KR100475351B1 - Apparatus having functions of monitoring and attenuating optical signal and wdm module using this - Google Patents

Abstract

The present invention relates to an optical element having both a sensing function and a variable attenuation function, but with a smaller size and a modularity. The present invention relates to a plurality of variable attenuators, a plurality of variable attenuators, and a tap coupler module and a tap coupler module for branching signals. And a monitor means for detecting a branched signal, wherein the tap coupler module branches a signal that does not affect optical signal transmission, and the monitor means monitors the branched signal to control the plurality of variable attenuators. The present invention provides a module in which sensing and variable attenuation functions are integrated.

Description

Apparatus with optical signal sensing and variable attenuation and WMD module using the same {APPARATUS HAVING FUNCTIONS OF MONITORING AND ATTENUATING OPTICAL SIGNAL AND WDM MODULE USING THIS}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to devices used in the field of optical communications, and more particularly to devices having the function of monitoring a plurality of optical signals having different wavelengths and equalizing or adjusting the levels between these signals.

Optical communication has many advantages over telecommunications in terms of transmission capacity, reliability, relay distance, etc., but because light is used as a signal transmission medium, optical communication and optical communication are widely used in various fields such as light source, modulation method, multiplexing method, coupler and optical cable. Different techniques are required.

The present invention particularly relates to the field of multiplexing among the above-mentioned fields. Optical multiplexing includes optical time division multiplexing (Optical TDM), which divides information into fixed units of time, and optical frequency division multiplexing (OFDM), which loads information at different frequencies. In this case, optical wavelength multiplexing (OWDM) is used.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device having a function of monitoring an optical signal and equalizing or adjusting levels of a plurality of optical signals having different wavelengths among devices in the field of optical wavelength multiplexing.

Conventionally, only the monitoring function is coupled to the WDM device or only the variable attenuation function is combined. Since there is no device in which these two functions are integrated into a single pack, the signal light is monitored and controlled by the variable attenuator to ensure transmission reliability. In order to improve the quality and quality, it is expensive to combine the separate devices, and the miniaturization of the entire system has been a hurdle. The WDM device and its problems will be described in more detail with reference to FIGS. 1 and 2 as follows.

FIG. 1 shows a configuration in which a photodiode 12 is connected to each optical signal channel at an end of the demultiplexer 10 of the WDM device. By the photodiode 12, the magnitude of each optical signal is converted into an electrical signal, and by analyzing the converted electrical signal in the controller 14, the magnitude of the optical signal for each channel is sensed.

In particular, in order to sense the optical signal output from the WDM element during the signal transmission, the fiber type tap coupler 16 per channel is used, which is an obstacle in minimizing the element size.

2 discloses a configuration in which a variable attenuator 22 is coupled to each optical signal channel at an end of the demultiplexer 20 of the WDM element. Here, the variable attenuator 22 generally uses a polymer element, and has a structure in which a thin film heater is coupled to a linear waveguide. The operation principle is to control the intensity of the optical signal by adjusting the degree of heating the thin film heater by applying a control signal.

1 and 2, the optical signal detector and the optical signal variable attenuator are each configured as separate elements. However, in order to control the optical signal, it is preferable to monitor the optical signal and apply the generated control signal to the variable attenuator to adjust the degree of attenuation, so that the optical signal detector and the optical signal variable attenuator have a close relationship. It is a device having.

Therefore, the optical signal sensing function and the optical signal variable attenuation function have been required to be combined and used in the WDM device, and conventionally, these devices have been used in combination separately.

However, as described above, in order to monitor the optical signal output from the WDM device during the optical signal transmission, a fiber type tap coupler is used for each channel, which causes a considerable cost and impedes the integration of the device.

In addition, when the variable attenuator is combined, if the terminal portion senses and adjusts the amount of attenuation, it is impossible to combine with the multiplexing element, which causes difficulty in network management and optical signal control.

In order to solve the problems of the prior art as described above, an object of the present invention is to provide a module in which the variable attenuation function of the optical signal and the sensing function of the optical signal are integrated in one pack.

Another object of the present invention is to provide a small WDM element having a variable attenuation function of an optical signal and a sensing function of the optical signal.

A first aspect of the present invention for achieving the above object comprises a plurality of variable attenuators, a tap coupler module coupled to a plurality of variable attenuators and a monitor means for sensing a signal branched from the tap coupler module, the tap The coupler module branches the signal to a degree that does not affect the optical signal transmission, and the monitor means monitors the branched signal to generate a signal for controlling the plurality of variable attenuators. do.

The second aspect of the present invention further includes a fiber block in the small sensing and variable attenuation module provided in the first aspect of the present invention, the fiber block coupled to the tap coupler module, the optical signal and information being branched for signal detection. The optical signals for transmission are alternately transmitted over the fibers of the fiber block to provide a compact sensing and attenuation module.

The third aspect of the present invention provides a WDM module in which the sensing and attenuation module provided in the second aspect of the present invention is combined with a multiplexer, and the multiplexer and the monitor means are formed to be stacked on each other, further miniaturizing the device. . Hereinafter, the first aspect of the present invention will be described with reference to FIG. 3, and the second and third aspects of the present invention will be described with reference to FIG. 4.

FIG. 3 illustrates one embodiment of a Machine-Zenhder (MZ) type 8 channel optical signal sensing and variable attenuator module according to the first aspect of the invention. As shown in FIG. 3, the sensing and variable attenuation module according to the first aspect of the present invention combines a 3 dB coupler 32 with an input and an output of the variable attenuator 30, respectively, and a 3 dB coupled to the output. The tap coupler module 34 is coupled to the coupler 32. The tap coupler module 34 branches the optical signal for information transmission and the optical signal for the monitor. The optical signal branched for the monitor is input to the photodiode 36 included in the monitor means 38 and converted into an electrical signal. The monitor means 38 transmits a control signal to the variable attenuator 30 which adjusts the optical signal strength of the corresponding channel based on the input signal. The variable attenuator 30 adjusts the optical signal magnitude in accordance with the control signal, thereby maintaining the optical signal magnitude required for each channel, thereby enabling good quality optical communication. On the other hand, the monitor means 38 may improve the channel efficiency by monitoring not only the magnitude of the optical signal but also the presence of the optical signal, thereby recycling the unused channel.

On the other hand, the tap coupler module 34 maintains a coupling ratio of about 99: 1 to 95: 5, so that it is preferable to branch and monitor the optical signal only so as not to affect signal transmission. At this time, the coupling interval and the length of the 3dB coupler 32 and the tap coupler 34 are appropriately determined according to the refractive index difference between the core and the cladding and the wavelength band used.

As described above, the first aspect of the present invention couples the tap coupler 34 module to the variable attenuator 30, branches off some of the optical signals by the tap coupler 34 module into a signal for the monitor, The means 38 generate a control signal capable of controlling the variable attenuator 30 from the branched optical signal, and the variable attenuator 30 controls the magnitude of the optical signal by means of a control signal from the monitor means 38. In particular, the device can be miniaturized by using the tap coupler 34 module.

Next, referring to FIG. 4, an embodiment according to the second aspect of the present invention will be described. As shown in FIG. 4, the tap coupler module 44 is coupled to the fiber block 50, and the optical signal branched for the monitor is transmitted to the monitor means via, for example, even-numbered fibers, and transmits information. The optical signal branched to the outside is transmitted to the outside through odd-numbered fibers. As such, by arranging the optical signals transmitted to the monitor means and the fibers, which are means for transmitting the optical signals transmitted to the outside, to cross each other, the fiber length can be shortened to minimize the signal transmission path and miniaturize the module size.

On the other hand, the third aspect of the present invention is a WDM module in which the small sensing and attenuation module provided in the second aspect of the present invention is combined with the demultiplexer 10 or the multiplexer 60, and the demultiplexer or the multiplexer 60 and By stacking the monitor means 38 together, there is a feature that the module size is further downsized.

That is, the third aspect of the present invention combines the demultiplexer 10 with the variable attenuator 30 of the small sensing and attenuation module provided in the second aspect of the present invention, as shown in FIG. 10) and the monitor means 38 are stacked on top of each other to further reduce the module size, or as shown in FIG. 6, a multiplexer to the variable attenuator 30 of the small sense and attenuation module provided in the second aspect of the present invention. The invention combines 60 and stacks the multiplexer 10 and the monitor means 38 with each other to further reduce the module size.

As mentioned above, the present invention has been described by way of example, and the present invention is not limited to the above-described examples, and the rights of the present invention are determined according to the appended claims. In addition, various modifications of the present invention can be carried out by those skilled in the art, but it is obvious that all belong to the scope of the present invention.

As described above, the present invention can provide a small sensing and variable module having a variable attenuation function and a sensing function by combining a variable attenuator and a monitoring means using a tap coupler module. In addition, the present invention can provide a WDM module having a smaller size by combining a small sensing and variable module with a multiplexer and forming a multiplexer and a monitor means in a stacked structure.

Application of the present invention to a multi-channel WDM device allows direct monitoring of the signal light transmitted on each channel passing through the demultiplexer, and the monitored optical signal can be equalized or differentiated in a variable attenuator. Channel monitoring has the effect of equalizing the signal light of the entire channel or checking the remaining amount of the channel during transmission to increase the transmission quality. In particular, compared with the conventional case of separately combining the monitoring element and the damping control element, by reducing unnecessary elements, there is an effect of reducing the production cost and miniaturization of the module size.

1 is a block diagram showing a conventional optical signal detector.

2 is a block diagram showing a conventional variable attenuator.

3 is a diagram illustrating one embodiment of a module having a sensing function and an attenuation function constructed in accordance with a first aspect of the present invention;

4 is a schematic diagram of an embodiment of a WDM module constructed in accordance with a second aspect of the present invention. FIG. 5 is a schematic diagram of an embodiment of a WDM module constructed in accordance with a third aspect of the present invention. Is a block diagram illustrating one embodiment of a WDM module constructed in accordance with a fourth aspect of the present invention.

Explanation of symbols on the main parts of the drawings

10, 20 ... demultiplexer

12, 36 .... photodiodes

14 .... controller

16 .... fiber tap coupler

22, 30 .... Variable Attenuator

32 .... 3 dB Coupler

34 .... Tap Coupler Module

38 ... monitor means

Claims (4)

A tap coupler module for dividing an optical signal input to at least two channels into an information transmission optical signal and a monitor optical signal; A plurality of variable attenuators installed in at least two channels in front of the tap coupler module and configured to adjust the magnitude of the optical signal transmitted to the tap coupler module for each channel by an input control signal; As the monitor optical signal is input, the magnitude of the input optical signal and the existence of the optical signal are monitored, and a control signal for adjusting the intensity of the optical signal of the corresponding channel is sent to the plurality of variable attenuators according to the monitoring result. Monitor means; And A plurality of fibers are installed between the tap coupler module and the monitor means to output an optical signal for transmitting information branched from the tap coupler module to the outside through an odd or even numbered fiber, and a branch branched from the tap coupler module. And a fiber block for sending the optical signal to the monitor means through an even or odd numbered fiber. delete A tap coupler module for dividing an optical signal input to at least two channels into an information transmission optical signal and a monitor optical signal; A plurality of variable attenuators installed in at least two channels in front of the tap coupler module and configured to adjust the magnitude of the optical signal transmitted to the tap coupler module for each channel by an input control signal; As the monitor optical signal is input, the magnitude of the input optical signal and the existence of the optical signal are monitored, and a control signal for adjusting the intensity of the optical signal of the corresponding channel is sent to the plurality of variable attenuators according to the monitoring result. Monitor means; A plurality of fibers are installed between the tap coupler module and the monitor means to output an optical signal for transmitting information branched from the tap coupler module to the outside through an odd or even numbered fiber, and a branch branched from the tap coupler module. A fiber block for sending the optical signal to the monitor means through an even or odd number fiber; And It includes a demultiplexer coupled to the plurality of variable attenuators, WDM module, characterized in that the demultiplexer and the monitor means are stacked. A tap coupler module for dividing an optical signal input to at least two channels into an information transmission optical signal and a monitor optical signal; A plurality of variable attenuators installed in at least two channels in front of the tap coupler module and adjusting the magnitude of the optical signal transmitted to the tap coupler module for each channel by an input control signal; As the monitor optical signal is input, the magnitude of the input optical signal and the existence of the optical signal are monitored, and a control signal for adjusting the intensity of the optical signal of the corresponding channel is sent to the plurality of variable attenuators according to the monitoring result. Monitor means; A plurality of fibers are installed between the tap coupler module and the monitor means to output an optical signal for transmitting information branched from the tap coupler module to the outside through an odd or even numbered fiber, and a branch branched from the tap coupler module. A fiber block for sending the optical signal to the monitor means through an even or odd number fiber; And A multiplexer coupled to the plurality of variable attenuators, And the multiplexer and the monitor means are stacked.