阅读说明：本技术 一种单轴Sagnac干涉仪相位偏置控制装置及方法 (A kind of single shaft Sagnac interferometer phase bias controller and method ) 是由 胡肖潇 姚飞 鞠涛 蒋灵芝 于 2019-09-19 设计创作，主要内容包括：本发明公开一种单轴Sagnac干涉仪相位偏置控制装置及方法,该装置包括光脉冲发射机、光脉冲接收机、单轴Sagnac光纤干涉仪、传感光缆、光反射器和偏振控制器；光脉冲发射机、偏振控制器、单轴Sagnac光纤干涉仪、传感光缆、和光反射器依次连接,单轴Sagnac光纤干涉仪还连接光脉冲接收机；光脉冲发射机用于产生脉冲光信号,偏振控制器用于改变输入的光信号的偏振态,传感光缆用于传感振动信号,光反射器用于反射光信号,单轴Sagnac光纤干涉仪用于使传感光缆中散射和反射回来的信号产生干涉,光脉冲接收机用于将接收到的脉冲光信号转换为电信号。本发明能够使单轴Sagnac干涉仪的相位偏置于期望值附近,从而获得较好的小信号响应灵敏度。(It includes optical pulse transmitter, light pulse receiver, single shaft Sagnac fibre optic interferometer, sensing optic cable, reflective optical system and Polarization Controller that the present invention, which discloses a kind of single shaft Sagnac interferometer phase bias controller and method, the device,；Optical pulse transmitter, Polarization Controller, single shaft Sagnac fibre optic interferometer, sensing optic cable and reflective optical system are sequentially connected, and uniaxial Sagnac fibre optic interferometer is also connected with light pulse receiver；Optical pulse transmitter is for generating pulsed optical signals, Polarization Controller for changing the optical signal of input polarization state, sensing optic cable is used for sense vibration signal, reflective optical system is used for reflected light signal, for making scattering and reflected signal in sensing optic cable generate interference, light pulse receiver is used to the pulsed optical signals received being converted to electric signal uniaxial Sagnac fibre optic interferometer.The present invention can make the phase bias of uniaxial Sagnac interferometer near desired value, to obtain preferable small-signal response sensitivity.)

1. a kind of single shaft Sagnac interferometer phase bias controller, which is characterized in that including optical pulse transmitter, light pulse Receiver, single shaft Sagnac fibre optic interferometer, sensing optic cable, reflective optical system and Polarization Controller；

The optical pulse transmitter, Polarization Controller, single shaft Sagnac fibre optic interferometer, sensing optic cable and reflective optical system are successively Connection, the single shaft Sagnac fibre optic interferometer are also connected with the light pulse receiver；

The optical pulse transmitter for generating pulsed optical signals, the Polarization Controller for changing input optical signal it is inclined Polarization state, the sensing optic cable are used for sense vibration signal, and the reflective optical system is used for reflected light signal, the single shaft Sagnac light For making scattering and reflected signal in the sensing optic cable generate interference, the light pulse receiver is used for fine interferometer The pulsed optical signals received are converted into electric signal.

2. single shaft Sagnac interferometer phase bias controller according to claim 1, which is characterized in that the single shaft Sagnac fibre optic interferometer includes 2x2 optical splitter, 1x2 optical splitter and optical-fibre delay line.

3. single shaft Sagnac interferometer phase bias controller according to claim 1, which is characterized in that the single shaft Sagnac fibre optic interferometer includes 3x3 optical splitter, 1x2 optical splitter and optical-fibre delay line.

4. single shaft Sagnac interferometer phase bias controller according to claim 1, which is characterized in that the smooth arteries and veins Rush transmitter sending is single polarization, periodic optical pulse signal, and the light source type used is F-PLD or SLD, operation wavelength model It encloses for 1230nm~1650nm.

5. single shaft Sagnac interferometer phase bias controller according to claim 1, which is characterized in that the sensing Optical cable is single mode optical fiber.

6. single shaft Sagnac interferometer phase bias controller according to claim 4, which is characterized in that the smooth arteries and veins The period value range for rushing the light pulse signal of transmitter transmitting is 1 × 10²S~2 × 10 μ³μs。

7. single shaft Sagnac interferometer phase bias controller according to claim 4, which is characterized in that the smooth arteries and veins Periodic quantity is rushed greater than (L1+L2)/50, wherein L1 is the length of sensing optic cable, and L2 is the length of optical-fibre delay line.

8. single shaft Sagnac interferometer phase bias controller according to claim 1, which is characterized in that the light is anti- The emissivity of emitter is greater than -25dB.

9. a kind of single shaft Sagnac interferometer phase bias control method is applied to the described in any item single shafts of claim 1-8 The biasing control of Sagnac interferometer phase, comprising:

The single polarization pulse signal of optical pulse transmitter transmitting is inputted into single shaft Sagnac fibre optic interferometer；

Obtain the reflected light pulse signal range value of the reflective optical system；

The first phase biasing of the single shaft Sagnac fibre optic interferometer is calculated according to the signal amplitude value；

Judge the first phase biasing whether beyond the first setting range；

If it is not, then the phase bias of the single shaft Sagnac fibre optic interferometer enters lock state；

If so, so that the angle of polarization of the single polarization pulse signal is changed 1 stepping angle towards positive direction using Polarization Controller, Obtain second phase biasing；

Judge whether second phase biasing is less than first phase biasing and the first setting range at a distance from the first setting range Distance；

If so, continuing to change the angle of polarization of the single polarization pulse signal towards positive direction, going to step, it is described to obtain The reflected light pulse signal range value of reflective optical system, until obtained phase bias enters in first setting range；

If it is not, then so that the angle of polarization of the single polarization pulse signal is changed 1 stepping angle towards negative direction using Polarization Controller, It gos to step and obtains the reflected light pulse signal range value of the reflective optical system, until obtained phase bias enters institute It states in the first setting range.

Technical field

The present invention relates to technical field of optical fiber sensing, bias and control more particularly to a kind of single shaft Sagnac interferometer phase Device and method.

Background technique

Using distributed fiber-optic sensor come detecting optical cable vibration when, frequently with uniaxial Sagnac fibre optic interferometer (also by Referred to as unbalanced Mach-Zehnder interferometer) structure.Simplest single shaft Sagnac fibre optic interferometer structure is by one group of light point Road device and one section of optical-fibre delay line are constituted.In general, this group of optical splitter can be the 2x2 optical splitter and 1 of 1 uniform splitting ratio The 1x2 optical splitter of a uniform splitting ratio combines, and the 3x3 optical splitter for being also possible to 1 uniform splitting ratio and 1 are uniformly divided The 1x2 optical splitter of ratio combines.If combined using 2x2 optical splitter and 1x2 optical splitter, uniaxial Sagnac fibre optic interferometer Theoretical static phase be π or 0；If combined using 3x3 optical splitter and 1x2 optical splitter, uniaxial Sagnac fiber optic interferometric The theoretical static phase of instrument is 2 π/3 or 4 π/3.In addition to this, since the additive phase of optical splitter can also be many by temperature etc. Extraneous factor influences, and the static phase of uniaxial Sagnac fibre optic interferometer is in continually changing state, for two beams Coherent light, interference signal amplitude and phase relation are cosine function, if static phase is near π or 0, in small letter Response in the case of number can be very poor.Therefore ideal in order to which preferable signal response sensitivity can be obtained under small signal condition Static phase should be biased at pi/2.Currently, the method master of the static phase of single shaft Sagnac fibre optic interferometer is solved the problems, such as If being needed using to phase-modulator, volume is big, at high cost, and scheme is complex using phase modulation method.

Summary of the invention

The object of the present invention is to provide a kind of single shaft Sagnac interferometer phase bias controller and methods, can make list The phase bias of axis Sagnac interferometer is near desired value, to obtain preferable small-signal response sensitivity.

To achieve the above object, the present invention provides the following technical scheme that

A kind of single shaft Sagnac interferometer phase bias controller, including optical pulse transmitter, light pulse receiver, list Axis Sagnac fibre optic interferometer, sensing optic cable, reflective optical system and Polarization Controller；

The optical pulse transmitter, Polarization Controller, single shaft Sagnac fibre optic interferometer, sensing optic cable and reflective optical system It is sequentially connected, the single shaft Sagnac fibre optic interferometer is also connected with the light pulse receiver；

The optical pulse transmitter for generating pulsed optical signals, the Polarization Controller for changing input optical signal Polarization state, the sensing optic cable be used for sense vibration signal, the reflective optical system be used for reflected light signal, the single shaft For making scattering and reflected signal in the sensing optic cable generate interference, the light pulse connects Sagnac fibre optic interferometer Receipts machine is used to the pulsed optical signals received being converted to electric signal.

Optionally, the single shaft Sagnac fibre optic interferometer includes 2x2 optical splitter, 1x2 optical splitter and optical-fiber time-delay Line.

Optionally, the single shaft Sagnac fibre optic interferometer includes 3x3 optical splitter, 1x2 optical splitter and optical-fiber time-delay Line.

Optionally, what the optical pulse transmitter issued is single polarization, periodic optical pulse signal, the light source type of use For F-PLD or SLD, operating wavelength range is 1230nm~1650nm.

Optionally, the sensing optic cable is single mode optical fiber.

Optionally, the period value range of the light pulse signal of the optical pulse transmitter transmitting is 1 × 10²S~2 μ × 10³μs。

Optionally, the light pulse periodic quantity is greater than (L1+L2)/50, wherein L1 is the length of sensing optic cable, and L2 is light The length of fine line of time delay.

Optionally, the emissivity of the reflective optical system is greater than -25dB.

A kind of single shaft Sagnac interferometer phase bias control method, applied to the uniaxial Sagnac interferometer phase Biasing control, comprising:

The single polarization pulse signal of optical pulse transmitter transmitting is inputted into single shaft Sagnac fibre optic interferometer；

Obtain the reflected light pulse signal range value of the reflective optical system；

The first phase biasing of the single shaft Sagnac fibre optic interferometer is calculated according to the signal amplitude value；

Judge the first phase biasing whether beyond the first setting range；

If it is not, then the phase bias of the single shaft Sagnac fibre optic interferometer enters lock state；

If so, making the angle of polarization of the single polarization pulse signal change 1 step towards positive direction using Polarization Controller Into angle, second phase biasing is obtained；

Judge whether second phase biasing is less than first phase biasing and the first setting model at a distance from the first setting range The distance enclosed；

If so, continuing to change the angle of polarization of the single polarization pulse signal towards positive direction, go to step acquisition The reflected light pulse signal range value of reflective optical system, until obtained phase bias enters first setting range It is interior；

If it is not, then making the angle of polarization of the single polarization pulse signal change 1 step towards negative direction using Polarization Controller It into angle, gos to step and obtains the reflected light pulse signal range value of the reflective optical system, until obtained phase bias Into in first setting range.

The specific embodiment provided according to the present invention, the invention discloses following technical effects:

The present invention changes the polarization state for being input to the optical signal of uniaxial Sagnac interferometer by Polarization Controller, makes single shaft The phase bias of Sagnac interferometer is near desired value, to obtain preferable small-signal response sensitivity.

Detailed description of the invention

It in order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, below will be to institute in embodiment Attached drawing to be used is needed to be briefly described, it should be apparent that, the accompanying drawings in the following description is only some implementations of the invention Example, for those of ordinary skill in the art, without creative efforts, can also obtain according to these attached drawings Obtain other attached drawings.

Fig. 1 is the optic cable vibration sensing arrangement schematic diagram of existing single shaft Sagnac fibre optic interferometer；

Fig. 2 is single shaft Sagnac interferometer phase bias controller structural schematic diagram of the invention；

Fig. 3 is single shaft Sagnac interferometer phase bias control method flow chart of the invention.

Specific embodiment

Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other Embodiment shall fall within the protection scope of the present invention.

The object of the present invention is to provide a kind of single shaft Sagnac interferometer phase bias controller and methods, can make list The phase bias of axis Sagnac interferometer is near desired value, to obtain preferable small-signal response sensitivity.

In order to make the foregoing objectives, features and advantages of the present invention clearer and more comprehensible, with reference to the accompanying drawing and specific real Applying mode, the present invention is described in further detail.

The principle of the present invention is:

Usual single shaft Sagnac fibre optic interferometer is by the 2x2 optical splitter of 1 uniform splitting ratio, 1 uniform splitting ratio The 3x3 optical splitter of 1x2 optical splitter and an optical-fibre delay line composition or 1 uniform splitting ratio, 1 uniformly light splitting The 1x2 optical splitter of ratio and an optical-fibre delay line composition.The side the A port Liang Ge of 2x2 (or 3x3) optical splitter connects light respectively Transmitter and photoreceiver；The port of the side B 1 of 2x2 (or 3x3) optical splitter connects optical-fibre delay line, is then connected to 1x2 light again 1 port of the side splitter A；The port of the side B 1 of 2x2 (or 3x3) optical splitter is connected to by optical fiber stub (short fiber) 1 port of the side 1x2 optical splitter A；1x2 optical splitter B side ports connect sensing optic cable.

When work, the optical signal of optical sender transmitting enters back into sensing optic cable after entering uniaxial Sagnac fibre optic interferometer, And it is reflected by the reflective optical system of sensing optic cable end；Backscatter signal and reflection signal in sensing optic cable enter single shaft Sagnac fibre optic interferometer enters back into photoreceiver.Uniaxial Sagnac fibre optic interferometer is used to make the back scattering in sensing optic cable Signal and reflection signal interfere after fibre optic interferometer.

The device of the invention and tradition are using the systematic differences of single shaft Sagnac fibre optic interferometer: optical sender it is defeated Optical signals are the pulsed optical signals of single polarization state, and increase by one between optical sender and single shaft Sagnac fibre optic interferometer A Polarization Controller.

Specific method is: being to be used as single shaft Sagnac fibre optic interferometer using the pulsed optical signals periodically singly polarized first Input signal；At photoreceiver, three light pulses reflected to the reflective optical system of sensing optic cable end are received, Amplification, sampling and digital processing, and single shaft Sagnac fibre optic interferometer is calculated according to the signal amplitude value of these three light pulses Phase bias state；Then believed using the additive phase and input light of the optical splitter in single shaft Sagnac fibre optic interferometer structure Number polarization state have and be related to this characteristic, the polarization state of input optical signal is controlled by Polarization Controller, makes uniaxial Sagnac light The static phase of fine interferometer is offset to always near desired value (such as pi/2).

The invention has the advantages that using the device of better simply control method and low cost, so that it may so that single shaft Sagnac The phase bias of fibre optic interferometer is located near desired value, to obtain preferable optic cable vibration detectivity.

It is the optic cable vibration sensing arrangement schematic diagram of current uniaxial Sagnac fibre optic interferometer shown in Fig. 1.The list Axis Sagnac fibre optic interferometer include the 2x2 optical splitter of 1 uniform splitting ratio, 1 uniform splitting ratio 1x2 optical splitter and Optical-fibre delay line, wherein optical sender and photoreceiver can be pulse, be also possible to continuous.

Shown in Fig. 2 is single shaft Sagnac interferometer phase bias controller structural schematic diagram of the invention, such as Fig. 2 institute Show, a kind of single shaft Sagnac interferometer phase bias controller includes 1 optical pulse transmitter, 1 light pulse receiver, 1 A single shaft Sagnac fibre optic interferometer, sensing optic cable, 1 reflective optical system and 1 Polarization Controller.

What optical pulse transmitter issued is single polarization, periodic optical pulse signal, and light pulse signal first passes through Polarization Control Then device enters sensing optic cable using uniaxial Sagnac fibre optic interferometer, sensing optic cable end connects a reflective optical system, and light is anti- The reflection signal that emitter generates enters light pulse receiver after returning to single shaft Sagnac fibre optic interferometer, is then connect by light pulse The amplification of receipts machine, D/A switch, Digital Signal Processing.

Different according to path experienced in above-mentioned optical signal traveling process, light pulse signal is divided into four tunnels:

1st tunnel, optical sender-Polarization Controller -2x2 optical splitter-optical-fibre delay line -1x2 optical splitter-quilt Survey optical fiber-reflective optical system-tested optical fiber -1x2 optical splitter-optical-fibre delay line -2x2 optical splitter-photoreceiver；The 2 tunnels, optical sender-Polarization Controller -2x2 optical splitter-optical-fibre delay line -1x2 optical splitter-tested optical fiber-light Reflector-tested optical fiber-short the connecting line of 1x2 optical splitter-optical fiber -2x2 optical splitter-photoreceiver；3rd tunnel, light hair Penetrate machine-Polarization Controller-short connecting line of 2x2 optical splitter-optical fiber -1x2 optical splitter-tested optical fiber-light reflection Device-tested optical fiber -1x2 optical splitter-optical-fibre delay line -2x2 optical splitter-photoreceiver；4th tunnel, optical sender- Polarization Controller-short the connecting line of 2x2 optical splitter-optical fiber -1x2 optical splitter-tested optical fiber-reflective optical system-is tested Optical fiber-short the connecting line of 1x2 optical splitter-optical fiber -2x2 optical splitter-photoreceiver.

Wherein the 2nd is identical with the 3rd the walked distance of road signal, but direction is different, and the optical path difference of this two paths of signals is believed less than light Number coherence length, interference is generated at uniaxial Sagnac fibre optic interferometer output, which can be used for detecting light Cable vibration；1st and the 4th the walked distance of road signal is not identical, and optical signal is by optical-fibre delay line twice all the way, and separately and all the way light is believed Number then without passing through optical-fibre delay line.

After the reflective optical system that optical fiber connector is connect reflects pulsed optical signals, due to uniaxial Sagnac fiber optic interferometric There is the optical-fibre delay line of one section of regular length in instrument, once there are Fresnel reflections for the certain point in fibre circuit, from light emitting Machine sets out, and the distance that the optical signal by walking the 4th path is passed through is most short, and first arrival photoreceiver walks the light in the 1st path The distance longest that signal is passed through, the last one reaches photoreceiver, walks the path length that the optical signal in the 2nd, 3 paths is passed through In the length of above-mentioned two distance, second arrival photoreceiver, so light pulse receiver receives three reflection letters Number light pulse.

If the length long enough of optical-fibre delay line, the signal for the reflective optical system reflection that sensing optic cable end is connect returns to light It does not overlap when pulse receiver, three pulse signals is obtained in light pulse receiver, defined by received time sequencing Are as follows: first pulse signal, second pulse signal and third pulse signal.In these three the reflection signal light arteries and veins received In punching, optical-fibre delay line is not passed through in the path that first light pulse is walked, and path is most short, reaches at first；Third light pulse The path walked is by optical-fibre delay line, path longest finally reach twice；The path that second light pulse is walked only passes through one Secondary optical-fibre delay line, second light pulse are obtained after the light pulse signal interference that two-way path is identical, contrary, are contained There is optic cable vibration information.

In light pulse receiver received signal, if the amplitude of first pulse signal is A1, second pulse letter Number amplitude be A2, the amplitude of third pulse signal is A3, they have following relationship:

A2=A1+A3+2 × (A1 × A3) 0.5 × COS (θ)

The wherein phase difference of light pulse signal θ identical, contrary for two-way path.

By A1, A2, A3, the size of θ can be obtained, that is to say, that can by measure three pulse signals amplitude come Calculate the static phase of single shaft Sagnac fibre optic interferometer.

It is carried out in the optic cable vibration sensing arrangement that the biasing of single shaft Sagnac interferometer phase controls of the invention, due to the Two light pulses contain optic cable vibration information, and the range value A2 obtained after sampling to it, which is formed by data, can be used to characterize biography Vibration suffered by sensing optical cable.

It no matter in single shaft Sagnac fibre optic interferometer is 2x2 optical splitter or 3x3 optical splitter, what is generated is attached Add the polarization state relationship of phase and input very big, uniaxial Sagnac fiber optic interferometric is calculated according to this characteristic in photoreceiver The static phase value of instrument, then adjusts Polarization Controller, so that the static phase value of single shaft Sagnac fibre optic interferometer reaches pre- The value of phase completes the phase bias control function of single shaft Sagnac fibre optic interferometer.

Fig. 3 is single shaft Sagnac interferometer phase bias control method flow chart of the invention, as shown in figure 3, a kind of single shaft Sagnac interferometer phase bias control method biases control applied to the uniaxial Sagnac interferometer phase, comprising:

Step 301: the single polarization pulse signal of optical pulse transmitter transmitting is inputted into single shaft Sagnac fibre optic interferometer；

Step 302: obtaining the reflected light pulse signal range value of the reflective optical system；

Step 303: being biased according to the first phase that the signal amplitude value calculates the single shaft Sagnac fibre optic interferometer；

Step 304: judging the first phase biasing whether beyond the first setting range；

Step 305: if it is not, then the phase bias of the single shaft Sagnac fibre optic interferometer enters lock state；

Step 306: if so, changing the angle of polarization of the single polarization pulse signal towards positive direction using Polarization Controller Become 1 stepping angle, obtains second phase biasing；

Step 307: judging whether second phase biasing is less than first phase biasing and the with the first setting range at a distance from The distance of one setting range；

Step 308: if so, continuing to change the angle of polarization of the single polarization pulse signal towards positive direction, jumping to Step 302 obtains the reflected light pulse signal range value of the reflective optical system, until described in obtained phase bias entrance In first setting range；

Step 309: if it is not, then changing the angle of polarization of the single polarization pulse signal towards negative direction using Polarization Controller Become 1 stepping angle, go to step the reflected light pulse signal range value of the 302 acquisitions reflective optical system, until obtaining Phase bias enter first setting range in.

It comprises the concrete steps that:

Optical pulse transmitter emits input signal of the single polarization pulse signal as single shaft Sagnac fibre optic interferometer；

At light pulse receiver, three light pulses reflected to sensing optic cable end-reflector carry out connecing retractable Greatly, sampling and digital processing, obtain the signal amplitude value of these three light pulses, are denoted as A1, A2, A3 respectively；

According to relational expression A2=A1+A3+2 × (A1 × A3) 0.5 × COS (θ), θ is that two-way path is identical, contrary The phase of light pulse signal, the i.e. phase of single shaft Sagnac fibre optic interferometer, are denoted as the first of uniaxial Sagnac fibre optic interferometer Phase bias；

If range (θ of the first phase biasing beyond setting of single shaft Sagnac fibre optic interferometer₀- a)~(θ₀+ a), it is fixed The phase bias of adopted single shaft Sagnac fibre optic interferometer is in non-locking state；It is inclined in the first phase of Sagnac fibre optic interferometer It sets under non-locking state, so that the angle of polarization of optical signal is changed 1 towards a direction (such as positive direction) using Polarization Controller Stepping angle gos to step and " according to relational expression A2=A1+A3+2 × (A1 × A3) 0.5 × COS (θ), calculates single shaft Sagnac light The phase theta of fine interferometer " obtains the second phase biasing of uniaxial Sagnac fibre optic interferometer；Then more uniaxial Sagnac light The change direction of the second phase biasing of fine interferometer；If the change that the second phase of single shaft Sagnac fibre optic interferometer biases It is the bias θ towards setting₀Close, continuing with Polarization Controller changes the angle of polarization of optical signal towards above-mentioned direction, and jumps It goes to step and " according to relational expression A2=A1+A3+2 × (A1 × A3) 0.5 × COS (θ), calculates single shaft Sagnac fibre optic interferometer Phase theta ", until obtained phase bias enters the range (θ of setting₀- b)~(θ₀+ b) within；If single shaft Sagnac optical fiber The change of the second phase biasing of interferometer is the bias θ for deviateing setting₀, then make the polarization of optical signal using Polarization Controller The opposite direction (such as negative direction) of angle towards above-mentioned a direction changes 1 stepping angle, and gos to step " according to relational expression A2= A1+A3+2 × (A1 × A3) 0.5 × COS (θ) calculates the phase theta of single shaft Sagnac fibre optic interferometer ", until obtained phase It is biased into the range (θ of setting₀- b)~(θ₀+ b) within；Once obtained phase bias enters the range (θ of setting₀- b)~ (θ₀+ b) in, then stop the angle of polarization for changing optical signal, the phase bias of uniaxial Sagnac fibre optic interferometer enters lock state； Wherein, π/3 > a > b > π/30.

Running parameter used in the device of the invention:

Light source type used by the optical pulse transmitter be F-PLD or SLD, operating wavelength range be 1230nm~ 1650nm。

Sensing optic cable uses communication single mode optical fiber.

The value range of the light pulse cycle T of transmitting is 1 × 10²S~2 × 10 μ³μ s, light pulse period value need to consider It is greater than (L1+L2)/50 to the length L1 of the sensing optic cable and length L2 of optical-fibre delay line, light pulse periodic quantity T, the list of L1, L2 Position is m, and the unit of T is μ s.

The value range of light impulse length t is 50ns~20000ns, and the value of light impulse length t is needed in view of optical fiber The length L2 of line of time delay, so that light pulse receiver is receiving reflected three arteries and veins of the connect reflective optical system in sensing optic cable end When rushing, these three pulses can be distinguished completely in time, the value of light impulse length t is less than L2/5, and the unit of L2 is m, t Unit be ns.

The emissivity of reflective optical system is greater than -25dB.

The invention also discloses following technical effects:

The present invention changes the polarization state for being input to the optical signal of uniaxial Sagnac interferometer by Polarization Controller, makes single shaft The phase bias of Sagnac interferometer is near desired value, to obtain preferable small-signal response sensitivity.

Each embodiment in this specification is described in a progressive manner, the highlights of each of the examples are with other The difference of embodiment, the same or similar parts in each embodiment may refer to each other.

Used herein a specific example illustrates the principle and implementation of the invention, and above embodiments are said It is bright to be merely used to help understand method and its core concept of the invention；At the same time, for those skilled in the art, foundation Thought of the invention, there will be changes in the specific implementation manner and application range.In conclusion the content of the present specification is not It is interpreted as limitation of the present invention.