Fiber coding method based on binary amplitude shift keying and binary wavelength coding

Abstract

This invention discloses a fiber optic encoding method based on binary amplitude shift keying (APS) and binary wavelength coding. A C-band pulse signal is emitted from a light source module. The pulse signal contains m optical pulses with different center wavelengths but overlapping in the time domain. An optical splitter equally distributes the optical pulses to different binary APS encoders. Each binary APS encoder uses the light entering the encoder to generate a binary amplitude-coded optical pulse with a fixed codeword. Each binary APS encoder output is connected to a multi-port binary fiber Bragg grating wavelength encoder. The binary APS codeword is used as the first encoding, and then each codeword is encoded a second time using different combinations of wavelength components. The final result of the two encodings constitutes the set of all codes. This method solves the problem that existing real-time encoding methods are still limited in scale and cannot meet the requirements of large-scale network applications.

Description

Technical Field

[0001] This invention belongs to the field of optical fiber coding technology, and particularly relates to an optical fiber coding method based on binary amplitude shift keying and binary wavelength coding. Background Technology

[0002] Fiber optic coding is the foundation and core technology for realizing all-optical network digitization. Fiber optic link security is fundamental to ensuring the security of optical access networks. Studies have shown that approximately one-third of optical network failures are caused by fiber optic cable faults. Therefore, digitizing each fiber optic link in the optical access network and using this coding to monitor network status, achieving more accurate, reliable, intelligent, and efficient all-optical network digitization management, is a prerequisite for the efficient and stable operation of the optical access network. The efficiency of fiber optic coding directly affects the effectiveness of all-optical network digitization. Fiber optic coding methods based on binary amplitude keying (BSK) and fiber Bragg gratings can encode more links using fewer wavelengths, saving spectrum resources. In the current context of limited fiber optic channels and a gradually increasing number of users, this can significantly increase the scale of networks that can be monitored by all-optical network digitization technology.

[0003] Most current fiber optic coding technologies utilize fiber Bragg gratings (FBGs) to encode monitoring optical pulses in one or two dimensions. One-dimensional wavelength coding assigns a single wavelength as a unique tag to each link. Its advantages include simple structure and ease of implementation, with the encoder consisting of only a single FBG located at the user end. However, its disadvantages are obvious: the spectral resources used increase linearly with the number of coded links, limiting its applicability to small-scale optical networks. Two-dimensional wavelength coding uses an optical encoder composed of a FBG and a 1-to-2 optical splitter. The encoder is placed at the central office in the access network, employing centralized coding to reduce user-end complexity and significantly improving coding efficiency compared to one-dimensional coding. However, in practical applications, it is still limited by spectral resources and can only encode a few hundred links.

[0004] Commonly used methods to increase the number of codes primarily involve time-domain multiplexing. Multiple users are grouped together, and a polling method is used. Only the fiber optic links of a specific group of users are coded within a certain time period. By setting an appropriate polling period, each fiber optic link is effectively coded. Combining time-division multiplexing wavelength coding methods can easily increase the number of codes effectively through optical switching and control circuits. However, when monitoring links are long, the polling window allocated to each group of users also needs to be increased accordingly. Furthermore, an increase in the number of users requires polling more groups to meet the demand, which inevitably prolongs the polling period. This increases the time users are not identified and managed, reducing the response efficiency of fault monitoring.

[0005] Existing coding techniques are not suitable for real-time coding of large-scale, high-reliability all-optical networks. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide an optical fiber coding method based on binary amplitude keying and binary wavelength coding, so as to solve the problems that existing optical fiber coding technology cannot be applied to realize real-time coding for large-scale, high-reliability all-optical networks, and that the real-time coding scale of existing technology is still limited and cannot meet the requirements of large-scale network use.

[0007] The technical solution of this invention is:

[0008] A fiber optic coding method based on binary amplitude shift keying (BPS) and binary wavelength coding, the method comprising:

[0009] Step 1: The light source module emits a C-band pulse signal, which contains m light pulses with different center wavelengths but overlapping in the time domain.

[0010] Step 2: Use an optical splitter to equally distribute the optical pulses to different binary amplitude keying encoders. Each binary amplitude keying encoder uses the light entering the encoder to generate a binary amplitude encoded optical pulse with a fixed codeword. The optical pulse codewords generated by different binary amplitude keying encoders are different.

[0011] Step 3: Connect a multi-port binary fiber Bragg grating wavelength encoder to the output of each binary amplitude keying encoder.

[0012] Step 4: Use binary amplitude keying codewords as the first encoding, and then use different combinations of wavelength components for each codeword as the second encoding. The final result of the two encodings constitutes the set of all codes.

[0013] The light source module is controlled by an external signal and simultaneously generates m optical pulses from the laser array. These pulses have the same width, power, and period in the time domain, different center wavelengths in the wavelength domain, and the same 3dB bandwidth. The center wavelength interval between adjacent optical pulses is greater than the bandwidth. Each pulse leaves the laser at the same time and is combined into a single pulse in the time domain through a coupler built into the light source module.

[0014] A binary amplitude keying encoder consists of a 1-in-p-out optical splitter, a delay line, and a coupler. The pulse width of the light pulse output by the light source is defined as one unit time. The total length of the light pulse output by a binary amplitude keying n-bit encoder is equal to n units of time. When the encoded digital information is 1, there is light at the encoder output port within one unit time. When the digital information is 0, there is no light at the output port within that unit time.

[0015] In a binary amplitude keying encoder, if the distance light travels in an optical fiber per unit time is defined as one unit length, then the length of the delay line is always equal to one or more unit lengths.

[0016] In a binary amplitude keying encoder, the number of branches p of the optical splitter is equal to the number of digits 1 in the final encoded sequence. To determine the starting position of the encoded pulse, each codeword begins with the digit 1. Therefore, only p-1 of the p outputs of the splitter require additional delay lines. In these p-1 branches, delay lines of a corresponding multiple of unit length are added according to the position of the digit 1 in the encoded sequence. The branches are combined into one output by a coupler. The number of codewords generated by an n-bit binary encoder is (n-1). 2 .

[0017] The binary fiber grating wavelength encoder is composed of one or more 1-to-2 optical splitters connected in stages. The two output ports of the upper-level optical splitter are respectively connected to the input ports of the two splitters in the lower level. Only one fiber grating is placed on one of the two output ports of an optical splitter. Each fiber grating can completely reflect one wavelength generated by the light source and transmit the other wavelengths. The fiber gratings used in each stage have the same parameter specifications.

[0018] A binary fiber optic grating wavelength encoder retains at least one wavelength pulse at each port to ensure light output, achieving (m-1) possible outputs using m different optical wavelengths. 2 Wavelength encoding.

[0019] An amplitude keying encoder containing m wavelengths of light pulses and n-bit codewords generates a total of (n-1) 2 ·(m-1) 2 Each type of code uniquely corresponds to a fiber optic link.

[0020] The beneficial effects of this invention are:

[0021] This invention combines binary amplitude keying coding technology and fiber optic grating wavelength coding technology to increase the number of fiber optic links that can be encoded simultaneously. It multiplies the number of available codes without increasing the wavelength resources used, solving the problems that the real-time coding scale of existing technologies is still limited and cannot meet the requirements of large-scale network use. Attached Figure Description

[0022] Figure 1 A diagram showing the devices that an encoded optical pulse passes through from its generation to its entry into the optical fiber link;

[0023] Figure 2 The spectrum of the optical pulses output by a multi-wavelength laser;

[0024] Figure 3 This is a structural diagram of a binary amplitude keying encoder;

[0025] Figure 4 The time-domain waveform of an encoded optical pulse generated by a 6-bit binary amplitude keying encoder is shown.

[0026] Figure 5 This is a structural diagram of a binary fiber Bragg grating wavelength encoder;

[0027] Figure 6 The spectrum of several coded optical pulses generated by a 6-wavelength fiber Bragg grating encoder is shown. Detailed Implementation

[0028] To increase the number of fiber optic links that can be encoded simultaneously, this invention proposes the following encoding method: a fiber optic encoding method based on binary amplitude shift keying (APS) and binary wavelength coding, comprising the following steps:

[0029] (1) A C-band pulse signal is emitted by the light source module. The signal contains m light pulses with different center wavelengths but overlapping in the time domain.

[0030] (2) The pulse light is divided equally into n different binary amplitude keying encoders by an optical splitter. Each encoder uses the incoming light to generate a binary amplitude encoded light pulse with a fixed code word. The light pulse code words generated by different encoders are different.

[0031] (3) Each binary amplitude keying encoder is followed by an (m-1) encoder. 2 A port binary fiber optic grating wavelength encoder contains different wavelength combinations in optical pulses from different ports leaving the same binary wavelength encoder.

[0032] (4) Use binary amplitude keying codewords as the first encoding, and then use different combinations of wavelength components for each codeword as the second encoding. The final result of the two encodings constitutes the set of all codes.

[0033] The light source is controlled by an external signal and generates m optical pulses from an array of m lasers. These pulses have the same width, power, and period in the time domain, but different center wavelengths and the same 3dB bandwidth in the wavelength domain. The center wavelength interval between adjacent optical pulses is greater than their bandwidth to ensure that the pulses do not overlap in the wavelength domain. The pulses leave the lasers at the same time and are combined into a single pulse in the time domain through a coupler built into the light source module.

[0034] The binary amplitude keying encoder in the above scheme consists of a 1-in-p-out optical splitter, a delay line, and a coupler. The pulse width of the light pulse output by the light source is defined as one unit time. The total length of the light pulse output by an n-bit encoder is equal to n units of time. When the encoded digital information is 1, there is light at the encoder output port within that unit time. When the digital information is 0, there is no light at the output port within that unit time.

[0035] The delay line used in an amplitude encoder is defined as the distance light travels in an optical fiber in one unit time as one unit length. The length of the delay line is equal to one or more unit lengths. Its function is to delay the optical pulse by one or more pulse widths before outputting it.

[0036] The number of branches, p, in the optical splitter used in the amplitude encoder is equal to the number of digits 1 in the final encoded sequence. To determine the starting position of the encoded pulse, each codeword begins with a digit 1. Therefore, only p-1 of the p outputs of the splitter require delay lines. In these p-1 branches, delay lines of a multiple of the unit length are added according to the position of the digit 1 in the encoded sequence. All branches are combined into one output by a coupler. The number of codewords that an n-bit binary encoder can produce is (n-1). 2 .

[0037] The multi-port binary fiber optic grating wavelength encoder consists of 2... m A series of 1-to-2 optical splitters are connected in stages. The two output ports of the previous stage optical splitter are connected to the input ports of the two next-stage splitters, respectively. Only one of the two output ports of an optical splitter is used to place a fiber Bragg grating. Each fiber Bragg grating can completely reflect one wavelength generated by the light source and transmit the remaining wavelengths. The fiber Bragg gratings used in each stage have the same parameters (such as center wavelength reflectivity and 3dB bandwidth). Since optical pulse output must be guaranteed, each port of the encoder should retain at least one wavelength pulse to ensure optical output. Therefore, it can be calculated that (m-1) optical wavelengths can be used. 2 Wavelength encoding.

[0038] In the above scheme, an amplitude keying encoder containing m wavelengths of light pulses and n-bit codewords can generate a total of (n-1) signals. 2 ·(m-1) 2 Each type of code can uniquely correspond to a single fiber optic link.

[0039] Figure 1This diagram illustrates the components that encode an optical pulse as it travels from generation to entry into the optical fiber link. A C-band pulse signal is emitted from a light source module. This signal contains m optical pulses with different center wavelengths that overlap in the time domain. An optical splitter divides the pulsed light equally into multiple different binary amplitude keying encoders. Each encoder uses the incoming light to generate a binary amplitude-coded optical pulse with a fixed codeword. The codewords generated by different encoders are distinct. Each binary amplitude keying encoder is followed by an (m-1)-band optical pulse encoder. 2 A port-based binary fiber Bragg grating wavelength encoder contains different wavelength combinations in optical pulses leaving different ports of the same wavelength encoder. The first encoding uses binary amplitude keying codewords, and then a second encoding is performed on each codeword using different combinations of wavelength components. The final result of these two encodings constitutes the set of all codes.

[0040] Figure 2 This is a spectrum of the optical pulses output by a multi-wavelength laser. An optical pulse is composed of multiple pulses with different center wavelengths. The spacing between adjacent center wavelengths is the same, and the spacing between center wavelengths is controlled to be greater than 3dB bandwidth to ensure that the main frequency components of each wavelength do not overlap.

[0041] Figure 3 This is a structural diagram of a binary amplitude keying encoder. The encoder consists of a p-channel optical splitter, a delay line, and a p-channel coupler. A unit of time is defined as the pulse width of the light pulse output from the light source. The total length of the light pulses output by an n-bit encoder is equal to n units of time. When the encoded digital information is 1, there is light at the encoder output port within that unit of time; when the digital information is 0, there is no light at the output port within that unit of time.

[0042] The delay line used in an amplitude encoder is defined as the distance light travels in an optical fiber in one unit time as one unit length. The length of the delay line is always equal to one or more unit lengths. Its function is to delay the optical pulse by one or more pulse widths before outputting it.

[0043] The number of branches, p, in the optical splitter used in the amplitude encoder is equal to the number of digits 1 in the final encoded sequence. To determine the starting position of the encoded pulse, each codeword begins with a digit 1. Therefore, only p-1 of the p outputs of the splitter require delay lines. In these p-1 branches, delay lines of a corresponding multiple of unit length are added based on the position of the digit 1 in the encoded sequence. All branches are combined into one output by a coupler. The number of codewords that an n-bit binary encoder can produce is (n-1). 2 .

[0044] Figure 4This is a time-domain waveform diagram of the coded light pulses generated by a 6-bit binary amplitude keying encoder. The codeword is 100011. Each unit length in the time domain records one bit of coded information. When there is light signal, it represents coded information 1, and when there is no light, it represents coded information 0.

[0045] Figure 5 This is a structural diagram of a fiber Bragg grating encoder. This encoder consists of multiple 1-to-2 optical splitters connected in stages. The two output ports of the previous stage optical splitter are connected to the input ports of the two next-stage splitters, respectively. Only one fiber Bragg grating is placed on one of the two output ports of an optical splitter. Each fiber Bragg grating can completely reflect one wavelength generated by the light source and transmit the remaining wavelengths. The fiber Bragg gratings used in each stage have the same parameters (such as center wavelength reflectivity and 3dB bandwidth). Since optical pulse output must be guaranteed, each port of the encoder should retain at least one wavelength pulse. Therefore, it can be calculated that (m-1) different optical wavelengths can be used. 2 Wavelength encoding.

[0046] Figure 6 The images show the spectra of several coded optical pulses generated by a 6-wavelength fiber Bragg grating encoder. Four of the images contain binary coded information of 000110, 001011, 100011, and 110101, respectively. Optical peaks exist in several wavelength ranges representing coded information 1. The binary code on the amplitude and the wavelength combination together serve as the unique coded information for a single optical link. Using an amplitude keying encoder containing m wavelengths and n-bit codewords, a total of (n-1) optical pulses can be generated. 2 ·(m-1) 2 Type of encoding.

[0047] The embodiments of this invention illustrate the specific implementation process of an optical fiber coding method based on optical frequency combs and fiber Bragg gratings. The number of optical wavelengths and the number of bits used in the binary amplitude keying coding method can be adjusted according to actual conditions.

Claims

1. A fiber optic coding method based on binary amplitude shift keying (BPS) and binary wavelength coding, characterized in that: The method includes: Step 1: The light source module emits a C-band pulse signal, which contains m light pulses with different center wavelengths but overlapping in the time domain. Step 2: Use an optical splitter to equally distribute the optical pulses to different binary amplitude keying encoders. Each binary amplitude keying encoder uses the light entering the encoder to generate a binary amplitude encoded optical pulse with a fixed codeword. The optical pulse codewords generated by different binary amplitude keying encoders are different. A binary amplitude keying (BSK) encoder consists of a 1-in-p-out optical splitter, delay lines, and couplers. Taking the pulse width of the light pulse output from the light source as one unit of time, the total length of the light pulses output by an n-bit binary ASK encoder is equal to n units of time. When the encoded digital information is 1, there is light at the encoder output port per unit of time; when the digital information is 0, there is no light at the output port per unit of time. The delay line in the binary ASK encoder is always equal to one or more units of length if the distance light travels in the optical fiber per unit of time is defined as one unit length. The number of branches p in the optical splitter used in the binary ASK encoder is equal to the number of digits 1 in the final encoded sequence. To determine the starting position of the encoded pulse, each codeword begins with the digit 1. Therefore, only p-1 of the p outputs of the splitter need to have delay lines added. In these p-1 branches, delay lines of a corresponding multiple of unit length are added according to the position of the encoded digit 1 in the encoded sequence. All branches are combined into one output by the coupler. The number of codewords generated by the n-bit binary encoder is... ; Step 3: Connect a multi-port binary fiber Bragg grating wavelength encoder to the output of each binary amplitude keying encoder. Step 4: Use binary amplitude keying codewords as the first encoding, and then use different combinations of wavelength components for each codeword as the second encoding. The final result of the two encodings constitutes the set of all codes.

2. The fiber optic coding method based on binary amplitude shift keying and binary wavelength coding according to claim 1, characterized in that: The light source module is controlled by an external signal and simultaneously generates m optical pulses from the laser array. These pulses have the same width, power, and period in the time domain, different center wavelengths in the wavelength domain, and the same 3dB bandwidth. The center wavelength interval between adjacent optical pulses is greater than the bandwidth. Each pulse leaves the laser at the same time and is combined into a single pulse in the time domain through a coupler built into the light source module.

3. The fiber coding method based on binary amplitude shift keying and binary wavelength coding according to claim 1, characterized in that: The multi-port binary fiber Bragg grating wavelength encoder is composed of one or more 1-to-2 optical splitters connected in stages. The two output ports of the upper-stage optical splitter are respectively connected to the input ports of the two splitters in the lower stage. Only one fiber Bragg grating is placed on one of the two output ports of an optical splitter. Each fiber Bragg grating can completely reflect one wavelength generated by the light source and transmit the other wavelengths. The fiber Bragg gratings used in each stage have the same parameter specifications.

4. The fiber optic coding method based on binary amplitude shift keying and binary wavelength coding according to claim 3, characterized in that: A binary fiber optic wavelength encoder retains at least one wavelength pulse at each port to ensure light output, using m different optical wavelengths to achieve [the desired output]. Wavelength encoding.

5. The fiber optic coding method based on binary amplitude shift keying and binary wavelength coding according to claim 1, characterized in that: An amplitude keying encoder containing m wavelengths of light pulses and n-bit codewords generates a total of Each type of code uniquely corresponds to a fiber optic link.

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