CN115791090A - System and method for improving signal measurement sensitivity and polarization stability - Google Patents
System and method for improving signal measurement sensitivity and polarization stability Download PDFInfo
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Abstract
The invention discloses a system and a method for improving signal measurement sensitivity and polarization stability, wherein the system for improving the signal measurement sensitivity and the polarization stability comprises a white light source, a front optical fiber coupler, an optical fiber circulator, an electric control optical fiber delay line, a wavelength division multiplexer component, a rear optical fiber coupler component and a signal detection and acquisition module: the optical fiber circulator and a transmission optical path of the wavelength division multiplexer component form a signal arm, the electric control optical fiber delay line and another transmission optical path of the wavelength division multiplexer component form a reference arm, and beat frequency interference occurs at the rear optical fiber coupler component by output light of the signal arm and the reference arm. The invention improves the measurement sensitivity and stability of the system, only uses a single wide-spectrum light source and only uses one-time scanning test time based on the characteristic of spectrum multiplexing; the single scanning test is equivalent to N times of repeated measurement on the DUT to be tested, so that the material cost and the time cost of the system are greatly saved, and the method has excellent popularization prospect.
Description
Technical Field
The invention relates to the technical field of optical measurement, in particular to a system and a method for improving signal measurement sensitivity and polarization stability.
Background
White light interference is an effective means and scheme for measuring optical weak signals and accurately positioning; the detection of the optical fiber distributed echo signals and the accurate positioning of fault points can be realized by utilizing the white light short coherence length; in the white light interference, a section of optical path distance is increased by scanning an optical fiber delay line, the existence and the height of an interference peak value of a beat frequency spectrum in the increased section of optical path length are observed, and the existence of an event point, the position of the event point and the magnitude of the echo power of the event point are judged.
However, due to the low coherence of the white light, the sensitivity of the measurement of weak signals based on the white light interferometry is not particularly high, and the sensitivity can not meet the requirements on certain application occasions; ultra-weak signals such as Rayleigh scattering and weak bending; this condition causes much less return loss than a typical APC connector and most fiber optic measurement equipment cannot measure such low optical power.
Therefore, a system or a method for improving signal measurement sensitivity and polarization stability is urgently needed to be presented at present, and the echo signal detection capability can be greatly improved on the weak signal of the existing white light interferometry; meanwhile, the problem of inaccurate return loss measurement caused by random polarization state of the DUT to be measured is solved, and many harsh use conditions can be solved, so that the measured signal is more accurate and stable, and the application range is wider.
Disclosure of Invention
In order to overcome the defects of related products in the prior art, the invention provides a system or a method for improving the signal measurement sensitivity and the polarization stability, so as to solve the problem of a scheme of low distributed return loss sensitivity of a link measured in a white light interference mode, improve the detection capability of an ultra-micro optical signal and improve the polarization stability of a measurement result.
The invention provides a system for improving signal measurement sensitivity and polarization stability, which comprises: the device comprises a white light source, a front optical fiber coupler, an optical fiber circulator, an electric control optical fiber delay line, a wavelength division multiplexer component, a rear optical fiber coupler component and a signal detection and acquisition module; the white light source is connected with the input end of the first optical fiber coupler, and the first output end and the second output end of the first optical fiber coupler are respectively connected with the first port of the optical fiber circulator and the input end of the electric control optical fiber delay line in two paths; the second port of the optical fiber circulator is connected with a DUT link to be tested, and the third port of the optical fiber circulator is connected with a wavelength division multiplexer component; the output end of the electric control optical fiber delay line is connected with the wavelength division multiplexer component; the wavelength division multiplexer assembly, the rear optical fiber coupler assembly and the signal detection and acquisition module are sequentially connected; the optical fiber circulator and a transmission optical path of the wavelength division multiplexer component form a signal arm, the electric control optical fiber delay line and another transmission optical path of the wavelength division multiplexer component form a reference arm, and beat frequency interference occurs at the rear optical fiber coupler component by output light of the signal arm and the reference arm.
In some embodiments of the invention, the wavelength division multiplexer assembly comprises a plurality of sets of wavelength division multiplexers connected in series in sequence.
In some embodiments of the present invention, the rear optical fiber coupler assembly includes a plurality of groups of optical fiber couplers connected in parallel, and the set number of the optical fiber couplers corresponds to the set number of wavelength division multiplexers in the wavelength division multiplexer assembly.
In some embodiments of the present invention, the wavelength division multiplexer assembly includes three sets of wavelength division multiplexers, such as a first wavelength division multiplexer, a second wavelength division multiplexer, and a third wavelength division multiplexer, connected in series, and accordingly, the rear optical fiber coupler assembly includes three sets of optical fiber couplers connected in parallel, that is, a first rear optical fiber coupler, a second rear optical fiber coupler, and a third rear optical fiber coupler, where wavelengths and bandwidths of the first wavelength division multiplexer, the second wavelength division multiplexer, and the third wavelength division multiplexer are different, and the three sets of optical fiber couplers correspond to beat frequency interferences occurring at the first rear optical fiber coupler, the second rear optical fiber coupler, and the third rear optical fiber coupler, respectively.
In some embodiments of the present invention, the third port of the optical fiber circulator and the output end of the electrically controlled optical fiber delay line are respectively connected to the input end of the first wavelength division multiplexer; a first output end and a second output end of the first wavelength division multiplexer are respectively connected with the first rear optical fiber coupler, and a third output end of the first wavelength division multiplexer is connected with an input end of the second wavelength division multiplexer; a first output end and a second output end of the second wavelength division multiplexer are respectively connected with the second rear optical fiber coupler, and a third output end of the second wavelength division multiplexer is connected with an input end of a third wavelength division multiplexer; a first output end and a second output end of the third wavelength division multiplexer are respectively connected with the third rear optical fiber coupler; and the output ends of the first rear optical fiber coupler, the second rear optical fiber coupler and the third rear optical fiber coupler are respectively connected with the signal detection and acquisition module.
In some embodiments of the invention, 50% of the light output by the front fiber coupler enters the signal arm and 50% enters the reference arm.
The invention also provides a method for improving the signal measurement sensitivity and the polarization stability, which is applied to any system for improving the signal measurement sensitivity and the polarization stability, and comprises the following steps:
the wide-spectrum light emitted by the white light source is divided into two paths through the front optical fiber coupler and respectively enters the signal arm and the reference arm, wherein the optical fiber circulator and a transmission optical path of the wavelength division multiplexer component form the signal arm, the electric control optical fiber delay line and another transmission optical path of the wavelength division multiplexer component form the reference arm, the output light of the signal arm and the reference arm generates beat frequency interference at the rear optical fiber coupler component, the wavelength division multiplexer component comprises a plurality of groups of wavelength division multiplexers which are sequentially connected in series, the rear optical fiber coupler component comprises a plurality of groups of optical fiber couplers which are connected in parallel, and the setting number of the optical fiber couplers corresponds to the setting number of the wavelength division multiplexers in the wavelength division multiplexer component one to one;
a white light signal in the reference arm is connected with an electric control optical fiber delay line capable of changing the optical path of an optical fiber link, the output end of the electric control optical fiber delay line is connected with a wavelength division multiplexer component, and the filtered white light enters a rear optical fiber coupler component;
white light signals in the signal arm enter a fiber DUT link to be tested through the fiber circulator, echo signals returned from the fiber DUT link to be tested in real time are connected with the wavelength division multiplexer assembly, and filtered light signals enter the rear fiber coupler assembly;
and detecting beat frequency signals from the rear optical fiber coupler assembly through a signal detection and acquisition module, and completely superposing and averaging the final N groups of interference curves to obtain an echo signal curve of the final event point.
Compared with the prior art, the invention has the following advantages:
the system for improving the signal measurement sensitivity and the polarization stability is based on the characteristic of spectral multiplexing, a wide-spectrum white light source divides the spectrum by a plurality of wavelength division multiplexers with different central wavelengths and different bandwidths, white lights with different wavelengths interfere independently, and the system is equivalent to realize multiple measurements by single scanning of a DUT (device under test) at the same event point, so that the signal height is improved, the noise thickness is suppressed, and the signal-to-noise ratio of the system is improved; on the other hand, after spectrum multiplexing, as the spectrum bandwidth is narrowed, the coherence length is lengthened, the signal interference time in unit time is also lengthened, the useful interference signal proportion is larger, and after data processing change, the peak value is increased, and the capability of the system for measuring the link weak signal is also improved; for the same DUT, after the same DUT passes through single-mode optical fiber optical paths with different lengths, the polarization state changes randomly, and the uncertainty of single interference is greatly weakened after the interference results of a plurality of different polarization states are averaged, so that the system measurement signal result is more accurate and stable; in conclusion, the invention only uses a single wide-spectrum light source and only uses one-time scanning test time while improving the measurement sensitivity and stability of the system; the single scanning test is equivalent to repeatedly measuring the DUT to be tested for N times, so that the material cost and the time cost of the system are greatly saved, and the method has an excellent popularization prospect.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of the schematic structure of the system for improving signal measurement sensitivity and polarization stability according to the present invention;
FIG. 2 is a schematic diagram of spectral multiplexing of 3 wavelength division multiplexers according to the embodiment of the present invention;
FIG. 3 is a schematic diagram showing the relationship between the interference time and the interference peak height according to the present invention;
FIG. 4 is a diagram illustrating an embodiment of the invention for enhancing noise reduction by peak value of a curve after superposition averaging;
FIG. 5 is a schematic diagram showing the peak value after interference corresponding to different polarization state included angles.
Description of reference numerals:
1. a white light source; 2. a front fiber coupler; 3. a fiber optic circulator; 4. an electrically controlled fiber optic delay line; 5. a first wavelength division multiplexer; 6. a second wavelength division multiplexer; 7. a third wavelength division multiplexer; 8. a first rear fiber coupler; 9. a second rear fiber coupler; 10. a third rear fiber coupler; 11. a signal detection and acquisition module; 12. a fiber DUT link to be tested; 13. a signal arm; 14. the reference arm.
Description of the preferred embodiment
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention; while the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Referring to fig. 1, the system for improving signal measurement sensitivity and polarization stability includes a white light source 1, a front optical fiber coupler 2, an optical fiber circulator 3, an electrically controlled optical fiber delay line 4, a wavelength division multiplexer component, a rear optical fiber coupler component, and a signal detection and collection module 11; the white light source 1 is connected with the input end of a first optical fiber coupler, and the first output end and the second output end of the first optical fiber coupler are respectively connected with the first port of an optical fiber circulator 3 and the input end of an electric control optical fiber delay line 4 in two ways; the second port of the optical fiber circulator 3 is connected with a to-be-tested optical fiber DUT link 12, the optical fiber circulator 3 is connected with the to-be-tested optical fiber DUT link 12 and is used for measuring an echo signal of the to-be-tested optical fiber DUT link 12, and the third port of the optical fiber circulator 3 is connected with a wavelength division multiplexer component; the output end of the electric control optical fiber delay line 4 is connected with the wavelength division multiplexer component; the wavelength division multiplexer assembly, the rear optical fiber coupler assembly and the signal detection and acquisition module 11 are sequentially connected; the optical fiber circulator 3 and a transmission optical path of the wavelength division multiplexer component form a signal arm 13, the electric control optical fiber delay line 4 and another transmission optical path of the wavelength division multiplexer component form a reference arm 14, 50% of light output by the front optical fiber coupler 2 enters the signal arm 13, 50% of light output by the front optical fiber coupler 2 enters the reference arm 14, and beat frequency interference occurs at the rear optical fiber coupler component by output light of the signal arm 13 and the reference arm 14.
The wavelength division multiplexer subassembly includes the wavelength division multiplexer that the multiunit was established ties in proper order, back optical fiber coupler subassembly includes the parallelly connected optical fiber coupler of multiunit, just optical fiber coupler set up quantity with wavelength division multiplexer's in the wavelength division multiplexer subassembly set up quantity one-to-one.
For example, in the embodiment of the present invention, the wavelength division multiplexer assembly includes three sets of wavelength division multiplexers, such as a first wavelength division multiplexer 5, a second wavelength division multiplexer 6, and a third wavelength division multiplexer 7, which are sequentially connected in series, and accordingly, the rear optical fiber coupler assembly includes three sets of optical fiber couplers connected in parallel, namely, a first rear optical fiber coupler 8, a second rear optical fiber coupler 9, and a third rear optical fiber coupler 10, where the wavelengths and bandwidths of the first wavelength division multiplexer 5, the second wavelength division multiplexer 6, and the third wavelength division multiplexer 7 are different, and the three sets of optical fiber couplers correspond to the first rear optical fiber coupler 8, the second rear optical fiber coupler 9, and the third rear optical fiber coupler 10, respectively, and beat frequency interference occurs.
Wherein, the third port of the optical fiber circulator 3 and the output end of the electrically controlled optical fiber delay line 44 are respectively connected with the input end of the first wavelength division multiplexer 5; a first output end (signal arm 13 output) and a second output end (reference arm 14 output) of the first wavelength division multiplexer 5 are respectively connected with the first rear optical fiber coupler 8, and a third output end of the first wavelength division multiplexer 5 is connected with an input end of the second wavelength division multiplexer 6; a first output end (output of the signal arm 13) and a second output end (output of the reference arm 14) of the second wavelength division multiplexer 6 are respectively connected with the second rear optical fiber coupler 9, and a third output end of the second wavelength division multiplexer 6 is connected with an input end of a third wavelength division multiplexer 7; a first output end (output of the signal arm 13) and a second output end (output of the reference arm 14) of the third wavelength division multiplexer 7 are respectively connected with the third rear optical fiber coupler 10; the output ends of the first rear optical fiber coupler 8, the second rear optical fiber coupler 9 and the third rear optical fiber coupler 10 are respectively connected with the signal detection and acquisition module 11; in another embodiment of the present invention, the number of wavelength division multiplexers and rear optical fiber couplers built in the wavelength division multiplexer module may be other plural numbers, for example, four groups, five groups, etc., according to actual requirements, and the present invention is not limited thereto.
The system for improving the signal measurement sensitivity and the polarization stability in the embodiment of the invention has the following specific working principle:
as shown in FIG. 1, the coherence length of the white light source 1 can be expressed by the following formula, taking 3-set wavelength division multiplexer as an example
Because each group of interference data is from the same white light source, the central wavelengths lambda corresponding to 1,3 groups of wavelength division multiplexers are approximately the same; and the bandwidth Δ λ is reduced by a factor of two, the coherence length of the system interference is determined by the corresponding filter bandwidths of the first wavelength-division multiplexer 5, the second wavelength-division multiplexer 6 and the third wavelength-division multiplexer 7; after the original spectrum is divided, the bandwidth is greatly reduced, and the coherence length of the original spectrum is increased; the coherence length is increased, the number of sinusoidal signals after interference is greatly increased, the relative interference signal ratio is also improved, and finally the signal-to-noise ratio of an interference curve is improved; the higher the interference peak value of the echo signal with the same size is, the stronger the capability of measuring a weak signal is, and the higher the sensitivity is.
Referring to fig. 2-3, the first rear optical fiber coupler 8, the second rear optical fiber coupler 9, and the third rear optical fiber coupler 10 output interference curves of 3 groups of light sources with different wavelengths and bandwidths, and by adjusting the lengths of the optical fibers of the signal arm 13 and the reference arm 14, the optical path of the signal arm 13 returned by the same section of DUT link 12 to be tested is exactly equal to the optical path of the reference arm 14 passed by the whole scanning process of the electrical control optical fiber delay line 4 (since the white light coherence length is short, it can be considered that the optical paths are equal to each other, and then interference occurs); if the scanning range of the electrically controlled optical fiber delay line 4 is S, the measurable length of the signal arm 13 is S/2; the 3 groups of multiplexed light source interference curves are all the same section of DUT measurement curve, which is equivalent to obtaining 3 times of results for the same section of DUT measurement; the signal detection and acquisition module 11 with multiple channels is used for detecting and acquiring the independent measurement results for 3 times, the independent measurement results are added and then averaged, and the averaged curve is used as the final measurement result.
According to the statistical principle, the noise is randomly distributed, the noise level can be eliminated to a certain extent after the noise is superposed for multiple times, the interference signal is a peak which is close to Gaussian distribution, an average height is obtained after the interference signal is averaged for multiple times, and the noise level is weakened by increasing the peak height through phase change after comprehensive treatment; the beneficial effects of increasing the peak height of the two devices are combined, the capability of the system for measuring ultra-weak signals is finally improved, and the system measurement sensitivity is greatly improved.
Meanwhile, after optical signals returned by the optical fiber DUT link 12 to be tested pass through each wavelength division multiplexer, the polarization state changes randomly (the optical fiber bends, and the change of the polarization state is caused by the length of the optical path), so that the included angle of the polarization states of the two arms of each group of interference beat signals is random, the peak value curve after interference is unstable, and when the included angle is 0 degree or 180 degrees, the peak value is the largest, and when the included angle is perpendicular to each other, the peak value is the smallest (the peak is hardly seen); the influence of the polarization state on return loss signal measurement is well weakened by the plurality of interference links; in the first wavelength division multiplexer 5, the second wavelength division multiplexer 6 and the third wavelength division multiplexer 7, the optical fiber lengths and the bending degrees corresponding to each wavelength division multiplexer are different, and the polarizations of the corresponding related reference arm 14 and the signal arm 13 are different and randomly change; after the interference peaks with different heights are averaged for multiple times, the inaccuracy and the stability of the measurement result caused by the randomness of the polarization state in single measurement are greatly weakened.
Specifically, the wide-spectrum light emitted by the white light source 1 is split into two paths by the front fiber coupler 2, and the two paths enter the signal arm 13 and the reference arm 14 respectively.
The white light signal in the reference arm 14 is connected to an electric control optical fiber delay line 4 capable of changing the optical path of the optical fiber link; the output access bandwidth of the electric control optical fiber delay line 4 is lambda 1, the wavelength division multiplexer with the center wavelength of lambda 1, and the filtered white light enters the rear optical fiber coupler component.
The white light signal in the signal arm 13 enters the optical fiber DUT link 12 to be tested through the optical fiber circulator 3, the echo signal returned from the optical fiber DUT link 12 to be tested in real time is also connected with the bandwidth of λ 1, the center wavelength of λ 1 is a wavelength division multiplexer, and the filtered optical signal enters the rear optical fiber coupler component.
The beat frequency signal from the rear optical fiber coupler component is detected by the signal detection and acquisition module 11,
according to the connection method of the wavelength division multiplexers, the wavelength division multiplexers with the filtering bandwidths of Δ λ 2 and center wavelength λ 2 are connected in series behind the first group of wavelength division multiplexers with the bandwidth of λ 1 and the center wavelength of λ 1; the combined wave is output by an optical fiber coupler and is detected and processed by a signal detection and acquisition module, and N groups of wavelength division multiplexers with different bandwidths and central wavelengths can be connected in series in the same connection mode; the more groups of light source multiplexing, the more groups of final interference data, the higher the sensitivity of the measurement signal after data processing and the better the polarization stability.
As shown in fig. 4, the result curves of multiple measurements are averaged after superposition, and the effect is schematically shown.
Fig. 5 is a schematic diagram showing the heights of the peaks after the interference corresponding to the included angles of different polarization states.
The system for improving the signal measurement sensitivity and the polarization stability is based on the characteristic of spectral multiplexing, a wide-spectrum white light source divides the spectrum by a plurality of wavelength division multiplexers with different central wavelengths and different bandwidths, white lights with different wavelengths interfere independently, and the system is equivalent to realize multiple measurements by single scanning of a DUT (device under test) at the same event point, so that the signal height is improved, the noise thickness is suppressed, and the signal-to-noise ratio of the system is improved; on the other hand, after spectrum multiplexing, as the spectrum bandwidth is narrowed, the coherence length is lengthened, the signal interference time in unit time is also lengthened, the useful interference signal proportion is larger, and after data processing change, the peak value is increased, and the capability of the system for measuring the link weak signal is also improved; for the same DUT, after the same DUT passes through single-mode optical fiber optical paths with different lengths, the polarization state changes randomly, and the uncertainty of single interference is greatly weakened after the interference results of a plurality of different polarization states are averaged, so that the system measurement signal result is more accurate and stable; in conclusion, the invention only uses a single wide-spectrum light source and only uses one-time scanning test time while improving the measurement sensitivity and stability of the system; the single scanning test is equivalent to N times of repeated measurement on the DUT to be tested, so that the material cost and the time cost of the system are greatly saved, and the method has excellent popularization prospect.
On the basis of the above embodiment, the present invention further provides a method for improving signal measurement sensitivity and polarization stability, which includes the following steps:
the wide-spectrum light emitted by a white light source 1 is divided into two paths through a front optical fiber coupler 2 and respectively enters a signal arm 13 and a reference arm 14, wherein the optical fiber circulator 3 and a transmission light path of a wavelength division multiplexer component form the signal arm 13, an electric control optical fiber delay line 4 and another transmission light path of the wavelength division multiplexer component form the reference arm 14, beat frequency interference occurs at the position of a rear optical fiber coupler component by output light of the signal arm 13 and the reference arm 14, the wavelength division multiplexer component comprises a plurality of groups of wavelength division multiplexers which are sequentially connected in series, the rear optical fiber coupler component comprises a plurality of groups of optical fiber couplers which are connected in parallel, and the setting number of the optical fiber couplers corresponds to the setting number of the wavelength division multiplexers in the wavelength division multiplexer component one to one;
a white light signal in the reference arm 14 is connected to an electric control optical fiber delay line 4 capable of changing the optical path of an optical fiber link, the output end of the electric control optical fiber delay line 4 is connected to a wavelength division multiplexer component, and the filtered white light enters a rear optical fiber coupler component;
white light signals in the signal arm 13 enter the optical fiber DUT link 12 to be tested through the optical fiber circulator 3, echo signals returned from the optical fiber DUT link 12 to be tested in real time are connected with the wavelength division multiplexer assembly, and filtered optical signals enter the rear optical fiber coupler assembly;
the beat frequency signal from the rear optical fiber coupler assembly is detected by the signal detection and acquisition module 11, and the final N groups of interference curves are all superposed and averaged to obtain an echo signal curve of the final event point.
The system for improving signal measurement sensitivity and polarization stability according to the above embodiment may execute the method for improving signal measurement sensitivity and polarization stability provided by the embodiment of the present invention, where the method for improving signal measurement sensitivity and polarization stability has the corresponding functional components and beneficial effects of the system for improving signal measurement sensitivity and polarization stability according to the above embodiment, and please refer to the embodiment of the system for improving signal measurement sensitivity and polarization stability specifically, which is not described herein again.
Those not described in detail in this specification are well within the skill of the art; although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing detailed description, or equivalent changes may be made in some of the technical features of the embodiments; all equivalent structures made by using the contents of the specification and the attached drawings of the invention can be directly or indirectly applied to other related technical fields, and are also within the protection scope of the patent of the invention.
Claims (7)
1. A system for improving signal measurement sensitivity and polarization stability, comprising: the device comprises a white light source (1), a front optical fiber coupler (2), an optical fiber circulator (3), an electric control optical fiber delay line (4), a wavelength division multiplexer component, a rear optical fiber coupler component and a signal detection and acquisition module (11); the white light source (1) is connected with the input end of a first optical fiber coupler, and the first output end and the second output end of the first optical fiber coupler are respectively connected with the first port of the optical fiber circulator (3) and the input end of the electric control optical fiber delay line (4) in two ways; a second port of the optical fiber circulator (3) is connected with an optical fiber DUT link (12) to be tested, and a third port of the optical fiber circulator (3) is connected with a wavelength division multiplexer component; the output end of the electric control optical fiber delay line (4) is connected with the wavelength division multiplexer component; the wavelength division multiplexer assembly, the rear optical fiber coupler assembly and the signal detection and acquisition module (11) are sequentially connected; the optical fiber circulator (3) and a transmission optical path of the wavelength division multiplexer component form a signal arm (13), the electric control optical fiber delay line (4) and another transmission optical path of the wavelength division multiplexer component form a reference arm (14), and beat frequency interference occurs at the rear optical fiber coupler component by output light of the signal arm (13) and the reference arm (14).
2. The system for improving signal measurement sensitivity and polarization stability of claim 1, wherein: the wavelength division multiplexer assembly comprises a plurality of groups of wavelength division multiplexers which are connected in series in sequence.
3. The system for improving signal measurement sensitivity and polarization stability of claim 2, wherein: the rear optical fiber coupler assembly comprises a plurality of groups of optical fiber couplers connected in parallel, and the set number of the optical fiber couplers corresponds to the set number of wavelength division multiplexers in the wavelength division multiplexer assembly one by one.
4. The system for improving signal measurement sensitivity and polarization stability of claim 3, wherein: the wavelength division multiplexer subassembly includes the wavelength division multiplexer that three group is established ties in proper order, first wavelength division multiplexer (5), second wavelength division multiplexer (6) and third wavelength division multiplexer (7) promptly, it is corresponding, back fiber coupler subassembly contains the parallelly connected fiber coupler of three groups, and fiber coupler (10) after first fiber coupler (8), second and fiber coupler (9) and the third promptly, the wavelength and the bandwidth of first wavelength division multiplexer (5), second wavelength division multiplexer (6) and third wavelength division multiplexer (7) are all inequality, and the three corresponds respectively and takes place beat frequency interference after first fiber coupler (8), second and fiber coupler (9) and third and fiber coupler (10) department.
5. The system for improving signal measurement sensitivity and polarization stability of claim 4, wherein: the third port of the optical fiber circulator (3) and the output end of the electric control optical fiber delay line (4) are respectively connected with the input end of the first wavelength division multiplexer (5); a first output end and a second output end of the first wavelength division multiplexer (5) are respectively connected with the first rear optical fiber coupler (8), and a third output end of the first wavelength division multiplexer (5) is connected with an input end of the second wavelength division multiplexer (6); a first output end and a second output end of the second wavelength division multiplexer (6) are respectively connected with the second rear optical fiber coupler (9), and a third output end of the second wavelength division multiplexer (6) is connected with an input end of a third wavelength division multiplexer (7); a first output end and a second output end of the third wavelength division multiplexer (7) are respectively connected with the third rear optical fiber coupler (10); and the output ends of the first rear optical fiber coupler (8), the second rear optical fiber coupler (9) and the third rear optical fiber coupler (10) are respectively connected with the signal detection and acquisition module (11).
6. The system for improving signal measurement sensitivity and polarization stability of claim 1, wherein: and 50% of light output by the front fiber coupler (2) enters the signal arm (13) and 50% enters the reference arm (14).
7. A method for improving signal measurement sensitivity and polarization stability, which is applied to the system for improving signal measurement sensitivity and polarization stability of any one of claims 1-6, and comprises the following steps:
the broadband light emitted by the white light source (1) is divided into two paths through the front optical fiber coupler (2) and respectively enters the signal arm (13) and the reference arm (14), wherein the optical fiber circulator (3) and a transmission optical path of the wavelength division multiplexer component form the signal arm (13), the electric control optical fiber delay line (4) and another transmission optical path of the wavelength division multiplexer component form the reference arm (14), the output light of the signal arm (13) and the reference arm (14) generates beat frequency interference at the rear optical fiber coupler component, the wavelength division multiplexer component comprises a plurality of groups of wavelength division multiplexers which are sequentially connected in series, the rear optical fiber coupler component comprises a plurality of groups of optical fiber couplers which are connected in parallel, and the setting number of the optical fiber couplers corresponds to the setting number of the wavelength division multiplexers in the wavelength division multiplexer component one to one;
a white light signal in a reference arm (14) is connected into an electric control optical fiber delay line (4) capable of changing the optical path of an optical fiber link, the output end of the electric control optical fiber delay line (4) is connected into a wavelength division multiplexer component, and the filtered white light enters a rear optical fiber coupler component;
white light signals in the signal arm (13) enter an optical fiber DUT link (12) to be tested through the optical fiber circulator (3), echo signals returned from the optical fiber DUT link (12) to be tested in real time are connected with the wavelength division multiplexer assembly, and filtered optical signals enter the rear optical fiber coupler assembly;
beat frequency signals from the rear optical fiber coupler assembly are detected through a signal detection and acquisition module (11), and the final N groups of interference curves are completely superposed and averaged to obtain an echo signal curve of a final event point.
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| EP1972926A1 (en) * | 2007-03-20 | 2008-09-24 | Danmarks Tekniske Universitet | Assessment of parameters by optical measurement |
| CN105806231A (en) * | 2016-03-10 | 2016-07-27 | 哈尔滨工程大学 | Thickness gauge based on optical fiber white light interference principle |
| CN109520532A (en) * | 2018-11-26 | 2019-03-26 | 重庆大学 | A kind of the multisensor multiplexing demodulation system and processing method of white light interference type optical fiber Fabry-Perot sensor |
| CN109520429A (en) * | 2018-11-26 | 2019-03-26 | 重庆大学 | The few spectrum sample point high-speed measuring system and method for white light interference type optical fiber Fabry-Perot sensor |
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