CN101320502A - Optical fiber perimeter alarm method and device for implementing anti-polarization decay - Google Patents

Abstract

The present invention provides an optical fiber perimeter warning method for realizing anti-polarization comedown and a device thereof. Concretely, a signal modulating module is used for modulating the phase of a light path signal and feeds back and controls the polarization state of the light path signal after the phase modulation; a polarization controller is arranged at one path sensing optical fiber of a Mach-Zehnder interferometer; the polarization controller is used for feeding back and controlling the input polarization state of a one path Mach-Zehnder interferometer and adjusting the output light path signal of the path, so the visibility of light path output can be stabilized by the technology of feeding back polarization control to provide the stable light path output signal for signal identification; at the same time, the feeding back and controlling process of a system is also simpler, thereby reducing the operating and maintaining cost of the system.

Description

Realize the optical fiber perimeter alarm method and the device of anti-polarization decay

Technical field

The present invention relates to the warning system field, relate in particular to a kind of optical fiber perimeter alarm method and device of realizing anti-polarization decay.

Background technology

Current, the demand of security protection equipment rolls up, and is also more and more higher to the requirement of perimeter alarm system: monitoring distance length, low-power consumption, high reliability, high stability, warning bearing accuracy height or the like.In present implementation, very high advantage and attractive force are arranged based on the perimeter alarm system of the full optical fiber form of distributed optical fiber stress Fundamentals of Sensors.And in the implementation of distributed optical fiber stress sensor, adopt the bidirectional Mach-Zehnder interferometer scheme of mistiming location to have highly sensitive, real-time response and long based on Mach-Zehnder (Mach-Zehnder) interferometer principle, very strong applicability is arranged apart from advantages such as location.

Be illustrated in figure 1 as system's location structure synoptic diagram of employing bidirectional Mach-Zehnder interferometer scheme, comprise light source LD, coupling mechanism A, coupling mechanism B, coupling mechanism C, detector PD1 and detector PD2 among the figure.When light source LD through coupling mechanism A, B two arms to interferometer, interfere when arriving coupling mechanism C, form a clockwise Mach-Zehnder interferometer, the signal after the interference is received by detector PD2 behind guiding fiber; Another Lu Guangzhi coupling mechanism C through coupling mechanism A tells behind two arms of interferometer, arrives coupling mechanism B and interferes, and also forms a counterclockwise Mach-Zehnder interferometer, and the signal after the interference is received by detector PD1 behind guiding fiber.

When the external world has disturbing signal to act on two arms of Mach-Zehnder interferometer, will make the brachium of interferometer two arms change, produced phase differential between the light of two arms transmission

This disturbing signal apart from the distance of coupling mechanism B is: L1=t ₁* c/n; Distance apart from coupling mechanism C is: L2=t ₂* c/n; And the total arm length of whole interferometer guiding fiber is: L3=t ₃* c/n.Wherein n is an optical fibre refractivity, and c is the light velocity in the vacuum.

At this moment, detector PD1 output signal is:

Detector PD2 output signal is:

By formula (5) and (6) as can be known, free poor τ between signal x (t) and the y (t), and also the position of τ and disturbing signal is linear:

$\mathrm{\&tau;}={\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="A20081011701700141.png"\; state="\{\{state\}\}">t</figure-callout>}}_2+t_3-{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="A20081011701700141.png"\; state="\{\{state\}\}">t</figure-callout>}}_1$

$=\frac{(\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20081011701700141.png"\; state="\{\{state\}\}">L</figure-callout>}2+L3-L1)\&times;n}{c}$

$=\frac{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="A20081011701700142.png"\; state="\{\{state\}\}">L</figure-callout>}3\&times;n}{c}+\frac{(L2-L1)\&times;n}{c}---\left(7\right)$

Only require like this mistiming τ between signal x (t) and the y (t), just can obtain the position of disturbance.Specifically can try to achieve disturbing signal by formula (7) apart from the position L1 of coupling mechanism B is:

L1＝L2+L3-τ·c/n (8)

Formula (8) also can be expressed as:

$\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20081011701700141.png"\; state="\{\{state\}\}">L</figure-callout>}1=\frac{(\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20081011701700141.png"\; state="\{\{state\}\}">L</figure-callout>}1+\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20081011701700141.png"\; state="\{\{state\}\}">L</figure-callout>}2+L3)-\mathrm{\&tau;}\&CenterDot;c/n}{2}---\left(9\right)$

Wherein, be the total length of whole optical fiber (L1+L2+L3), be a constant; And mistiming τ can be obtained by the relation between signal x (t) and the y (t), like this by monitoring output signal x (t) that disturbing signal produced and the relation between the y (t), just can accurately orient the position of disturbing signal, and this disturbing signal is analyzed accordingly.

But in the implementation procedure of above technical scheme, if the Mach-Zehnder interferometer is to adopt single-mode fiber because the single-mode fiber transmission is the linearly polarized mode of two quadratures, and in fact in the single-mode fiber with these two refractive index ns that linearly polarized mode is corresponding _xAnd n _yAnd unequal, so just produced birefringent phenomenon.When optical fiber micro-bending, distortion and environment temperature etc. change, the refractive index n of two linearly polarized mode correspondences of Optical Fiber Transmission _xAnd n _yChange thereupon yet, thereby caused that variation has taken place for Mach-Zehnder interferometer signal arm or reference arm output polarization state of light, two-beam just is not to interfere fully when interfering like this, thereby the signal visibility V after causing interfering changes between 0～1; The phase place of interfering the back signal simultaneously also can be subjected to the influence of polarization state, light source and environment and cause that thereby phase of output signal changes the position calculation error that causes, and this also can cause very big influence to the performance of system.

This shows, implementation according to prior art, owing to interfere the visibility of back signal to change, the amplitude instability that will cause output signal, the signal of amplitude stability is provided therefore can not for follow-up judgement, has influenced the identification and the judgement of signal, make that the rate of failing to report of system and false alarm rate are higher, and the feedback control procedure of existing system is complicated, and the Operation and Maintenance cost is also higher.

Summary of the invention

Embodiment of the present invention technical matters to be solved is to provide a kind of optical fiber perimeter alarm method and device of realizing anti-polarization decay, can be by the feedback polarization control technology, stablize the visibility of light path output, for the identification of signal provides stable light path output signal, the feedback control procedure of simultaneity factor is more simplified, and has reduced the Operation and Maintenance cost of system.

Embodiment of the present invention provides a kind of optical fiber perimeter alarm method of realizing anti-polarization decay, comprising:

The modulation signal that passes through to be produced carries out phase modulation (PM) to optical path signal, and the optical path signal after the phase modulation (PM) is exported;

Obtain the change information of the optical path signal of described output, control the polarization state that Polarization Controller comes the FEEDBACK CONTROL light signal according to described change information;

Described Polarization Controller is arranged on one road sensor fibre of Mach-Zehnder interferometer, by the input polarization of described Polarization Controller FEEDBACK CONTROL one road Mach-Zehnder interferometer, adjusts this road output light path signal.

Described method also comprises:

When needs are controlled another road output light path signal,, adjust the visibility of this road output light path signal by the input polarization on this road sensor fibre of described Polarization Controller FEEDBACK CONTROL.

Described method also comprises:

Output light path signal after the phase modulation (PM) is carried out demodulation process, the inconsistent and position calculation error that causes of the optical path signal phase place of eliminating output.

The described modulation signal that passes through to be produced carries out phase modulation (PM) to optical path signal, specifically comprises:

The modulation signal that is produced is loaded to light source, modulate, realize phase modulation (PM) optical path signal by optical frequency to described light source.

The described modulation signal that passes through to be produced carries out phase modulation (PM) to optical path signal, specifically comprises:

The modulation signal that is produced is loaded to phase-modulator PZT, optical path signal is carried out phase modulation (PM) by described phase-modulator PZT.

Embodiment of the present invention also provides a kind of optical fiber perimeter alarm device of realizing anti-polarization decay, and described device comprises:

The signal modulation module, the modulation signal that is used for passing through to be produced carries out phase modulation (PM) to optical path signal, and the optical path signal after the phase modulation (PM) is exported;

The polarization state feedback control module is used to obtain the change information of the optical path signal of output, the polarization state of coming the FEEDBACK CONTROL light signal according to described change information control Polarization Controller; Described Polarization Controller is arranged on one road sensor fibre of Mach-Zehnder interferometer, by the input polarization of described Polarization Controller FEEDBACK CONTROL one road Mach-Zehnder interferometer, adjusts this road output light path signal.

Also comprise in the described device:

The signal demodulation module is used for the output light path signal after the phase modulation (PM) is carried out demodulation process, the inconsistent and position calculation error that causes of the optical path signal phase place of eliminating output.

Described signal modulation module is specially:

Light signal modulation module, the modulation signal that is used for being produced load to light source, modulate by the optical frequency to described light source, realize the phase modulation (PM) to optical path signal.

In addition, described signal modulation module is specially:

PZT signal modulation module, the modulation signal that is used for being produced loads to phase-modulator PZT, by described phase-modulator PZT optical path signal is carried out phase modulation (PM).

Described device is arranged at the signal processing of optical fiber perimeter alarm system, or is arranged to independent functional entity.

By the above-mentioned technical scheme that provides as can be seen, the modulation signal that at first passes through to be produced carries out phase modulation (PM) to optical path signal, and the optical path signal after the phase modulation (PM) is exported; Obtain the change information of this output light path signal, control the polarization state that Polarization Controller comes the FEEDBACK CONTROL light signal according to this change information; The Polarization Controller here is arranged on one road sensor fibre of Mach-Zehnder interferometer, by the input polarization of described Polarization Controller FEEDBACK CONTROL one road Mach-Zehnder interferometer, adjusts this road output light path signal.Like this, just can stablize the visibility that light path is exported by the feedback polarization control technology, for the identification of signal provides stable light path output signal, the feedback control procedure of simultaneity factor is more simplified, and has reduced the Operation and Maintenance cost of system.

Description of drawings

Fig. 1 is for adopting system's location structure synoptic diagram of bidirectional Mach-Zehnder interferometer scheme;

Fig. 2 is the schematic flow sheet of method that embodiment of the present invention provides;

Fig. 3 is the structural representation of the described phase modulation (PM) of embodiment of the present invention;

Fig. 4 is another structural representation of the described phase modulation (PM) of embodiment of the present invention;

Fig. 5 is the structural representation of embodiment of the present invention institute generator.

Embodiment

Embodiment of the present invention provides a kind of optical fiber perimeter alarm method and device of realizing anti-polarization decay.At first obtain change information, then the polarization state of coming the FEEDBACK CONTROL light signal according to described change information control Polarization Controller through the output light path signal after the phase modulation (PM); The Polarization Controller here is set on a certain road sensor fibre of Mach-Zehnder interferometer, come the input polarization of this road Mach-Zehnder interferometer of FEEDBACK CONTROL by this Polarization Controller, thereby adjust the output light path signal on this road, for the identification of signal provides stable amplitude signal, finally realize high stable, high-precision optical fiber perimeter alarm system, improved the performance of system; The feedback control procedure of simultaneity factor is more simplified, and has also further reduced the Operation and Maintenance cost of system.

For better describing embodiment of the present invention, now in conjunction with the accompanying drawings the specific embodiment of the present invention is described, be illustrated in figure 2 as the schematic flow sheet of the described implementation method of embodiment of the present invention, described implementation method comprises:

Step 21: the modulation signal that passes through to be produced carries out phase modulation (PM) to optical path signal, and the optical path signal after the phase modulation (PM) is exported.

Specifically, can produce phase modulated signal, utilize the phase modulated signal that is produced that optical path signal is carried out the respective phase modulation then, again the optical path signal after the phase modulation (PM) be exported normally by specific functional module.

Above-mentioned specific functional module can be arranged on the signal processing of optical fiber perimeter alarm system, produces phase modulated signal by this specific functional module.And can comprise following several to the mode that optical path signal carries out phase modulation (PM):

The structural representation of phase modulation (PM) as shown in Figure 3 comprises signal processing, panalarm, light source 3, detector 1, detector 2, coupling mechanism 4, coupling mechanism 7, coupling mechanism 13, guiding fiber 5, guiding fiber 6, guiding fiber 9, guiding fiber 12, sensor fibre 10, sensor fibre 11, Polarization Controller 8 among the figure.The input light that light source 3 is produced interferes when promptly sensor fibre 10 and 11 backs arrive coupling mechanism 13 through two arms of coupling mechanism 4,7 to interferometer, forms a clockwise Mach-Zehnder interferometer, and the signal after the interference is received by detector 1 behind guiding fiber 9; Simultaneously, another Lu Guangzhi coupling mechanism 13 through coupling mechanism 4 is told interferes when arriving coupling mechanism 7 behind sensor fibre 10 and 11, also forms a counterclockwise Mach-Zehnder interferometer, and the signal after the interference is received by detector 2 behind guiding fiber 5; Above-mentioned detector 1 and 2 light signals that received can pass to signal processing and handle accordingly; Signal processing part branch exports corresponding signal to panalarm according to result, carries out successor operation by panalarm.

In the present embodiment: functional module specific in the signal processing produces modulation signal; Then the modulation signal that is produced is loaded to light source 3, modulate the optical frequency of described light source 3 at 3 places at light source, realizes phase modulation (PM) to optical path signal with this.

In addition, can also realize phase modulation (PM) to optical path signal by phase-modulator PZT, be illustrated in figure 4 as another structural representation of phase modulation (PM), among the figure: functional module specific in the signal processing produces modulation signal; Then the modulation signal that is produced is loaded to phase-modulator 14, carry out phase modulation (PM) by 14 pairs of optical path signals of described phase-modulator.The phase-modulator 14 here can be set in place in the indoor comprehensive treatment equipment of optical fiber perimeter alarm system monitoring together with guiding fiber, also guiding fiber and phase-modulator 14 can be arranged on outside the Control Room, by tele-control system phase-modulator 14 is controlled, also can be realized optical path signal is carried out the function of phase modulation (PM).

Step 22: obtain the change information of output light path signal, control the polarization state that Polarization Controller comes the FEEDBACK CONTROL light signal according to this change information.

Specifically, at first obtain change information through the output light path signal after the above-mentioned phase modulation (PM), because this change information can reflect the variation of visibility, so come the FEEDBACK CONTROL Polarization Controller by surveying this change information, just can utilize this Polarization Controller to adjust described output light path signal, it is stable that this output light path signal is in, thereby reach the purpose of stablizing visibility.

Above-mentioned Polarization Controller is arranged on a certain road sensor fibre of Mach-Zehnder interferometer, input polarization by this this road Mach-Zehnder interferometer of Polarization Controller FEEDBACK CONTROL, adjust the output light path signal on this road, thereby adjust the output light path signal on this road.

For instance, in Fig. 3 and 4 described structural representations, Polarization Controller 8 just is arranged on the sensor fibre 11 of one road Mach-Zehnder interferometer.Like this, this Polarization Controller 8 just can be used for the input polarization of this road Mach-Zehnder interferometer of FEEDBACK CONTROL.When needs are controlled the output light path signal on another road, can also adjust the visibility of this road output light path signal by the input polarization on an amount of this road sensor fibre of adjustment of this Polarization Controller.That is to say that in fact this Polarization Controller can be adjusted simultaneously to the input polarization on the two-way sensor fibre, the feedback control procedure of system is just more simplified like this, has also further reduced the Operation and Maintenance cost of system.

In addition,, can also carry out corresponding demodulation process, eliminate the inconsistent and position calculation error that causes of output light path signal phase with this to the output light path signal after the phase modulation (PM) with after the optical path signal after the phase modulation (PM) output.Specifically, carrying out after above step carries out phase modulation (PM) to optical path signal the output light path signal after the receiving phase modulation; Optical path signal to this output carries out corresponding demodulation process then, obtain because the phase differential between the two sensor fibre transmitting optical signals that external disturbance causes, and eliminate because the optical path signal phase place of output is inconsistent the error that external environment variation just and internal system parameter drift are brought.

Embodiment of the present invention also provides a kind of optical fiber perimeter alarm device of realizing anti-polarization decay, be illustrated in figure 5 as the structural representation of described device, described device comprises signal modulation module and polarization state feedback control module, the modulation signal that wherein said signal modulation module is used for passing through to be produced carries out phase modulation (PM) to optical path signal, and the optical path signal after the phase modulation (PM) is exported; The mode of concrete modulation is seen described in the said method embodiment.

Described polarization state feedback control module is used to obtain the change information of the optical path signal of output, then the polarization state of coming the FEEDBACK CONTROL light signal according to described change information control Polarization Controller.Wherein, Polarization Controller described here is arranged on one road sensor fibre of Mach-Zehnder interferometer, by the input polarization of described Polarization Controller FEEDBACK CONTROL one road Mach-Zehnder interferometer, adjusts this road output light path signal.

In addition, also comprise the signal demodulation module in described device, described signal demodulation module is used for the output light path signal after the phase modulation (PM) is carried out demodulation process, the inconsistent and position calculation error that causes of the optical path signal phase place of eliminating output.

Above-described signal modulation module is specifically as follows the light signal modulation module, and the modulation signal that described light signal modulation module is used for being produced loads to light source, modulates by the optical frequency to described light source, realizes the phase modulation (PM) to optical path signal.

Optionally, above-described signal modulation module is specifically as follows PZT signal modulation module, the modulation signal that described PZT signal modulation module is used for being produced loads to phase-modulator PZT, by described phase-modulator PZT optical path signal is carried out phase modulation (PM).Described phase-modulator PZT can be placed in together with guiding fiber and be arranged in the indoor comprehensive treatment equipment of optical fiber perimeter alarm system monitoring, also guiding fiber and phase-modulator PZT can be arranged on outside the Control Room, by tele-control system phase-modulator PZT is controlled, realize phase modulation (PM) bidirectional Mach-Ceng Deyi.

Above-described device can integratedly be arranged in the signal processing of optical fiber perimeter alarm system, also can be arranged to independent functional entity, maintains the connection with the signal processing of optical fiber perimeter alarm system.

In sum, embodiments of the present invention can stablize the visibility that light path is exported by the feedback polarization control technology, for the identification of signal provides stable light path output signal, the feedback control procedure of simultaneity factor is more simplified, and has reduced the Operation and Maintenance cost of system.

The above; only be the preferable embodiment of the present invention; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the embodiment of the invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.

Claims (10)

1, a kind of optical fiber perimeter alarm method of realizing anti-polarization decay is characterized in that:

The modulation signal that passes through to be produced carries out phase modulation (PM) to optical path signal, and the optical path signal after the phase modulation (PM) is exported;

Obtain the change information of the optical path signal of described output, control the polarization state that Polarization Controller comes the FEEDBACK CONTROL light signal according to described change information;

Described Polarization Controller is arranged on one road sensor fibre of Mach-Zehnder interferometer, by the input polarization of described Polarization Controller FEEDBACK CONTROL one road Mach-Zehnder interferometer, adjusts this road output light path signal.

2, the method for claim 1 is characterized in that, described method also comprises:

When needs are controlled another road output light path signal,, adjust the visibility of this road output light path signal by the input polarization on this road sensor fibre of described Polarization Controller FEEDBACK CONTROL.

3, the method for claim 1 is characterized in that, after with the output of the optical path signal after the phase modulation (PM), described method also comprises:

Output light path signal after the phase modulation (PM) is carried out demodulation process, the inconsistent and position calculation error that causes of the optical path signal phase place of eliminating output.

4, the method for claim 1 is characterized in that, the described modulation signal that passes through to be produced carries out phase modulation (PM) to optical path signal, specifically comprises:

The modulation signal that is produced is loaded to light source, modulate, realize phase modulation (PM) optical path signal by optical frequency to described light source.

5, the method for claim 1 is characterized in that, the described modulation signal that passes through to be produced carries out phase modulation (PM) to optical path signal, specifically comprises:

The modulation signal that is produced is loaded to phase-modulator PZT, optical path signal is carried out phase modulation (PM) by described phase-modulator PZT.

6, a kind of optical fiber perimeter alarm device of realizing anti-polarization decay is characterized in that described device comprises:

The signal modulation module, the modulation signal that is used for passing through to be produced carries out phase modulation (PM) to optical path signal, and the optical path signal after the phase modulation (PM) is exported;

The polarization state feedback control module is used to obtain the change information of the optical path signal of output, the polarization state of coming the FEEDBACK CONTROL light signal according to described change information control Polarization Controller; Described Polarization Controller is arranged on one road sensor fibre of Mach-Zehnder interferometer, by the input polarization of described Polarization Controller FEEDBACK CONTROL one road Mach-Zehnder interferometer, adjusts this road output light path signal.

7, as device as described in the claim 6, it is characterized in that, also comprise in the described device:

The signal demodulation module is used for the output light path signal after the phase modulation (PM) is carried out demodulation process, the inconsistent and position calculation error that causes of the optical path signal phase place of eliminating output.

8, device as claimed in claim 6 is characterized in that, described signal modulation module is specially:

Light signal modulation module, the modulation signal that is used for being produced load to light source, modulate by the optical frequency to described light source, realize the phase modulation (PM) to optical path signal.

9, device as claimed in claim 6 is characterized in that, described signal modulation module is specially:

PZT signal modulation module, the modulation signal that is used for being produced loads to phase-modulator PZT, by described phase-modulator PZT optical path signal is carried out phase modulation (PM).

10, as one of them described device of claim 6-9, it is characterized in that described device is arranged at the signal processing of optical fiber perimeter alarm system, or be arranged to independent functional entity.

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