KR100439226B1 - Apparatus and method for state monitoring of optical multiplexor/demultiplexor in wavelength division Multiplexing system - Google Patents

Abstract

The present invention is to provide an apparatus and method for monitoring the state of the optical multiplexer / demultiplexer in the wavelength division multiplexing system, the present invention comprises: a channel detector for detecting the optical signal of the input channel; An AWG for receiving multiplexed optical signals and multiple optical signals passing through the channel detector; A transmission signal detector for detecting an optical signal output from the AWG; A filter unit for filtering outputs of the channel detector and the transmission signal detector; It comprises a photo detector for measuring the optical power of the optical signal of the filter unit and the transmission signal detection unit, to monitor the optical characteristics of the AWG used for multiplexing / demultiplexing multiple wavelengths in a wavelength division multiplexing system It is possible to produce the optimal output light.

Description

Apparatus and method for state monitoring of optical multiplexor / demultiplexor in wavelength division multiplexing system for optical multiplexer / demultiplexer in wavelength division multiplexing system

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and method for monitoring the state of an optical multiplexer / demultiplexer in a wavelength division multiplexing system (WDM), in particular for multiplexing / demultiplexing multiple wavelengths in a wavelength division multiplexing system. The present invention relates to a state monitoring device and a method of the optical multiplexer / demultiplexer in a wavelength division multiplexing system that performs monitoring of optical characteristics of an arrayed waveguide grating (AWG) to be used to produce an optimal output light.

Recently, with the development of scientific technology and the information society, the development of communication technology is being made rapidly. The type is also diversified from the existing wired communication, and various developments such as wireless communication and satellite communication are being made.

In addition, the form of communication is required not only for simple text transmission or voice transmission but also for image transmission, and a complex transmission for simultaneously transmitting audio, data and video is required. There is a demand for a technology capable of handling a transmission amount.

Such a transmission technology that satisfies the desire is optical transmission. In contrast to conventional wired transmission using conventional copper wire or wireless transmission using radio waves, optical transmission is a communication method of transmitting a signal carried by light through a transmission medium called an optical fiber. .

In the optical transmission system, a process of converting an existing electrical signal into an optical signal, transmitting the optical signal through an optical fiber, and then converting the optical signal into an electrical signal is added. Alternatively, a light emitting diode is used, and a photodiode, which is a light receiving element, is used to convert an optical signal into an electrical signal.

The wavelength division type optical communication is widely used for long-distance transmission of a large amount of digital signals because it has advantages such as being able to accommodate a large number of data lines with less optical paths, less transmission loss, and no induction interference. Doing.

Such an optical transmission method is a transmission method suitable for long distance transmission because it has less transmission loss and has a merit of transmitting a large amount of data compared with a conventional transmission method.

Even in a wavelength division optical transmission system, when transmitting a signal over a certain distance, it is necessary to amplify the signal, and the optical amplifier plays such a role.

Meanwhile, AWG (Arrayed Waveguide Grating) is mainly used to multiplex each other in a wavelength division multiplexing system. AWG is a module capable of multiplexing / demultiplexing. When used as a multiplexing unit, two or more channels having different wavelengths are input to the input and the multiplexed optical signal is transmitted through one optical transmission path. When used as a demultiplexer, the multiplexed optical signal enters one optical transmission path, and the optical signals of the channels are demultiplexed according to wavelength characteristics.

1 is a block diagram of a state monitoring apparatus of an optical multiplexing unit in a conventional wavelength division multiplexing system.

As shown here, an AWG 1 for multiplexing a plurality of channels of optical signals;

A tap (2) for detecting the multiplexed optical signal of the AWG (1);

It consists of a photo detector (PD) (3) for measuring the optical power of the optical signal detected by the tap (2).

2 is a flowchart illustrating a state monitoring method of an optical multiplexer in a conventional wavelength division multiplexing system.

As shown therein, multiplexing optical signals of a plurality of channels in the AWG (ST1);

Detecting the multiplexed optical signal (ST2);

The optical power is measured from the detected optical signal to monitor the state of the entire optical signal (ST3).

According to this prior art, the current state of the multiplexed optical signal is monitored by using one tap 2 and photodetector 3 for monitoring the transmitted optical signal.

When the AWG 1 is used as the multiplexing unit, a slight optical signal is detected at the tab 2 located at the rear end of the AWG 1 to measure the total optical power through the photodetector 3, and thus the total optical signal. Be able to see the state of.

When the AWG 1 is used as the demultiplexing unit, the tab 2 is positioned at the front end of the AWG 1 to measure the total optical power.

In this case, it is possible to monitor the state of the transmission signal or the multiplexed optical signal, but it is impossible to monitor the loss of the transmission signal due to the abnormality of the multiplexer.

The prior art will be described in more detail as follows.

First, an optical signal having two or more channels enters the input of the AWG 1. The optical signal coming into the input corresponding to the wavelength characteristic of the AWG 1 is wavelength multiplexed through the AWG 1, and the multiplexed optical signal does not affect the transmission signal through the tap 2 before being transmitted through the transmission path. Some signal is detected. By analyzing the signal detected through the tap (2) it is possible to know the total power of the transmission signal, through which it is possible to monitor the current state of the transmission signal.

At this time, the detected optical signal can know the total power of the optical signal. In case of loss, two cases can be assumed. It can be assumed that there are two cases in which the total power is reduced due to the loss of the optical signal of the input channel and the power is reduced due to the abnormal operation of the multiplexer.

However, according to the prior art, when there is a loss of the optical signal, there is a problem in that it is not possible to accurately monitor whether the total power is reduced due to the loss of the optical signal of the input channel or the power is reduced due to abnormal operation of the multiplexer.

Therefore, the present invention has been proposed to solve the above-mentioned conventional problems, and an object of the present invention is to monitor the optical characteristics of AWG used for multiplexing / demultiplexing multiple wavelengths in a wavelength division multiplexing system. The present invention provides a state monitoring device and a method for monitoring a light multiplexer / demultiplexer in a wavelength division multiplexing system capable of producing optimal output light.

In order to achieve the above object, a state monitoring apparatus for an optical multiplexer / demultiplexer in a wavelength division multiplexing system according to an embodiment of the present invention comprises: a channel detector for detecting an optical signal of an input channel; An AWG for receiving multiplexed optical signals and multiple optical signals passing through the channel detector; A transmission signal detector for detecting an optical signal output from the AWG; A filter unit for filtering outputs of the channel detector and the transmission signal detector; Technical features of the present invention include a photo detector for measuring the optical power of the optical signal of the filter unit and the transmission signal detection unit.

In order to achieve the above object, a state monitoring method of an optical multiplexer / demultiplexer in a wavelength division multiplexing system according to an embodiment of the present invention is provided at the front and rear ends of an AWG for performing optical signal multiplexing / demultiplexing. Detecting an optical signal to monitor optical power; And a second step of determining whether the AWG is abnormal by comparing the optical power measured in the first step.

1 is a block diagram of a state monitoring apparatus of an optical multiplexer in a conventional wavelength division multiplexing system.

2 is a flowchart illustrating a state monitoring method of an optical multiplexer in a conventional wavelength division multiplexing system.

3 is a block diagram of a state monitoring apparatus of an optical multiplexer / demultiplexer in a wavelength division multiplexing system according to the present invention;

4 is a flowchart illustrating a state monitoring method of an optical multiplexer / demultiplexer in a wavelength division multiplexing system according to the present invention;

FIG. 5 is a detailed flowchart of the monitoring step, which is the first step in FIG. 4;

FIG. 6 is a detailed flowchart of the control step, which is the second step in FIG. 4.

Explanation of symbols on the main parts of the drawings

10: channel detector 20: AWG

30: transmission signal detection unit 40: filter unit

50: Photo Detector

Hereinafter, an embodiment according to the present invention, a state monitoring apparatus for an optical multiplexer / demultiplexer and a method thereof in a wavelength division multiplexing system will be described with reference to the accompanying drawings.

3 is a block diagram of a state monitoring apparatus of an optical multiplexer / demultiplexer in a wavelength division multiplexing system according to the present invention.

As shown therein, the channel detector 10 detects the optical signal of the input channel;

An AWG 20 for receiving and multiplexing the input optical signals of the plurality of channels and the optical signals passing through the channel detector 10;

A transmission signal detector 30 detecting an optical signal output from the AWG 20 and transmitted;

A filter unit (40) for filtering the outputs of the channel detector (10) and the transmission signal detector (30);

It comprises a photo detector 50 for measuring the optical power of the optical signal of the filter unit 40 and the transmission signal detection unit 30.

The transmission signal detector 30 includes: a second tap 31 for detecting an optical signal transmitted from the AWG 20; And a third tab 32 for detecting the optical signal passing through the second tab 31.

The filter unit 40 includes: a first band filter (41) for filtering an output of the channel detector (10) to allow an optical signal of one channel to pass through the channel detector (10); And a second band filter 42 through which an optical signal of one channel of the multiple channels to filter the optical signal output from the second tap 31 in the transmission signal detector 30 passes.

The photo detector 50 measures the optical power of the optical signal output from the first band filter 41 in the filter unit 40 to measure the filtered optical power of the optical signal before multiplexing. A detector 51; A second photo detector 52 for measuring the optical power of the optical signal output from the second band filter 42 in the filter unit 40 and measuring the filtered optical power of the optical signal after multiplexing; And a third photodetector 53 which measures the optical power of the optical signal output from the third tap 32 in the transmission signal detector 30 and measures the optical power of the optical signal after multiplexing.

Reference numeral 11 denotes a first tap constituting the channel detector 10.

4 is a flowchart illustrating a state monitoring method of an optical multiplexer / demultiplexer in a wavelength division multiplexing system according to the present invention.

As shown therein, a first step (ST10) of monitoring the optical power by detecting the optical signals at the front and rear ends of the AWG 20 performing the multiplexing / demultiplexing of the optical signals;

Comprising a second step (ST20) to determine whether the abnormal operation of the AWG 20 by comparing the optical power measured in the first step.

FIG. 5 is a detailed flowchart of the monitoring step, which is the first step in FIG. 4.

As shown therein, step (ST11) of detecting and filtering optical power for one of the plurality of channels to perform first monitoring; Multiplexing a plurality of channels in the AWG 20 (ST12); Performing second monitoring by filtering the multiplexed signal (ST13); Performing a third monitoring on the multiplexed signal (ST14); It includes the step (ST15) to measure the optical power by using the first to third monitoring results.

6 is a detailed flowchart of the control step, which is the second step in FIG.

As shown in the figure, if the loss of the total optical power is to be determined, comparing the third monitoring result in the third photodetector 53 to determine whether there is a loss of the optical signal (ST21 to ST23); If there is no loss, determining that there is no loss of total optical power and that the optical signal is normal (ST24); If there is the loss, comparing the first monitoring result at the first photo detector 51 with the second monitoring result at the second photo detector 52 and determining whether the comparison value is the same (ST25) (ST26) and ; If the comparison value is the same, determining that there is a loss in the optical signal input to the AWG (ST27); If the comparison value is not the same, it is determined that there is a loss in the optical signal due to an abnormal operation in the AWG 20 (ST28).

Operation of the state monitoring device and method of the optical multiplexer / demultiplexer in the wavelength division multiplexing system according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

First, the configuration of the present invention can measure the multiplexing / demultiplexing module AWG 20, three taps 11, 31, 32, two band filters 41, 42, and the detected optical signal. Consisting of three photodetectors 51 to 53.

The AWG 20 is an optical module capable of multiplexing / demultiplexing two or more channels. Looking at the characteristics of the AWG 20, since the loss for a signal of one channel is the same as the loss characteristic for a signal of another channel, the present invention utilizes this.

The tabs 11, 31 and 32 detect small signals small enough not to affect the transmission signal. The band filters 41 and 42 are filters that match the wavelength of the optical signal coming into the input channel. When several channels are input, only one channel passes and the other channels do not pass. The photodetectors 51 to 53 have a sensitivity in a range in which the optical signals detected through the tabs 11, 31 and 32 can be measured.

Thus, by detecting the input signal using the first tap 11 in a specific channel used as the input of the AWG 20 and passing it through the first band filter 41, the power of the signal corresponding to the wavelength is increased by the first photodetector ( 51).

After passing through the AWG 20 which is a multiplexing / demultiplexing module, a small signal of the multiplexed or demultiplexed light is detected using the second tap 31, and the detected small signal is the same as that of the first band filter 42. The second band filter 42 filters the signal having a specific wavelength and measures the measured signal with the second photodetector 52.

The third tap 32, which is another tap, is also used to measure the multiplexed or demultiplexed optical power.

By comparing the optical power obtained through the first to third photo detectors 51 to 53 as described above, the operating state of the AWG 20 can be examined.

Referring to the operation of the present invention in more detail as follows.

First, the present invention relates to the monitoring and control of the multiplexing / demultiplexing unit when using the multiplexing / demultiplexing unit having a function of combining / branching optical channels in a WDM system.

First, the monitoring in the multiplexer is as follows.

That is, some optical power is detected using the first tap 11 of the channel detector 10 before the multiplexing, and the first band filter 41 having the filter width corresponding to the wavelength of the channel is detected. The first monitoring is performed by measuring the optical power with the first photodetector 51 using the first photodetector 51.

Channels 2 through N other than the channel 1 passing through the first tap 11 of the channel detector 10 are multiplexed or demultiplexed while passing through the AWG 20 which is a multiplexer / demultiplexer. The multiplexed or demultiplexed optical signal is transmitted through one transmission path, and the multiplexed or demultiplexed optical signal is multiplexed or demultiplexed while passing through another second tap 31 in the transmission signal detector 30. Detect some light signal in the signal. Thus, some optical signals are detected by the second tap 31 and the third tap 32 in the transmission signal detector 30.

The optical signal detected through the second tap 31 in the transmission signal detector 30 is the same filter as the first band filter 41 through which the detected signal in front of the AWG 20, which is a multiplexer or demultiplexer, passes. After the filtering is performed using the second band filter 42, the second power is measured by measuring the optical power through the second photo detector 52 in the photo detector 50.

In addition, the multiplexed or demultiplexed optical signal detected through the other third tap 32 is measured through the third photodetector 53 in the photodetector 50 without filtering and performs third monitoring.

By comparing the three optical powers measured in this way, it is possible to know the current operating state, which is used to control the AWG 20 which is a multiplexer or a demultiplexer.

Meanwhile, the steps of controlling through comparison are as follows.

First, since the optical power measured by the third photodetector 53 is the total optical power up to the channel 1 and the channel N, it can be seen whether there is a loss of the total optical power. That is, the multiplexing module AWG 20 has a loss in itself, but since it is a known loss, it can be known through the third photodetector whether there is a loss of optical power except this loss.

If the loss is not experienced, the multiplexer AWG 20 operates normally, and it can be seen that the input optical signal has a normal optical signal.

However, if there is a loss, it is not known whether it is due to abnormal operation of the multiplexer AWG 20 or there is a problem in the transmission signal itself. The optical powers measured by the first and second photodetectors 51 and 52 using the first and second band filters 41 and 42 are compared with each other. Then, if there is a loss, it may be determined whether the reason is due to abnormal operation of the multiplexer AWG 20 or the problem of the input channels. That is, the value compensated for the loss of the AWG 20 as a multiplexer to the optical power measured by the second photodetector 52 through the filtering at the rear stage and the value of the optical power measured by the first photodetector 51 at the front stage are In the same case, there is a problem in the optical signal input to the AWG 20, it can be seen that the lost optical signal is input to the AWG 20. In addition, it can be seen that the optical signal has been lost due to abnormal operation of the AWG 20 when there is a difference between the comparison results.

In this case, by applying the temperature control to the AWG 20, the AWG 20 can be easily operated normally.

The same can be applied to the demultiplexer.

As such, the present invention provides an optimal output light by monitoring the optical characteristics of the AWG used for multiplexing / demultiplexing multiple wavelengths in a wavelength division multiplexing system.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

As described above, the apparatus and method for monitoring the state of the optical multiplexer / demultiplexer in the wavelength division multiplexing system according to the present invention and the method of the optical fiber of the AWG used for multiplexing / demultiplexing a plurality of wavelengths in the wavelength division multiplexing system By monitoring the characteristics, there is an effect that can produce an optimal output light.

In addition, since the present invention enables monitoring of the current optical signal, there is an effect of performing temperature control on the AWG.

In addition, the present invention has an effect that can provide the user with information about the optical power of the current optical signal.

Furthermore, since the present invention can provide information about the optical signal coming into the input of the AWG by monitoring, there is also an effect that can control the optical signal coming into the input of the AWG through the information of the front end.

Claims (7)

A channel detector detecting an optical signal of an input channel; An AWG for receiving multiplexed optical signals and multiple optical signals passing through the channel detector; A transmission signal detector for detecting an optical signal output from the AWG; A filter unit for filtering outputs of the channel detector and the transmission signal detector; And a photo detector for measuring the optical power of the optical signal of the filter unit and the transmission signal detection unit. The state monitoring apparatus of the optical multiplexer / demultiplexer of the wavelength division multiplexing system. The method of claim 1, wherein the transmission signal detector, A second tap detecting a transmitted optical signal output from the AWG; And a third tap configured to detect the optical signal passing through the second tap. The apparatus for monitoring a state of an optical multiplexer / demultiplexer in a wavelength division multiplexing system, comprising: a third tap; The method of claim 1, wherein the filter unit, A first band filter which filters an output of the channel detector to pass an optical signal of one channel among several channels; An optical multiplexer in the wavelength division multiplexing system, comprising: a second band filter configured to pass an optical signal of one channel among the channels to filter the optical signal output from the second tap in the transmission signal detector; State monitoring device of demultiplexer. The method of claim 1, wherein the photo detector, A first photo detector for measuring the optical power of the optical signal output from the first band filter in the filter unit and measuring the filtered optical power of the optical signal before multiplexing; A second photo detector for measuring the optical power of the optical signal output from the second band filter in the filter unit and measuring the filtered optical power of the optical signal after multiplexing; And a third photodetector for measuring the optical power of the optical signal output from the third tap in the transmission signal detector and measuring the optical power of the optical signal after multiplexing. Status monitoring device for multiplexer / demultiplexer. A first step of monitoring the optical power by detecting the optical signals at the front and rear ends of the AWG performing the multiplexing / demultiplexing of the optical signals; And a second step of determining whether an abnormal operation of the AWG is performed by comparing the optical power measured in the first step. The method of claim 1, wherein the optical multiplexer / demultiplexer of the optical multiplexer / demultiplexer is performed. The method of claim 5, wherein the first step, Detecting and filtering optical power for one of the plurality of channels to perform first monitoring; Multiplexing a plurality of channels in an AWG; Filtering the multiplexed signal to perform a second monitoring; Performing a third monitoring on the multiplexed signal; And measuring the optical power using the first to third monitoring results. 2. The method of claim 1, wherein the optical multiplexer / demultiplexer is used in the wavelength division multiplexing system. The method of claim 5, wherein the second step, If the loss of the total optical power is to be determined, comparing the third monitoring result in the third photodetector to determine whether there is a loss of the optical signal; If there is no loss, determining that there is no loss of total optical power and that the optical signal is normal; If there is the loss, comparing the first monitoring result at the first photodetector with the second monitoring result at the second photodetector to determine whether the comparison value is the same; If the comparison value is the same, determining that there is a loss in the optical signal input to the AWG; And determining that there is a loss in the optical signal due to an abnormal operation in the AWG if the comparison values are not the same. The method for monitoring the state of the optical multiplexer / demultiplexer in the wavelength division multiplexing system.