CN102401670A - Fiber optic interferometric system for reducing influence of fiber birefringence - Google Patents
Fiber optic interferometric system for reducing influence of fiber birefringence Download PDFInfo
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Abstract
The invention relates to a fiber optic interferometric system for reducing the influence of fiber birefringence. Laser is emitted by a laser device and transmitted to a fiber optic coupler through a source fiber; the laser is split by the coupler and then output to a metric arm and a reference arm of the fiber optic interferometric system respectively, wherein, one path of light is incident to light reflection device of the metric arm through a fiber optic depolarizer of the metric arm and an optical fiber of the metric arm; the reflected light returns to the fiber optic coupler through the original path; the other path of light is incident to a light reflection device of the reference arm through a fiber optic depolarizer of the reference arm and an optical fiber of the reference arm; the reflected light returns to the fiber optic coupler through the original path; the two path of reflected light form an interference light signal in the coupler; the signal is received by a photoelectric detector as an interference signal through an optical fiber of the detector; and the interference signal is transmitted to an operational processing system through a signal transmission line to obtain the size of the outside physical quantity signal. The fiber optic interferometric system used for metering outside physical quantities such as vibration eliminates the influence of the random variation of the polarization state in the ordinary fiber optic interferometric system on the signal of the fiber optic interferometric system.
Description
Technical field
The present invention relates to the optical fibre interference system, particularly measure the optical fibre interference system of external physical quantity function based on having of Michelson optical fibre interference device.
Background technology
The optical fibre interference system adopts full optical fibre device, has characteristics such as anti-electromagnetic interference capability is strong, detection sensitivity is high, the passive work of sensor, in the measurement of physical quantitys such as vibration, temperature, displacement, is widely used.
Theoretical according to the interference of light, have only the light of same polarization state could form interference, when having birefringence in the optical fiber, the light velocity of propagation of different polarization state is different, and the interference signal of generation also changes thereupon.Therefore, when having birefringence in the optical fiber, except the interference that external physical quantity causes, can occur remaining polarization in the system and induce phase noise, i.e. polarization noise causes the measuring error of system.For optical fiber, because the influence of factors such as temperature, in actual use, birefringent phenomenon is inevitable, in order to reduce measuring error, need take measures to suppress birefringent influence.
Fig. 1 has schematically provided in the prior art scheme basic structure based on the optical fibre interference system of Michelson optical fibre interference device.Light from laser instrument 1 sends transfers to fiber coupler 4 through luminous source optical fiber 2, is divided into the two-beam that light intensity equates through fiber coupler 4, is transferred to the gage beam and the reference arm of Michelson optical fibre interference device.Wherein a branch of light transmits in as gage beam optical fiber 7, and another Shu Guang is transmission in arm optical fiber 8 as a reference, and two-beam converges at fiber coupler 4 places and interferes after light reflecting device 9,10 reflects.When external physical quantity changes on gage beam optical fiber 7 and the reference arm optical fiber 8; Interference light signal also changes; Interference light signal is received by photodetector 11 through detector fibres 3; Arithmetic processing system 12 can obtain the size of external physical quantity signal through reading the magnitude of voltage on the photodetector.
If light reflecting device adopts faraday rotation mirror, theoretically, when the laser beam one way is passed through faraday rotation mirror; 45 ° of its polarization principal axis rotations; When laser beam was reflected, folded light beam was rotated 45 ° once more, thus with the incident beam quadrature.Laser along optical fiber returns optical fiber behind faraday rotation mirror and Michelson catoptron transmission matrix is:
T is the optical power attenuation factor in the formula.
Light is in transmission course; The birefringent influence that single-mode fiber brings can utilize Jones matrix
and
of normalized oval delayer to represent.
When laser beam passed through optical fiber, the Jones matrix of fl transmission can be expressed as:
* representes conjugation in the formula,
The loss of expression optical fiber, d
2=aa*+bb*, parameter a and b are the single-mode fiber birefraction factor.
When laser beam returned, the back can be expressed as to the Jones matrix of transmission:
Using the Jones matrix
and
can get arbitrarily polarized transmission matrix:
We can find out that transmission matrix is a constant through type (4); Under faraday rotation mirror keeps complete 90 ° polarization rotating conditions; Can suppress the influence that the single-mode fiber birefringence brings effectively, thereby improve the stability of Michelson optical fibre interference device.But in actual use; Because the error of the polarization anglec of rotation of faraday rotation mirror itself; It is relevant with light source center wavelength, environment temperature and magnetic field simultaneously, can't keep complete 90 ° polarization rotation, can cause the instability of optical fibre interference system.
When there was anglec of rotation error in faraday rotation mirror, its transmission matrix can be expressed as:
In the formula,
is the angular error of faraday rotation mirror with respect to 45 ° of the anglecs of rotation.
According to Fig. 1, be output as based on the Michelson optical fibre interference device normalization of imperfect faraday rotation mirror:
In the formula,
Coupling coefficient for coupling mechanism;
Be the parameter relevant with b with single-mode fiber birefraction factor a; r
sAnd r
RIt is the lump loss of two arms;
Be the phase differential of two arms, when external physical quantity such as receiving stress influences,
Directly reacted the variation of external physical quantity.
During as
,
shows that Michelson optical fibre interference device output does not receive that single-mode fiber is birefringent to be influenced; As
(in actual use; Because itself there is error in the polarization anglec of rotation of faraday rotation mirror; It is relevant with light source center wavelength, environment temperature and magnetic field simultaneously; Can't keep complete 90 ° polarization rotation);
then the output of Michelson optical fibre interference device still can receive the birefringent influence of single-mode fiber, and its factor of influence normalization relation is as shown in Figure 3.When
faraday rotation mirror loses the control action to polarization fully; Be equivalent to use fiber reflector as light reflecting device, Michelson optical fibre interference device output receives that single-mode fiber is birefringent completely influences 14.
Can find out commentary from top based on the Michelson optical fibre interference device of imperfect faraday rotation mirror; Because itself there is error in the polarization anglec of rotation of faraday rotation mirror; Simultaneously can this polarization selected angle change because of the variation in light source center wavelength, environment temperature and magnetic field; Make it can't keep complete 90 ° polarization rotation; The polarization noise that the single-mode fiber birefringence brings be can't effectively suppress, thereby the stability and the practicality of optical fibre interference system greatly reduced.
Summary of the invention
In order to solve the deficiency in the above-mentioned prior art scheme; The present invention proposes a kind of optical fibre interference system that is used to measure external physical quantity; This invention goes inclined to one side device to be used in combination with faraday rotation mirror optical fiber; Calculate to high resolving power, high stability the external physical quantity signal, and eliminate in the ordinary optic fibre interferometric measuring means polarization state random variation interfering the influence of restituted signal.
The objective of the invention is to realize through following technical scheme:
A kind of optical fibre interference system that reduces the fiber birefringence influence; Laser is launched by laser instrument; Transfer to fiber coupler through luminous source optical fiber, laser outputs to the gage beam and the reference arm of optical fibre interference system respectively through the fiber coupler beam split; Wherein one road light goes inclined to one side device, gage beam optical fiber input to the gage beam light reflecting device through gage beam optical fiber, is reflected after former road turns back to fiber coupler; Another road light goes inclined to one side device, reference arm optical fiber to incide the reference arm light reflection unit through reference arm optical fiber; Turn back to fiber coupler by former road after being reflected; The two-way reflected light forms interference light signal at fiber coupler; This signal is received by photodetector through detector fibres becomes interference signal, and interference signal transfers to arithmetic processing system through signal transmssion line and handles, and draws the size of external physical quantity signal.
In technique scheme; Said optical fiber goes inclined to one side device to be added in the gage beam of optical fibre interference device and the front end of reference arm; After the light wave of laser (often being partial poolarized light) removes inclined to one side device through optical fiber, become complete nonpolarized light, be equivalent to light intensity be evenly distributed on each polarization state; Therefore the light intensity amplitude that arrives photodetector is evenly constant; Optical fiber is gone being used in combination of inclined to one side device and faraday rotation mirror, can reduce the harsh requirement of faraday rotation mirror, under actual user mode, eliminate in the ordinary optic fibre interferometric measuring means polarization state random variation interfering the influence of restituted signal to environment.
Description of drawings
With reference to accompanying drawing, disclosure of the present invention will be easier to understand.Those skilled in the art are understood that easily: these accompanying drawings only are used to illustrate technical scheme of the present invention, and are not to be intended to protection scope of the present invention is constituted restriction.Among the figure:
Fig. 1 is based on the structural representation of the optical fibre interference system of Michelson optical fibre interference device in the prior art scheme.
Fig. 2 is a structural representation of the present invention.
Fig. 3 is the relation that receives birefringence influence degree and faraday rotation mirror angular error in the output of Michelson optical fibre interference device.
The 1st, laser instrument, the 2nd, luminous source optical fiber, the 3rd, detector fibres; The 7th, gage beam optical fiber, the 8th, reference arm optical fiber, the 4th, fiber coupler; 5, the 6th, optical fiber removes inclined to one side device, and the 9, the 10th, faraday rotation mirror, the 11st, photodetector; The 12nd, arithmetic processing system, the 13rd, adopting degree of polarization is 5% optical fiber greatest birefringence factor of influence when removing inclined to one side device, the 14th, greatest birefringence factor of influence when not using optical fiber to remove inclined to one side device.
Embodiment
Fig. 2-3 and following declarative description optional embodiment of the present invention how to implement with instruction those skilled in the art and reproduce the present invention.In order to instruct technical scheme of the present invention, simplified or omitted some conventional aspects.Those skilled in the art should understand that the modification or the replacement that are derived from these embodiments will be within the scope of the invention.Those skilled in the art should understand that following characteristics can make up to form a plurality of modification of the present invention in every way.Thus, the present invention is not limited to following optional embodiment, and is only limited claim and their equivalent.
Consulting accompanying drawing can know: as shown in Figure 2; A kind of optical fibre interference system that reduces the fiber birefringence influence of the present invention, laser transfers to fiber coupler 4 by laser instrument 1 emission through luminous source optical fiber 2; Laser is divided into the light output that several power equates through fiber coupler 4; Wherein one the tunnel go inclined to one side device 5, gage beam optical fiber 7 to incide faraday rotation mirror 9, after faraday rotation mirror 9 reflections, turn back to fiber coupler 4 through former road via optical fiber; Another road goes inclined to one side device 6, reference arm optical fiber 8 to incide faraday rotation mirror 10 through optical fiber; After faraday rotation mirror 10 reflections, turn back to fiber coupler 4 through former road, the two-way reflected light forms interference light signal at fiber coupler 4.The variation of gage beam optical fiber 7 and reference arm optical fiber 8 external physical quantity; Interference light signal changes; Interference light signal is received by photodetector 11 through detector fibres 3, transfers to arithmetic processing system 12 through signal transmssion line and handles, and draws the size of external physical quantity signal.
Go the Michelson optical fibre interference device normalization of inclined to one side device to be output as based on imperfect faraday rotation mirror and nonideal optical fiber:
In the formula;
is degree of polarization; Remove inclined to one side device for Lyot type optical fiber; Like θ is its angle error, and then its expression formula is:
If
using any light reflecting device can be suppressed on the birefringence;
time,
light reflecting means to control the polarization degree, determine the degree of inhibition of the birefringence.For the Michelson optical fibre interference device that the optical fiber that with degree of polarization is 5% goes inclined to one side device and faraday rotation mirror combination to use, its birefringence factor of influence normalization relation is as shown in Figure 3.
Fig. 3 shows: because the use that optical fiber removes inclined to one side device; The trend that can make the normalization factor of influence receive the influence of the faraday rotation mirror anglec of rotation becomes slow; It is thus clear that under identical condition; Requirement for anglec of rotation error
when utilizing optical fiber to remove inclined to one side device has also descended, and the size of decline goes the degree of polarization of inclined to one side device relevant with the actual optical fiber that uses.At this moment; Even employing fiber reflector etc. does not carry out the light reflecting device of Polarization Control; Perhaps light reflecting device that polarization is controlled such as faraday rotation mirror has lost the control to polarization state fully; Because the use that optical fiber removes inclined to one side device still can guarantee certain contrast, the polarization noise that birefringence is introduced still has certain inhibiting effect 13.
As do not use optical fiber to remove inclined to one side device, and the inhibiting effect of the polarization noise of then birefringence being introduced depends on the control of light reflecting device to polarization state, along with the reduction of light reflecting device to the polarization state control ability, the polarization noise that birefringence is introduced increases sharply.At this moment, as adopted fiber reflector etc. not carry out the light reflecting device of Polarization Control, perhaps light reflecting device that polarization is controlled such as faraday rotation mirror has lost the control to polarization state fully, then can't carry out any inhibition 14 to birefringence.
Outstanding feature of the present invention is based on the optical fibre interference device; Go inclined to one side device to be used in combination optical fiber with faraday rotation mirror; Suppressed the polarization noise that causes by fiber birefringence more effectively; Significantly reduced the susceptibility of traditional fiber interferometric measuring means to fiber birefringence; Reduced the influence of light source center wavelength, environment temperature and magnetic field, improved, had practical value based on the stability of optical fibre interference system in the actual working environment optical fibre interference device, that have the external physical quantity measurement function for the output of optical fibre interference device.
Claims (7)
1. one kind is reduced the optical fibre interference system that fiber birefringence influences; It is characterized in that: laser is launched by laser instrument; Transfer to fiber coupler through luminous source optical fiber, laser outputs to the gage beam and the reference arm of optical fibre interference system respectively through the fiber coupler beam split; Wherein one road light goes inclined to one side device, gage beam optical fiber input to the gage beam light reflecting device through gage beam optical fiber, is reflected after former road turns back to fiber coupler; Another road light goes inclined to one side device, reference arm optical fiber to incide the reference arm light reflection unit through reference arm optical fiber; Turn back to fiber coupler by former road after being reflected; The two-way reflected light forms interference light signal at fiber coupler; This signal is received by photodetector through detector fibres becomes interference signal, and interference signal transfers to the size that arithmetic processing system draws the external physical quantity signal through signal transmssion line.
2. system according to claim 1 is characterized in that light reflecting device is a fiber reflector, or faraday rotation mirror.
3. system according to claim 1 is characterized in that the luminous power of fiber coupler is divided equally.
4. system according to claim 1 is characterized in that luminous source optical fiber and detector fibres use single-mode fiber, perhaps uses multimode optical fiber.
5. system according to claim 1 is characterized in that gage beam optical fiber and reference arm optical fiber use single-mode fiber.
6. system according to claim 5 is characterized in that reference arm optical fiber and gage beam fiber package in 1 optical cable, perhaps are encapsulated in respectively in 2 optical cables.
7. system according to claim 1 is characterized in that laser instrument is the semiconductor light-emitting-diode laser instrument, or semiconductor laser diode, or superradiance semiconductor light-emitting-diode laser instrument.
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102914418A (en) * | 2012-09-24 | 2013-02-06 | 北京航空航天大学 | Optical fiber Shupe constant testing device and method thereof |
| CN102914265A (en) * | 2012-10-09 | 2013-02-06 | 哈尔滨工程大学 | Optical fiber strain gauge and high-sensitivity disc-type displacement sensor with ultra-short base line |
| CN102927914A (en) * | 2012-10-10 | 2013-02-13 | 哈尔滨工程大学 | Optical fiber displacement sensor with ultra-short baseline compliant cylinder structure and optical fiber strain gauge |
| CZ305889B6 (en) * | 2015-03-05 | 2016-04-20 | Vysoká Škola Báňská - Technická Univerzita Ostrava | Optical-fiber interferometric sensor for monitoring traffic operations |
| CN105973452A (en) * | 2016-05-12 | 2016-09-28 | 秦皇岛市地方道路管理处 | Remote bridge vibration monitoring system and method |
| CN106525256A (en) * | 2016-11-25 | 2017-03-22 | 威海北洋光电信息技术股份公司 | Narrow linewidth laser device phase noise measurement device and method |
| CN107179097A (en) * | 2016-03-10 | 2017-09-19 | 南京理工大学 | The optical fiber interference type sensing modulation-demo-demodulation method and device modulated based on phase shift signal |
| CN107946877A (en) * | 2017-12-08 | 2018-04-20 | 华中科技大学 | A kind of bicyclic optical-electronic oscillator stablized from polarization state |
| CN110631684A (en) * | 2019-10-23 | 2019-12-31 | 吉林大学 | Sensing probe, optical fiber interference device and method for inhibiting polarization fading |
| CN112525372A (en) * | 2020-11-10 | 2021-03-19 | 广东工业大学 | Device and method for simultaneously measuring strain temperature based on polarization maintaining optical fiber double-arm hetero-axial interferometer |
| CN113916269A (en) * | 2021-12-15 | 2022-01-11 | 南京恒高光电研究院有限公司 | Coherent polarization analyzer and measuring method |
| CN114754669A (en) * | 2022-03-22 | 2022-07-15 | 南京理工大学 | Method for suppressing coherent noise of interferometer by multimode fiber bundle extended light source |
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Cited By (19)
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| CN102914418B (en) * | 2012-09-24 | 2015-03-11 | 北京航空航天大学 | Optical fiber Shupe constant testing device and method thereof |
| CN102914418A (en) * | 2012-09-24 | 2013-02-06 | 北京航空航天大学 | Optical fiber Shupe constant testing device and method thereof |
| CN102914265A (en) * | 2012-10-09 | 2013-02-06 | 哈尔滨工程大学 | Optical fiber strain gauge and high-sensitivity disc-type displacement sensor with ultra-short base line |
| CN102914265B (en) * | 2012-10-09 | 2015-02-25 | 哈尔滨工程大学 | Optical fiber strain gauge and high-sensitivity disc-type displacement sensor with ultra-short base line |
| CN102927914A (en) * | 2012-10-10 | 2013-02-13 | 哈尔滨工程大学 | Optical fiber displacement sensor with ultra-short baseline compliant cylinder structure and optical fiber strain gauge |
| CN102927914B (en) * | 2012-10-10 | 2015-08-12 | 哈尔滨工程大学 | A kind of ultra-short baseline paravariable column body structured optical fiber displacement transducer and fibre strain instrument |
| CZ305889B6 (en) * | 2015-03-05 | 2016-04-20 | Vysoká Škola Báňská - Technická Univerzita Ostrava | Optical-fiber interferometric sensor for monitoring traffic operations |
| CN107179097B (en) * | 2016-03-10 | 2019-08-09 | 南京理工大学 | Optical fiber interference type sensing modulation-demo-demodulation method and device based on phase shift signal modulation |
| CN107179097A (en) * | 2016-03-10 | 2017-09-19 | 南京理工大学 | The optical fiber interference type sensing modulation-demo-demodulation method and device modulated based on phase shift signal |
| CN105973452A (en) * | 2016-05-12 | 2016-09-28 | 秦皇岛市地方道路管理处 | Remote bridge vibration monitoring system and method |
| CN106525256A (en) * | 2016-11-25 | 2017-03-22 | 威海北洋光电信息技术股份公司 | Narrow linewidth laser device phase noise measurement device and method |
| CN107946877A (en) * | 2017-12-08 | 2018-04-20 | 华中科技大学 | A kind of bicyclic optical-electronic oscillator stablized from polarization state |
| CN110631684A (en) * | 2019-10-23 | 2019-12-31 | 吉林大学 | Sensing probe, optical fiber interference device and method for inhibiting polarization fading |
| CN110631684B (en) * | 2019-10-23 | 2024-02-13 | 吉林大学 | Sensing probe, optical fiber interference device and method for inhibiting polarization fading |
| CN112525372A (en) * | 2020-11-10 | 2021-03-19 | 广东工业大学 | Device and method for simultaneously measuring strain temperature based on polarization maintaining optical fiber double-arm hetero-axial interferometer |
| CN113916269A (en) * | 2021-12-15 | 2022-01-11 | 南京恒高光电研究院有限公司 | Coherent polarization analyzer and measuring method |
| CN113916269B (en) * | 2021-12-15 | 2022-03-04 | 南京恒高光电研究院有限公司 | Coherent polarization analyzer and measuring method |
| CN114754669A (en) * | 2022-03-22 | 2022-07-15 | 南京理工大学 | Method for suppressing coherent noise of interferometer by multimode fiber bundle extended light source |
| CN114754669B (en) * | 2022-03-22 | 2024-01-30 | 南京理工大学 | Method for inhibiting coherent noise of interferometer by multimode fiber bundle extended light source |
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