CN113804283B - Interference type optical fiber hydrophone phase noise testing system and method - Google Patents
Interference type optical fiber hydrophone phase noise testing system and method Download PDFInfo
- Publication number
- CN113804283B CN113804283B CN202111077639.6A CN202111077639A CN113804283B CN 113804283 B CN113804283 B CN 113804283B CN 202111077639 A CN202111077639 A CN 202111077639A CN 113804283 B CN113804283 B CN 113804283B
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- interference
- phase
- division multiplexing
- time division
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 127
- 238000012360 testing method Methods 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 title claims abstract description 33
- 230000003287 optical effect Effects 0.000 claims abstract description 24
- 230000008859 change Effects 0.000 claims abstract description 20
- 230000005540 biological transmission Effects 0.000 claims description 37
- 230000008878 coupling Effects 0.000 claims description 29
- 238000010168 coupling process Methods 0.000 claims description 29
- 238000005859 coupling reaction Methods 0.000 claims description 29
- 239000000919 ceramic Substances 0.000 claims description 23
- 239000000835 fiber Substances 0.000 claims description 19
- 230000008569 process Effects 0.000 claims description 15
- 238000002955 isolation Methods 0.000 claims description 7
- 238000012935 Averaging Methods 0.000 claims description 4
- 230000009471 action Effects 0.000 claims description 2
- 230000008602 contraction Effects 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 abstract description 11
- 238000013461 design Methods 0.000 abstract description 3
- 238000011156 evaluation Methods 0.000 abstract description 3
- 238000012545 processing Methods 0.000 abstract description 3
- 230000005693 optoelectronics Effects 0.000 abstract 1
- 238000005452 bending Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000010998 test method Methods 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- AIXMJTYHQHQJLU-UHFFFAOYSA-N chembl210858 Chemical compound O1C(CC(=O)OC)CC(C=2C=CC(O)=CC=2)=N1 AIXMJTYHQHQJLU-UHFFFAOYSA-N 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000000149 penetrating effect Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000013139 quantization Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/30—Assessment of water resources
Abstract
The invention discloses an interference type optical fiber hydrophone phase noise testing system and method, which designs a time division multiplexing array noise testing optical system and an optoelectronic signal processing system which comprise an optical fiber phase controller, wherein the phase controller is driven to enable the initial phase of an array interference signal to sweep 0-2 pi, phase noise at the corresponding initial phase is synchronously tested and averaged in a short time, and the conversion result from the intensity noise to the phase noise of a remote system to be tested under the full state is obtained through the phase noise testing result of one initial phase change period. The method can effectively eliminate noise test errors caused by initial phase change, shortens test time, synchronously obtains the light intensity noise and noise conversion characteristics of the system to be tested, and is particularly suitable for phase noise floor test and performance evaluation of a remote large-scale optical fiber hydrophone multiplexing array system with low signal to noise ratio.
Description
Technical Field
The invention relates to the technical field of phase noise testing, in particular to a system and a method for testing phase noise of an interference type optical fiber hydrophone.
Background
The optical fiber hydrophone is a water acoustic sensor taking optical fibers as optical sensing and transmission media, can be used for detecting ocean acoustic fields and seismic fields, and is of an optical fiber interference type structure at present. By combining with the existing optical fiber communication technology, the optical fiber hydrophone can conveniently construct various underwater optical fiber sensing and transmission networks, effectively improve the array scale and the remote transmission distance, and provide an ideal technical approach for solving the problems of large-scale application such as marine underwater sound detection and submarine energy exploration.
With the continuous expansion of the scale of the optical fiber hydrophone array, the number of elements is increased from hundreds to tens of thousands, the transmission distance is also gradually increased to hundreds or even thousands of kilometers, the optical loss of the system is greatly increased, and different optical amplifiers are required to be added at different positions to compensate the system loss, such as an optical power amplifier, an optical on-line amplifier, an optical preamplifier and the like. Meanwhile, the addition of the multi-stage optical amplifier also brings amplified spontaneous emission noise, the noise is the random disturbance of broadband light intensity, the optical signal to noise ratio of the hydrophone is reduced, and finally the overall rise of the phase noise background of the hydrophone system is caused.
In the optical fiber hydrophone system, the signal light power is assumed to be P p The intensity noise light power introduced by light amplification is P n The optical signal-to-noise ratio of the interference light intensity of the hydrophone is as follows:
in the case of only taking into account the noise of the hydrophone system, the phase signal is madeThe interference signal containing the light intensity noise is photoelectrically converted into:
v is the visibility of the interferometer, the value is 1 under ideal conditions, and R is the photoelectric conversion response rate;is system intrinsic phase noise related to laser frequency jitter, photodetector, A/D quantization, etc, +.>Is the initial phase of the two arms of the interferometer. />Is influenced by factors such as temperature drift of the external extremely low frequency, environmental disturbance and the like, slowly randomly drifts between 0 pi and 2 pi, and has larger uncertainty on the time and amplitude of the slow drift.
In a general optical fiber hydrophone short-range noise test system, P n Very low is usually negligible andthe +.f. can be eliminated by high pass filtering without the hydrophone signal detection band>The influence of slow drift on signal detection, the actually measured phase noise is the intrinsic noise +.>But at P n In a large-scale remote optical fiber hydrophone test system with high occupation ratio, because the intensity noise has larger amplitude and is broadband white noise, the white noise cannot be directly filtered, and therefore, after phase demodulation and high-pass filtering, I (t) is subjected to phase noise floor at last>The method comprises the following steps:
in the aboveIs the conversion term of intensity to phase noise, and +.>F is a nonlinear noise transfer function which is +.>The value, the optical fiber hydrophone phase demodulation method and the system OSNR and other parameters are closely related. In general, when->And k is an integer>Maximum; />When (I)>Minimum; when->Random variation in multiple periods of 0-2 pi,/v>And also fluctuates. Especially in optical fiber hydrophones where the OSNR is low and +.>Under the condition of->Will lead to->A large amplitude of variation. FIG. 1 shows the measured phase noise floor (0 dB = 1rad/sqrt (Hz)) of a fiber optic hydrophone system with an OSNR below 18dB as a function of initial phase +.>Results of the changes:
in FIG. 1, the initial phase is changed between-87 dB and-94 dB in the linear rising process, and the fluctuation amplitude is about 7dB. The results indicate that the intensity to phase noise conversion is nonlinear and is closely related to the initial phase of the hydrophone system. Therefore, the special rule that the intensity-to-phase noise conversion changes along with the initial phase brings difficulty to the accurate test of the phase noise of the optical fiber hydrophone system under the condition of low signal-to-noise ratio.
The existing optical fiber hydrophone noise floor test scheme is not consideredInstead, a direct test and averaging test method is adopted, so that the method is suitable for a short-distance small-scale optical fiber hydrophone system with high OSNR. However, the analysis shows that the direct test method is used for testing the large-scale long-distance transmission optical fiber hydrophone system, and the multi-stage optical amplifying equipment is introduced>Occupy a relatively large, measured->Along with->A large fluctuation occurs, which will greatly influence +.>Is used for testing the accuracy of the test. In addition, when the phase noise test is carried out, the hydrophone to be tested is usually required to be well shielded from external environment sound/vibration, < + >>The method is less affected by the outside and changes slowly, long initial phase random drift and average time are often required to be waited for to obtain a comprehensive phase noise average result, and uncertainty is brought to the test time and test result of the phase noise of the optical fiber hydrophone.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides an interference type optical fiber hydrophone phase noise testing system and method, which can effectively eliminate noise testing errors caused by initial phase change, shorten testing time, synchronously obtain light intensity noise and noise conversion characteristics of a system to be tested, and are particularly suitable for phase noise floor testing and performance evaluation of a remote large-scale optical fiber hydrophone multiplexing array system with low signal to noise ratio.
In order to achieve the above object, the present invention provides an interference type optical fiber hydrophone phase noise testing system, comprising:
the signal transmitting unit is used for outputting a single pulse signal of the system to be tested;
the remote transmission unit comprises a downlink transmission optical fiber, an uplink transmission optical fiber and an optical amplifier, wherein the incident end of the downlink transmission optical fiber is connected with the signal transmitting unit and is used for remotely transmitting the single pulse signal;
the interference unit comprises an input end, an output end and a phase controller, wherein the input end of the interference unit is connected with the emergent end of the downlink transmission optical fiber and is used for converting the single pulse signal into a single pulse interference signal and then outputting the single pulse interference signal;
the time division multiplexing unit comprises an input end and an output end, wherein the input end of the time division multiplexing unit is connected with the output end of the interference unit, and the output end of the time division multiplexing unit is connected with the incident end of the uplink transmission optical fiber and is used for converting the single pulse interference signal into a time division multiplexing interference pulse signal and then outputting the time division multiplexing interference pulse signal;
the signal receiving unit is connected with the emergent end of the uplink transmission optical fiber and is used for receiving the time division multiplexing interference pulse signal and demodulating the time division multiplexing interference pulse signal to obtain phase noise of the system to be detected;
and the control unit is electrically connected with the phase controller and is used for actively controlling the initial phase of the single-pulse interference signal.
In one embodiment, the interference unit is a michelson interference structure, and includes an optical fiber coupler, a first single-mode optical fiber, a second single-mode optical fiber, a first faraday mirror, a second faraday mirror, and the phase controller;
the optical fiber coupler is provided with an input port, a first output port, a second output port and a third output port, wherein the input port of the optical fiber coupler is the input end of the interference unit, and the third output port of the optical fiber coupler is the output end of the interference unit;
the first output port of the optical fiber coupler is connected with the first Faraday mirror through the first single mode fiber, and the second output port of the optical fiber coupler is connected with the second Faraday mirror through the second single mode fiber;
the phase controller is arranged on the first single-mode optical fiber.
In one embodiment, the phase controller is a piezoelectric ceramic ring with a cylindrical structure, and the piezoelectric ceramic ring is electrically connected with the control unit, so that the piezoelectric ceramic ring stretches under the action of a voltage signal;
and part of the first single mode fibers are tightly wound along the circumferential direction and are orderly arranged on the piezoelectric ceramic ring, so that the length of the first single mode fibers wound on the piezoelectric ceramic ring is changed along with the extension and contraction of the piezoelectric ceramic ring, and the phase difference of the single pulse interference signals is changed.
In one embodiment, the time division multiplexing unit comprises N-1 beam splitting couplers and N-1 beam combining couplers, wherein N is a time division multiplexing number and N is a natural number greater than 1, and the beam splitting couplers and the beam combining couplers are provided with a public port, a small coupling ratio port and a large coupling ratio port;
the common port of the a-th beam splitting coupler is connected with the large coupling ratio port of the a-1-th beam splitting coupler through a delay optical fiber, and the common port of the a-th beam combining coupler is connected with the large coupling ratio port of the a-1-th beam combining coupler, wherein a=2-N-1;
the large coupling ratio port of the (N-1) -th beam splitting coupler is connected with the large coupling ratio port of the (N-1) -th beam combining coupler through a delay optical fiber, the common port of the (1) -th beam splitting coupler is the input end of the time division multiplexing unit, and the common port of the (1) -th beam combining coupler is the output end of the time division multiplexing unit;
the small coupling ratio port of the b-th beam splitting coupler is connected with the small coupling ratio port of the b-th beam combining coupler through a connecting optical fiber, wherein b=1-N-1.
In one embodiment, the device further comprises a vacuum isolation tank, and the interference unit and the time division multiplexing unit are arranged in the vacuum isolation tank.
In one embodiment, the signal receiving unit includes:
the photoelectric detector comprises an input end and an output end, wherein the input end of the photoelectric detector is connected with the emergent end of the uplink transmission optical fiber and is used for converting a time division multiplexing interference pulse signal into a time division multiplexing interference electric signal;
the analog-to-digital converter comprises an input end and an output end, wherein the input end of the analog-to-digital converter is connected with the output end of the photoelectric detector and is used for converting the time division multiplexing interference electric signal into a digital signal from an analog signal;
the phase noise demodulator comprises an input end and an output end, wherein the input end of the phase noise demodulator is connected with the output end of the analog-to-digital converter and is used for demodulating digital signals to obtain the phase noise of the system to be tested.
In one embodiment, the control unit comprises:
an analog-to-digital converter electrically coupled to the phase controller for applying a voltage signal to the phase controller;
and the control display module is electrically connected with the digital-to-analog converter and the phase noise demodulator and is used for controlling the output voltage of the digital-to-analog converter to obtain the phase noise level of the system to be tested in the initial phase full-change process.
In order to achieve the above purpose, the invention also provides an interference type optical fiber hydrophone phase noise test system, which adopts the interference type optical fiber hydrophone phase noise test system, and specifically comprises the following steps:
step 1, changing the voltage applied by a phase controller from small to large, and collecting the interference light intensity I (t) of a time division multiplexing interference pulse signal point by point;
step 2, obtaining the maximum value I of the interference light intensity I (t) in a change period max And minimum value I min And corresponding voltage V omax And V omin Obtaining half-wave voltage of the phase controller, wherein the half-wave voltage is as follows:
V πp ＝|V omax- V omin |
wherein V is πp Is the half-wave voltage of the phase controller;
step 3, gradually changing the voltage V applied by the phase controller o In the range of 0 to 2V πp Step length V mp Number of changes m=2v πp /V mp And by setting step length V mp Let M be an integer:
at every change of voltage V oi And wait for the phase controller settling time τ m Then, the time division multiplexing interference pulse signals are collected, the phase noise of the system to be tested is demodulated, K seconds of noise data are stored, one group of K groups are stored per second, and the K groups are recorded asWherein i=1 to M, j=1 to K;
after finishing M times of noise collection, averaging the noise data of M multiplied by K seconds to obtain the phase noise level of the system to be tested under the initial phase full change process:
in the method, in the process of the invention,the phase noise level of the system to be tested in the initial phase full change process is obtained.
Aiming at the problems of the testing method in the prior art, the invention provides an interference type optical fiber hydrophone phase noise testing system and method, which designs a time division multiplexing array noise testing optical system and a photoelectric signal processing system containing an optical fiber phase controller, and the system and method have the following beneficial technical effects:
(1) Taking ofActively controlled noise test scheme by controlling +.>1 or N periods are changed, and phase noise test is carried out in the complete period, so that comprehensive noise test results such as maximum, minimum, average value and the like of the conversion from the intensity noise of the tested system to the phase noise can be obtained, and the accuracy of the test results is improved;
(2)controlled by D/A signal of control unit, the variation amplitude and time are driven by program, ++>The time of the full period change and the phase noise test is efficient and controllable;
(3) The time division multiplexing noise test array with the interference separated from the multiplexing light path is designed, and the time division multiplexing array signal can be realized only by 1 phase controller wound by piezoelectric ceramicsThe control and phase noise comprehensive test system has simple structure and low cost.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of the phase noise of an optical fiber hydrophone according to the prior art along with the initial phase change;
FIG. 2 is a schematic diagram of a phase noise test system of an interference type optical fiber hydrophone in an embodiment of the invention;
fig. 3 is a schematic structural diagram of an interference unit and a time division multiplexing unit in an embodiment of the present invention;
fig. 4 is a schematic flow chart of a method for testing phase noise of an interference type optical fiber hydrophone in an embodiment of the invention.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; the device can be mechanically connected, electrically connected, physically connected or wirelessly connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present invention.
The embodiment discloses an interference type optical fiber hydrophone phase noise testing system which is applied to comprehensive testing of light intensity to phase noise conversion characteristics and system phase noise floor of a remote large-scale optical fiber hydrophone array under the condition of low signal-to-noise ratio and comprises a signal transmitting unit, a remote transmission unit, an interference unit, a time division multiplexing unit, a signal receiving unit and a control unit. The signal transmitting unit is used for outputting a single pulse signal of the system to be tested; the remote transmission unit comprises an incidence end of a downlink transmission optical fiber, is connected with the signal transmitting unit and is used for remotely transmitting a single pulse signal; the interference unit comprises an input end, an output end and a phase controller, wherein the input end of the interference unit is connected with the emergent end of the downlink transmission optical fiber and is used for converting a single pulse signal into a single pulse interference signal and then outputting the single pulse interference signal; the time division multiplexing unit comprises an input end and an output end, the input end of the time division multiplexing unit is connected with the output end of the interference unit, and the output end of the time division multiplexing unit is connected with the incident end of the uplink transmission optical fiber and is used for converting the single-pulse interference signal into a time division multiplexing interference pulse signal and then outputting the time division multiplexing interference pulse signal; the signal receiving unit is connected with the emergent end of the uplink transmission optical fiber and is used for receiving the time division multiplexing interference pulse signal and demodulating the time division multiplexing interference pulse signal to obtain phase noise of the system to be tested; the control unit is electrically connected with the phase controller and is used for actively controlling the initial phase of the single-pulse interference signal.
In this embodiment, the signal transmitting unit includes a narrow linewidth laser and an acousto-optic modulator AOM as light sources. The remote transmission unit consists of a downlink transmission optical fiber and an uplink transmission optical fiber, wherein the downlink transmission optical fiber is provided with an erbium-doped optical fiber power amplifier EDFA-BA and an erbium-doped optical fiber line amplifier EDFA-LA, and the uplink transmission optical fiber is provided with an erbium-doped optical fiber line amplifier EDFA-LA and an erbium-doped optical fiber preamplifier EDFA-PA. The signal receiving unit comprises a photoelectric Detector (D), an analog-to-digital converter (analog to digital converter, A/D) and a phase noise demodulator, and the control unit comprises a digital-to-analog converter (digital to analog converter, D/A) and a control display module. The photoelectric detector comprises an input end and an output end, wherein the input end of the photoelectric detector is connected with the emergent end of the uplink transmission optical fiber and is used for converting a time division multiplexing interference pulse signal into a time division multiplexing interference electric signal; the analog-to-digital converter comprises an input end and an output end, wherein the input end of the analog-to-digital converter is connected with the output end of the photoelectric detector and is used for converting the time division multiplexing interference electric signal into a digital signal from an analog signal; the phase noise demodulator comprises an input end and an output end, wherein the input end of the phase noise demodulator is connected with the output end of the analog-to-digital converter and is used for demodulating the digital signal to obtain the phase noise of the system to be tested. The digital-to-analog converter is electrically connected with the phase controller and is used for applying a voltage signal to the phase controller; the display module, the acousto-optic modulator and the analog-to-digital converter are controlled. The digital-to-analog converter and the phase noise demodulator are electrically connected and used for controlling the output voltage of the analog-to-digital converter to obtain the phase noise level of the system to be tested in the initial phase full-change process.
Referring to fig. 2, the interference type optical fiber hydrophone phase noise testing system is composed of three parts:
(1) The active initial phase control time division multiplexing noise test array unit specifically comprises an interference unit and a time division multiplexing unit in the embodiment;
(2) The active initial phase control time division multiplexing array noise test photoelectric signal processing unit specifically comprises a signal transmitting unit, a signal receiving unit and a control unit in the embodiment;
(3) The remote transmission and optical amplification unit to be tested is specifically a remote transmission unit in this embodiment.
Referring to fig. 3, a schematic structural diagram of the above active initial phase control time division multiplexing noise test array unit, i.e. the interference unit and the time division multiplexing unit is shown.
In this embodiment, the interference unit is a michelson interference structure, including a first single mode fiber isolator ISO 1 Bending-resistant 3dB single-mode fiber coupler C 0 First single-mode optical fiber L resistant to bending 1 Second single-mode optical fiber L resistant to bending 2 First Faraday mirror FRM with rotation angle of 45 DEG 1 Second Faraday mirror FRM with 45-degree rotation angle 2 And an all-fiber phase controller F-PK.
The optical fiber coupler comprises an input port, a first output port, a second output port and a third output port, wherein the input port of the optical fiber coupler is the input end of the interference unit and passes through the first single-mode fiber isolator ISO 1 The device is connected with the emergent end of the downlink transmission optical fiber; the third output port of the optical fiber coupler is the output end of the interference unit, and is connected with the input end of the time division multiplexing unit through the connecting optical fiber. The first output port of the optical fiber coupler is connected with the first Faraday mirror through a first single-mode fiber, the second output port of the optical fiber coupler is connected with the second Faraday mirror through a second single-mode fiber, and tail fibers among the devices are connected in a fusion mode.
Specifically, the phase controller is provided on the first single-mode optical fiber. In this embodiment, the body of the phase controller is a piezoelectric ceramic ring PZT having a cylindrical configuration with a diameter of about 20mm and a height of about 5 mm. The piezoelectric ceramic ring PZT adopts an axial voltage-applying mode, and the positive and negative (-) poles of the piezoelectric ceramic ring PZT are respectively welded with wires and led out to an interface of a control electric signal input end, namely a digital-to-analog converter D/A. Second single mode optical fiber L 2 The 1-2 m bending-resistant optical fibers are tightly wound and orderly arranged along the circumferential direction of the piezoelectric ceramic ring PZT, and fiber inlet and fiber outlet openings on the piezoelectric ceramic ring PZT are fixed by glue to prevent the optical fibers from being separated from the piezoelectric ceramic ring PZT. Applying voltage signal V to piezoelectric ceramic ring PZT through D/A of digital-to-analog converter o The stretching state of the piezoelectric ceramic ring PZT can be changed, and the piezoelectric ceramic ring PZT stretches to drive the length of the optical fiber wound on the piezoelectric ceramic ring PZT to change delta L, so that a phase difference is generated at the output end of the interferometerWherein k is 0 The optical wave vector is input to the interferometer, and n is the refractive index of the optical fiber, so that the addition of the phase controller enables the interference unit to have the function of realizing active initial phase control.
In this embodiment, the time division multiplexing unit includes N-1 beam-splitting couplers C a1 ～C aN-1 N-1 beam-combining couplers C b1 ～C bN-1 N-1 single-mode delay optical fibers D 1 ～D N-1 Wherein N is a natural number greater than 1, and D 1 ～D N-1 Is equal in length and meets the time division multiplexing channel spacing requirement, C a1 ～C aN-1 And C b1 ～C bN-1 The coupling ratio of the optical fiber is sequentially increased, and the optical power balance requirement of the time division multiplexing channel is met. Wherein, the beam splitting coupler and the beam combining coupler are provided with a common port (1 port in fig. 3), a small coupling ratio port (2 port in fig. 3) and a large coupling ratio port (3 port in fig. 3). The common port of the a-th beam splitting coupler is connected with the large coupling ratio port of the a-1-th beam splitting coupler through a delay optical fiber, and the common port of the a-th beam combining coupler is connected with the large coupling ratio port of the a-1-th beam combining coupler through a delay optical fiberWherein a=2 to N-1; the large coupling ratio port of the (N-1) -th beam splitting coupler is connected with the large coupling ratio port of the (N-1) -th beam combining coupler through a delay optical fiber, the common port of the (1) -th beam splitting coupler is the input end of the time division multiplexing unit, and the common port of the (1) -th beam combining coupler is the output end of the time division multiplexing unit; the small coupling ratio port of the b-th beam splitting coupler is connected with the small coupling ratio port of the b-th beam combining coupler through a connecting optical fiber, wherein b=1-N-1. The connection of devices in the time division multiplexing unit is mainly divided into three groups:
(1)C a1 ～C aN-1 and C b1 ～C bN-1 Directly welding the ports with small coupling ratio one by one to form N-1 time division multiplexing optical loops, D N-1 And C bN-1 The large coupling ratio port of the optical fiber is welded to form an N time division multiplexing optical loop;
(2)C a2 ～C aN-1 common port, C a1 ～C aN-1 Large coupling ratio port and D of (2) 1 ～D N-1 The serial welding is a time division multiplexing beam splitting delay branch;
(3)C b1 ～C bN-2 large coupling ratio port, C b2 ～C bN-1 Is connected in series and welded into a time division multiplexing beam combining branch;
wherein C is a1 The common end of the optical fiber coupler is an input end of the time division multiplexing unit and is welded with a third output port of the optical fiber coupler through a connecting optical fiber; c (C) b1 The public end of the (E) is the output end of the time division multiplexing unit and is connected with the optical fiber isolator ISO 2 And outputting the time division multiplexing interference optical signal with controllable initial phase. Through the design, the primary phase control of the N paths of time division multiplexing interference signals can be completed by only 1 phase controller.
It should be noted that the above-mentioned interference unit and time division multiplexing unit are all set in the vacuum isolation tank. The outside of the vacuum isolation tank is provided with 1 optical fiber penetrating sealing piece (comprising 2 optical fibers serving as an optical interface), 1 electric penetrating sealing piece (comprising 2 electric wires serving as an electric interface) and 1 vacuum extraction valve. The vacuum isolation tank is vacuumized to be between-0.075 Mpa and-0.085 Mpa to achieve good sound/vibration shielding effect, and under the condition, phase noise floor measured by the test system is mainly introduced by self noise of the optical fiber hydrophone system.
The working process of the interference type optical fiber hydrophone phase noise testing system is as follows:
continuous light output by narrow linewidth laser for optical fiber hydrophone is chopped into pulse width tau through acousto-optic modulator AOM 0 Repetition frequency f AOM The pulse optical signal is connected to the interference unit and the time division multiplexing unit after passing through the downlink transmission and amplifying unit, then the interference optical output signal is sent to the control and display unit after passing through the series of processes of the photoelectric detector (D), the analog-to-digital conversion (A/D) and the phase noise demodulation unit, etc., so as to obtain the phase noise floor level of the time division multiplexing array of the system to be tested. The control and display unit has the functions of driving AOM pulse and A/D synchronous acquisition, generates a digital control signal, converts the digital control signal into a voltage signal through D/A, and accesses the control electric signal input end of the F-PK to realize the primary phase active control of the test system.
Based on the above-mentioned interference type optical fiber hydrophone phase noise testing system, the embodiment also discloses an interference type optical fiber hydrophone phase noise testing method, referring to fig. 4, specifically comprising the following steps:
step 1, controlling D/A output, changing the voltage applied by a phase controller from small to large, and collecting the interference light intensity I (t) of a time division multiplexing interference pulse signal point by point through A/D;
step 2, obtaining the maximum value I of the interference light intensity I (t) in a change period max And minimum value I min And corresponding voltage V omax And V omin Obtaining half-wave voltage of the phase controller, wherein the half-wave voltage is as follows:
V πp ＝|V omax- V omin |
wherein V is πp Is the half-wave voltage of the phase controller;
step 3, gradually changing the voltage V applied by the phase controller o In the range of 0 to 2V πp Step length V mp Number of changes m=2v πp /V mp And by setting step length V mp Let M be an integer:
at every change of voltage V oi And wait for phase controller F-PK settling time τ m Then, the time division multiplexing interference pulse signals are collected, the phase noise of the system to be tested is demodulated, K seconds of noise data are stored, one group of K groups are stored per second, and the K groups are recorded asWherein i=1 to M, j=1 to K;
after finishing M times of noise collection, averaging the noise data of M multiplied by K seconds to obtain the phase noise level of the system to be tested under the initial phase full change process:
in the method, in the process of the invention,the phase noise level of the system to be tested in the initial phase full change process is obtained.
Considering that the D/A output control voltage and the waiting time for the F-PK to stabilize are short, the time for completing one test in the above steps 1-3 is approximately equal to M×K seconds.
In summary, this embodiment provides an optical fiber hydrophone time division multiplexing test array structure including an initial phase controller and a phase noise test method. The voltage of the primary phase controller is actively controlled and changed, so that the primary phase of the test interferometer is changed between 0 pi and 2 pi, and the phase noise of the hydrophone system to be tested corresponding to each primary phase is synchronously acquired and demodulated. After one period test is completed, the phase noise and the average noise level of the system to be tested under the condition of full initial phase change can be obtained. The test method can effectively eliminate noise test errors caused by initial phase change, shortens test time, and can synchronously obtain the light intensity noise and noise conversion characteristic of the system to be tested. The method is particularly suitable for phase noise floor testing and performance evaluation of a remote large-scale optical fiber hydrophone multiplexing array system with low signal-to-noise ratio.
The foregoing description is only of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, and all equivalent structural changes made by the description of the present invention and the accompanying drawings or direct/indirect application in other related technical fields are included in the scope of the invention.
Claims (6)
1. An interferometric fiber optic hydrophone phase noise testing system, comprising:
the signal transmitting unit is used for outputting a single pulse signal of the system to be tested;
the remote transmission unit comprises a downlink transmission optical fiber, an uplink transmission optical fiber and an optical amplifier, wherein the incident end of the downlink transmission optical fiber is connected with the signal transmitting unit and is used for remotely transmitting the single pulse signal;
the interference unit comprises an input end, an output end and a phase controller, wherein the input end of the interference unit is connected with the emergent end of the downlink transmission optical fiber and is used for converting the single pulse signal into a single pulse interference signal and then outputting the single pulse interference signal;
the time division multiplexing unit comprises an input end and an output end, wherein the input end of the time division multiplexing unit is connected with the output end of the interference unit, and the output end of the time division multiplexing unit is connected with the incident end of the uplink transmission optical fiber and is used for converting the single pulse interference signal into a time division multiplexing interference pulse signal and then outputting the time division multiplexing interference pulse signal;
the signal receiving unit is connected with the emergent end of the uplink transmission optical fiber and is used for receiving the time division multiplexing interference pulse signal and demodulating the time division multiplexing interference pulse signal to obtain phase noise of the system to be detected;
the control unit is electrically connected with the phase controller and used for actively controlling the initial phase of the single-pulse interference signal;
the signal receiving unit includes:
the photoelectric detector comprises an input end and an output end, wherein the input end of the photoelectric detector is connected with the emergent end of the uplink transmission optical fiber and is used for converting a time division multiplexing interference pulse signal into a time division multiplexing interference electric signal;
the analog-to-digital converter comprises an input end and an output end, wherein the input end of the analog-to-digital converter is connected with the output end of the photoelectric detector and is used for converting the time division multiplexing interference electric signal into a digital signal from an analog signal;
the phase noise demodulator comprises an input end and an output end, wherein the input end of the phase noise demodulator is connected with the output end of the analog-to-digital converter and is used for demodulating a digital signal to obtain the phase noise of the system to be tested;
the control unit includes:
a digital-to-analog converter electrically coupled to the phase controller for applying a voltage signal to the phase controller;
and the control display module is electrically connected with the digital-to-analog converter and the phase noise demodulator and is used for controlling the output voltage of the digital-to-analog converter to obtain the phase noise level of the system to be tested in the initial phase full-change process.
2. The interference type optical fiber hydrophone phase noise testing system of claim 1, wherein the interference unit is a michelson interference structure, and comprises an optical fiber coupler, a first single-mode optical fiber, a second single-mode optical fiber, a first faraday mirror, a second faraday mirror and the phase controller;
the optical fiber coupler is provided with an input port, a first output port, a second output port and a third output port, wherein the input port of the optical fiber coupler is the input end of the interference unit, and the third output port of the optical fiber coupler is the output end of the interference unit;
the first output port of the optical fiber coupler is connected with the first Faraday mirror through the first single mode fiber, and the second output port of the optical fiber coupler is connected with the second Faraday mirror through the second single mode fiber;
the phase controller is arranged on the first single-mode optical fiber.
3. The interference type optical fiber hydrophone phase noise testing system according to claim 2, wherein the phase controller is a piezoelectric ceramic ring with a cylindrical structure, and the piezoelectric ceramic ring is electrically connected with the control unit, so that the piezoelectric ceramic ring stretches under the action of a voltage signal;
and part of the first single mode fibers are tightly wound along the circumferential direction and are orderly arranged on the piezoelectric ceramic ring, so that the length of the first single mode fibers wound on the piezoelectric ceramic ring is changed along with the extension and contraction of the piezoelectric ceramic ring, and the phase difference of the single pulse interference signals is changed.
4. The interference type optical fiber hydrophone phase noise testing system of claim 1, 2 or 3, wherein the time division multiplexing unit comprises N-1 beam splitting couplers and N-1 beam combining couplers, wherein N is a time division multiplexing number and N is a natural number larger than 1, and the beam splitting couplers and the beam combining couplers are provided with a common port, a small coupling ratio port and a large coupling ratio port;
the common port of the a-th beam splitting coupler is connected with the large coupling ratio port of the a-1-th beam splitting coupler through a delay optical fiber, and the common port of the a-th beam combining coupler is connected with the large coupling ratio port of the a-1-th beam combining coupler, wherein a=2-N-1;
the large coupling ratio port of the (N-1) -th beam splitting coupler is connected with the large coupling ratio port of the (N-1) -th beam combining coupler through a delay optical fiber, the common port of the (1) -th beam splitting coupler is the input end of the time division multiplexing unit, and the common port of the (1) -th beam combining coupler is the output end of the time division multiplexing unit;
the small coupling ratio port of the b-th beam splitting coupler is connected with the small coupling ratio port of the b-th beam combining coupler through a connecting optical fiber, wherein b=1-N-1.
5. The interference type optical fiber hydrophone phase noise testing system according to claim 1, 2 or 3, further comprising a vacuum isolation tank, wherein the interference unit and the time division multiplexing unit are arranged in the vacuum isolation tank.
6. The method for testing the phase noise of the interference type optical fiber hydrophone is characterized by adopting the system for testing the phase noise of the interference type optical fiber hydrophone according to any one of claims 1 to 5, and specifically comprising the following steps:
step 1, changing the voltage applied by a phase controller from small to large, and collecting the interference light intensity I (t) of a time division multiplexing interference pulse signal point by point;
step 2, obtaining the maximum value I of the interference light intensity I (t) in a change period max And minimum value I min And corresponding voltage V omax And V omin Obtaining half-wave voltage of the phase controller, wherein the half-wave voltage is as follows:
V πp ＝|V omax- V omin |
wherein V is πp Is the half-wave voltage of the phase controller;
step 3, gradually changing the voltage V applied by the phase controller o In the range of 0 to 2V πp Step length V mp Number of changes m=2v πp /V mp And by setting step length V mp Let M be an integer:
at every change of voltage V oi And wait for the phase controller settling time τ m Then, the time division multiplexing interference pulse signals are collected, the phase noise of the system to be tested is demodulated, K seconds of noise data are stored, one group of K groups are stored per second, and the K groups are recorded asWherein i=1 to M, j=1 to K;
after finishing M times of noise collection, averaging the noise data of M multiplied by K seconds to obtain the phase noise level of the system to be tested under the initial phase full change process:
in the method, in the process of the invention,the phase noise level of the system to be tested in the initial phase full change process is obtained.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111077639.6A CN113804283B (en) | 2021-09-15 | 2021-09-15 | Interference type optical fiber hydrophone phase noise testing system and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111077639.6A CN113804283B (en) | 2021-09-15 | 2021-09-15 | Interference type optical fiber hydrophone phase noise testing system and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113804283A CN113804283A (en) | 2021-12-17 |
| CN113804283B true CN113804283B (en) | 2023-10-20 |
Family
ID=78940857
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111077639.6A Active CN113804283B (en) | 2021-09-15 | 2021-09-15 | Interference type optical fiber hydrophone phase noise testing system and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113804283B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114777898B (en) * | 2022-03-28 | 2024-03-26 | 中国人民解放军国防科技大学 | Symmetrical time division multiplexing structure and high-reliability optical fiber hydrophone array system |
| CN114826408B (en) * | 2022-06-27 | 2022-09-02 | 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 |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007057251A (en) * | 2005-08-22 | 2007-03-08 | Anritsu Corp | Optical interferometer type phase detection apparatus |
| CN106338658A (en) * | 2016-08-25 | 2017-01-18 | 南京航空航天大学 | Phase noise measurement method and device based on radio frequency cancellation |
| WO2017054564A1 (en) * | 2015-09-28 | 2017-04-06 | 中兴通讯股份有限公司 | Laser phase noise cancellation device, system, and method |
| CN106768398A (en) * | 2016-12-01 | 2017-05-31 | 长沙聚宇光电科技有限公司 | The method of testing and device of a kind of source phase noise |
| CN107727367A (en) * | 2017-10-12 | 2018-02-23 | 北京大学 | A kind of laser frequency noise measuring method and system |
| CN108362388A (en) * | 2018-02-26 | 2018-08-03 | 肖世涛 | A kind of measurement method of double passage differential laser phase noise |
| JP2019020143A (en) * | 2017-07-11 | 2019-02-07 | 日本電信電話株式会社 | Optical fiber vibration detection sensor and method therefor |
| CN110530500A (en) * | 2019-09-20 | 2019-12-03 | 中国人民解放军国防科技大学 | Optical fiber hydrophone array structure based on compensation interference |
-
2021
- 2021-09-15 CN CN202111077639.6A patent/CN113804283B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007057251A (en) * | 2005-08-22 | 2007-03-08 | Anritsu Corp | Optical interferometer type phase detection apparatus |
| WO2017054564A1 (en) * | 2015-09-28 | 2017-04-06 | 中兴通讯股份有限公司 | Laser phase noise cancellation device, system, and method |
| CN106338658A (en) * | 2016-08-25 | 2017-01-18 | 南京航空航天大学 | Phase noise measurement method and device based on radio frequency cancellation |
| CN106768398A (en) * | 2016-12-01 | 2017-05-31 | 长沙聚宇光电科技有限公司 | The method of testing and device of a kind of source phase noise |
| JP2019020143A (en) * | 2017-07-11 | 2019-02-07 | 日本電信電話株式会社 | Optical fiber vibration detection sensor and method therefor |
| CN107727367A (en) * | 2017-10-12 | 2018-02-23 | 北京大学 | A kind of laser frequency noise measuring method and system |
| CN108362388A (en) * | 2018-02-26 | 2018-08-03 | 肖世涛 | A kind of measurement method of double passage differential laser phase noise |
| CN110530500A (en) * | 2019-09-20 | 2019-12-03 | 中国人民解放军国防科技大学 | Optical fiber hydrophone array structure based on compensation interference |
Non-Patent Citations (4)
| Title |
|---|
| Cao C等.An improved PMDI-TDM structure for remotely interrogated optical fiber hydrophone arrays.Symposium on Novel Photoelectronic Detection Technology and Applications.2020,全文. * |
| 吴悦峰等.基于法拉第旋转镜的Michelson干涉仪偏振相位噪声研究.光电子·激光.2008,第19卷(第11期),1446-1449. * |
| 尚凡等.基于光纤光栅的时分复用传感阵列相位噪声研究.光学学报.2021,第41卷(第13期),73-83. * |
| 曹春燕.光纤水听器阵列超远程光传输低噪声光放大链关键技术研究.中国博士学位论文全文数据库 基础科学.2016,(第1期),全文. * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113804283A (en) | 2021-12-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11079269B2 (en) | Method and apparatus for optical sensing | |
| CN113804283B (en) | Interference type optical fiber hydrophone phase noise testing system and method | |
| CN110456410B (en) | Distributed hydrophone based on superstrong bending resistance multicore optical fiber flexible optical cable | |
| CN104019836A (en) | Brillouin optical-time-domain analyzer based on coherence dual-pulse pair sequence technology and method for restraining common-mode noise by utilizing same | |
| CN110617872B (en) | Optical fiber hydrophone remote transmission array system and method based on compensation interference | |
| CN107421628A (en) | A kind of anti-polarization decay interference type optical fiber hydrophone system | |
| CN109708743B (en) | Interference type optical fiber hydrophone detection system | |
| CN110530500B (en) | Optical fiber hydrophone array structure based on compensation interference | |
| AU2022203821B2 (en) | Method and apparatus for optical sensing | |
| CN108592963B (en) | Method and system for inhibiting multiplicative noise of time division multiplexing optical fiber sensing system | |
| Peng et al. | Optical fiber hydrophone systems | |
| Akkaya et al. | Time-division-multiplexed interferometric sensor arrays | |
| CN115200691A (en) | Few-mode optical fiber distributed acoustic sensing system and signal processing method thereof | |
| CN107328404B (en) | Oversized Sagnac interference type fiber-optic gyroscope with N-multiplied effective fiber-optic length | |
| CN113483880A (en) | Vibration sensing system based on few-mode optical fiber | |
| CN111128217B (en) | Distributed multi-channel coherent laser radar voice interception method and device | |
| Ma et al. | An ultra-low crosstalk and polarization independent inline interferometric fiber Bragg grating sensor array | |
| CN209689741U (en) | A kind of partition type optical fiber vibration measuring system | |
| CN113466871A (en) | All-fiber towed linear array | |
| AU2015201357B2 (en) | Optical sensor and method of use | |
| CN116047526B (en) | Superfine continuous optical fiber towed sonar and underwater mobile platform | |
| Cheng et al. | Distributed Vibration Sensor Based on Mode Coupling in Weakly Coupled Multi-Core Fibers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |