KR20000033360A - Apparatus for monitoring multichannel light source - Google Patents

Abstract

PURPOSE: An apparatus for monitoring multichannel light source is provided to efficiently maintain system performance by monitoring and controlling the variation in the central wavelength of a multichannel light source and the strength of the light source, according to the conversion of wavelength and the insertion and abstraction. CONSTITUTION: One input terminal of a variable optical filter(212) is connected to the output terminal of a multichannel light source(211). A waveform generator(213) is connected to the other input terminal of the variable optical filter(212). The input terminal of an optical separator(214) is connected to the output terminal of the variable optical filter(212). The input terminal of an optical detector(215) is connected to one output terminal of the optical separator(214). The input terminal of the separator(216) is connected to the other output terminal of the optical separator(214). The input terminal of an optical amplifier(217) is connected to one output terminal of the optical separator(216). An optical fiber delay device(226) is connected to the other output terminal of the optical separator(216). The port of an optical circulator(218) is connected to the output terminal of the optical amplifier(217). An optical fiber for stimulated brilluin scattering optical signal generation(219) is connected to the b port of the optical circulator(218). Two input terminals of an optical coupler(220) are connected to the c port of the optical circulator(218) and the optical fiber delay device(226). The input terminal of an optical detector(221) is connected to the output terminal of the optical coupler(220). One terminal of a top-down converter(222) is connected to the output terminal of the optical detector(221). The output terminal of a reference frequency generator(223) is connected to the other input terminal of the top-down converter(222). The input terminal of a light-to-voltage converter(224) is connected to the output terminal of the top-down converter(222). The input terminals of a processor(225) is connected to the output terminal of the optical detector(215).

Description

Multichannel Light Source Monitoring Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for monitoring multichannel light sources in a wavelength division multiplexing (WDM) system. In particular, the present invention relates to a multichannel light source capable of continuously measuring and monitoring the center wavelength of a multiplexed multichannel light source and the intensity of the light source. It relates to a monitoring device.

In the conventional technique, the linewidth measuring method of a multichannel light source using Stimulated Brilluin Scattering light is a frequency shifted signal generated by the induced Brillouin scattering phenomenon in an optical fiber when high intensity light enters the optical fiber. Measuring the line width of the multi-channel light source using light, which is described with reference to FIG. 1 as follows.

That is, FIG. 1 is a block diagram of a conventional apparatus for measuring line width of a multichannel light source using inductive Brillouin scattered light, and includes a multichannel light source 111, an optical separator 112, an optical amplifier 113 having a high output, and And an optical circulator 114, an optical fiber retarder 115, an optical coupler 116, a photodetector 117, a frequency amplifier 118, and a frequency spectrum analyzer 119.

The operation of the line width measuring apparatus of the multi-channel light source using the conventional guided Brillouin scattered light having such a structure will be described below.

When the multi-channel light source 111 generates a multiplexed multi-channel optical signal and transmits the multi-channel optical signal to the optical splitter 112, the optical splitter 112 separates the transmitted multi-channel optical signal and the optical amplifier 113 and the optical combiner 116. To pass).

Subsequently, the optical amplifier 113 transmits the optical signal amplified by amplifying the optical signal separated and transmitted by the optical separator 112 to the optical coupler 116 via the optical circulator 114.

In addition, the optical coupler 116 combines the optical signals transmitted from the optical separator 112 and the optical circulator 114 and transmits the optical signals to the photodetector 117, and the photodetector 117 intensifies the combined optical signal. Is detected and delivered to the frequency spectrum analyzer 119 through the frequency amplifier 118.

Accordingly, the frequency spectrum analyzer 119 analyzes the spectral characteristics of the transmitted optical signal.

However, in the case of the line width measuring apparatus of the multi-channel light source using the conventional induction Brillouin scattering light as described above, in order to induce induced Brillouin scattering in the optical fiber, a high output optical amplifier is required in proportion to the number of channels, which is inefficient. When using an optical amplifier with a limited output, the number of channels that can be measured is limited, and because the signal-to-noise ratio of the measurement spectrum is increased due to the nonlinear phenomenon in the optical fiber due to the high output, there is a problem that the accurate spectrum cannot be measured.

Accordingly, the present invention has been made to solve the above problems, and by monitoring and controlling the change of the center wavelength and the intensity of the light source according to the wavelength conversion, insertion and extraction in the wavelength division multiplexing system, the performance of the system It is an object of the present invention to provide a multi-channel light source detection device that can efficiently maintain the.

1 is a block diagram of a line width measuring apparatus of a multi-channel light source using a conventional guided Brillouin scattered light.

2 is a block diagram of an embodiment of a multi-channel light source monitoring apparatus according to the present invention.

3 is an operation timing diagram of a multi-channel light source monitoring apparatus according to the present invention.

Explanation of symbols on the main parts of the drawings

211: multi-channel light source 212: variable optical filter

213: waveform generator 214, 216: optical separator

215, 221: photodetector 217: optical amplifier

218: optical circulator 219: optical fiber

220: optical coupler 222: down converter

223: reference frequency generator 224: optical / voltage converter

225: processor

In the present invention for achieving the above object, in the multi-channel light source monitoring apparatus, the center frequency is shifted by the transmitted waveform, and the multi-channel optical signals transmitted from the multi-channel light source by filtering at a predetermined time interval to one Optical filtering means for sequentially extracting an optical signal; Waveform generation means for generating the waveform for moving the center frequency of the optical filtering means at regular time intervals; Optical separation means for separating the optical signals sequentially transmitted from the optical filtering means at predetermined time intervals into first and second optical signals; After dividing the first optical signal into third and fourth optical signals, respectively, amplifying and delaying the signals, the amplified third optical signal is used to generate a Stimulated Brilluin Scattering (SBS) optical signal. Separating and combining means for coupling the induced Brillouin scattering optical signal and the delayed fourth optical signal; First light detecting means for detecting an intensity of the second optical signal; Second light detecting means for detecting the induced Brillouin scattering light signal and the light signal output from the multi-channel light source from the light signal output from the separating and combining means; Signal conversion means for down-converting the optical signal detected by the second light detecting means and converting it into a voltage signal according to a predetermined reference frequency; And light source monitoring means for monitoring the state of the multi-channel light source by using the light intensity value detected by the first light detecting means and the optical signal converted by the signal converting means.

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

2 is a block diagram of an embodiment of a multi-channel light source monitoring apparatus according to the present invention.

As shown in FIG. 2, the multi-channel light source monitoring apparatus of the present invention includes a multi-channel light source 211, a variable optical filter 212 connected to one output terminal of the multi-channel light source 211, and an output terminal. A waveform generator 213 connected to the other input of the variable optical filter 212, an optical separator 214 connected to the output of the variable optical filter 212, and an input terminal connected to one output of the optical separator 214. A photodetector 215, an optical separator 216 having an input coupled to the other output of the optical separator 214, an optical amplifier 217 having an input coupled to one output of the optical separator 216, and an optical separator 216 Optical retarder 226 connected to the other output terminal of < RTI ID = 0.0 >), < / RTI > an optical port 218 connected to the output terminal of the optical amplifier 217, and an induced Brillouin scattering optical signal connected to the b port of the optical cycler 218. The optical fiber 219 and two input terminals are respectively the c port of the optical circulator 218 and the optical fiber retarder 226. An optical coupler 220 connected, an optical detector 221 having an input terminal connected to an output terminal of the optical coupler 220, a down converter 222 having one input terminal connected to an output terminal of the photo detector 221, and an output terminal having a down converter A reference frequency generator 223 connected to the other input of 222, an optical / voltage converter 224 whose input is connected to the output of the downconverter 222, and a processor whose inputs are connected to the output of the photodetectors 215 and 224. 225.

The operation of the multi-channel light source monitoring apparatus of the present invention having the structure as described above will be described in detail as follows.

The variable optical filter 212 extracts one optical signal by filtering the multichannel optical signals transmitted from the multichannel light source 211 and outputs the optical signal to the optical separator 217, wherein the variable optical filter 212 is the waveform generator 213. The center frequency is shifted by the waveform transmitted from), and the optical signals are sequentially extracted by filtering the multichannel optical signals at regular time intervals.

The waveform generator 213 generates a waveform for shifting the center frequency of the variable optical filter 212. That is, the waveform generator 213 serves to constantly adjust the time interval of the optical signals extracted and transmitted by the variable optical filter 212.

The optical separator 217 separates the optical signal output from the variable optical filter 217 and transmits the optical signal to the photodetector 215 and the optical combiner 216.

The photodetector 215 detects the intensity of the optical signal separated and transmitted by the optical separator 214 and transmits the detected light intensity value to the processor 225.

The optical separator 216 separates the optical signal separated by the optical separator 214 again, and one optical signal separated by the optical signal is amplified by the optical amplifier 217 and then passed through the optical circulator 218. The induced Brillouin scattering light signal is transmitted to the optical fiber 219 for generating, and the other split optical signal is delayed through the optical fiber retarder 226 and transmitted to the optical coupler 220.

The optical fiber for generating the induced Brillouin scattering optical signal 219 is induced to generate the induced Brillouin scattering optical signal by the optical signal separated and transmitted by the optical separator 216, thereby generating the induced Brillouin scattering optical signal. In addition, the induced Brillouin scattering light signal generated in this way is transmitted to the optical coupler 220 through the b port and the c port of the optical circulator 218.

The optical coupler 220 combines the separated optical signal and the induced Brillouin scattering optical signal transmitted through the optical fiber retarder 226 and the optical circulator 218, respectively, and transmits the combined optical signal to the photodetector 221.

The photodetector 221 detects the induced Brillouin scattering optical signal and the multichannel optical signal generated from the multichannel light source 211 in the optical signal coupled by the optical coupler 220 and transmits the multichannel optical signal to the down converter 222.

The down converter 222 mixes the optical signal of the 10 GHz frequency band transmitted from the reference frequency generator 223 and the optical signal of the 10 GHz frequency band detected by the photodetector 221, thereby detecting the optical signal detected by the photodetector 221. Down-converts to an optical signal in the several hundred MHz frequency band and transmits the optical signal to the optical / voltage converter 225.

The reason for converting the optical signal in the 10 GHz frequency band into the optical signal in the several hundred MHz frequency band through the down converter 222 is generated between the multi-channel optical signal generated from the multi-channel light source 211 and the induced Brillouin scattering optical signal. This is to enable the processor 225 to easily analyze the high frequency spectrum signal in the low frequency region.

The optical / voltage converter 224 converts the optical signal transmitted from the down converter 222 into a voltage signal suitable for the processor 225, and then transfers the optical signal to the processor 225.

The processor 225 corresponds to the light intensity of the multi-channel light source 211 and the detection value of the photodetector 221 corresponding to the central wavelength and the output value of the light / voltage converter 224, and calculates a channel spacing to calculate the multi-channel. The light intensity of the light source is determined, and the state of the multichannel light source is monitored.

3 is an operation timing diagram of the multi-channel light source monitoring apparatus according to the present invention, where (A) is a multi-channel optical signal output from the multi-channel light source 211, (B) is a optical signal output from the multi-channel light source 211 The optical signal filtered by the variable call optical filter 212, (C) is an output signal of the photodetector 213, (D) is an output signal of the light / voltage converter 224.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention has the following effects.

First, unlike the conventional method of simultaneously inputting multi-channel light sources, the multi-channel light sources are extracted at regular time intervals (about 1 msec) through a variable optical filter having a narrow line width, and then the multi-channel light sources are sequentially incident on the optical fiber. Low-power optical amplifiers can also be used to induce induced Brillouin scattering (SBS).

Second, by using the optical amplifier with low power by sequentially entering the multi-channel light source into the optical fiber, the signal-to-noise ratio can be increased to obtain an accurate spectrum of the multi-channel light source, and at the same time, the intensity of the light source of each channel is measured. can do.

Third, by using the 10 GHz frequency oscillator to analyze the high frequency spectrum signals of the 10 GHz band generated between the multi-channel light source and the induced Brillouin scattering signal in the low frequency region, the spectrums of the hundreds of MHz frequency bands corresponding to the multi-channel light source can be obtained. You can get it.

Claims (3)

In the multi-channel light source monitoring device, An optical filtering means for shifting a center frequency by the transmitted waveform to sequentially extract one optical signal by filtering the multichannel optical signals transmitted from the multichannel light sources at predetermined time intervals; Waveform generation means for generating the waveform for moving the center frequency of the optical filtering means at regular time intervals; First optical separation means for separating the optical signals sequentially transmitted from the optical filtering means at predetermined time intervals into first and second optical signals; After dividing the first optical signal into third and fourth optical signals and amplifying and delaying the respective optical signals, the amplified Brilluin Scattering optical signal is generated using the amplified third optical signal, and Separating and combining means for combining the induced Brillouin scattering optical signal and the delayed fourth optical signal; First light detecting means for detecting an intensity of the second optical signal; Second light detecting means for detecting the induced Brillouin scattering light signal and the light signal output from the multi-channel light source from the light signal output from the separating and combining means; Signal conversion means for downconverting the optical signal detected by the second photodetector to a low frequency according to a predetermined reference frequency and then converting the optical signal into a voltage signal; And Light source monitoring means for monitoring the state of the multi-channel light source by using the light intensity value detected by the first light detecting means and the optical signal converted by the signal converting means Multi-channel light source monitoring device comprising a. The method of claim 1, The separation and coupling means, Second optical separation means for separating the first optical signal into the third and fourth optical signals; Optical amplification means for amplifying a third optical signal separated by the second optical separation means; Delay means for delaying a fourth optical signal separated by said second optical separation means; Signal generating means for receiving the third optical signal amplified by the optical amplifying means and generating the induced Brillouin scattering optical signal; Optical coupling means for coupling the induced Brillouin scattering optical signal and a fourth optical signal transmitted through the delay means; And Optical circulation means for transmitting the third optical signal amplified by the optical amplification means to the signal generating means and for transferring the induced Brillouin scattering optical signal generated from the signal generating means to the optical coupling means; Multi-channel light source monitoring device comprising a. The method of claim 1, The signal conversion means, Reference frequency generating means for generating the predetermined reference frequency; Down-converting means for down-converting the optical signal detected by the second light detecting means to a low frequency in accordance with the predetermined reference frequency; And Optical / voltage conversion means for converting the optical signal output from the down conversion means into a voltage signal Multi-channel light source monitoring device comprising a.