CN115102623A - Intensive optical fiber coding method based on optical frequency comb and fiber bragg grating - Google Patents
Intensive optical fiber coding method based on optical frequency comb and fiber bragg grating Download PDFInfo
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 39
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
- H04B10/548—Phase or frequency modulation
- H04B10/556—Digital modulation, e.g. differential phase shift keying [DPSK] or frequency shift keying [FSK]
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- H—ELECTRICITY
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- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
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Abstract
The invention discloses an intensive optical fiber coding method based on an optical frequency comb and an optical fiber grating, which comprises the following steps: emitting a C-waveband pulse signal through a light source module, wherein the signal comprises more than m optical pulses with different central wavelengths and overlapped in a time domain; the method comprises the steps that pulse light is equally divided into m different adjustable optical frequency comb sources by an optical splitter, each adjustable optical frequency comb source generates comb teeth in an optical pulse wavelength domain at fixed intervals, and the optical comb intervals generated by the different optical frequency comb sources are different; each optical frequency comb source is followed by one (m-1) 2 A port wavelength encoder, wherein the wavelength combinations contained by different port light pulses leaving the same encoder are different; using different optical comb intervals as the first encoding, and using different combinations of wavelength components for each code word as the second encoding, twice encodingThe final result constitutes a set of all codes; the problem that the real-time coding scale of the prior art is still limited and cannot meet the use requirement of a large-scale network is solved.
Description
Technical Field
The invention belongs to the technical field of network digitization, and particularly relates to an intensive optical fiber coding method based on an optical frequency comb and an optical fiber grating.
Background
Optical fiber coding is the basic and core technology for realizing all-optical network digitization. The optical fiber link safety is the basis for ensuring the safety of the optical access network, and researches show that about one third of optical network faults are caused by optical fiber cable faults, so that each optical fiber link in the optical access network is digitally encoded, and the network state is monitored by using the codes, and the premise that the optical access network can operate efficiently and stably is realized by realizing more accurate, reliable, intelligent and efficient all-optical-network digital management. The efficiency of optical fiber coding directly affects the effect of all-optical network digitization.
Most of the currently used optical fiber coding techniques only use fiber gratings to perform one-dimensional or two-dimensional wavelength coding on monitoring optical pulses. The one-dimensional coding wavelength coding only can allocate a single wavelength to one link as a unique label, and has the advantages of simple structure and convenient implementation, the coder only comprises one fiber grating arranged at a user end, and the defect is obvious, and the used spectrum resources are linearly increased along with the number of the coding links and only can be suitable for the coding requirement of a small-scale optical network. The two-dimensional wavelength coding uses an optical encoder consisting of a fiber grating and a one-to-two optical splitter, the encoder is placed at the local side in an access network, the complexity of a user side is reduced by adopting centralized coding, the coding efficiency is greatly improved compared with the one-dimensional encoding, but the two-dimensional wavelength coding is limited by spectral resources in actual use and can only realize the coding of hundreds of links.
The method for increasing the number of codes generally used mainly includes multiplexing in the time domain, grouping a plurality of users into a group, encoding only the optical fiber links of a certain group of users within a period of time by using a polling mode, and setting a proper polling period to enable each optical fiber link to be effectively encoded. The effective coding quantity increase can be realized simply by the light switching and control circuit combined with the time division multiplexing wavelength coding method, but when the monitoring link is longer, the polling window allocated to each group of users also needs to be correspondingly increased, and in addition, the increase of the number of the users also needs to poll more groups to meet the requirements, so that the polling period is inevitably prolonged, the time for the users not to be identified and managed is increased, and the response efficiency of fault monitoring is reduced.
The targeted encoding technology is not suitable for realizing real-time encoding of an all-optical network with large-scale and high reliability requirements.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the intensive optical fiber coding method based on the optical frequency comb and the optical fiber grating is provided to solve the technical problems that the real-time coding scale in the prior art is still limited, the use requirement of a large-scale network cannot be met, and the like.
The technical scheme of the invention is as follows:
a method for dense fiber coding based on an optical frequency comb and a fiber grating, the method comprising:
step 1, emitting a C-waveband pulse signal through a light source module, wherein the signal comprises more than m optical pulses with different central wavelengths and overlapped in a time domain;
step 3, each optical frequency comb source is connected with one (m-1) 2 A port wavelength encoder, wherein the wavelength combinations contained by the optical pulses of different ports leaving the same encoder are different;
and 4, taking different optical comb intervals as first encoding, taking different combinations of wavelength components of each code word as second encoding, and forming a set of all the codes by the final results of the two encoding.
The light source is controlled by an external signal, and m laser arrays generate m laser arrays with the same width, power and period in a time domain; the optical pulse laser comprises optical pulses with different central wavelengths and the same 3dB bandwidth in a wavelength domain, wherein the interval between the central wavelengths of the adjacent optical pulses is larger than the bandwidth of the adjacent optical pulses so as to ensure that the pulses cannot be mixed in the wavelength domain, and the pulses leave a laser at the same time and are combined into one pulse in a time domain through a coupler arranged in an optical source module.
When the optical frequency comb source works in the wavelength range used by the light source, the intervals of the generated frequency combs are equal and smaller than the interval of the central wavelengths of the adjacent optical pulses, and the interval of the central wavelengths of the pulses can divide the interval of the frequency combs completely.
N different codes are generated by an adjustable optical frequency comb source with n different comb tooth intervals.
The encoder is composed of (m-1) 2 The optical fiber grating coupler is characterized by being formed by connecting 1 one-to-two optical splitters in a cascade mode, wherein two output ports of the upper-stage optical splitter are respectively connected with input ports of the two lower-stage splitters, and only one port of the two output ports of one optical splitter is selected to be provided with one optical fiber grating.
Each fiber grating finishes one of the wavelengths generated by the total reflection light source and transmits the rest of the wavelengths, and the fiber gratings used in each stage have the same parameter index; at least one wavelength pulse is retained at each port of the encoder.
This is achieved using m wavelengths of light (m-1) 2 And (5) wavelength coding.
Using a frequency comb comprising light pulses of m wavelengths and n separations to produce n (m-1) in total 2 And codes, each code uniquely corresponding to one optical fiber link.
The invention has the beneficial effects that:
the invention takes multi-wavelength retrieval optical pulse synchronously output by a multi-wavelength pulse light source as a carrier of coded information, and codes the pulse wavelength twice by the optical pulse through the adjustable optical frequency comb source and the fiber bragg grating, thereby realizing the coding of a large number of users under the condition of using limited wavelength resources. The method comprises the steps that a light source module emits a C-band pulse signal, the signal comprises a plurality of optical pulses with different central wavelengths and overlapped in a time domain, then the optical pulses are averagely distributed to a plurality of adjustable optical frequency comb sources through a splitter, the optical frequency comb sources generate frequency combs on the optical pulses at different intervals, light leaving each optical frequency comb source enters a fiber grating encoder, cascade gratings in the optical frequency comb sources selectively reflect the pulse wavelengths to form unique pulse wavelength combinations at output ports, the encoders behind all the optical frequency comb sources have the same structure, the output ports of the encoders are connected to all optical fiber links in a descending mode, and for a certain link, the wavelength combination type of the optical pulses entering the certain link and the number of comb teeth contained in each wavelength jointly form unique encoding information of the certain link.
The invention completes coding more links by using less wavelength resources, saves spectrum resources, and can greatly improve the scale of the all-optical network digital technology which can monitor the network when the optical fiber channel is in shortage and the number of users is gradually increased.
The invention utilizes the combination of the fiber grating coding technology and the optical frequency comb coding method to improve the number of optical fiber links which can be coded simultaneously and solve the problems that the real-time coding scale of the prior art is still limited and the large-scale network use requirements cannot be met.
Drawings
FIG. 1 is a diagram of a device through which encoded optical pulses pass from being generated to entering an optical fiber link;
FIG. 2 is a spectral diagram of optical pulses output by a multi-wavelength laser;
FIG. 3 is a spectrum diagram of an optical pulse after passing through a tunable optical frequency comb source;
FIG. 4 is a diagram of a fiber grating encoder;
FIG. 5 is a spectral diagram of an optical pulse after passing through a fiber grating encoder.
Detailed Description
In order to increase the number of simultaneously encodable optical fiber links, the invention proposes the following encoding method: the dense optical fiber coding method based on the optical frequency comb and the optical fiber grating comprises the following steps (see figure 1):
step 1, a light source module emits a C-waveband pulse signal, wherein the signal comprises m optical pulses with different central wavelengths and overlapped on a time domain;
the multi-wavelength pulse light source can be controlled by an external signal, and m lasers with different central wavelengths generate m lasers with the same width, power and period in a time domain; the optical pulses with different central wavelengths and the same 3dB bandwidth in a wavelength domain are separated by the distance between the central wavelengths of the adjacent optical pulses which is larger than the width of the optical pulses so as to ensure that the pulses cannot be mixed in the wavelength domain, and the pulses leave the laser at the same time and are combined into one pulse in a time domain through a coupler arranged in the light source module.
and 3, connecting an m-port wavelength encoder behind each optical frequency comb source, wherein the wavelength combinations contained by the optical pulses leaving different ports of the same encoder are different.
And 4, taking different optical comb intervals as first encoding, taking different combinations of wavelength components of each code word as second encoding, and forming a set of all the codes by the final results of the two encoding.
The size of a frequency comb modulated by a light-adjustable frequency comb source in the working process within the wavelength range used by a light source is close, the space between comb teeth is kept stable, the intervals of the generated frequency combs are equal and far smaller than the interval of the central wavelengths of adjacent light pulses, the number of comb teeth of 5 or more than 5 is generally ensured in one light pulse spectrum, and the interval of the central wavelengths of the light pulses can divide the interval of the frequency combs evenly so as to ensure that each pulse has the same number of comb teeth in the wavelength domain; the comb sources with different optical frequencies ensure that the number of comb teeth falling into optical pulses is obviously different, and n different codes can be generated by the comb sources with the adjustable optical frequencies at intervals of n different comb teeth.
Multi-port wavelength encoder consists of (m-1) 2 The optical fiber grating light source comprises-1 one-to-two optical splitters which are connected in a step-by-step mode, two output ports of the upper-level optical splitter are respectively connected with input ports of the lower-level two splitters, only one port of the two output ports of one optical splitter is selected to be provided with one optical fiber grating, each optical fiber grating can finish one wavelength generated by the total reflection light source and transmit the rest wavelengths, and the optical fiber gratings used in each level have the same parameter indexes (such as central wavelength reflectivity and 3dB bandwidth). Since the output of the optical pulses must be guaranteed, the encoder ports should retain pulses of at least one wavelength, so that it can be calculated that the use of m optical wavelengths is all possible (m-1) 2 And (4) wavelength coding.
In the above scheme, n (m-1) can be generated in total using an optical frequency comb comprising optical pulses of m wavelengths and n intervals 2 And each code can uniquely correspond to one optical fiber link.
The optical frequency comb source of the invention generates frequency combs on optical pulses at different intervals, light leaving each optical frequency comb source enters a fiber grating encoder, the cascade grating positioned therein selectively reflects the pulse wavelength to form a unique pulse wavelength combination at an output port, the encoders connected behind all the optical frequency comb sources have the same structure, the output ports of the encoders are connected to all the optical fiber links, and for a certain link, the optical pulse entering the certain link forms unique encoding information by the comb tooth interval width and wavelength combination type in the wavelength domain.
Fig. 2 is a spectrum diagram of an optical pulse output from a multi-wavelength laser. One optical pulse is formed by combining a plurality of pulses with different central wavelengths, the distances between adjacent central wavelengths are the same, and the main frequency components of the wavelengths do not overlap with each other.
Fig. 3 is a spectrum diagram of an optical pulse after passing through a tunable optical frequency comb source. In order to ensure that the pulses with the central wavelengths are generated with comb teeth with the same number, the optical frequency comb source should generate frequency combs at a fixed frequency interval, and the interval should be much smaller than the interval of the central wavelengths of the pulses, usually 5 or more comb teeth are ensured in one optical pulse spectrum, and the interval of the central wavelengths of the optical pulses can divide the interval of the frequency combs evenly, so as to ensure that the same number of frequency comb teeth can be generated in the bandwidth of each wavelength, the number of comb teeth is as much as possible, and simultaneously one comb tooth exists at the central wavelength, and the comb teeth are symmetrically distributed in each wavelength by taking the center as an axis.
FIG. 4 is a diagram of a fiber grating encoder. The encoder is formed by connecting a plurality of one-to-two optical splitters step by step, two output ports of the upper-stage optical splitter are respectively connected with input ports of the two lower-stage optical splitters, only one port is selected from the two output ports of one optical splitter to be provided with one fiber grating, each fiber grating can completely reflect one wavelength generated by a light source and transmit the rest wavelengths, and the fiber gratings used in each stage have the same parameter indexes (such as central wavelength reflectivity and 3dB bandwidth). Since the output of the optical pulses must be guaranteed, the encoder ports should retain pulses of at least one wavelength, so that it can be calculated that the use of m optical wavelengths is all possible (m-1) 2 And (4) wavelength coding.
FIG. 5 is a spectral diagram of an optical pulse exiting a port of a 6-wavelength fiber grating encoder. In which at several selected wavelengths (lambda) 1 ,λ 3 ,λ 5 ,λ 6 And) the same number of comb teeth are present in the range, and the combination of the number of comb teeth and the wavelength is used as the unique coded information of one optical link.
The embodiment of the invention lists a specific implementation flow of the intensive optical fiber coding method based on the optical frequency comb and the optical fiber grating, and the number of optical wavelengths and the comb tooth interval of the adjustable optical frequency comb source used in the method can be adjusted according to the actual situation.
Claims (8)
1. An intensive optical fiber coding method based on an optical frequency comb and an optical fiber grating is characterized in that: the method comprises the following steps:
step 1, emitting a C-waveband pulse signal through a light source module, wherein the signal comprises more than m optical pulses with different central wavelengths and overlapped in a time domain;
step 2, equally dividing the pulsed light to m different adjustable optical frequency comb sources by using an optical splitter, wherein each adjustable optical frequency comb source generates comb teeth in an optical pulse wavelength domain at fixed intervals, and the optical comb intervals generated by different optical frequency comb sources are different;
step 3, each optical frequency comb source is connected with one (m-1) 2 A port wavelength encoder, wherein the wavelength combinations contained by the optical pulses of different ports leaving the same encoder are different;
and 4, taking different optical comb intervals as first encoding, taking different combinations of wavelength components of each code word as second encoding, and forming a set of all the codes by the final results of the two encoding.
2. The method as claimed in claim 1, wherein the dense fiber coding method based on optical frequency comb and fiber grating is characterized in that: the light source is controlled by an external signal, and m laser arrays generate m laser arrays with the same width, power and period in a time domain; the optical pulse laser comprises optical pulses with different central wavelengths and the same 3dB bandwidth in a wavelength domain, wherein the interval between the central wavelengths of the adjacent optical pulses is larger than the bandwidth of the adjacent optical pulses so as to ensure that the pulses cannot be mixed in the wavelength domain, and the pulses leave a laser at the same time and are combined into one pulse in a time domain through a coupler arranged in an optical source module.
3. The method as claimed in claim 1, wherein the dense fiber coding method based on optical frequency comb and fiber grating is characterized in that: when the optical frequency comb source works in the wavelength range used by the light source, the intervals of the generated frequency combs are equal and smaller than the interval of the central wavelengths of the adjacent optical pulses, and the interval of the central wavelengths of the pulses can divide the interval of the frequency combs completely.
4. The method as claimed in claim 3, wherein the dense fiber coding method based on optical frequency comb and fiber grating is characterized in that: n different codes are generated by an adjustable light frequency comb source with n different comb tooth intervals.
5. The method as claimed in claim 1, wherein the dense fiber coding method based on optical frequency comb and fiber grating is characterized in that: encoder consists of (m-1) 2 The optical fiber grating coupler is characterized by being formed by connecting 1 one-to-two optical splitters in a cascade mode, wherein two output ports of the upper-stage optical splitter are respectively connected with input ports of the two lower-stage splitters, and only one port of the two output ports of one optical splitter is selected to be provided with one optical fiber grating.
6. The method as claimed in claim 5, wherein the dense fiber coding method based on optical frequency comb and fiber grating is characterized in that: each fiber grating finishes one of the wavelengths generated by the total reflection light source and transmits the rest of the wavelengths, and the fiber gratings used in each stage have the same parameter index; each port of the encoder retains pulses of at least one wavelength.
7. The method as claimed in claim 6, wherein the dense fiber coding method based on optical frequency comb and fiber grating comprises: can be realized by using m kinds of light wavelength (m-1) 2 And (5) wavelength coding.
8. The method as claimed in claim 1, wherein the dense fiber coding method based on optical frequency comb and fiber grating is characterized in that: using a frequency comb comprising light pulses of m wavelengths and n separations to produce n (m-1) in total 2 And codes, each code uniquely corresponding to one optical fiber link.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100221010A1 (en) * | 2009-02-27 | 2010-09-02 | Oki Electric Industry Co., Ltd. | Encoding-decoding method, optical pulse time spreading apparatus, optical add-drop-multiplexer, and optical communication system |
| US7917039B1 (en) * | 2007-02-09 | 2011-03-29 | University Of Central Florida Research Foundation, Inc. | Signal processing using spectrally phase-encoded optical frequency combs |
| CN105187130A (en) * | 2015-08-17 | 2015-12-23 | 东南大学 | Fiber Bragg Grating (FBG) cascading shunt encoding device and encoding and decoding methods |
| CN105406918A (en) * | 2015-11-03 | 2016-03-16 | 南京航空航天大学 | Photon-type multi-frequency phase-coded signal generation device and method |
| CN109560875A (en) * | 2018-12-28 | 2019-04-02 | 东南大学 | A kind of fiber grating code device and method with temperature detection and compensation function |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7917039B1 (en) * | 2007-02-09 | 2011-03-29 | University Of Central Florida Research Foundation, Inc. | Signal processing using spectrally phase-encoded optical frequency combs |
| US20100221010A1 (en) * | 2009-02-27 | 2010-09-02 | Oki Electric Industry Co., Ltd. | Encoding-decoding method, optical pulse time spreading apparatus, optical add-drop-multiplexer, and optical communication system |
| CN105187130A (en) * | 2015-08-17 | 2015-12-23 | 东南大学 | Fiber Bragg Grating (FBG) cascading shunt encoding device and encoding and decoding methods |
| CN105406918A (en) * | 2015-11-03 | 2016-03-16 | 南京航空航天大学 | Photon-type multi-frequency phase-coded signal generation device and method |
| CN109560875A (en) * | 2018-12-28 | 2019-04-02 | 东南大学 | A kind of fiber grating code device and method with temperature detection and compensation function |
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