1 optical couplers, and four 1 × 16 optical demultiplexers can be used, and some other configuration methods can be considered.
[0026]
(Comparative example)
FIG. 4 shows a configuration of an optical cross-connect device of a comparative example. Here, an optical cross-connect device including an 8 × 1 optical coupler and an optical amplifier for 8-wave multiplexing is described. This optical cross-connect device has a configuration in which an 8-wavelength multiplexed optical amplifier (OA) is added to the DMUX having the configuration shown in FIG.
[0027]
FIG. 5 shows the principle of the optical cross-connect function using the present optical cross-connect device. The wavelength multiplexed signal optical amplifier (OA) amplifies a maximum of eight wavelength multiplexed signals. The 1 × 8 optical demultiplexer (AWG) demultiplexes a maximum of eight wavelength-division multiplexed signals and outputs them to respective output ports. The optical signal of λ1 input to the input port # 1 of the DMUX # 1 is multiplexed by 8 × 10C, amplified by the wavelength division multiplexing optical amplifier (OA), and then demultiplexed by the 1 × 8 optical demultiplexer (AWG). , Output from the output port # 1, and guided to the output transponder TDR-2 # 01 connected to the output port # 1. Other descriptions are the same as those described above.
[0028]
FIG. 6 is a level diagram of the optical cross-connect device. The loss of the split / mix flow type optical switch DC-SW and the 8 × 1 optical coupler is compensated for by the wavelength division multiplexing optical amplifier in the DMUX, and a level diagram is received by a normal PD type receiver. However, since ASE noise is superimposed in the wavelength division multiplexing optical amplifier, it is necessary to sufficiently increase the transmission level of the input transponder into the TDR-1 device.
[0029]
By comparing FIG. 6 with FIG. 3, it can be seen that the optical power level of FIG. 3 is more stable than that of FIG.
[0030]
【The invention's effect】
As described above, since there is no need to perform optical amplification of the wavelength multiplexed signal, it is possible to provide an optical cross-connect device capable of performing high-speed optical cross-connect switching in milliseconds or less. Further, since an optical amplifier for a wavelength multiplex signal for amplifying the wavelength multiplex signal light is not required, there is a possibility that the apparatus cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an optical cross-connect device of the present embodiment.
FIG. 2 is a diagram illustrating an operation principle of the optical cross-connect device according to the embodiment; FIG. 3 is a diagram illustrating a level diagram of the optical cross-connect device according to the embodiment;
FIG. 4 is a configuration diagram of an optical cross-connect device of a comparative example.
FIG. 5 is a diagram showing the operation principle of the optical cross-connect device of the comparative example.
FIG. 6 is a diagram showing a level diagram of an optical cross-connect device of a comparative example.
FIG. 7 is a block diagram of a conventional optical cross-connect device.
FIG. 8 is a diagram showing the operating principle of a split / mix flow optical switch.
[Explanation of symbols]
1, 11-1 Input transponder (TDR-1)
1-1 to 1-N input optical fiber 2, 5-1 to 5-N, 12-1 mixed flow type optical switch (DC-SW)
2-1 to 2-N Pre-optical amplifier 3, 13-1 Optical multiplexer / demultiplexer (DMUX)
3-1-3-N wavelength demultiplexer 4, 14-1 output transponder (TDR-2)
4-1 to 4-NM Wavelength converters 6-1 to 6-N Optical couplers 7-1 to 7-N Post optical amplifiers 8-1 to 8-N Output optical fibers 11-1 to 11-M 1 × N Switches 12-1 to 12-N M × 1 optical coupler

Claims (3)

Means for receiving an optical signal from another device, means for transmitting an optical signal to the inside of the device, and M × N input / output transmission / reception circuits comprising means for varying the output wavelength of the transmitting means,
Means for switching the input signal input from the input port to the output port in a non-blocking manner;
N M × 1 optical couplers for multiplexing the inputs from the N divided mixed flow optical switch units;
N 1 × M wavelength separation units for separating up to M wavelength multiplexed signal lights for each wavelength;
M × N output transmission / reception circuits including a unit for receiving a signal from the 1 × M wavelength separation unit and a unit for transmitting an optical signal to another device,
An optical cross-connect device that connects between the input port and the output port by setting an output wavelength of the input unit transmitting / receiving circuit and an output port of the split / mix flow optical switch unit to predetermined values.
An optical cross-connect device comprising: an optical amplifier in each of the optical signal transmission units of the M × N input / output transmission / reception circuits. Means for receiving an optical signal from another device, means for transmitting an optical signal to the inside of the device, and M × N input / output transmission / reception circuits comprising means for varying the output wavelength of the transmitting means,
Means for switching the input signal input from the input port to the output port in a non-blocking manner, and N divided / combined flow type optical switch units comprising means for multiplexing and outputting a plurality of signal lights of different wavelengths,
N M × 1 optical couplers for multiplexing the inputs from the N divided mixed flow optical switch units;
N 1 × M wavelength separation units for separating up to M wavelength multiplexed signal lights for each wavelength;
M × N output transmission / reception circuits including a unit for receiving a signal from the 1 × M wavelength separation unit and a unit for transmitting an optical signal to another device,
An optical cross-connect device that connects between the input port and the output port by setting an output wavelength of the input unit transmitting / receiving circuit and an output port of the split / mix flow optical switch unit to predetermined values.
An optical cross-connect device comprising an APD (Avalanche Photodiode) receiver in each of the receiving units of the M × N output transmitting / receiving circuits. Means for receiving an optical signal from another device, means for transmitting an optical signal to the inside of the device, and M × N input / output transmission / reception circuits comprising means for varying the output wavelength of the transmitting means,
Means for switching the input signal input from the input port to the output port in a non-blocking manner, and N divided / combined flow type optical switch units comprising means for multiplexing and outputting a plurality of signal lights of different wavelengths,
N M × 1 optical couplers for multiplexing the inputs from the N divided mixed flow optical switch units;
N 1 × M wavelength separation units for separating up to M wavelength multiplexed signal lights for each wavelength;
M × N output transmission / reception circuits including a unit for receiving a signal from the 1 × M wavelength separation unit and a unit for transmitting an optical signal to another device,
An optical cross-connect device that connects between the input port and the output port by setting an output wavelength of the input unit transmitting / receiving circuit and an output port of the split / mix flow optical switch unit to predetermined values.
An optical cross-connect device, wherein each of the receiving units of the M × N output transmitting / receiving circuits includes an optical pre-amplification receiver.

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