Electric field sensor demodulation system and method based on dual-wavelength balance detection demodulation

Abstract

The invention discloses an electric field sensor demodulation system based on dual-wavelength balance detection demodulation, which can reduce system noise while improving accuracy and has strong anti-interference capability. The system comprises a decoherence light source, a wavelength division multiplexer I, a coupler I, a coupler II, a circulator, an electric field sensor, a wavelength division multiplexer II, an adjustable attenuator and a balance detector, an optical signal output by the decoherence light source is divided into two paths through a wavelength division multiplexer I, each path of optical signal is divided into two paths through a corresponding coupler I, the first path of optical signal is injected into the same coupler II and is combined into one path through the coupler II, and the second path of optical signal is injected into a corresponding adjustable attenuator; optical signals passing through the coupler II are injected into the electric field sensor for modulation through the circulator, sensing light carrying modulation signals is injected into the wavelength division multiplexer II through the circulator, and after the wavelength division multiplexer II divides the sensing light into two paths, the two paths of sensing light and optical signals sent by the corresponding adjustable attenuators are injected into the same corresponding balanced detector for demodulation.

Description

Technical Field

[0001] This invention relates to the field of electric field measurement technology, and in particular to an electric field sensor demodulation system and method based on dual-wavelength balanced detection and demodulation. Background Technology

[0002] In the field of electric field measurement, the measurement accuracy and system noise level of electric field sensors are key indicators restricting their engineering applications. Traditional electric field sensors (such as capacitive sensors based on metal electrodes and crystal sensors based on the Pockels effect) generally face the problem of insufficient accuracy due to electromagnetic interference. Metal electrodes are susceptible to interference from environmental electromagnetic field coupling, which introduces noise into the measurement signal, especially in strong electromagnetic environments where the measurement error can exceed 10%. At the same time, the photoelectric detection modules of traditional sensors mostly use single-channel signal acquisition, which makes it difficult to effectively suppress common-mode noise such as light source power fluctuations and temperature drift. The noise equivalent electric field strength is usually higher than 1kV / m, which cannot meet the precision measurement requirements of noise <100V / m in scenarios such as partial discharge monitoring. In addition, some crystal-based sensors are susceptible to optical path difference drift due to optical path design defects such as single-arm interference, which are affected by mechanical vibration and temperature changes, further introducing measurement deviations. Existing schemes to suppress common-mode noise through balanced detection technology often fail to achieve both high accuracy and low noise due to problems such as poor optical path matching and low wavelength division multiplexing efficiency.

[0003] Therefore, in electric field sensor measurement, how to achieve both high measurement accuracy and low system noise has become a technical challenge that urgently needs to be solved in precision measurement in fields such as power systems and scientific research and testing. Summary of the Invention

[0004] One of the objectives of this invention is, at least, to provide an electric field sensor demodulation system and method based on dual-wavelength balanced detection and demodulation, which addresses the problems existing in the prior art and can improve the measurement accuracy of the electric field sensor while reducing system noise.

[0005] To achieve the above objectives, the technical solution adopted by the present invention includes the following aspects.

[0006] A demodulation system for an electric field sensor based on dual-wavelength balanced detection and demodulation includes: a decoherent light source, a wavelength division multiplexer I, a coupler I, a coupler II, a circulator, an electric field sensor, a wavelength division multiplexer II, an adjustable attenuator, and a balanced detector.

[0007] The decoherent light source provides an initial decoherent signal. The optical signal output by the decoherent light source is split into two paths by a wavelength division multiplexer (WDM). Each optical signal is split into two paths by a corresponding coupler. The first optical signal is injected into the same coupler as the measurement light and then combined into one path by the coupler. The second optical signal is injected into the corresponding adjustable attenuator as the reference light. The optical signal from the coupler is injected into the circulator through port one and then into the electric field sensor through port two for modulation. The sensing light carrying the modulation signal is injected into the WDM through port three of the circulator. The WDM splits the sensing light into two paths, and the split sensing light and the reference light emitted by the corresponding adjustable attenuator are injected into the same balanced detector for demodulation.

[0008] Preferably, the wavelength division multiplexer one and wavelength division multiplexer two output light frequencies are the same.

[0009] Preferably, the adjustable attenuator is used to adjust the power of the reference optical path so that the reference optical power and the sensing optical power entering the same balanced detector are matched.

[0010] Preferably, the coupler has a splitting ratio of 1:1, and the adjustable attenuator has an adjustment range of 0-30dB.

[0011] Preferably, the decoherent light source is not limited to spontaneous emission light sources or superluminescent diodes.

[0012] The present invention also provides a demodulation method for an electric field sensor, comprising:

[0013] The optical signal output from the decoherent light source is output as two or more optical signals after passing through a wavelength division multiplexer.

[0014] Each optical signal is output as two paths through the corresponding coupler one. The first path is injected into the same coupler two as the measurement light, and the coupler two merges them into one signal. The second path is injected into the corresponding adjustable attenuator as the reference light. The adjustable attenuator adjusts the power of the input reference light according to the power of the sensing light carrying the modulation signal input to the same balanced detector, so that the power of the two are matched.

[0015] The signal output from the coupler 2 after merging is injected into the circulator through port 1 of the circulator, and output to the electric field sensor through port 2 of the circulator. After being electro-optically modulated in the electric field sensor, it is reflected back to the circulator and output to wavelength division multiplexer 2 through port 3 of the circulator.

[0016] The modulated signal is output as two or more optical sensing channels after passing through a wavelength division multiplexer.

[0017] The DC component in the modulation signal is filtered out in the same balanced detector for each sensing light and the corresponding reference light input.

[0018] By combining the output signals of the balanced detectors corresponding to the wavelengths of adjacent signals, the waveguide optical path difference of the electric field sensor is obtained, and then the magnitude of the electric field detected by the electric field sensor is obtained.

[0019] Preferably, when wavelength division multiplexer one splits the optical signal output from the decoherent light source into two optical signals with wavelengths λ1 and λ2, λ1 and λ2 satisfy: Wherein, FSR represents the free spectral region. Where n represents the refractive index of the medium and L represents the cavity length.

[0020] Preferably, when the wavelength division multiplexer outputs two sensing light signals with wavelengths of λ1 and λ2 respectively, the two sensing light signals are as follows:

[0021]

[0022] Where I(λ1) and I(λ2) represent the light intensities of the two sensing beams, respectively, and I0 ′ Let n represent the incident light intensity, n represent the refractive index of the medium, and L represent the optical path difference of the waveguide in the electric field sensor, satisfying the following:

[0023] Preferably, the balanced detector eliminates common-mode noise and extracts sensing information through differential detection. The DC component in the modulated signal is filtered out from the signal output by the balanced detector, according to:

[0024]

[0025] The optical path difference of the waveguide of the electric field sensor is obtained, and then the magnitude of the electric field detected by the electric field sensor is demodulated; where φ represents the phase of the sensing light with wavelength λ1.

[0026] Preferably, after the decoherent light source outputs an optical signal, it is processed by a wavelength division multiplexer to output multiple paths, namely λ1, λ2...λ. N When there are N independent optical signals, the wavelength λ of any two adjacent signals is... m , λ m+1 satisfy Where m≥0 and m≤N-2; during demodulation, the output signals of the balanced detectors corresponding to the wavelengths of adjacent signals are combined, and demodulation is performed using the same method as in claim 9. The magnitude of the electric field is obtained by judging based on the N-1 calculated results.

[0027] In summary, by adopting the above technical solution, the present invention has at least the following beneficial effects:

[0028] Using a decoherent light source can reduce system noise. The optical signals output by wavelength division multiplexer one and wavelength division multiplexer two have overlapping spectral lines in the frequency domain. An adjustable attenuator is provided on the optical path connecting coupler one and the balanced detector. The adjustable attenuator is used to adjust the power of the optical path so that the power of the optical path matches the power of the optical signal entering the same balanced detector after being modulated by the electric field sensor, thus improving the matching of the optical path. The balanced detector eliminates common-mode noise and extracts sensing information through differential detection. By optimizing the optical structure and detection mechanism, the system noise can be reduced while improving the measurement accuracy of the electric field sensor. The system has the characteristics of strong anti-interference ability and no need to control the operating point. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an electric field sensor demodulation system based on dual-wavelength balanced detection and demodulation, an exemplary embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of an electric field sensor demodulation system based on multi-wavelength balanced detection and demodulation.

[0031] The diagram is labeled as follows: 1-Decoherent light source, 2-Wavelength division multiplexer one, 3-Coupler one, 4-Coupler two, 5-Circulator, 6-Electric field sensor, 7-Wavelength division multiplexer two, 8-Adjustable attenuator, 9-Balanced detector. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so that the objectives, technical solutions, and advantages of the present invention will be clearer. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0033] like Figure 1 As shown, the electric field sensor demodulation system based on dual-wavelength balanced detection demodulation of the exemplary embodiment of the present invention includes a decoherent light source 1, a wavelength division multiplexer 1 2, a coupler 1 3, a coupler 2 4, a circulator 5, an electric field sensor 6, a wavelength division multiplexer 2 7, an adjustable attenuator 8, and a balanced detector 9.

[0034] Among them, the decoherent light source 1 can be an spontaneously emitted light source (ASE), a superluminescent diode (SLED), etc. The decoherent light source 1 provides an initial decoherent signal. The optical signal output by the decoherent light source 1 is split into two paths by wavelength division multiplexer 2. Each optical signal is split into two paths by the corresponding coupler 3. The first optical signal is injected into the same coupler 4 as the measurement light and then combined into one path by coupler 4. The second optical signal is injected into the corresponding adjustable attenuator 8 as the reference light. The optical signal through coupler 4 is injected into circulator 5 through port 1 of circulator 5 and then into electric field sensor 6 through port 2 of circulator 5 for modulation. The sensing light carrying the modulation signal is injected into wavelength division multiplexer 7 through port 3 of circulator 5. Wavelength division multiplexer 7 splits the sensing light into two paths. The split sensing light and the reference light emitted by the corresponding adjustable attenuator 8 are injected into the same balanced detector 9 for demodulation.

[0035] In the aforementioned system, wavelength division multiplexer 2 is used to separate the decoherent signal generated by the decoherent light source into two independent optical signals of different wavelengths, and transmit them to the corresponding optical channels or ports respectively; coupler 3 is a 1*2 coupler (splitting ratio of 1:1), coupler 4 is a 2*1 coupler, and wavelength division multiplexer 7 is used to divide the sensing light carrying the modulation signal into two frequency signals for output.

[0036] In the aforementioned system, the use of a decoherent light source can reduce system noise. The output optical signals of wavelength division multiplexer 1 and wavelength division multiplexer 2 have overlapping spectral lines in the frequency domain (i.e., the output light frequencies are the same). The adjustable attenuator 8 can adjust the power of its reference optical path, with an adjustment range of 0-30dB, so that the reference light power and sensing light power entering the same balanced detector 9 are matched. The balanced detector 9 eliminates common-mode noise and extracts sensing information through differential detection. The sensing light and reference light entering the same balanced detector 9 have the same frequency, which improves optical path matching and wavelength division multiplexing efficiency, thereby improving measurement accuracy while reducing system noise.

[0037] The electric field sensor demodulation system based on dual-wavelength balanced detection and demodulation of the present invention includes the following working steps:

[0038] The optical signal output from decoherent light source 1 is processed by wavelength division multiplexer 2 to output two optical signals with wavelengths λ1 and λ2, where λ1 and λ2 satisfy the following: Where FSR represents the free spectral region, the calculation formula is: Where n represents the refractive index of the medium, and L represents the cavity length;

[0039] Each optical signal is output as two paths through the corresponding coupler 3. The first path is injected into the same coupler 4 as the measurement light and is combined into one signal by the coupler 4. The second path is injected into the corresponding adjustable attenuator 8 as the reference light. The adjustable attenuator 8 adjusts the power of the input reference light according to the power of the sensing light carrying the modulation signal input to the same balanced detector so that the power of the two is matched.

[0040] The signal output by coupler 2 after merging is injected into circulator 5 through port 1 of circulator 5, and output to electric field sensor through port 2 of circulator 5. After electro-optic modulation in electric field sensor, it is reflected back to circulator 5 and output to wavelength division multiplexer 2 7 through port 3 of circulator 5.

[0041] The modulated signal is output as two sensing light signals with wavelengths λ1 and λ2 after passing through wavelength division multiplexer 7. The two sensing light signals are as follows:

[0042]

[0043] Where I(λ1) and I(λ2) represent the light intensities of the two sensing beams, respectively, and I0 ′ Let n represent the incident light intensity, n represent the refractive index of the medium, and L represent the optical path difference of the waveguide in the electric field sensor, satisfying the following:

[0044] The DC component in the modulated signal is filtered out from the signal output by the balanced detector. The waveguide optical path difference of the electric field sensor can be obtained by processing it according to the following formula, and then the magnitude of the electric field detected by the electric field sensor can be demodulated:

[0045]

[0046] In the formula, φ represents the phase of the sensing light with wavelength λ1.

[0047] In application, a demodulation system based on multi-wavelength balanced detection and demodulation of electric field sensors can also be used for demodulation, as referenced. Figure 2 The structure of this system is roughly the same as that of the electric field sensor demodulation system based on dual-wavelength balanced detection demodulation. The difference is that the wavelength division multiplexer-2 separates the decoherent signal generated by the decoherent light source into wavelengths λ1, λ2…λ. N The system provides N independent optical signals (N is a positive integer greater than 2, and the specific value of N is determined according to design requirements). The number of couplers 3 corresponds to the number of wavelength division multiplexers 2. The number of adjustable attenuators 8 and balanced detectors 9 are the same as the number of couplers 3. Coupler 4 uses an N*1 coupler. Wavelength division multiplexer 7 divides the sensing light carrying the modulation signal into N frequency signals for output. In this example, the wavelength λ of any two adjacent signals of the N independent optical signals in the multi-wavelength balanced detection demodulation electric field sensor demodulation system is...m , λ m+1 (m≥0 and m≤N-2) satisfies During demodulation, the same method as in dual-wavelength demodulation is used to demodulate the signals of each pair of adjacent channels. The system is then judged based on the N-1 calculated results to improve system accuracy.

[0048] The above description is merely a detailed illustration of specific embodiments of the present invention and is not intended to limit the invention. Various substitutions, modifications, and improvements made by those skilled in the art without departing from the principles and scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A demodulation system for an electric field sensor based on dual-wavelength balanced detection and demodulation, characterized in that, include: Decoherent light source, wavelength division multiplexer I, coupler I, coupler II, circulator, electric field sensor, wavelength division multiplexer II, adjustable attenuator, and balanced detector; The decoherent light source provides an initial decoherent signal. The optical signal output by the decoherent light source is split into two paths by a wavelength division multiplexer. Each optical signal is split into two paths by a corresponding coupler. The first optical signal is injected into the same coupler as the measurement light and then combined into one path by the coupler. The second optical signal is injected into the corresponding adjustable attenuator as the reference light. The optical signal from coupler 2 is injected into the circulator through port 1 of the circulator, and then into the electric field sensor through port 2 of the circulator for modulation. The sensing light carrying the modulation signal is injected into wavelength division multiplexer 2 through port 3 of the circulator. Wavelength division multiplexer 2 splits the sensing light into two paths. The split sensing light and the reference light emitted by the corresponding adjustable attenuator are then injected into the same balanced detector for demodulation.

2. The electric field sensor demodulation system based on dual-wavelength balanced detection and demodulation according to claim 1, characterized in that, The wavelength division multiplexer 1 and wavelength division multiplexer 2 output light at the same frequency.

3. The electric field sensor demodulation system based on dual-wavelength balanced detection and demodulation according to claim 1, characterized in that, The adjustable attenuator is used to adjust the power of the reference optical path so that the reference optical power and the sensing optical power entering the same balanced detector are matched.

4. The electric field sensor demodulation system based on dual-wavelength balanced detection and demodulation according to claim 1, characterized in that, The coupler has a splitting ratio of 1:1, and the adjustable attenuator has an adjustment range of 0-30dB.

5. The electric field sensor demodulation system based on dual-wavelength balanced detection and demodulation according to any one of claims 1 to 4, characterized in that, The decoherent light source is not limited to spontaneous emission light sources or superluminescent light-emitting diodes.

6. A demodulation method for an electric field sensor, characterized in that, include: The optical signal output from the decoherent light source is output as two or more optical signals after passing through a wavelength division multiplexer. Each optical signal is output as two paths through the corresponding coupler one. The first path is injected into the same coupler two as the measurement light, and the coupler two merges them into one signal. The second path is injected into the corresponding adjustable attenuator as the reference light. The adjustable attenuator adjusts the power of the input reference light according to the power of the sensing light carrying the modulation signal input to the same balanced detector, so that the power of the two are matched. The signal output from the coupler 2 after merging is injected into the circulator through port 1 of the circulator, and output to the electric field sensor through port 2 of the circulator. After being electro-optically modulated in the electric field sensor, it is reflected back to the circulator and output to wavelength division multiplexer 2 through port 3 of the circulator. The modulated signal is output as two or more optical sensing channels after passing through a wavelength division multiplexer. The DC component in the modulation signal is filtered out in the same balanced detector for each sensing light and the corresponding reference light input. By combining the output signals of the balanced detectors corresponding to the wavelengths of adjacent signals, the waveguide optical path difference of the electric field sensor is obtained, and then the magnitude of the electric field detected by the electric field sensor is obtained.

7. The demodulation method for an electric field sensor according to claim 6, characterized in that, When wavelength division multiplexer 1 splits the optical signal output from the decoherent light source into two optical signals with wavelengths λ1 and λ2, λ1 and λ2 satisfy the following: Wherein, FSR represents the free spectral region. Where n represents the refractive index of the medium and L represents the cavity length.

8. The demodulation method for an electric field sensor according to claim 7, characterized in that, When the wavelength division multiplexer outputs two sensing light signals with wavelengths of λ1 and λ2 respectively, the two sensing light signals are as follows: Where I(λ1) and I(λ2) represent the light intensities of the two sensing beams, respectively, and I0 ′ Let n represent the incident light intensity, n represent the refractive index of the medium, and L represent the optical path difference of the waveguide in the electric field sensor, satisfying the following:

9. The demodulation method for an electric field sensor according to claim 8, characterized in that, The balanced detector eliminates common-mode noise and extracts sensing information through differential detection. The DC component in the modulated signal is filtered out from the signal output by the balanced detector, according to: The optical path difference of the waveguide of the electric field sensor is obtained, and then the magnitude of the electric field detected by the electric field sensor is demodulated; where φ represents the phase of the sensing light with wavelength λ1.

10. The demodulation method for an electric field sensor according to claim 6, characterized in that, When the decoherent light source outputs an optical signal, it is multiplexed by a wavelength division multiplexer, resulting in multiple output paths, namely λ1, λ2...λ. N When there are N independent optical signals, the wavelength λ of any two adjacent signals is... m , λ m+1 satisfy Where m≥0 and m≤N-2; during demodulation, the output signals of the balanced detectors corresponding to the wavelengths of adjacent signals are combined, and demodulation is performed using the same method as in claim 9. The magnitude of the electric field is obtained by judging based on the N-1 calculated results.

Images