KR100248411B1 - Wdm type buffer memory implementation method - Google Patents

Abstract

The present invention relates to a wavelength division multiplexer (WDM) buffer memory implementation method using an optical waveguide switch, in which an optical ATM adopts a WDM scheme to fully exhibit its function, and in the WDM scheme, the buffer memory is already in one cell. It performs the function of serially rearranging signals multiplexed in multiple wavelengths on the time axis, secures optical transparency of optical buffer memory, manages buffer size and wavelength size independently, provides flexibility in buffer capacity, and separate header processing function. By providing an optical buffer memory that performs a buffer function without the need for high-speed electric devices, it is possible to detect information on the number and type of multiplexed wavelengths without using high-speed electric devices, and to secure optical transparency and to buffer high-speed optical data. There is.

Description

Wavelength Division Multiplexing Buffer Memory

The present invention relates to a method of implementing a wavelength division multiplexer (WDM) buffer memory using an optical waveguide switch.

Recently, as the types of services used by subscribers of the communication network have evolved from simple text transmission to communication through multimedia, the transmission speed has been continuously increasing.

In order to satisfy these demands, transmission over light has been attempted, and has been developed to 2.488Gbps and 10Gbps transmission.

At present, attempts to simply improve the transmission capacity through the transmission speed have led to an increase in the transmission capacity through the multiplexing of the use wavelengths as the development speed is slowed down by the electric elements before and after the transmission through the light.

As the optical transmission develops, many research institutes have attempted to perform switching functions while maintaining optical transparency of optical data transmitted without optical / electrical / electrical / optical conversion.

At present, efforts are being made to implement a new electronic exchange, Asynchronous Transfer Mode (hereinafter referred to as ATM), through light.

Apart from these efforts, the optical transmission research groups are proposing and developing optical add / drop multiplexing devices with some switching functions in the transmission part.

This effort to switch the light itself requires devices and modules that perform the functions previously performed by electrical devices as light in addition to optical transmission.

Among them, there is a great need for an optical buffer memory to solve the blocking problem caused by contention.

The optical buffer memory simply adds a buffer function for wavelength-multiplexed optical signals over time in a function of selectively delaying optical signals on the time axis.

Currently, the structure of FIG. 4 is proposed as a structure capable of performing a buffer function with respect to the wavelength multiplexed optical signal.

However, at present, there is no optical variable filter 403 having a wide variable wavelength range and performing fast variable of nsec.

Therefore, as illustrated in FIG. 4, structures for implementing a fast variable filter function using a gate switch and an arrayed waveguide grating filter (hereinafter referred to as AWGF) 305 have been proposed.

However, although the structure of FIG. 4 has an advantage in optical loss, there is a dependency on the transmission speed of the AWGF 305, and thus, the higher the optical transmission speed such as 20Gbps, the more difficult it is to implement.

Moreover, the research on how to transfer information about contention to implement buffer function to buffer memory is done separately from the round buffer memory that proposes a new header.

In order to solve the above problems, the present invention obtains a buffer control signal through optical / pre conversion, and transmits only by checking the presence or absence of an optical signal demultiplexed for each wavelength through a WDM coupler instead of reading and decoding a specific header into an optical receiver. All the information for driving the optical buffer can be obtained while avoiding the difficulty of receiving high speed optical information.

This reduces the amount of electrical control that decodes the information received behind the optical receiving end.

Also, the 1 × L optical coupler 108 of FIG. 1, which determines the size of the buffer for each function of the optical buffer, and an optical delay line (hereinafter referred to as an ODL) 103, which gives an optical signal delay by a multiple of the cell length. The capacity of the optical buffer is divided into a 1 × n optical waveguide switch 109, an optical fixation filter 110, and an N × 1 optical coupler 111, which determine the portion of the gate switch 104 and the number of available wavelengths. It is designed to be able to adjust to system requirements and to enable buffering of data of more than a few tens of Gbps by using optical switches that have proven optical transparency.

1 is a configuration diagram of a WDM buffer memory using an optical waveguide switch to which the present invention is applied;

2a to 2c is a configuration diagram of the buffering process of the cell seen on the time axis in the WDM optical buffer memory using the optical waveguide switch according to the present invention,

3 is a configuration diagram of a WDM optical buffer memory using a conventional NTT gate switch;

4 is a conventional optical buffer memory configuration diagram.

<Description of the symbols for the main parts of the drawings>

101: 10: 1 1 × 2 optical coupler 102: optical delay line

103,302,402: optical delay line giving optical signal delay by multiple of cell length

104,303 gate switch 105 wavelength division multiplexer (WDM)

106: photoelectric converter (O / E) 107: control unit

108,301,401: 1 × L optical coupler 109: 1 × N optical waveguide switch

110: optical fixation filter 111: N × 1 optical coupler

304: EDF optical amplifier 305: arrayed waveguide grating filter

403: variable light filter

In order to achieve the above object, the present invention obtains optical data information for buffering wavelength-multiplexed and then obtains optical data information for buffering to have optical buffer optical transparency using an optical waveguide switch. It is characterized by implementing a wavelength selective high speed filter using a switch and an optical filter.

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

1 is a configuration diagram of a WDM buffer memory using an optical waveguide switch to which the present invention is applied, wherein a 10: 1 1 × 2 optical coupler 101 and an optical coupler for manipulating wavelength-multiplexed optical signals into different types of signals are shown in FIG. Optical Delay Line (ODL) 102 for passing the passed information, and Wavelength Division Multiplexer (WDM) for receiving a portion of the optical signal passing through the ODL and demultiplexing it for each wavelength. 105) an optical / electric converter (O / E) 106 for converting the multiplexed optical signal into information about the presence or absence of an optical signal through a limiting amplifier, and the number of wavelengths of the multiplexed optical signal and A control unit 107 for identifying the type, a 1 × L optical coupler 108 for manipulating the maximum number of cells that can buffer the optical signal passing through the ODL, and a form in which the manipulated optical signal is arranged in series on a time axis Only multiples of cell length copied to An optical delay line 103 for delaying the optical signal, a gate switch 104 for sending the appropriate signal of the delayed optical signal to each switch, and a 1xn optical waveguide switch for controlling the waveguide type optical signal with the appropriate signal of the gate switch. 109, an optical fixed filter 110 for passing the waveguide type optical signal of the waveguide switch only in a specific frequency band, and an n × 1 optical coupler 111 for buffering the filtered optical signal with a specific number of cells.

1 transmits a portion of an optical signal that is wavelength multiplexed using a 10: 1 1 × 2 optical coupler 101 to the WDM optical coupler 105.

The WDM optical coupler 105 demultiplexes the incoming optical signal for each wavelength and sends it to the optical / electric converter 106.

Since the high speed optical signals respectively entered into the opto-electric converter 106 are transmitted to the control unit 107 only after the limiting amplifier (limiting amplifier) about the existence of the optical signal, it is not necessary to receive the high speed optical information.

Since the information inputted to the control unit 107 is information on which photoelectric converters have received light, the control unit 107 can know the number and types of wavelengths that have been multiplexed.

Using this information, an appropriate signal for controlling the gate switch 104 and the 1xn optical waveguide switch 109 is sent to each switch.

The information passing through the 10: 1 1 × 2 optical coupler 101 passes through the optical delay line 102.

The length of the optical delay line is set in consideration of the delay time required for the control unit 107 to send a control signal to the switch.

The optical data passing through the 1 × L optical coupler 108 is copied in series arranged on the time axis by the optical retardation line 103 and directed to the gate switch 104, where L can be buffered. It is the maximum number of cells that are present.

2A to 2C are diagrams illustrating a buffering process of a cell viewed on a time axis in a WDM optical buffer memory using an optical waveguide switch according to an embodiment of the present invention.

2A illustrates wavelength multiplexed optical data coming into the 1 × L optical coupler 108 of FIG. 1.

This data is copied by L while passing through the optical coupler 108 and then adjusts the number of copied cells by the number multiplexed by the gate switch 104.

2B sends optical data entering the 1 × n optical waveguide switch 109 via the L × 1 optical coupler 108 after passing through the gate switch 104.

It can be seen that 201 of FIG. 2A is copied to 3 of 201 of FIG. 2B, and the number of cells to be copied is adjusted by OM / OFF of the gate switch 104.

The gate switch 104 turns on the gate switch corresponding to the number of wavelengths of the multiplexed cell-1 and then turns off the remaining gate switches except the last gate switch within the guard time. Set in consideration of the performance of the optical device.

The optical data in the form of FIG. 2B enters the 1 × n optical waveguide switch 109.

The optical switch designates an output port with a fixed optical filter according to the information of the controller so that optical data having one wavelength exists within one cell time as shown in FIG. 2C.

The size L of the optical buffer may be set in consideration of the size of data to be transmitted.

In addition, since the 1 × n optical waveguide switch 109 is dependent on the guard time rather than the transmission speed of the optical data, optical information buffering of several tens of Gbps is possible if only a proper guard time is given.

As described above, the present invention uses only the optical / electric converter 106 to check the existence of the optical signal without receiving the optical data, thereby detecting information on the number and type of the multiplexed wavelengths without using a high-speed electric device. can do.

In addition, by using the 1xn optical waveguide switch 109, it is possible to secure optical transparency and to buffer high speed optical data of several tens of Gbps.

Claims (4)

A method of implementing a wavelength division multiplexer (WDM) buffer memory using an optical waveguide switch, A first process of obtaining information on optical data for wavelength multiplexed buffering; A second process having optical buffer optical transparency by using an optical waveguide switch after obtaining optical data information for buffering; And a third process of implementing a wavelength selective high-speed filter using an optical waveguide switch and an optical filter. The method of claim 1, wherein the first process Sending a portion of an optical signal wavelength-multiplexed using a 10: 1 1 × 2 optical coupler to a wavelength division multiplexer optical coupler; The wavelength division multiplexer optical coupler includes a second step of demultiplexing an incoming optical signal for each wavelength and sending the optical signal to an optical / electric converter; A third step of passing the high speed optical signals respectively entered into the opto-electric converters through the limiting amplifiers, and sending only information on the presence or absence of the optical signals to the controller; 4. A method of implementing a wavelength division multiplexing buffer memory, comprising: a fourth step of determining the number and types of wavelengths multiplexed through information on which optical / electric converters have received light. The method of claim 1, wherein the second process A first step of sending an appropriate signal to each switch to control the gate switch and the 1 × n optical waveguide switch using information identifying the number and types of wavelengths which have been multiplexed; A second step of passing information passing through the 10: 1 1 × 2 optical coupler through an optical delay line; And a third step of setting by considering the delay time required for the control unit to send a control signal to the switch by using the length of the optical delay line. The method of claim 1, wherein the third process is A first step of copying optical data passing through a 1 × L optical coupler in a form arranged in series on a time axis using the optical delay line; And a second step of obtaining a maximum number of cells that can be buffered by sending optical data in a form arranged in series on the copied time axis to a gate switch.

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