CN112468233A - System for suppressing phase noise of remote unrepeatered transmission optical fiber hydrophone system - Google Patents
System for suppressing phase noise of remote unrepeatered transmission optical fiber hydrophone system Download PDFInfo
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Abstract
The invention provides a system for suppressing phase noise of a remote unrepeatered transmission optical fiber hydrophone system, which comprises a laser modulation device, an optical fiber hydrophone system and a picked signal amplitude post-processing module, wherein the optical fiber hydrophone system comprises an optical fiber hydrophone and an optical fiber hydrophone array, the optical fiber hydrophone array is respectively connected with the laser modulation device and the picked signal amplitude post-processing module, the laser modulation device applies signals with reasonable parameters of phase modulation amplitude and frequency to ensure the optical power required by the work of the optical fiber hydrophone array, the optical fiber hydrophone array picks up signals related to the phase modulation amplitude and the frequency applied by the laser modulation device, and the signals picked up by the optical fiber hydrophone array are subjected to optical power amplification and pre-processing in the picked signal post-processing module. The invention adds phase modulation at the output end of the laser, and reasonably configures the amplitude and frequency of the phase modulation by synthesizing system parameters, thereby effectively improving the maximum fiber-entering power and transmission distance of the system and simultaneously keeping lower phase noise.
Description
Technical Field
The invention relates to the technical field of optical fiber hydrophones, in particular to a system for suppressing phase noise of a remote unrepeatered transmission optical fiber hydrophone system.
Background
With the development of phase modulation technology, optical fiber amplification technology, interference type optical fiber sensing technology, array multiplexing technology and large-scale array technology, the novel optical fiber hydrophone system is developing towards remote and array scale, so that the key of guaranteeing that the remote optical fiber hydrophone system is applied from offshore to offshore is that optical power can be transmitted remotely and the system has lower phase noise. However, as the transmission distance of the system increases, nonlinear effects in the fiber, such as Stimulated Brillouin Scattering (SBS), occur most easily in the remote transmission system, which results in a large loss of forward transmission optical power, severely affects the amplitude of the pickup signal of the remote fiber hydrophone system, and results in an increase in the phase noise of the system.
At present, a phase modulation method is widely adopted for suppressing SBS in a remote optical transmission system, the phase modulation method is that a phase modulator is used for directly modulating laser phase to generate multi-frequency laser to suppress SBS, but the simple phase modulation brings additional phase noise while suppressing SBS, and the application of the phase modulation in an interference type optical fiber hydrophone system is limited.
Disclosure of Invention
The invention provides a system for inhibiting phase noise of a remote unrepeatered transmission optical fiber hydrophone system, which is characterized in that phase modulation is added at the output end of a laser, and phase modulation amplitude and frequency are reasonably configured by integrating system parameters, so that the maximum fiber-entering power and transmission distance of the system are effectively improved, and meanwhile, the phase noise of the remote unrepeatered transmission optical fiber hydrophone system is kept low, and the system aims to solve the technical problem that the remote optical fiber hydrophone system is applied from offshore to open sea in the background art.
In order to achieve the above object, an embodiment of the present invention provides a system for suppressing phase noise of a remote unrepeatered transmission optical fiber hydrophone system, including a laser modulation device, an optical fiber hydrophone system, and a post-processing module for picking up signal amplitude, where the optical fiber hydrophone system includes an optical fiber hydrophone and an optical fiber hydrophone array, the optical fiber hydrophone array is connected to the laser modulation device and the post-processing module for picking up signal amplitude, the laser modulation device applies signals with reasonable parameters, such that optical power required for the operation of the optical fiber hydrophone array is ensured, the optical fiber hydrophone array picks up signals related to the phase modulation amplitude and frequency applied by the laser modulation device, and the signals picked up by the optical fiber hydrophone array are subjected to optical power amplification and pre-processing in the post-processing module for picking up signals.
Preferably, laser modulation device is including narrow linewidth laser light source, phase modulator, acoustic optical modulator and the erbium-doped fiber amplifier that can connect in proper order the light, erbium-doped fiber amplifier with optic fibre hydrophone array passes through fiber connection, narrow linewidth laser light source produces single-frequency laser, single-frequency laser via phase modulator produces multifrequency laser through corresponding amplitude and frequency modulation, and multifrequency laser warp acoustic optical modulator produces pulse optical signal, warp get into behind the optic fibre transmission behind the erbium-doped fiber amplifier enlargies optic fibre hydrophone array.
Preferably, the pickup signal amplitude post-processing module includes an erbium fiber amplification module and an optoelectronic signal processing module, the laser with phase modulation amplitude and frequency enters the erbium fiber amplification module for power amplification after passing through the optical fiber hydrophone array, and the amplified signal light is converted into an electrical signal through the optoelectronic signal processing module.
Preferably, the erbium fiber amplification module is a bidirectional pump, and is configured to remotely amplify the signal light, and includes two high-power lasers, two pump power transmission fibers, a transmission fiber, a tail end raman amplifier, and a front end fiber amplifier, where the two high-power lasers perform bidirectional remote pumping through the two pump power transmission fibers to remotely amplify the signal light, and the amplified signal light passes through the transmission fiber for transmission, passes through the tail end raman amplifier to perform reverse pumping at the tail end of the transmission fiber, passes through the front end fiber amplifier to perform power amplification, and then enters the photoelectric signal processing module.
Preferably, the method for acquiring the signal parameters of the amplitude and the frequency of the phase modulation with reasonable application parameters comprises the following steps:
step S1, converting the picked signal into an output current signal waveform to obtain a corresponding waveform amplitude and frequency algorithm;
s2, obtaining a laser modulation frequency algorithm according to the waveform characteristics of the current signal and the optical path difference of two arms of the optical fiber hydrophone probe;
step S3, the source of the additional noise brought to the optical fiber hydrophone system by the phase modulation is caused by the reduction of the amplitude of the picked-up signal due to the beat frequency between the multi-frequency optical sidebands, and the modulation amplitude algorithm applied by the phase modulator (12) is correspondingly obtained;
and step S4, determining the modulation amplitude and the modulation frequency according to the modulation frequency algorithm in the step S2 and the modulation amplitude algorithm in the step S3.
Preferably, the step S1 is specifically: applying single-frequency cosine modulation to laser, converting the picked signal into current signal by photoelectric converter, and spreading Bessel function to the current signalm/2 and its multiple harmonic term, where ωmRepresents a modulation frequency;
the output current signal of the photoelectric converter can be expressed as:
σJ0(C) representing the amplitude of the signal picked up, where C-2 Asin (ω)mΔ t/2), A represents the modulation amplitude, and the system phase noise is contained in
In terms, it is known that phase modulation does not affect the phase noise term;
when the optical path difference of the optical fiber hydrophone is constant, the amplitude of the picked signal can be along with the modulation amplitude A and the modulation frequency omegamThe corresponding changes occur;
by matching the frequency of the phase modulated signal with the optical path difference between the two arms of the fiber optic hydrophone probe, i.e. omegamWhen Δ t is 2k pi and k is a positive integer, C is 0, J0(C) Pick-up signal amplitude σ J of 10(C) The amplitude of the picked-up signal is increased by taking a maximum value, so that the signal to noise ratio is enhanced, and the phase noise caused by phase modulation is effectively inhibited.
Preferably, the step S2 is specifically:
the amplitude of the signal picked up by the fiber hydrophone system is related to the phase modulation amplitude and the modulation frequency;
when the optical path difference of the two arms of the optical fiber hydrophone probe is constant, the amplitude of the picked-up signal can be along with the modulation amplitude A and the modulation frequency omegamCorrespondingly changes to meet the matching condition omegamWhen Δ t is 2k pi and k is 1, the optical path difference L between the two arms of the optical fiber hydrophone probe is 2nl, and L is the arm difference of the optical fiber hydrophone probe, there is a phase modulation frequency:
fm＝2π/ωm＝2π/(2kπ/Δt)＝k/Δt＝kc/L
wherein c is 3 × 108m/s is the propagation speed of light in vacuum.
Preferably, the step S3 is specifically:
the source of the additional noise introduced by phase modulation into the fiber optic hydrophone system is due to the reduction in amplitude of the picked-up signal caused by the beat frequency between the multi-frequency optical sidebands, the amplitude of the picked-up signal and the J0(C) Proportional ratio, where C ═ 2Asin (ω)mΔt/2)；
When single-frequency phase modulation is applied, the value of C is 0-2A along with the change of modulation frequency, so that the amplitude of a picked signal is correspondingly changed;
the modulation amplitude to be applied to the phase modulator (12) when the matching condition is satisfied is:
V＝AVπ/π
a is the phase modulation amplitude, VπIs the half-wave voltage of the phase modulator (12).
Preferably, the step S4 is specifically:
calculating and determining modulation amplitude and modulation frequency, wherein when a matching condition is met, the modulation frequency is greater than the natural Brillouin gain line width, and the Brillouin scattering threshold is determined by the maximum sideband power generated by modulation;
and by reasonably designing modulation parameters, taking the modulation amplitude as integral multiple of A.
The technical effects which can be achieved by adopting the invention are as follows: the phase modulation is added at the output end of the laser, and the amplitude and the frequency of the phase modulation are reasonably configured by integrating system parameters, so that the maximum fiber-entering power and the transmission distance of the system are effectively improved, and meanwhile, lower phase noise is kept. The application of the optical fiber hydrophone system in the fields of offshore target acoustic detection, ocean resource exploration, seabed observation network, underwater security, seismic wave detection and the like is facilitated.
Drawings
FIG. 1 is a schematic diagram of a system for suppressing phase noise in a remote unrepeatered transmission fiber optic hydrophone system according to the present invention;
fig. 2 shows experimental results of phase noise of a system for suppressing phase noise of a remote unrepeatered transmission fiber optic hydrophone system according to the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The invention aims at the existing problems and provides a system for suppressing the phase noise of a remote unrepeatered transmission optical fiber hydrophone system, as shown in fig. 1, the optical fiber hydrophone system comprises a laser modulation device 1, a fiber optic hydrophone system and a picked-up signal amplitude post-processing module 3, the optical fiber hydrophone system comprises an optical fiber hydrophone and an optical fiber hydrophone array 2, the optical fiber hydrophone array 2 is respectively connected with a laser modulation device 1 and a picked signal amplitude post-processing module 3, the laser modulation device 1 applies signals with reasonable parameters, phase modulation amplitude and frequency, to ensure the optical power required by the operation of the optical fiber hydrophone array 2, the optical fiber hydrophone array 2 picks up signals related to the phase modulation amplitude and frequency applied by the laser modulation device 1, and the signals picked up by the optical fiber hydrophone array 2 are subjected to optical power amplification and pretreatment in the picked-up signal post-processing module 3.
Laser modulation device 1 is including narrow linewidth laser light source 11, phase modulator 12, acousto-optic modulator 13 and the erbium-doped fiber amplifier 14 that can connect in proper order the light, erbium-doped fiber amplifier 14 with optic fibre hydrophone array 2 passes through the fiber connection, narrow linewidth laser light source 11 produces single-frequency laser, single-frequency laser via phase modulator 12 produces multifrequency laser through corresponding amplitude and frequency modulation, and multifrequency laser warp acousto-optic modulator 13 produces pulsed light signal, warp behind the erbium-doped fiber amplifier 14 enlargies after the fiber transmission get into optic fibre hydrophone array 2.
The pickup signal amplitude post-processing module 3 includes an erbium fiber amplifier module 31 and a photoelectric signal processing module 32, the laser with phase modulation amplitude and frequency passes through the optical fiber hydrophone array 2 and then enters the erbium fiber amplifier module 31 for power amplification, and the amplified signal light is converted into an electrical signal through the photoelectric signal processing module 32.
The erbium fiber amplification module 31 is a bidirectional pump, and is configured to remotely amplify signal light, and includes two high power lasers 311, two pump power transmission fibers 312, a transmission fiber 313, a tail raman amplifier 314, and a front fiber amplifier 315, where the two high power lasers 311 perform bidirectional remote pumping through the two pump power transmission fibers 312 to remotely amplify signal light, and the amplified signal light is transmitted through the transmission fiber 313, reversely pumped at the tail end of the transmission fiber 313 through the tail raman amplifier 314, and subjected to power amplification through the front fiber amplifier 314, and then enters the photoelectric signal processing module 32.
The signal parameter acquisition method for applying the phase modulation amplitude and frequency with reasonable parameters comprises the following steps:
step S1, converting the picked signal into an output current signal waveform to obtain a corresponding waveform amplitude and frequency algorithm;
s2, obtaining a laser modulation frequency algorithm according to the waveform characteristics of the current signal and the optical path difference of two arms of the optical fiber hydrophone probe;
step S3, the source of the additional noise brought to the fiber optic hydrophone system by the phase modulation is caused by the reduction of the amplitude of the picked-up signal due to the beat frequency between the multiple frequency optical sidebands, and correspondingly obtains the modulation amplitude algorithm applied by the phase modulator 12;
and step S4, determining the modulation amplitude and the modulation frequency according to the modulation frequency algorithm in the step S2 and the modulation amplitude algorithm in the step S3.
The step S1 specifically includes: applying single-frequency cosine modulation to laser, converting the picked signal into current signal by photoelectric converter, and spreading Bessel function to the current signalm/2 and its multiple harmonic term, where ωmRepresents a modulation frequency;
the output current signal of the photoelectric converter can be expressed as:
σJ0(C) representing the amplitude of the signal picked up, where C-2 Asin (ω)mΔ t/2), A represents the modulation amplitude, and the system phase noise is contained in
In terms, it is known that phase modulation does not affect the phase noise term;
when the optical path difference of the optical fiber hydrophone is constant, the amplitude of the picked signal can be along with the modulation amplitude A and the modulation frequency omegamThe corresponding changes occur;
by matching the frequency of the phase modulated signal with the optical path difference between the two arms of the fiber optic hydrophone probe, i.e. omegamWhen Δ t is 2k pi and k is a positive integer, C is 0, J0(C) Pick-up signal amplitude σ J of 10(C) The amplitude of the picked-up signal is increased by taking a maximum value, so that the signal to noise ratio is enhanced, and the phase noise caused by phase modulation is effectively inhibited.
The step S2 specifically includes:
the amplitude of the signal picked up by the fiber hydrophone system is related to the phase modulation amplitude and the modulation frequency;
when the optical path difference of the two arms of the optical fiber hydrophone probe is constant, the amplitude of the picked-up signal can be along with the modulation amplitude A and the modulation frequency omegamCorrespondingly changes to meet the matching condition omegamWhen Δ t is 2k pi and k is 1, the optical path difference L between the two arms of the optical fiber hydrophone probe is 2nl, and L is the arm difference of the optical fiber hydrophone probe, there is a phase modulation frequency:
fm＝2π/ωm＝2π/(2kπ/Δt)＝k/Δt＝kc/L
wherein c is 3 × 108m/s is the propagation speed of light in vacuum.
The step S3 specifically includes:
the source of the additional noise introduced by phase modulation into the fiber optic hydrophone system is due to the reduction in amplitude of the picked-up signal caused by the beat frequency between the multi-frequency optical sidebands, the amplitude of the picked-up signal and the J0(C) Proportional ratio, where C ═ 2Asin (ω)mΔt/2)；
When single-frequency phase modulation is applied, the value of C is 0-2A along with the change of modulation frequency, so that the amplitude of a picked signal is correspondingly changed;
the modulation amplitude to be applied to the phase modulator (12) when the matching condition is satisfied is:
V＝AVπ/π
a is the phase modulation amplitude, VπIs the half-wave voltage of the phase modulator (12).
The step S4 specifically includes:
calculating and determining modulation amplitude and modulation frequency, wherein when a matching condition is met, the modulation frequency is greater than the natural Brillouin gain line width, and the Brillouin scattering threshold is determined by the maximum sideband power generated by modulation;
by reasonably designing modulation parameters and taking the modulation amplitude as integral multiple of A, the SBS suppression efficiency can be greatly improved, and the fiber-entering optical power of remote transmission is effectively provided.
In a preferred embodiment of the system for suppressing phase noise in a remote unrepeatered transmission fiber optic hydrophone system of the present invention, the light source used is a single frequency narrow linewidth laser 11 with a wavelength of 1550.12nm and linewidth less than 5 kHz. The single-frequency laser is modulated by the phase modulator 12 to generate a multi-frequency laser, in order to satisfy the parameter matching condition, the optical path difference L of the fiber hydrophone is 1.53m, the matching modulation frequency should be 196MHz, and the modulation voltage of the phase modulator 12 is 3.2 Vpp. The multi-frequency laser generates pulse light signals through the acousto-optic modulator 13, then the pulse light signals are amplified through the erbium-doped fiber amplifier 14(EDFA), transmitted through 100km of optical fibers and then enter the optical fiber hydrophone array 2, the working wavelength C wave band of the erbium-doped fiber amplifier 14(EDFA) is adopted, and the output optical power is 20 dBm.
The upstream light enters the erbium fiber amplification module 31 after passing through the optical fiber hydrophone array 2, and the erbium fiber amplification module 31 carries out bidirectional pumping on the signal light by two high-power lasers 311 with the wavelength of 1480nm through two 100km pumping power transmission optical fibers 312 so as to carry out remote amplification; the amplified signal light is transmitted through a 100km uplink transmission optical fiber 313, then reverse pumping is carried out on the tail end of the 100km transmission optical fiber 313 by a tail end Raman amplifier 314 of 1455nm pump light, finally power amplification is carried out on the signal light by a front optical fiber amplifier 315, then the signal light enters an optoelectronic converter (PIN) to convert an optical signal into an electric signal, and an analog signal is converted into a digital signal by optoelectronic signal processing, as shown in figure 2, the phase noise of the system obtained by adopting a PGC demodulation method is about-100 dB/Hz @1.0kHz, the phase noise level of a remote optical fiber hydrophone system at a frequency point of 1.0kHz is equivalent to that of a short-range system, and the SBS and the phase noise caused by the SBS are effectively inhibited by adopting the invention.
The system for inhibiting the phase noise of the remote unrepeatered transmission optical fiber hydrophone system provided by the invention has the following technical advantages:
the phase modulation is added at the output end of the laser, and the amplitude and the frequency of the phase modulation are reasonably configured by integrating system parameters, so that the maximum fiber-entering power and the transmission distance of the system are effectively improved, and meanwhile, lower phase noise is kept. The application of the optical fiber hydrophone system in the fields of offshore target acoustic detection, ocean resource exploration, seabed observation network, underwater security, seismic wave detection and the like is facilitated.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (9)
1. A system for suppressing phase noise of a remote unrepeatered transmission optical fiber hydrophone system is characterized by comprising a laser modulation device (1), the optical fiber hydrophone system and a picked signal amplitude post-processing module (3), the optical fiber hydrophone system comprises an optical fiber hydrophone and an optical fiber hydrophone array (2), the optical fiber hydrophone array (2) is respectively connected with a laser modulation device (1) and a picked-up signal amplitude post-processing module (3), the laser modulation device (1) applies signals with reasonable parameters, phase modulation amplitude and frequency, to ensure the optical power required by the operation of the optical fiber hydrophone array (2), the optical fiber hydrophone array (2) picks up signals related to the phase modulation amplitude and frequency applied by the laser modulation device (1), and the signals picked up by the optical fiber hydrophone array (2) are subjected to optical power amplification and pretreatment in the picked-up signal post-processing module (3).
2. The system according to claim 1, wherein the laser modulation device (1) comprises a narrow linewidth laser light source (11), a phase modulator (12), an acousto-optic modulator (13) and an erbium-doped fiber amplifier (14), which are sequentially optically connected, the erbium-doped fiber amplifier (14) is connected with the fiber hydrophone array (2) through an optical fiber, the narrow linewidth laser light source (11) generates a single-frequency laser, the single-frequency laser generates a multi-frequency laser through the phase modulator (12) by corresponding amplitude and frequency modulation, the multi-frequency laser generates a pulse light signal through the acousto-optic modulator (13), and the pulse light signal enters the fiber hydrophone array (2) after being amplified by the erbium-doped fiber amplifier (14) and transmitted through the optical fiber.
3. The system according to claim 1, wherein the pickup signal amplitude post-processing module (3) comprises an erbium fiber amplifier module (31) and an optoelectronic signal processing module (32), the laser with phase modulation amplitude and frequency passes through the optical fiber hydrophone array (2) and then enters the erbium fiber amplifier module (31) for power amplification, and the amplified signal light passes through the optoelectronic signal processing module (32) to convert the optical signal into an electrical signal.
4. The system according to claim 3, wherein the system is configured to suppress phase noise in a remote unrepeatered transmission fiber optic hydrophone system, the erbium-doped fiber amplifier is characterized in that the erbium-doped fiber amplifier module (31) is a bidirectional pump and is used for remotely amplifying signal light, and comprises two high-power lasers (311), two pump power transmission fibers (312), a transmission fiber (313), a tail end Raman amplifier (314) and a front-end fiber amplifier (315), wherein the two high-power lasers (311) are subjected to bidirectional remote pumping through the two pump power transmission fibers (312), the signal light is remotely amplified, the amplified signal light is transmitted through the transmission optical fiber (313), is reversely pumped at the tail end of the transmission optical fiber (313) through the tail end Raman amplifier (314), is subjected to power amplification through the preposed optical fiber amplifier (315), and then enters the photoelectric signal processing module (32).
5. The system according to claim 2, wherein the signal parameter acquisition method for applying the phase modulation amplitude and frequency with reasonable parameters comprises:
step S1, converting the picked signal into an output current signal waveform to obtain a corresponding waveform amplitude and frequency algorithm;
s2, obtaining a laser modulation frequency algorithm according to the waveform characteristics of the current signal and the optical path difference of two arms of the optical fiber hydrophone probe;
step S3, the source of the additional noise brought to the optical fiber hydrophone system by the phase modulation is caused by the reduction of the amplitude of the picked-up signal due to the beat frequency between the multi-frequency optical sidebands, and the modulation amplitude algorithm applied by the phase modulator (12) is correspondingly obtained;
and step S4, determining the modulation amplitude and the modulation frequency according to the modulation frequency algorithm in the step S2 and the modulation amplitude algorithm in the step S3.
6. The system according to claim 5, wherein the step S1 is specifically to: applying single-frequency cosine modulation to laser, converting the picked signal into current signal by photoelectric converter, and spreading Bessel function to the current signalm/2 and its multiple harmonic term, where ωmRepresents a modulation frequency;
the output current signal of the photoelectric converter can be expressed as:
σJ0(C) representing the amplitude of the signal picked up, where C-2 Asin (ω)mΔ t/2), A represents the modulation amplitude, and the system phase noise is contained in
In terms, it is known that phase modulation does not affect the phase noise term;
when the optical path difference of the optical fiber hydrophone is constant, the amplitude of the picked signal can be along with the modulation amplitude A and the modulation frequency omegamThe corresponding changes occur;
by matching the frequency of the phase modulated signal with the optical path difference between the two arms of the fiber optic hydrophone probe, i.e. omegamWhen Δ t is 2k pi and k is a positive integer, C is 0, J0(C) Pick-up signal amplitude σ J of 10(C) The amplitude of the picked-up signal is increased by taking a maximum value, so that the signal to noise ratio is enhanced, and the phase noise caused by phase modulation is effectively inhibited.
7. The system according to claim 6, wherein the step S2 is specifically to:
the amplitude of the signal picked up by the fiber hydrophone system is related to the phase modulation amplitude and the modulation frequency;
when the optical path difference of the two arms of the optical fiber hydrophone probe is constant, the amplitude of the picked-up signal can be along with the modulation amplitude A and the modulation frequency omegamCorrespondingly changes to meet the matching condition omegamWhen Δ t is 2k pi and k is 1, the optical path difference L between the two arms of the optical fiber hydrophone probe is 2nl, and L is the arm difference of the optical fiber hydrophone probe, there is a phase modulation frequency:
fm＝2π/ωm＝2π/(2kπ/Δt)＝k/Δt＝kc/L
wherein c is 3 × 108m/s is the propagation speed of light in vacuum.
8. The system according to claim 7, wherein the step S3 is specifically to:
the source of the additional noise introduced by phase modulation into the fiber optic hydrophone system is due to the reduction in amplitude of the picked-up signal caused by the beat frequency between the multi-frequency optical sidebands, the amplitude of the picked-up signal and the J0(C) In direct proportion, wherein C is 2A sin (omega)mΔt/2)；
When single-frequency phase modulation is applied, the value of C is 0-2A along with the change of modulation frequency, so that the amplitude of a picked signal is correspondingly changed;
the modulation amplitude to be applied to the phase modulator (12) when the matching condition is satisfied is:
V＝AVπ/π
a is the phase modulation amplitude, VπIs the half-wave voltage of the phase modulator (12).
9. The system according to claim 8, wherein the step S4 is specifically to:
calculating and determining modulation amplitude and modulation frequency, wherein when a matching condition is met, the modulation frequency is greater than the natural Brillouin gain line width, and the Brillouin scattering threshold is determined by the maximum sideband power generated by modulation;
and by reasonably designing modulation parameters, taking the modulation amplitude as integral multiple of A.
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| CN114826408A (en) * | 2022-06-27 | 2022-07-29 | 中国人民解放军国防科技大学 | Optical fiber hydrophone remote all-optical transmission system and design method thereof |
| CN115102626A (en) * | 2022-07-15 | 2022-09-23 | 长沙军民先进技术研究有限公司 | Device and method for realizing space multi-polarization coding |
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| CN115102626A (en) * | 2022-07-15 | 2022-09-23 | 长沙军民先进技术研究有限公司 | Device and method for realizing space multi-polarization coding |
| CN115102626B (en) * | 2022-07-15 | 2024-01-16 | 长沙军民先进技术研究有限公司 | Device and method for realizing space multi-polarization coding |
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