Digital heterodyne interference demodulation technology based on chaotic signal enhancement array

Abstract

The invention provides a digital heterodyne interference demodulation technology based on a chaotic signal enhancement array. An all-optical random code optical path module, a heterodyne interference optical path module, a sensing array module and a data processing module are included. The all-optical random code optical path module is composed of a polarization controller (PC), an electro-optical modulator (EOM), an erbium-doped optical fiber amplifier (EDFA), a highly nonlinear optical fiber (HNLF), a band-pass filter (BPF) and a first optical fiber coupler which are sequentially connected through optical fibers, wherein EOM electric control signals are connected through a chaotic entropy source. The heterodyne interference light path module is composed of a single-frequency laser, a second optical fiber coupler, an upper interference arm, a lower interference arm, an optical fiber circulator, an acoustic optical modulator (AOM) and a third optical fiber coupler; the sensor array module is composed of a plurality of optical fiber weak reflection points (FWR) and optical fiber sensors connected between the FWR and the FWR. The data processing module is composed of a photoelectric detector (PD), a plurality of delay units, a plurality of multipliers, a phase demodulator and a computer. The method has the advantages that on the basis of a traditional digital heterodyne interference demodulation method, a chaotic entropy source all-optical true random code is introduced to serve as a digital modulation signal, and the spatial resolution of a demodulation system can be improved to the magnitude of cm as high as 10 Gb / s; the infinite code length effect of the all-optical random code in the chaotic signal enhanced heterodyne interference breaks through the signal-to-noise ratio limit of the traditional digital enhanced heterodyne interference method.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to a digital heterodyne interference demodulation technology based on chaotic signal array enhancement. Background Art

[0002] Heterodyne interferometry is a technique that measures tiny displacements by comparing the phase difference of coherent light waves. It has high sensitivity and accuracy and is widely used in optical measurements and sensors. By introducing pseudo-random noise (PRN) signals to form a digital interferometric demodulation system, the demodulation capability and anti-interference performance of the system can be effectively improved. However, although PRN signals help improve the signal-to-noise ratio, the noise generated by the circuit may also increase during system operation, affecting the final demodulation effect, which becomes a major limiting factor in limiting the improvement of spatial resolution. Summary of the invention

[0003] The technical problem to be solved by the present invention is: on the basis of the traditional digital heterodyne interferometry demodulation method, a chaotic entropy source all-optical true random code is introduced as a digital modulation signal, which can increase the spatial resolution of the demodulation system to the cm level up to 10Gb / s; in addition, the infinite code length effect of the all-optical random code in the chaotic signal enhanced heterodyne interferometry will break through the signal-to-noise ratio limit of the traditional digital enhanced heterodyne interferometry method.

[0004] The technical solution adopted by the present invention to solve the above technical problems is: a digital heterodyne interference demodulation technology based on chaotic signal array enhancement, characterized in that:

[0005] It includes an all-optical random code optical path module, a heterodyne interference optical path module, a sensor array module and a data processing module;

[0006] The all-optical random code optical path module is composed of a polarization controller (PC), an electro-optic modulator (EOM), an erbium-doped fiber amplifier (EDFA), a highly nonlinear fiber (HNLF), a bandpass filter (BPF) and a first fiber coupler connected in sequence by optical fibers, wherein the EOM electrical control signal is connected by a chaotic entropy source;

[0007] The heterodyne interference optical path module is composed of a single-frequency laser, a second fiber coupler, an upper interference arm, a lower interference arm, a fiber circulator, an acousto-optic modulator (AOM) and a third fiber coupler;

[0008] The sensor array module is composed of a number of optical fiber weak reflection points (FWR) and optical fiber sensors connected between the reflection points;

[0009] The data processing module is composed of a photodetector (PD), a number of delay units, a number of multipliers, a phase demodulator and a computer.

[0010] According to the above scheme, in the all-optical random code optical path module, the PC improves the generation effect of the chaotic signal by optimizing the polarization direction of the light, thereby enhancing the complexity and randomness of the all-optical random code and further improving the quality of the random code sequence; the EOM modulates the phase of the optical signal by utilizing the dynamic change of the chaotic signal array, so that the output optical signal has a highly randomized characteristic and forms a complex random code; the EDFA is used to amplify the optical signal to compensate for the energy loss during the transmission process in the optical path and ensure that the signal has sufficient intensity and signal-to-noise ratio in the subsequent processing link; the nonlinear characteristics of the HNLF are the key factors in realizing the chaotic optical effect. When the optical signal passes through the HNLF, it will trigger strong nonlinear effects such as self-phase modulation and four-wave mixing, thereby greatly enhancing the randomization characteristics of the signal and generating high-quality chaotic signals; the BPF performs spectrum filtering on the optical signal, selectively allowing the optical signal within a certain frequency range to pass, while effectively suppressing the noise in other frequency bands; the first optical fiber coupler divides the optical signal into two parts, one part is sent to the sensor array for measurement, and the other part is sent to the data processing module through the photoelectric detector for subsequent data analysis and processing.

[0011] According to the above scheme, in the heterodyne interference optical path module, the single-frequency laser provides a stable laser light source, usually a coherent single-frequency light, as the basic light source for interference to ensure high interference contrast; the second fiber coupler divides the optical signal from the single-frequency laser into two parts, one part is sent to the upper interference arm as the detection light, and the other part is transmitted to the lower interference arm as the reference light; the detection light in the upper interference arm will be affected by physical quantities (such as displacement, temperature, pressure, etc.), thereby causing phase changes, and by comparing it with the reference light for interference, information related to the measured physical quantity can be extracted; the fiber circulator is used to guide the transmission of the optical signal, and correctly guide the detection light signal returned by the sensor to the third fiber coupler; the AOM modulates the reference light through the acousto-optic effect generated by the sound wave in the optical fiber, so that the frequency of the reference light changes slightly; the third fiber coupler combines the detection light signal with the reference light signal after the AOM frequency shift to form a composite optical signal.

[0012] According to the above scheme, in the sensor array module, the FWR has a low reflectivity and can generate a small amount of reflection during the transmission of the optical signal. By monitoring these reflected light signals, information about the environment or structural changes along the optical fiber can be obtained; the optical fiber sensor connects the FWR with the light source and the detector to form an overall sensing network, and each optical fiber sensor is responsible for detecting the state of its corresponding reflection point.

[0013] According to the above scheme, in the data processing module, the PD is responsible for converting the optical signal coupled by the third coupler into an electrical signal, and provides a basis for subsequent data processing by detecting the intensity and frequency changes of the interference signal; the delay unit is used to introduce time delay to help adjust the phase of the signal so as to make a more accurate comparison with the reference signal; the multiplier can generate a beat frequency signal by multiplying the detection signal and the reference signal. This process helps to extract the phase information in the signal for further use in subsequent analysis; the phase demodulator extracts the phase information in the mixed signal and analyzes the phase difference, thereby obtaining information related to the measured physical quantity; the computer, as the control center of the entire data processing module, is responsible for processing, analyzing and storing the electrical signals from the photodetector.

[0014] According to the above scheme, the coupling ratios of the first, second and third optical fiber couplers are all 50:50, so as to ensure that the distribution and merging of light are balanced, providing a stable signal basis for subsequent interference measurement.

[0015] The beneficial effects of the present invention are:

[0016] 1. The digital heterodyne interferometry demodulation technology based on chaotic signal array enhancement combines the high sensitivity of heterodyne interferometry with the anti-interference ability of chaotic signals. By introducing highly complex chaotic signals and multi-channel parallel processing array technology, the signal-to-noise ratio and spatial resolution are significantly improved.

[0017] 2. The present invention performs beat frequency measurement in the heterodyne interference optical path, which effectively improves the signal-to-noise ratio and enhances the measurement sensitivity to small displacements; at the same time, through the frequency analysis of the beat frequency signal, it is easy to extract and process the interference signal and reduce the influence of noise, thereby achieving high-precision and high-stability measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of an overall embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the all-optical random code optical path module.

[0020] Figure 3 It is a schematic diagram of heterodyne interference optical path module.

[0021] Figure 4 It is a schematic diagram of the sensor array module.

[0022] Figure 5 It is a schematic diagram of the data processing module.

[0023] In the figure: 1. All-optical random code optical path module; 2. Heterodyne interference optical path module; 3. Sensor array module; 4. Data processing module; 5. Polarization controller; 6. Electro-optic modulator; 7. Erbium-doped fiber amplifier; 8. Highly nonlinear optical fiber; 9. Bandpass filter; 10. First fiber coupler; 11. Single-frequency laser; 12. Second fiber coupler; 13. Upper interferometer arm; 14. Lower interferometer arm; 15. Fiber circulator; 16. Acousto-optic modulator; 17. Third fiber coupler; 18. Fiber weak reflection point; 19. Fiber sensor; 20. Photodetector; 21. Delay unit; 22. Multiplier; 23. Phase demodulator; 24. Computer. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] See also Figure 1 The overall embodiment of the present invention includes an all-optical random code optical path module 1, a heterodyne interference optical path module 2, a sensor array module 3 and a data processing module 4.

[0026] The all-optical random code optical path module 1 is composed of a polarization controller 5, an electro-optic modulator 6, an erbium-doped fiber amplifier 7, a highly nonlinear fiber 8, a bandpass filter 9 and a first fiber coupler 10 connected in sequence by optical fibers, wherein the electrical control signal of the electro-optic modulator 6 is connected by a chaotic entropy source, such as Figure 2 As shown; the polarization controller 5 improves the generation effect of the chaotic signal by optimizing the polarization direction of the light, thereby enhancing the complexity and randomness of the all-optical random code and further improving the quality of the random code sequence; the electro-optic modulator 6 modulates the phase of the optical signal using the dynamic change of the chaotic signal array, so that the output optical signal has a highly randomized characteristic and forms a complex random code; the erbium-doped fiber amplifier 7 is used to amplify the optical signal to compensate for the energy loss during the transmission process in the optical path, ensuring that the signal has sufficient intensity and signal-to-noise ratio in the subsequent processing link; the nonlinear characteristics of the highly nonlinear optical fiber 8 are the key factors in realizing the chaotic optical effect. When the optical signal passes through the highly nonlinear optical fiber 8, it will trigger strong nonlinear effects such as self-phase modulation and four-wave mixing, thereby greatly enhancing the random characteristics of the signal and generating high-quality chaotic signals; the bandpass filter 9 performs spectrum filtering on the optical signal, selectively allowing the optical signal within a certain frequency range to pass, while effectively suppressing the noise of other frequency bands; the first optical fiber coupler 10 divides the optical signal into two parts, one part is sent to the sensor array module 3 for measurement, and the other part is sent to the data processing module 4 through the photoelectric detector 20 for subsequent data analysis and processing.

[0027] The heterodyne interference optical path module 2 is composed of a single-frequency laser 11, a second fiber coupler 12, an upper interference arm 13, a lower interference arm 14, a fiber circulator 15, an acousto-optic modulator 16 and a third fiber coupler 17. Figure 3 As shown; the single-frequency laser 11 provides a stable laser light source, usually a coherent single-frequency light, as the basic light source for interference to ensure high interference contrast; the second fiber coupler 12 divides the optical signal from the single-frequency laser into two parts, one part is sent to the upper interference arm 13 as the detection light, and the other part is transmitted to the lower interference arm 14 as the reference light; the detection light in the upper interference arm 13 will be affected by physical quantities (such as displacement, temperature, pressure, etc.), thereby causing a phase change, and by comparing it with the reference light for interference, information related to the measured physical quantity can be extracted; the fiber circulator 15 is used to guide the transmission of the optical signal, and correctly guide the detection light signal returned by the sensor to the third fiber coupler 17; the acousto-optic modulator 16 modulates the reference light through the acousto-optic effect generated by the sound wave in the optical fiber, so that the frequency of the reference light changes slightly; the third fiber coupler 17 combines the detection light signal with the reference light signal after the frequency shift by the acousto-optic modulator 16 to form a composite optical signal.

[0028] The sensor array module 3 is composed of a number of optical fiber weak reflection points 18 and optical fiber sensors 19 connected between the reflection points, such as Figure 4 As shown; the optical fiber weak reflection point 18 has a low reflectivity and can produce a small amount of reflection during the transmission of the optical signal. By monitoring these reflected light signals, information about the environment or structural changes along the optical fiber can be obtained; the optical fiber sensor 19 connects several optical fiber weak reflection points 18 with the light source 5 and the detector 20 to form an overall sensing network, and each optical fiber sensor 19 is responsible for detecting the state of its corresponding reflection point.

[0029] The data processing module 4 is composed of a photodetector 20, a plurality of delay units 21, a plurality of multipliers 22, a phase demodulator 23 and a computer 24. Figure 5 As shown; the photodetector 20 is responsible for converting the optical signal coupled by the third coupler 11 into an electrical signal, and provides a basis for subsequent data processing by detecting the intensity and frequency changes of the interference signal; the delay unit 21 is used to introduce a time delay to help adjust the phase of the signal so as to make a more accurate comparison with the reference signal; the multiplier 22 can generate a beat frequency signal by multiplying the detection signal and the reference signal. This process helps to extract the phase information in the signal for further subsequent analysis; the phase demodulator 23 extracts the phase information in the mixed signal and resolves the phase difference, thereby obtaining information related to the measured physical quantity; the computer 24, as the control center of the entire data processing module, is responsible for processing, analyzing and storing the electrical signals from the photodetector 20.

[0030] A digital heterodyne interference demodulation technology based on a chaotic signal enhancement array of the present invention comprises the following specific steps:

[0031] First, an optical path based on chaotic signal array enhanced digital heterodyne interferometry demodulation technology is constructed, including an all-optical random code optical path module 1, a heterodyne interferometry optical path module 2, a sensor array module 3 and a data processing module 4;

[0032] The upper interference arm 13 is connected to the input end of the deflection controller 5 to ensure that the optical signal can be smoothly transmitted and enter the all-optical random code optical path; then, the output of the first coupler 10 is connected to the input of the optical fiber circulator 15; then, the output of the optical fiber circulator 15 is connected to the input of the sensor array, and the detection signal reflected back by the sensor array 3 is injected into the third optical fiber coupler 17 through the circulator to couple with the reference signal output by the acousto-optic modulator 16 and enter the photodetector 20;

[0033] Finally, after completing the connection of all modules, perform an overall system test to ensure that the signal transmission between each module is normal.

[0034] The above embodiments are only used to illustrate the design ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, any equivalent changes or modifications made based on the principles and design ideas disclosed by the present invention are within the protection scope of the present invention.

Claims

1. A digital heterodyne interferometry demodulation technology based on chaotic signal enhancement array, characterized in that: It includes an all-optical random code optical path module, a heterodyne interference optical path module, a sensor array module and a data processing module; The all-optical random code optical path module is composed of a polarization controller (PC), an electro-optic modulator (EOM), an erbium-doped fiber amplifier (EDFA), a highly nonlinear fiber (HNLF), a bandpass filter (BPF) and a first optical fiber coupler connected in sequence by optical fibers, wherein the EOM electrical control signal is connected by a chaotic entropy source; The heterodyne interference optical path module is composed of a single-frequency laser, a second optical fiber coupler, an upper interference arm, a lower interference arm, an optical fiber circulator, an acousto-optic modulator (AOM) and a third optical fiber coupler; The sensor array module is composed of a plurality of optical fiber weak reflection points (FWR) and optical fiber sensors connected between the reflection points; The data processing module is composed of a photoelectric detector (PD), a plurality of delay units, a plurality of multipliers, a phase demodulator and a computer.

2. The digital heterodyne interferometry demodulation technology based on chaotic signal enhancement array according to claim 1 is characterized in that: In the all-optical random code optical path module, the PC improves the generation effect of the chaotic signal by optimizing the polarization direction of the light, thereby enhancing the complexity and randomness of the all-optical random code and further improving the quality of the random code sequence; the EOM modulates the phase of the optical signal by utilizing the dynamic change of the chaotic signal array, so that the output optical signal has a highly randomized characteristic and forms a complex random code; the EDFA is used to amplify the optical signal to compensate for the energy loss during the transmission process in the optical path and ensure that the signal has sufficient intensity and signal-to-noise ratio in the subsequent processing link; the nonlinear characteristic of the HNLF is a key factor in realizing the chaotic optical effect. When the optical signal passes through the HNLF, it will trigger strong nonlinear effects such as self-phase modulation and four-wave mixing, thereby greatly enhancing the randomization characteristics of the signal and generating a high-quality chaotic signal; the BPF performs spectrum filtering on the optical signal, selectively allows the optical signal within a certain frequency range to pass, and effectively suppresses the noise of other frequency bands; the first optical fiber coupler divides the optical signal into two parts, one part is sent to the sensor array for measurement, and the other part is sent to the data processing module through the photoelectric detector for subsequent data analysis and processing.

3. The digital heterodyne interferometry demodulation technology based on chaotic signal enhancement array according to claim 1 is characterized in that: In the heterodyne interference optical path module, a single-frequency laser provides a stable laser light source, usually a coherent single-frequency light, as a basic light source for interference to ensure high interference contrast; the second fiber coupler divides the optical signal from the single-frequency laser into two parts, one part is sent to the upper interference arm as detection light, and the other part is transmitted to the lower interference arm as reference light; the detection light in the upper interference arm will be affected by physical quantities (such as displacement, temperature, pressure, etc.), thereby causing phase changes, and by comparing it with the reference light for interference, information related to the measured physical quantity can be extracted; the fiber circulator is used to guide the transmission of the optical signal, and correctly guide the detection light signal returned by the sensor to the third fiber coupler; the AOM modulates the reference light through the acousto-optic effect generated by sound waves in the optical fiber, so that the frequency of the reference light changes slightly; the third fiber coupler combines the detection light signal with the reference light signal after the AOM frequency shift to form a composite optical signal.

4. The digital heterodyne interferometry demodulation technology based on chaotic signal enhancement array according to claim 1 is characterized in that: In the sensor array module, the FWR has a low reflectivity and can generate a small amount of reflection during the transmission of optical signals. By monitoring these reflected light signals, information about changes in the environment or structure along the optical fiber can be obtained; the optical fiber sensor connects the FWR with the light source and the detector to form an overall sensing network, and each optical fiber sensor is responsible for detecting the state of its corresponding reflection point.

5. The digital heterodyne interferometry demodulation technology based on chaotic signal enhancement array according to claim 1 is characterized in that: In the data processing module, the PD is responsible for converting the optical signal coupled by the third coupler into an electrical signal, and provides a basis for subsequent data processing by detecting the intensity and frequency changes of the interference signal; the delay unit is used to introduce a time delay to help adjust the phase of the signal so as to make a more accurate comparison with the reference signal; the multiplier can generate a beat frequency signal by multiplying the detection signal and the reference signal, and this process helps to extract the phase information in the signal for further use in subsequent analysis; the phase demodulator extracts the phase information in the mixed signal and resolves the phase difference, thereby obtaining information related to the measured physical quantity; The computer serves as the control center of the entire data processing module and is responsible for processing, analyzing and storing the electrical signals from the photodetector.

6. The digital heterodyne interferometry demodulation technology based on chaotic signal enhancement array according to claim 1, characterized in that: The coupling ratios of the first, second and third optical fiber couplers are all 50:50 to ensure that the distribution and merging of light are balanced, providing a stable signal basis for subsequent interference measurement.

7. A digital heterodyne interferometry demodulation technology based on chaotic signal array enhancement according to any one of claims 1 to 6, characterized in that: By introducing chaotic signal array enhancement and digital heterodyne interferometry demodulation technology, the system's response capability to tiny signals is effectively improved, especially in complex optical sensing and interferometry measurements, which can significantly improve measurement accuracy; the signal processing method enhanced by chaotic modulation not only enhances the system's anti-interference ability, but also can extract more accurate measurement data in a low signal-to-noise ratio environment.

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