Optical fiber hydrophone for realizing noise self-suppression based on narrow-spectrum ASE light source of SOA

Abstract

The invention relates to an SOA-based narrow-spectrum ASE light source-based optical fiber hydrophone for realizing noise self-suppression, which belongs to the technical field of sensor light sources, and comprises an SOA-based narrow-spectrum ASE light source, a circulator, a detector, a y waveguide modulator, a demodulation circuit module, an optical fiber ring assembly and a reflector assembly, the circulator is respectively connected with the narrow-spectrum ASE light source based on the SOA, the detector and the y waveguide modulator, and the demodulation circuit is respectively connected with the y waveguide modulator and the detector; the optical fiber ring assembly is respectively connected with the y waveguide modulator and the reflector assembly; the narrow-spectrum ASE light source based on the SOA realizes the noise self-suppression of the optical fiber hydrophone, the process is simple, and the stability is good.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor light sources, and particularly relates to an optical fiber hydrophone that realizes self-suppression of noise based on a narrow-spectrum ASE light source of an SOA. Background Art

[0002] Noise that interferes with the detection of optical wave signals will be generated in each link of an interferometric fiber optic hydrophone. According to different noise sources, the noise affecting the signal detection of the hydrophone mainly includes additional noise in the optical path, shot noise introduced by the photodetector, thermal phase noise of the sensing probe, and intensity noise of the light source. The light source power in practical applications reaches the mW level. At this time, the relative intensity noise becomes the main noise source. The magnitude of the relative intensity noise is inversely proportional to the spectral width. As the spectral width is compressed, the relative intensity noise also increases. In order to reduce the noise threshold of the interferometric fiber optic hydrophone, it is necessary to suppress the relative intensity noise of the light source to achieve higher detection accuracy. In addition, suppressing the relative intensity noise has become a difficult problem that urgently needs to be solved for the application of the light source in high-precision fiber optic sensors. Summary of the Invention

[0003] In view of the above problems, the present invention provides an optical fiber hydrophone that realizes self-suppression of noise based on a narrow-spectrum ASE light source of an SOA. The optical fiber hydrophone realizes self-suppression of the noise of the optical fiber hydrophone based on the narrow-spectrum ASE light source of the SOA, has a simple structure, effectively suppresses the intensity noise, has good stability, improves the detection accuracy, and is applied to high-precision fiber optic sensors.

[0004] The present invention provides an optical fiber hydrophone that realizes self-suppression of noise based on a narrow-spectrum ASE light source of an SOA, characterized by comprising:

[0005] A narrow-spectrum ASE light source 1 based on an SOA, a circulator 2, a detector 3, a y-waveguide modulator 4, a demodulation circuit module 5, an optical fiber loop assembly 6, and a mirror assembly 7;

[0006] The circulator 2 is respectively connected to the narrow-spectrum ASE light source 1 based on an SOA, the detector 3, and the y-waveguide modulator 4, and the demodulation circuit 5 is respectively connected to the y-waveguide modulator 4 and the detector 3;

[0007] The narrow-spectrum ASE light source 1 based on an SOA outputs partially coherent light that suppresses intensity noise;

[0008] The y-waveguide modulator 4 outputs an interference optical signal carrying acoustic wave information;

[0009] The optical fiber loop assembly 6 is respectively connected to the y-waveguide modulator 4 and the mirror assembly 7;

[0010] The demodulation circuit module 5 outputs acoustic wave information that suppresses intensity noise.

[0011] Optionally, the SOA-based narrow-spectrum ASE light source includes a narrow-spectrum ASE light source 1-1, a polarizer 1-2, a semiconductor optical amplifier SOA 1-3, and a first coupler 1-4;

[0012] The polarizer 1-2 is respectively connected to the narrow-spectrum ASE light source 1-1 and the semiconductor optical amplifier SOA 1-3, and the semiconductor optical amplifier SOA 1-3 is also connected to the first coupler 1-4.

[0013] Optionally, the first coupler 1-4 includes a port one 1-41, a port two 1-42, a port three 1-43, and a port four 1-44;

[0014] The polarizer 1-2 is respectively connected to the narrow-spectrum ASE light source 1-1 and the port one 1-41 of the first coupler 1-4; the semiconductor optical amplifier SOA 1-3 is respectively connected to the port two 1-42 and the port three 1-43 of the first coupler 1-4; the port four 1-44 outputs coherent light with suppressed intensity noise.

[0015] Optionally, the demodulation circuit module 5 includes a pre-amplification module 8, an A / D conversion module 9, a digital demodulation module 10, a control algorithm module 11, a D / A conversion module 12, and a drive circuit 13 that are connected in sequence;

[0016] Optionally, the control algorithm module 11 outputs an analyzed digital signal.

[0017] Optionally, the analyzed digital signal includes in-phase component baseband information and quadrature component baseband information, and the expressions are respectively:

[0018] I = LPF(I mix ), Q = LPF(Q mix )

[0019] where I is the in-phase component baseband information, Q is the quadrature component baseband information, LPF is low-pass filtering processing, I mix is the in-phase signal obtained after mixing, and Q mix is the quadrature signal after mixing.

[0020] Optionally, the first coupler 1-4 includes a port one 1-41, a port two 1-42, a port three 1-43, and a port four 1-44;

[0021] The polarizer 1-2 is respectively connected to the narrow-spectrum ASE light source 1-1 and the port one 1-41 of the first coupler 1-4; the semiconductor optical amplifier SOA1-3 is respectively connected to the port two 1-42 and the port three 1-43 of the first coupler 1-4; the port four 1-44 outputs coherent light with suppressed intensity noise.

[0022] Optionally, the narrow-spectrum ASE light source 1-1 includes a pump source 1-11, a second coupler 1-12, a first amplification module 1-13, and a second amplification module 1-14;

[0023] The second coupler 1-12 is respectively connected to the pump source 1-11, the first amplification module 1-13, and the second amplification module 1-14.

[0024] Optionally, the spectral width of the SOA-based narrow-spectrum ASE light source is 300-800 picometers.

[0025] Optionally, the output power of the narrow-spectrum ASE light source is 8-10 mw.

[0026] Optionally, the coherence length of the narrow-spectrum ASE light source is 0.1-0.7 cm.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] (1) The present invention adopts an SOA-based narrow-spectrum ASE light source to ensure the dynamic range and demodulation accuracy of the fiber optic hydrophone;

[0029] (2) The fiber optic hydrophone structure with noise self-suppression realized by the SOA-based narrow-spectrum ASE light source of the present invention has a simple structure and high stability. Description of the Drawings

[0030] The drawings are only for the purpose of showing specific embodiments and are not considered to be a limitation of the present invention.

[0031] Figure 1 It is a schematic diagram of the structure of the fiber optic hydrophone in the embodiment of the present invention;

[0032] Figure 2 It is a schematic diagram of the structure of the SOA-based narrow-spectrum ASE light source in the embodiment of the present invention;

[0033] Figure 3 It is a schematic diagram of the frequency of the partially coherent light with suppressed intensity noise output by the SOA-based narrow-spectrum ASE light source in the embodiment of the present invention;

[0034] Figure 4 It is a schematic diagram of the digital process of closed-loop processing in the embodiment of the present invention;

[0035] Reference Signs:

[0036] SOA-based narrow-spectrum ASE light source 1, circulator 2, detector 3, y-waveguide modulator 4, demodulation circuit module 5, fiber optic loop assembly 6, mirror assembly 7, narrow-spectrum ASE light source 1-1, polarizer 1-2, semiconductor optical amplifier SOA 1-3, first coupler 1-4, port one 1-41, port two 1-42, port three 1-43, and port four 1-44. Detailed implementation

[0037] In order to more clearly understand the above-mentioned objects, features, and advantages of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. In addition, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0038] A specific embodiment of the present invention, such as Figures 1-4 , discloses an optical fiber hydrophone for realizing self-noise suppression based on an SOA-based narrow-spectrum ASE light source, including:

[0039] SOA-based narrow-spectrum ASE light source 1, circulator 2, detector 3, y-waveguide modulator 4, demodulation circuit module 5, fiber optic loop assembly 6, and mirror assembly 7;

[0040] Optionally, the circulator 2 is respectively connected to the SOA-based narrow-spectrum ASE light source 1, the detector 3, and the y-waveguide modulator 4, and the demodulation circuit 5 is respectively connected to the y-waveguide modulator 4 and the detector 3;

[0041] The fiber optic loop assembly 6 is respectively connected to the y-waveguide modulator 4 and the mirror assembly 7; such as Figure 1 ;

[0042] Optionally, the demodulation circuit module 5 includes a demodulation circuit, an acquisition system, and a digital processing module;

[0043] The fiber optic loop assembly 6 includes a first fiber optic loop 61 and a second fiber optic loop 62;

[0044] The mirror assembly 7 includes a second mirror 71 and a third mirror 72;

[0045] In an embodiment of the present invention, the narrow-spectrum ASE light source 1 based on SOA outputs partially coherent light with suppressed intensity noise. The partially coherent light with suppressed intensity noise is input through the first port of the circulator 2 and then output through the second port of the circulator 2 to the y-waveguide modulator 4, outputting optical signal one and optical signal two. The optical signal one and optical signal two respectively pass through the optical fiber loop one 61 and the optical fiber loop two 62, are transmitted to the second mirror 71 and the third mirror 72 and return to the original optical path, and interfere with each other in the y-waveguide modulator 4 to obtain an interference optical signal carrying acoustic wave information.

[0046] The interference optical signal carrying acoustic wave information returns to the circulator 2, is transmitted through the third port to the detector 3, converts the interference optical signal carrying acoustic wave information into an electrical signal, and the electrical signal is input to the demodulation circuit module 5 to output an acoustic wave signal with suppressed intensity noise.

[0047] It can be understood that the partially coherent light with suppressed intensity noise combines the characteristics of partially coherent light and the advantage of low noise, and is suitable for a variety of high-precision and high-stability optical applications.

[0048] The present invention uses partially coherent light with suppressed intensity noise to significantly improve the sensitivity and stability of the fiber optic hydrophone, and can provide high-sensitivity and long-term stable acoustic wave detection capabilities in complex environments.

[0049] The fiber optic hydrophone with noise self-suppression based on the SOA narrow-spectrum ASE light source of the present invention has a simple structure, good stability, and realizes the suppression of intensity noise.

[0050] Optionally, the demodulation circuit module is a closed-loop detection circuit;

[0051] Optionally, the demodulation circuit module 5 includes a preamplification module 8, an A / D conversion module 9, a digital demodulation module 10, a control algorithm module 11, a D / A conversion module 12, and a drive circuit 13 connected in sequence;

[0052] In an embodiment of the present invention, the specific steps for the electrical signal to be input to the demodulation circuit module 5 and output the acoustic wave information with suppressed intensity noise include:

[0053] The electrical signal is amplified by the preamplification module 8 to obtain an analog signal. The analog signal is input to the A / D conversion module 9 to obtain a digital signal. The digital signal is subjected to a first delay process to ensure signal synchronization. The delayed digital signal is input to the digital demodulation module 10 to extract information. The information is input to the control algorithm module 11 to output an analyzed digital signal, and a phase difference is obtained based on the analyzed digital signal for phase adjustment.

[0054] The analyzed digital signal is input into the D / A conversion module 12 to obtain an analog digital signal; the analog digital signal is input into the drive circuit 13 to obtain a drive circuit signal, and signal modulation is performed based on the drive circuit signal to obtain an updated signal, and square wave modulation is performed based on the updated signal to output an acoustic wave signal with suppressed intensity noise.

[0055] Optionally, the processing process of the output acoustic wave signal with suppressed intensity noise is a digital closed-loop detection processing process;

[0056] Optionally, the coherent light expression for suppressing intensity noise is:

[0057] I(t) = I 0 [1 + cos(Δφ + φmod(t))]

[0058] where I(t) is the intensity of the coherent light with suppressed intensity noise at time t, I 0 is the basic light intensity, Δφ is the phase difference, which is caused by the acoustic wave signal on the sensing arm. φmod(t)) is the phase modulation function that changes with time.

[0059] Furthermore, the digital signal includes an in-phase reference signal and a quadrature reference signal, and the expressions are respectively:

[0060] RI(t) = sin(2πfmt), RQ(t) = cos(2πfmt)

[0061] where RI(t) is the in-phase reference signal at time t, RQ(t) is the quadrature reference signal at time t, and fm is the sampling rate.

[0062] The analyzed digital signal includes in-phase component baseband information and quadrature component baseband information, and the expressions are respectively:

[0063] I = LPF(I mix ), Q = LPF(Q mix )

[0064] where I is the in-phase component baseband information, Q is the quadrature component baseband information, LPF is the low-pass filtering process, I mix is the in-phase signal obtained after mixing, Q mix is the quadrature signal after mixing.

[0065] Furthermore, the in-phase signal obtained after mixing and the quadrature signal after mixing, the expressions are respectively:

[0066] I mix = S(t)·RI(t), Q mix = S(t)·RQ(t)

[0067] where I mixQ is the in-phase signal obtained after mixing. mix I is the quadrature signal after mixing, RI(t) is the in-phase reference signal at time t, RQ(t) is the quadrature reference signal at time t, and fm is the sampling rate.

[0068] The phase difference is expressed as:

[0069] Δφ = arctan(Q / I)

[0070] where Δφ is the phase difference and arctan is the arctangent function.

[0071] Optionally, two orthogonal digital reference signals are converted into analog voltages and loaded onto the modulation electrodes of the Y waveguide; the Y waveguide adjusts the phase of the reference arm through the electro-optic effect to compensate for the phase difference Δφ, so that the system is stabilized at the interference zero point.

[0072] Optionally, a high-frequency sinusoidal voltage fm = 10 kHz to 1 MHz is applied to the Y waveguide modulator to generate a periodic phase modulation, and the expression is:

[0073] φmod(t) = φ 0 sin(2πfmt)

[0074] where φ0 is the modulation depth, and by alternately switching the phase (±π / 2), the demodulation algorithm is simplified.

[0075] Optionally, the SOA-based narrow-spectrum ASE light source includes a narrow-spectrum ASE light source 1-1, a polarizer 1-2, a semiconductor optical amplifier SOA 1-3, and a first coupler 1-4;

[0076] Optionally, the first coupler 1-4 includes a port one 1-41, a port two 1-42, a port three 1-43, and a port four 1-44;

[0077] The polarizer 1-2 is respectively connected to the narrow-spectrum ASE light source 1-1 and the port one 1-41 of the first coupler 1-4; the semiconductor optical amplifier SOA 1-3 is respectively connected to the port two 1-42 and the port three 1-43 of the first coupler 1-4; the port four 1-44 outputs coherent light with suppressed intensity noise;

[0078] Optionally, the semiconductor optical amplifier SOA 1-3 includes a first port and a second port;

[0079] In some embodiments of the present invention, the narrow-spectrum ASE light source 1-1 outputs an original light source, and after passing through the polarizer 1-2, it outputs polarized light; the polarized light is input through port 1-41 of the coupler 1-4, and then transmitted through port 1-42 to the first port of the semiconductor optical amplifier SOA 1-3, and then output from the second port of the semiconductor optical amplifier SOA 1-3 to port 1-43 of the coupler 1-4, and coherent light with suppressed intensity noise is output through port 1-44;

[0080] Further, the polarized light is split by the coupler 1-4 for the original light source, and 98% of it enters the semiconductor optical amplifier SOA 1-3 through port 1-42 for cyclic amplification. During this process, the semiconductor optical amplifier SOA 1-3 is in a non-linear amplification working state, effectively suppressing the relative intensity noise while amplifying the power. It is output from the second port to port 1-43 of the coupler 1-4 to obtain coherent light with suppressed intensity noise;

[0081] It can be understood that the phase relationship of the coherent light with suppressed intensity noise remains consistent in time and space;

[0082] In the present invention, the light split by the coupler circulates through the ring cavity of the semiconductor optical amplifier SOA for multiple noise suppressions to achieve the effect of noise suppression.

[0083] Exemplarily, the splitting ratio of the coupler is 98:2, and both port 1 and port 2 are 98% splitting ports;

[0084] Both port 3 and port 4 are 2% splitting ports;

[0085] The coupler is a 2×2 coupler;

[0086] The spectral width of the SOA-based narrow-spectrum ASE light source of the present invention is 300 - 800 picometers. Among them, the coherence length of the light source reaches the centimeter level, meeting the requirements of the large dynamic range of fiber optic hydrophones.

[0087] Further, the narrow-spectrum ASE light source 1-1 includes a pump source 1-11, a second coupler 1-12, a first amplification module 1-13, and a second amplification module 1-14;

[0088] The second coupler 1-12 is respectively connected to the pump source 1-11, the first amplification module 1-13, and the second amplification module 1-14;

[0089] Optionally, the first amplification module 1-13 includes a first wavelength division multiplexer 1-15, a first erbium-doped fiber 1-16, a first filter 1-17, a first mirror 1-18, and a first isolator 1-19;

[0090] The second amplification module includes a second wavelength division multiplexer 1-20, a second erbium-doped fiber 1-21, a second isolator 1-22, and a second filter 1-23;

[0091] In some embodiments of the present invention, the pump source 1-11 outputs pump light through the second coupler 1-12;

[0092] The pump light enters the first erbium-doped fiber 1-16 after passing through the first wavelength division multiplexer 1-15. In the first erbium-doped fiber 1-16, broadband light is generated by spontaneous emission. The broadband light passes backward through the first filter 1-17, is converted into partially coherent light, and then is completely reflected by the first mirror 1-18 and passes through the first filter 1-17 again and enters the first erbium-doped fiber 1-16. The partially coherent light that is amplified again passes through the first isolator 1-19 and enters the second amplification module 1-14;

[0093] The partially coherent light enters the second erbium-doped fiber 1-21 after passing through the second wavelength division multiplexer 1-20. The amplified light passes through the second isolator 1-22 and the second filter 1-23 and is directly output to obtain a narrow-spectrum ASE light source.

[0094] Exemplarily, the output power of the narrow-spectrum ASE light source is 10 mw;

[0095] The pump source is a 980 nm pump source;

[0096] The spectral width of the first filter is 0.3 nm;

[0097] The first amplification part adopts a two-way forward amplification structure;

[0098] The first erbium-doped fiber is the first amplified erbium-doped fiber; the first erbium-doped fiber is the second amplified erbium-doped fiber;

[0099] The length of the second erbium-doped fiber is 5 meters, which can preferably provide a gain amplification function. The amplified light passes through the second isolator and the second filter and is directly output.

[0100] The narrow-spectrum ASE light source is a partially coherent light source with a spectral width of 0.3 nm.

[0101] Optionally, the pump source 1-11 is a 980 nm pump source;

[0102] The second coupler 1-12 is a 1×2 coupler with a splitting ratio of 50:50;

[0103] The output power of the narrow-spectrum ASE light source is 8-10 mw;

[0104] In some embodiments, the ratio of the length of the first erbium-doped fiber 1-16 to the length of the second erbium-doped fiber 1-21 is 3:5;

[0105] The length of the first erbium-doped fiber 1-16 is 3 meters, and the length of the second erbium-doped fiber 1-21 is 5 meters, which can preferably provide a gain amplification function.

[0106] In some embodiments, the coherence length of the narrow-spectrum ASE light source is 0.1-0.7 cm.

[0107] Exemplarily, the partially coherent light after noise suppression is verified by using the direct detection method of a spectrum analyzer.

[0108] Specifically, the present invention further includes an attenuator, a photodetector, and a multimeter.

[0109] The port four 1-44 is connected to the attenuator to ensure that the power reaching the detector is the same each time.

[0110] The attenuator is respectively connected to the detector 3 and the multimeter.

[0111] The port four outputs the partially coherent light suppressing intensity noise, which is transmitted to the attenuator to ensure the same output power of 100 μW, and then output to the detector 3. After photoelectric conversion, the detector signal is connected to the spectrum analyzer through the NPC adapter. The spectrum analyzer collects the spectrogram, and at the same time, the direct current voltage is measured by the multimeter.

[0112] During the detection process of the present invention, an attenuator is added during the test process. After being converted by the photodetector, the optical signal is converted into an electrical signal, and then collected by the multimeter and the spectrum analyzer to ensure that the power reaching the detector is consistent.

[0113] The spectrum analyzer is the core of the relative intensity noise detection system. It can measure the relative intensity noise on the detector. By combining the time-domain average direct current voltage collected by the multimeter, the relative intensity noise can be calculated.

[0114] The present invention can achieve a noise suppression of about 10 dBm.

[0115] Through the test of the spectrum analyzer, the noise of the narrow-spectrum ASE light source is reduced by 23 dBm in the present invention.

[0116] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A fiber optic hydrophone with noise self-suppression based on a narrow spectrum ASE light source of SOA, characterized in that: include: SOA-based narrow spectrum ASE light source (1), circulator (2), detector (3), y-waveguide modulator (4), demodulation circuit module (5), optical fiber ring assembly (6) and reflector assembly (7); The circulator (2) is respectively connected to the SOA-based narrow spectrum ASE light source (1), the detector (3) and the y-waveguide modulator (4), and the demodulation circuit (5) is respectively connected to the y-waveguide modulator (4) and the detector (3); The SOA-based narrow spectrum ASE light source (1) outputs partially coherent light with suppressed intensity noise; The y-waveguide modulator (4) outputs an interference light signal carrying sound wave information; The demodulation circuit module (5) outputs sound wave information suppressing intensity noise.

2. The fiber optic hydrophone for realizing noise self-suppression based on a narrow spectrum ASE light source of SOA according to claim 1, characterized in that: The SOA-based narrow-spectrum ASE light source comprises a narrow-spectrum ASE light source (1-1), a polarizer (1-2), a semiconductor optical amplifier SOA (1-3) and a first coupler (1-4); The polarizer (1-2) is respectively connected to a narrow spectrum ASE light source (1-1) and a semiconductor optical amplifier SOA (1-3), and the semiconductor optical amplifier SOA (1-3) is also connected to a first coupler (1-4).

3. The fiber optic hydrophone for realizing noise self-suppression based on a narrow spectrum ASE light source of SOA according to claim 1, characterized in that: The demodulation circuit module (5) comprises a preamplification module (8), an A / D conversion module (9), a digital demodulation module (10), a control algorithm module (11), a D / A conversion module (12) and a driving circuit (13) which are connected in sequence; The control algorithm module (11) outputs an analyzed digital signal.

4. The fiber optic hydrophone for realizing noise self-suppression based on a narrow spectrum ASE light source of SOA according to claim 3, characterized in that: The analyzed digital signal includes in-phase component baseband information and quadrature component baseband information, and the expressions are: I=LPF(I mix ),Q=LPF(Q mix ) Among them, I is the in-phase component baseband information, Q is the orthogonal component baseband information, LPF is low-pass filtering, I mix is the in-phase signal obtained after mixing, Q mix is the orthogonal signal after mixing.

5. The fiber optic hydrophone for realizing noise self-suppression based on a narrow spectrum ASE light source of SOA according to claim 2, characterized in that: The first coupler (1-4) comprises a port one (1-41), a port two (1-42), a port three (1-43) and a port four (1-44); The polarizer (1-2) is respectively connected to the narrow spectrum ASE light source (1-1) and the port one (1-41) of the first coupler (1-4); the semiconductor optical amplifier SOA (1-3) is respectively connected to the port two (1-42) and the port three (1-43) of the first coupler (1-4); and the port four (1-44) outputs coherent light that suppresses intensity noise.

6. The fiber optic hydrophone for realizing noise self-suppression based on a narrow spectrum ASE light source of SOA according to claim 2, characterized in that: The narrow spectrum ASE light source (1-1) comprises a pump source (1-11), a second coupler (1-12), a first amplification module (1-13) and a second amplification module (1-14); The second coupler (1-12) is respectively connected to the pump source (1-11), the first amplification module (1-13) and the second amplification module (1-14).

7. The fiber optic hydrophone for realizing noise self-suppression based on a narrow spectrum ASE light source of SOA according to claim 2, characterized in that: The spectrum width of the SOA-based narrow-spectrum ASE light source is 300-800 picometers.

8. The fiber optic hydrophone with noise self-suppression based on a narrow spectrum ASE light source of SOA according to claim 2, characterized in that: The output power of the narrow spectrum ASE light source is 8-10mw.

9. The fiber optic hydrophone for realizing noise self-suppression based on a narrow spectrum ASE light source of SOA according to claim 2, characterized in that: The coherence length of the narrow spectrum ASE light source is 0.1-0.7 cm.

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