CN102012599A - Novel Rayleigh demodulator and demodulation method thereof - Google Patents
Novel Rayleigh demodulator and demodulation method thereof Download PDFInfo
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- CN102012599A CN102012599A CN2010105007174A CN201010500717A CN102012599A CN 102012599 A CN102012599 A CN 102012599A CN 2010105007174 A CN2010105007174 A CN 2010105007174A CN 201010500717 A CN201010500717 A CN 201010500717A CN 102012599 A CN102012599 A CN 102012599A
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Abstract
The invention discloses a novel Rayleigh demodulator and a demodulation method thereof, and belongs to the technical field of fiber sensing. Two wave filters are connected with a light splitter in turn; and backward scattered light such as anti-Stokes light, Stokes light, Rayleigh scattered light and the like generated by sensing fibers are separated to obtain the anti-Stokes light serving as temperature measurement signals and the Rayleigh scattered light serving as reference signals. By adopting the technical scheme, the loss of the anti-Stokes light signals can be furthest reduced, and the signal to noise ratio of a system is improved; the influence of stimulated Raman scattering is avoided; and finally, the introduction of a fixed proportion coupler or a circulator can reduce the loss of input light power so as to improve the signal to noise ratio of the system.
Description
Technical field
The present invention relates to the distributing optical fiber sensing technical field, relate in particular to the light channel structure part of Rayleigh Demodulation Type distributing optical fiber sensing technology.
Background technology
Distributed optical fiber temperature sensing system (RDTS) is based on Raman scattering principle dorsad, when laser pulse in optical fiber in the transmission course, can constantly produce scattered lights such as Raman scattering (Stokes, anti-Stokes), Rayleigh scattering and Brillouin scattering in the optical fiber, wherein back scattering can take place in a part, and we claim this part scattered light to be " back-scattering light ".RDTS adopts in the Raman scattering dorsad anti-Stokes as a kind of temperature-sensing system of responsive to temperature signal, for the influence of the factors such as ess-strain of eliminating light source power, temperature measuring optical cable environment of living in, need introduce one road signal more as a reference to the temperature demodulation.
Adopting stokes scattering light or Rayleigh scattering light as the reference signal usually in the RDTS product at present, wherein in the majority with stokes scattering light especially.But find that in use the influence that stokes scattering light is easy to be subjected to stimulated Raman scattering causes the nonlinear distortion of signal, reduces system stability.And simultaneously the loss of traditional Rayleigh demodulation structure is big, signal to noise ratio (S/N ratio) is low, the disadvantages such as influence that also influenced by stimulated Raman scattering.
The light signal that distributed optical fiber temperature sensing system relates to mainly comprises injection light pulse signal, Rayleigh scattering light signal (Rayleigh), stokes scattering light signal (Stokes) and anti Stokes scattering light signal (Anti-Stokes), and demodulation light path structure set forth in the present invention is used to handle above light signal.
Summary of the invention
The objective of the invention is to overcome the shortcoming and defect of existing Rayleigh demodulation techniques, a kind of Rayleigh detuner that stimulated Raman scattering influences, low-loss that is not subjected to is provided.
The object of the present invention is achieved like this:
A kind of novel Rayleigh detuner comprises two filter plates and an optical splitter, and two filter plates link to each other by optical fiber, and wherein a slice filter plate links to each other with optical splitter by optical fiber.
Every wave filter only allows a kind of transmittance of wavelength, reflects the light of its commplementary wave length, and filter plate 1 is used for the transmission anti-Stokes light, reflects non-anti-Stokes light; Filter plate 2 is used for the transmission stokes light, reflects non-stokes light;
The incident laser pulse signal injects from the optical splitter input end, reflection through two filter plates enters follow-up sensor fibre, backscattering can take place in incident laser pulse in the Optical Fiber Transmission process, the Rayleigh scattering light signal that backscattering produces, Stokes light signal and anti-Stokes light signal return along the former road of the incident direction of light, after filtration during wave plate 1, wherein anti Stokes scattering light signal transmission filter wave plate 1 enters into subsequent optical electric treatment unit, remaining stokes light, Rayleigh scattering light then reflexes to filter plate 2 through filter plate 1, the Stokes light signal is whole transmission filter wave plates 2 during wave plate 2 after filtration, promptly obtain cleaner Rayleigh scattering signal in the backscattering light signal this moment, the Rayleigh scattering signal of be filtering also Stokes and anti Stokes scattering.
Described optical splitter can be mainly used in incident light is injected into optical fiber for coupling mechanism or circulator etc., and back-scattering light is injected into rear end light, electric treatment unit;
The present invention is with respect to the advantage of prior art: at first, scattered light directly after filtration wave plate 1 obtain the anti-Stokes light signal, can farthest reduce the loss of anti-Stokes light signal, improved system signal noise ratio; Secondly, Rayleigh scattering signal is carried out necessary filtering, thereby avoided the influence of stimulated Raman scattering (mainly being that Stokes is non-linear); At last, the introducing of certainty ratio coupling mechanism or circulator can reduce the loss of input optical power, thereby has also improved system signal noise ratio.
Description of drawings
Fig. 1 is a Rayleigh demodulation structure embodiment one.
Fig. 2 is a Rayleigh demodulation structure embodiment two.
Embodiment
Further specify concrete implementation step of the present invention below in conjunction with accompanying drawing.
Embodiment 1: as Fig. 1, filter plate 1 links to each other with filter plate 2, and filter plate 2 links to each other with coupling mechanism 6, and filter plate 1 only allows the transmission anti-Stokes light, reflects non-anti-Stokes light; Filter plate 2 only allows the transmission stokes light, reflects non-stokes light; Coupling mechanism 6 is 2 * 2 coupling mechanisms, and the splitting ratio of coupling mechanism port is 90% (port 7): 10% (port 8).Laser pulse signal enters filter plate 2 from port 7 through behind the coupling mechanism 6, because filter plate 2 is transmission Stokes light signal only, so pulsed light enters filter plate 1 through filter plate 2 reflections, filter plate 1 is the transmission anti-Stokes only, so pulsed light reflects away via port 5, in RDTS, port 5 can directly or be connected with sensor fibre indirectly.When pulsed light is propagated in sensor fibre, backscattering can take place, back-scattering light enters filter plate 1 through port 5, and anti-Stokes light wherein enters subsequent optical electric treatment unit by port 4.The remainder of back-scattering light then enters filter plate 2 by filter plate 1 reflection, and stokes light is wherein gone out from port 3 transmissions.Mainly be Rayleigh scattering light this moment in the back-scattering light, and it enters subsequent optical electric treatment unit through coupling mechanism 6 from port 8.So far, finish the extraction of responsive to temperature signal (anti Stokes scattering signal) and reference signal (Rayleigh scattering signal).
Embodiment 2: as Fig. 2, filter plate 1 links to each other with filter plate 2, and filter plate 2 links to each other with circulator 9, and filter plate 1 only allows the transmission anti-Stokes light, reflects non-anti-Stokes light; Filter plate 2 only allows the transmission stokes light, reflects non-stokes light.Laser pulse signal enters filter plate 2 from port 7 through behind the circulator 9, because filter plate 2 is transmission Stokes light signal only, so pulsed light enters filter plate 1 through filter plate 2 reflections, filter plate 1 is the transmission anti-Stokes only, so pulsed light reflects away via port 5, in RDTS, port 5 can directly or be connected with sensor fibre indirectly.When pulsed light is propagated in sensor fibre, backscattering can take place, back-scattering light enters filter plate 1 through port 5, and anti-Stokes light wherein enters subsequent optical electric treatment unit by port 4.The remainder of back-scattering light then enters filter plate 2 by filter plate 1 reflection, and stokes light is wherein gone out from port 3 transmissions.Mainly be Rayleigh scattering light this moment in the back-scattering light, and it enters subsequent optical electric treatment unit through circulator 9 from port 8.So far, finish the extraction of responsive to temperature signal (anti Stokes scattering signal) and reference signal (Rayleigh scattering signal).Rayleigh scattering light signal through filtering then enters subsequent optical electric treatment unit from port one 6 as the reference signal.The responsive to temperature signal port 4 that comes from then as the same.
Claims (5)
1. novel Rayleigh detuner, it is characterized in that: filter plate (1) links to each other with filter plate (2), and filter plate (2) links to each other with optical splitter.
2. a kind of novel Rayleigh detuner according to claim 1 is characterized in that: between described filter plate (1) and the filter plate (2), and link to each other by optical fiber between filter plate (2) and the optical splitter.
3. a kind of novel Rayleigh detuner according to claim 1, it is characterized in that: filter plate (1) only allows the transmission of anti-Stokes light signal, reflects non-anti-Stokes light signal; Filter plate (2) only allows the transmission of Stokes light signal, reflects non-Stokes light signal.
4. a kind of novel Rayleigh detuner according to claim 1 is characterized in that: described optical splitter can be that fiber coupler or optical fiber circulator etc. have a kind of in the device of beam split function.
5. the demodulation method of a novel Rayleigh detuner is characterized in that, described demodulation method comprises the following steps:
A, laser pulse signal arrive filter plate (2) through optical splitter, are all reflected to arrive filter plate (1);
B, laser pulse signal enter follow-up sensor fibre through filter plate (1) reflection;
Backscattering can take place when transmitting in c, light in sensor fibre, back-scattering light returns along the former road of direction that light enters;
D, back-scattering light be wave plate (1) after filtration, and anti-Stokes light transmission filter plate (1) wherein enters the subsequent treatment unit;
During wave plate (2), Stokes light transmission filter plate (2) wherein is separated the back-scattering light of e, filtered (1) reflected back after filtration;
F, this moment only are left cleaner Rayleigh scattering light in the back-scattering light, output to the subsequent treatment unit through optical splitter.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010105007174A CN102012599A (en) | 2010-09-30 | 2010-09-30 | Novel Rayleigh demodulator and demodulation method thereof |
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| CN2010105007174A CN102012599A (en) | 2010-09-30 | 2010-09-30 | Novel Rayleigh demodulator and demodulation method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103115696A (en) * | 2013-01-22 | 2013-05-22 | 山东大学 | Distribution type optical fiber Raman temperature measurement system and distribution type optical fiber Raman temperature measurement method capable of eliminating Rayleigh light crosstalk |
| CN109283140A (en) * | 2018-10-25 | 2019-01-29 | 合肥工业大学 | A kind of luminous intensity enhances the Enhancement Method of system and luminous intensity |
-
2010
- 2010-09-30 CN CN2010105007174A patent/CN102012599A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103115696A (en) * | 2013-01-22 | 2013-05-22 | 山东大学 | Distribution type optical fiber Raman temperature measurement system and distribution type optical fiber Raman temperature measurement method capable of eliminating Rayleigh light crosstalk |
| CN103115696B (en) * | 2013-01-22 | 2014-09-10 | 山东大学 | Distribution type optical fiber Raman temperature measurement system and distribution type optical fiber Raman temperature measurement method capable of eliminating Rayleigh light crosstalk |
| CN109283140A (en) * | 2018-10-25 | 2019-01-29 | 合肥工业大学 | A kind of luminous intensity enhances the Enhancement Method of system and luminous intensity |
| CN109283140B (en) * | 2018-10-25 | 2021-04-30 | 合肥工业大学 | Light intensity enhancing system and light intensity enhancing method |
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Application publication date: 20110413 |