KR100319025B1 - WDM optical buffer and frequency selector - Google Patents

Abstract

The present invention relates to a wavelength multiple optical buffer device and a frequency selector used in an optical exchange system of wavelength division, time / wavelength, and space / wavelength division. The optical buffer device according to the present invention is capable of storing and outputting the first and second optical separation / combining means formed of a shape combiner to separate and combine the optical signals, and the control of the separate optical signal output input and output pointers. A plurality of optical buffer units, optical switching means consisting of a space switch to switch wavelength wavelength multiplexed optical signals from the second optical separation / combining means, and optically multiplexed optical signals from the optical switching means. Wavelength routing means consisting of a waveguide grating to output only the optical signal corresponding to one wavelength received by the input port is characterized in that it is provided. The frequency selector of the present invention is used when the number of multiplexed wavelengths is large and includes a plurality of switches and wavelength routing portions. According to the present invention, it is possible to easily control the optical signal multiplexed in many wavelengths, it can be implemented through less hardware. In addition, since the optical buffer unit is configured in parallel, even if one buffer unit fails, it can operate without affecting the other buffer unit.

Description

Wavelength Multiple Optical Buffer and Frequency Selector {WDM optical buffer and frequency selector}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical buffer device, and more particularly, to a wavelength multiple optical buffer device used in an optical exchange system of wavelength division, time / wavelength, and space / wavelength division.

The present invention also relates to a frequency selector used when the number of multiplexed wavelengths is large.

In general, optical buffers are essentially required in optical exchange systems. Therefore, many types of buffer structures have been proposed so far, but it is not so easy in terms of control and feasibility and extensibility.

Therefore, the technical problem of this invention is providing the wavelength multiple optical buffer apparatus which shows easy controllability with respect to many wavelengths.

Another technical problem of the present invention is to provide a wavelength multiple optical buffer device capable of using less hardware than conventional optical buffer devices.

Another technical problem of the present invention is to provide a wavelength multiple optical buffer device having a buffer unit in a parallel form.

Another technical problem of the present invention is to provide a frequency selector used when the number of multiplexed wavelengths is quite large.

1 is a block diagram of a wavelength multiple optical buffer device according to an embodiment of the present invention;

2A to 2D are diagrams for explaining the operation of the buffer unit used in the embodiment of the present invention;

3 is a frequency routing table in the case of using an 8x1 wavelength routing unit as the wavelength routing unit;

4 is a diagram showing the configuration of a frequency selector used when the number of multiplexed wavelengths is quite large.

Explanation of symbols on the main parts of the drawings

101, 114... 1 × M light separation / combination unit

102, 106, 110... Optical input gate section

104, 108, 112... Optical output gate section

103, 107, 111... 2 × 2 optical split / couple

105, 109, 113... Optical Amplification / Gate Section

115. 1 × L switching part

116, 206. L × 1 Wavelength Routing Part

117, 118, 119... Optical delay unit

201... 1 x B optical separation / combination

202, 203... Optical tolerance gate part

204, 205... 1 × K switching part

The wavelength multiple optical buffer device of the present invention for achieving the above technical problem,

First optical separation / combining means comprising a shape combiner for separating the wavelength multiplexed input optical signal into a plurality; A plurality of optical buffer units for storing and outputting each optical signal separated by the first optical separation / combining means under control of an input pointer and an output pointer; Second optical separation / combining means comprising a shape combiner so as to combine the optical signals output from the plurality of optical buffer units; Optical switching means comprising a space switch to switch the wavelength multiplexed optical signal from the second optical separation / combining means for wavelength routing; It is characterized in that it comprises a wavelength routing means consisting of a waveguide grating to receive only the optical signal corresponding to one wavelength receives the wavelength multiplexed optical signal from the optical switching means to its corresponding input port.

In this case, each of the buffer units includes: an optical input gate means for passing an optical signal in accordance with an input pointer; 2x2 optical separation / combining means for separating the optical signal passing through the input gate into two optical signals; Loop means for storing, amplifying or removing any one of the two separated optical signals; It is preferable to include an optical output gate means for passing the other optical signal, which does not go through the loop means, out of the two separate optical signals according to the output pointer.

The loop means may further comprise: optical delay means for storing an optical signal; It is further preferred to include optical amplification / gate means for amplifying or eliminating the optical signal passing through the optical delay means.

In this case, the optical delay means is an optical fiber having one timeslot, and the optical amplification / gate means is more preferably constituted by a semiconductor optical amplifier.

On the other hand, the frequency selector of the present invention for achieving the another technical problem, the optical separation / combining means for separating the wavelength multiplexed optical signal from the optical buffer unit; A plurality of light permitting gate means each having an input / output gate and an optical amplification / gate section, each controlled by a control means using an input pointer and an output pointer, for passing each of the separated wavelength multiplexed optical signals; A plurality of switching means connected to each of the plurality of light allowing gate means to switch light passing through each of the plurality of light allowing gate means; It is characterized in that it comprises a wavelength routing means for receiving a wavelength multiplexed optical signal from the plurality of switching means to its input port and output only an optical signal corresponding to one wavelength.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

1 is a block diagram of a wavelength multiple optical buffer device according to an embodiment of the present invention.

According to the present invention shown in FIG. 1, L wavelength multiplexed optical signals can be stored in M buffer units and then output for each wavelength. Referring to FIG. 1, a wavelength multiple optical buffer device includes two 1 × M optical separation / coupling portions 101 and 114, M optical input gate portions 102, 106,..., 110, and M optical output gate portions ( 104, 108, ..., 112, M 2x2 optical separation / coupling units 103, 107 ..., 111, M optical amplification / gate units 105, 109, 113, M optical delay units 117, 118, ..., 119, one 1 × L switching section 115 and one L × 1 wavelength routing section 116, and the delay time of the optical delay section is T. When the wavelength multiple optical buffer device is divided into functions according to a function, each buffer includes one optical input gate portion, an optical output gate portion, a 2x2 optical separation / coupling portion, an optical retardation portion, and an optical amplification / gate portion. Can be defined as a unit. These buffer units M and two 1xM optical separation / combining units are combined to form a buffer unit, and one 1xL switching unit and one Lx1 wavelength routing unit are combined to form a frequency selection unit.

The operation process of the wavelength multiple optical buffer device configured as described above with the focus on the first buffer unit # 1 is as follows.

First, the wavelength multiplexed optical signal passing through the first 1 × M optical splitter / combiner 101 is divided into M and enters M optical input gates 102, 106, ..., 110, respectively. When the input gate section 102 is turned "on" to pass the optical signal, the first 2x2 optical splitter / coupling section 103 separates the two optical signals. One of the separated optical signals is stored through the first delay unit 117, and the other is output through the first optical output gate unit 104. Here, the first optical amplification / gate 105 connected to the first retarder 117 plays a role as follows: the first 2 × 2 optical splitter / combiner 103 and the first retarder 117 are as follows. If the optical signal passing through) is attenuated or amplified or the wavelength multiplexed optical signal is output and a new optical signal is to be received, the previous optical signal remaining in the first delay unit 117 is turned off. Remove it.

In addition, the wavelength multiplexed optical signal passing through the first optical output gate unit 104 is coupled by the second 1 × M optical splitter / combiner 114, and then corresponds through the 1 × L switching unit 115. It is input to the input port of the L × 1 wavelength routing section 116 is output after the wavelength routed. In the L × 1 wavelength routing section 116, an output wavelength is determined according to which input port is input to which input port.

In the present embodiment, the first and second 1 × M light separation / combining portions 101 and 114 are respectively 1 × M star couplers, and the plurality of light input gate portions 102, 106,. ) And each of the light output gate portions 104, 108, ..., 112 are modulators, and each of the plurality of 2x2 optical separation / coupling portions 103, 107, ..., 111 is a 2x2 coupler, Each of the optical amplification / gate portions 105, 109, ..., 113 is a semiconductor optical amplifier (SOA), the 1xL switching unit 115 is a 1xL spatial switch, and an Lx1 wavelength. The routing unit 116 is an L × 1 arrayed waveguide grating (AWG), and the plurality of optical delay units 117, 118,..., 119 are implemented with an optical fiber having one timeslot T.

2A to 2D are diagrams for explaining the operation of the buffer unit used in the embodiment of the present invention. Here, assuming that there are M buffer units and that L wavelength multiplexed cells can be stored, the wavelength multiplexed optical signal is first divided into M through 1 x M optical separation / combination units. Initially, the optical input gate and the optical amplification / gate indicated by the input pointer i are placed in an "on" state, and the optical output gate and the optical amplification / gate indicated by the output pointer j are placed in an "on" state.

2A shows a case where an optical signal multiplexed by the wavelengths of F1 and F3 enters a buffer in a state in which a cell is not stored in any buffer unit. First, the first optical input gate indicated by the input pointer i is normally turned on. Because of this, the wavelengths of F1 and F3, where the input pointer i points, allow to store the multiplexed optical signal. Then, since the light output gate indicated by the output pointer j is in the "on" state, the optical signal in which the wavelengths of F1 and F3 are multiplexed is output to the next frequency selector.

FIG. 2B shows a case where an optical signal in which wavelengths of F0, F1, F2, F3, F4, and FL-1 are multiplexed next comes in, where the position of the input pointer i points to the next second optical input gate. It can be seen. Here, the output pointer j remains as it is because only one signal of F1 or F3 has been selected and output, and there is still a signal to be output.

Figure 2c also shows that the input pointer i then points to the next third optical input gate to store the optical signals with F0, F3, F4 in the buffer. Herein, the output pointer j has wavelengths of F0, F1, F2, F3, F4, and FL-1, which are stored in the second buffer unit by outputting the optical signals having F1 and F3 and pointing to the next second optical output gate. The multiplexed optical signal is output.

2D illustrates that the input pointer i indicates the output pointer j when the optical signals are all stored in the M buffer units. In this case, therefore, the incoming optical signal is discarded by not "on" the optical input gate indicated by the input pointer i.

According to the present invention, as shown in Figs. 2A to 2D, only a buffer unit pointed to by the pointer, and only some of the components need to be controlled, so that no complicated algorithm is required. Therefore, control becomes easy.

When the optical signal multiplexed through the buffer unit is input to the input port of the 1 × L switching unit 115 of FIG. 1, the optical signal is switched to input the optical signal to the input port of the L × 1 wavelength routing unit 116 at an appropriate position.

3 shows a frequency routing table in the case of using an 8x1 wavelength routing unit as the wavelength routing unit.

The portion of the first column indicated by the arrow indicates the wavelength that can be actually output, and the other portion indicates the wavelength that cannot be output. For example, when the wavelength multiplexed optical cells of F0, F4, and F5 enter the fourth input port of the wavelength routing part of the wavelength separation part through the 1 × L switching part 115 of FIG. 1, only the optical signal corresponding to the wavelength of F4 is output. The optical signal corresponding to the remaining wavelengths disappears. In this way, the optical signal having the desired wavelength is extracted. Therefore, the present invention requires much less hardware than the conventional method requiring two L × 1 wavelength routing portions and L gate portions.

4 is a diagram showing the configuration of a frequency selector used when the number of multiplexed wavelengths is quite large. In the case of outputting such a large number of wavelengths, a plurality of switches and wavelength routing portions are used because the capacity of the switching portion is limited. The total number of wavelengths is calculated as L = K × B. Referring to FIG. 4, the frequency selector includes one 1 × B light separation / combining unit 201, B light allowing gate parts 202,..., 203, and B 1 × K switching parts 204. 205 and one L × 1 wavelength routing portion 206.

The operation of such a frequency selector is as follows.

The wavelength multiplexed optical signal coming from the optical buffer unit is first divided into B optical signals by the optical separation / combining unit 201. Here, in order to output an optical signal corresponding to the first 0-K th wavelength, the first light permitting gate unit 202 is turned on, and then the first 1 × K switching unit 204 is switched to As in the frequency routing table shown in FIG. 3, the optical signal goes to the input port of the appropriate wavelength routing unit 206 so that the optical signal of the appropriate wavelength is output. Then, the optical signal of the desired wavelength is output through the output port of the wavelength routing unit 206.

That is, it is possible to control easily even when there are many wavelengths because it is necessary to control one corresponding gate and one 1 × K switching unit.

According to the present invention, it is possible to easily control the optical signal multiplexed in many wavelengths, it can be implemented through less hardware.

In addition, since the optical buffer unit is designed in parallel, even if one buffer unit fails, it can operate without affecting the other buffer unit.

Claims (5)

First optical separation / combining means comprising a shape combiner for separating the wavelength multiplexed input optical signal into a plurality; A plurality of optical buffer units for storing and outputting each optical signal separated by the first optical separation / combining means under control of an input pointer and an output pointer; Second optical separation / combining means comprising a shape combiner so as to combine the optical signals output from the plurality of optical buffer units; Optical switching means comprising a space switch to switch the wavelength multiplexed optical signal from the second optical separation / combining means for wavelength routing; And a wavelength routing means consisting of a waveguide grating to receive only the optical signal corresponding to one wavelength by receiving the wavelength multiplexed optical signal from the optical switching means into its corresponding input port. The method of claim 1, wherein each of the buffer units is: An optical input gate means for passing an optical signal according to the input pointer; 2x2 optical separation / combining means for separating the optical signal passing through the input gate into two optical signals; Loop means for storing, amplifying or removing any one of the two separated optical signals; And an optical output gate means for passing the other optical signal, which does not pass through the loop means, out of the two optical signals according to the output pointer. The method of claim 2, wherein the loop means is: Optical delay means for storing an optical signal; And an optical amplification / gate means for amplifying or removing the optical signal passing through the optical retardation means. 4. The wavelength multiple optical buffer device according to claim 3, wherein the optical delay means is an optical fiber having a time slot, and the optical amplification / gate means is a semiconductor optical amplifier. Optical separation / combining means for separating the wavelength multiplexed optical signal from the optical buffer unit; A plurality of light permitting gate means each having an input / output gate and an optical amplification / gate section, each controlled by a control means using an input pointer and an output pointer, for passing each of the separated wavelength multiplexed optical signals; A plurality of switching means connected to each of said plurality of light allowing gate means to switch light passing through each of said plurality of light allowing gate means; And a wavelength routing means for receiving a wavelength multiplexed optical signal from the plurality of switching means through its input port and outputting only an optical signal corresponding to one wavelength.