CN103018836B - Optical fiber depolarizer with single-mode fiber serving as delay line - Google Patents
Optical fiber depolarizer with single-mode fiber serving as delay line Download PDFInfo
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- CN103018836B CN103018836B CN201210593866.9A CN201210593866A CN103018836B CN 103018836 B CN103018836 B CN 103018836B CN 201210593866 A CN201210593866 A CN 201210593866A CN 103018836 B CN103018836 B CN 103018836B
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Abstract
The invention discloses an optical fiber depolarizer with a single-mode fiber serving as a delay line. The optical fiber depolarizer comprises an optical fiber branching device, a first polarization beam splitter, the single-mode fiber, a faraday rotary reflector and a second polarization beam splitter. A beam combination port of the first polarization beam splitter and the faraday rotary reflector are connected to two ends of the single-mode fiber respectively to form a delay optical path, and two beam splitting ports of the first polarization beam splitter serve as an input port and an output port of the delay optical path respectively. The optical fiber branching device divides input light into two branches, one branch of light is directly inputted into one of beam splitting ports of the second polarization beam splitter, the other branch of light passes through the delay optical path to be inputted into the other beam splitting port of the second polarization beam splitter, and depolarized light is outputted from a beam combination port of the second polarization beam splitter. Cost of the optical fiber depolarizer is reduced by using the normal single-mode fiber as the delay line; and the polarization state is kept stable after the light passes through the delay optical path, and accordingly the optical fiber depolarizer can operate stably.
Description
Affiliated technical field
The present invention relates to a kind of Fibre Optic Depolarizer, particularly a kind of Fibre Optic Depolarizer of single-mode fiber as delay line of utilizing.
Background technology
In optical fibre interference, the contrast of interference signal is subject to the impact of optical polarization; In the time that the polarization direction of two light beams that interfere is consistent, the contrast maximum of interference signal; In the time that the polarization direction of two light beams that interfere is vertical, the contrast of interference signal is zero.
In order to ensure that interference signal has high contrast, can adopt polarization maintaining optical fibre and protect inclined to one side optical device to form the inclined to one side light path of all risk insurance, make the two-beam interfering there is identical polarization state, as polarization maintaining optical fibre gyro and polarization maintaining optical fibre nautical receiving set.Although adopt guarantor polarisation road can obtain good interference signal, be conducive to realize high precision interferometry, and obtained successful application; But the cost of polarization maintaining optical fibre and the inclined to one side optical device of guarantor is higher, carries out interferometry at the interferometer that still more adopts general single mode fiber to form the civil area of cost sensitivity.
At the interferometer that adopts single-mode fiber to form while carrying out interferometry, due to birefringence and the birefringent random variation of single-mode fiber, cause the contrast of two beam interferometer polarisation of light state random variation, interference signal unstable, measuring accuracy declines.For the interferometer that general single mode fiber is formed has stable interference signal, can adopt the light path scheme of polarization irrelevant or the scheme of depolarized light source.Wherein the light path scheme of polarization irrelevant is applicable to Michelson interferometer, by the birefringent impact of faraday rotator mirror compensated optical fiber; The Sagnac being formed by single-mode fiber or Mach-Ze Deer interferometer, and distributed fiberoptic sensor based on Brillouin scattering effect, need to adopt depolarizer to carry out depolarized to light wave, make light wave be evenly distributed on randomly all possible polarization state, thereby make interference signal keep certain contrast.
The typical scenario of Fibre Optic Depolarizer comprises Lyot Fibre Optic Depolarizer and the Fibre Optic Depolarizer based on delay line.Lyot Fibre Optic Depolarizer as shown in Figure 1, forms (seeing application for a patent for invention " a kind of double polarized light polarization-preserving fiber polarization eliminator ", application number 200910092743.5) by 2 sections or 3 sections of polarization maintaining optical fibre cascades, and weld length is l successively
1polarization maintaining optical fibre, length be l
2polarization maintaining optical fibre and length be l
3polarization maintaining optical fibre, and the birefringence main shaft of rear one section of polarization maintaining optical fibre successively with the birefringence main shaft angle at 45 ° of adjacent the last period of polarization maintaining optical fibre; Wherein l
3=4l
1, l
2=2l
1, Δ n
bl
1>=L
dc, Δ n
bfor the specific refractivity of polarization maintaining optical fibre two main shafts, L
dcfor the decoherence length of light source.
wherein
the mean wavelength of light source light spectrum, Δ λ
fWHMit is the full width at half maximum of light source light spectrum.Because the specific refractivity of polarization maintaining optical fibre two main shafts is less, for the narrower light source of spectrum width, polarization maintaining optical fibre that need to be very long; So Lyot Fibre Optic Depolarizer is only applicable to the wide spectrum light source such as super-radiance light emitting diode, Er-Doped superfluorescent fiber source to carry out depolarized.
For Distributed Feedback Laser, external cavity laser or fiber laser, the decoherence length of light source is large, conventionally adopts the Fibre Optic Depolarizer based on delay line.The existing single-mode fiber that utilizes (is shown in Silvia Diaz as the Fibre Optic Depolarizer of delay line, Stella Foaleng Mafang, Manuel Lopez-Amo, and Luc Th é venaz.A High-Performance Optical Time-Domain Brillouin Distributed Fiber Sensor.IEEE SENSORS JOURNAL, VOL.8, NO.7, JULY 2008) as shown in Figure 2, by fiber coupler 2a, incident light is divided into the two-way light of the different propagated along space, wherein thereby a road light makes optical path difference between the two-way light decoherence length much larger than light source by longer time delay single-mode fiber 4, by fiber coupler 2b by photosynthetic two-way be a branch of, make the two-way polarisation of light direction of input optical fibre coupling mechanism 2b mutually vertical by Polarization Controller 3, export depolarized light from fiber coupler 2b.The existing Fibre Optic Depolarizer of single-mode fiber as delay line of utilizing, the factors such as temperature variation, light path torsion, vibration cause the birefringence random variation of single-mode fiber 4, the output polarisation of light state of single-mode fiber 4 is unstable, thereby makes Fibre Optic Depolarizer be difficult to steady operation.Adopt the Fibre Optic Depolarizer of polarization maintaining optical fibre as delay line, can obtain good depolarized effect.But the live width of Distributed Feedback Laser can be low to moderate several MHz, decoherence length reaches hundreds of rice; External cavity laser, fiber laser, its live width can be low to moderate tens kHz or a few kHz, and decoherence length reaches several km or tens of km; Cause adopting polarization maintaining optical fibre high as the cost of the Fibre Optic Depolarizer of delay line.
Summary of the invention
Technical matters to be solved by this invention is: be not suitable for the depolarized of narrow linewidth light source for Lyot Fibre Optic Depolarizer, existing single-mode fiber is made the Fibre Optic Depolarizer unstable properties of delay line, and adopt polarization maintaining optical fibre to make the high problem of Fibre Optic Depolarizer cost of delay line, a kind of Fibre Optic Depolarizer of single-mode fiber as the steady operation of delay line that adopt proposed.
Technical scheme of the present invention is:
Utilize the Fibre Optic Depolarizer of single-mode fiber as delay line, it is characterized in that: Fibre Optic Depolarizer is made up of optical fiber splitter, the first polarization beam apparatus, single-mode fiber, faraday rotator mirror and the second polarization beam apparatus; Form time delay light path by the first polarization beam apparatus, single-mode fiber and faraday rotator mirror; The two ends of closing beam port, faraday rotator mirror and be connected to single-mode fiber of the first polarization beam apparatus, two points of beam ports of the first polarization beam apparatus are respectively as input port and the output port of time delay light path; Two output ports of optical fiber splitter connect respectively the input port of time delay light path and a point of beam port of the second polarization beam apparatus, and another point of beam port of the second polarization beam apparatus connects the output port of time delay light path; The input port of optical fiber splitter is as the input port of Fibre Optic Depolarizer, the second polarization beam apparatus close the output port of beam port as Fibre Optic Depolarizer.
Described faraday rotator mirror is the polarization direction half-twist with respect to incident light by catoptrical polarization direction.
Optical fiber splitter is polarization-maintaining fiber coupler.
Optical fiber splitter is to close beam port to adopt 45 ° of polarization beam apparatus that axle is coupled of polarization maintaining optical fibre.
The present invention's advantage is compared with prior art:
(1) a kind of Fibre Optic Depolarizer of single-mode fiber as delay line of utilizing disclosed by the invention, adopts general single mode fiber as delay line, has reduced the cost of Fibre Optic Depolarizer.
(2) a kind of Fibre Optic Depolarizer of single-mode fiber as delay line of utilizing disclosed by the invention, adopt polarization beam apparatus, single-mode fiber and faraday rotator mirror to form time delay light path, faraday rotator mirror is the polarization direction half-twist with respect to incident light by catoptrical polarization direction, make that two quadrature components of light are subject to single-mode fiber birefringent affect identical, the polarization direction of light after by time delay light path keeps vertical with the polarization direction of incident light all the time, it is stable that the output polarisation of light state of time delay light path keeps, thereby Fibre Optic Depolarizer is stably worked.
Brief description of the drawings
Fig. 1 is the schematic diagram of Lyot Fibre Optic Depolarizer;
Fig. 2 is the existing structural drawing of single-mode fiber as the Fibre Optic Depolarizer of delay line that utilize;
Fig. 3 is the structural drawing of single-mode fiber as the Fibre Optic Depolarizer of delay line that utilize of the present invention;
Description of reference numerals:
1... polarization maintaining optical fibre,
2a, 2b... fiber coupler,
3... Polarization Controller,
4... single-mode fiber,
5... optical fiber splitter,
6a, 6b... polarization beam apparatus,
7... faraday rotator mirror,
8... time delay light path.
Embodiment
As shown in Figure 3, a kind of Fibre Optic Depolarizer of single-mode fiber as delay line of utilizing of the present invention, is made up of single-mode fiber 4, optical fiber splitter 5, the first polarization beam apparatus 6a, the second polarization beam apparatus 6b, faraday rotator mirror 7; The two ends of closing beam port, faraday rotator mirror 7 and be connected to single-mode fiber 4 of the first polarization beam apparatus 6a, two points of beam ports that form time delay light path 8, the first polarization beam apparatus 6a are respectively as input port and the output port of time delay light path 8; Two output ports of optical fiber splitter 5 connect respectively the input port of time delay light path 8 and a point of beam port of the second polarization beam apparatus 6b, and another point of beam port of the second polarization beam apparatus 6b connects the output port of time delay light path 8; The input port of optical fiber splitter 5 is as the input port of Fibre Optic Depolarizer, and the second polarization beam apparatus 6b closes the output port of beam port as Fibre Optic Depolarizer.
Optical fiber splitter 5 adopts polarization-maintaining fiber coupler, or to close beam port be 45 ° of the polarization maintaining optical fibres polarization beam apparatus to axle coupling; Faraday rotator mirror 7 adopts the faraday rotator mirror of reflected light polarization direction with respect to 90 ° of incident light polarization direction rotations.The linearly polarized light of incident is divided into two-way by optical fiber splitter 5; Wherein a road light is inputted a point of beam port of the first polarization beam apparatus 6a, export from the beam port that closes of the first beam splitter 6a, entering single-mode fiber 4 transmits, and reflect, after the half-twist of polarization direction, transmit one point of beam port exporting and input the second polarization beam apparatus 6b from another point of beam port of the first beam splitter 6a through single-mode fiber 4 by faraday rotator mirror 7; Another road output light of optical fiber splitter 5, another point of beam port of input the second polarization beam combiner 6b.Single-mode fiber 4 provides the optical path difference of 2nL for two-way light, and wherein n is the refractive index of single-mode fiber 4, and L is the length of single-mode fiber 4, and optical path difference 2nL is much larger than the decoherence length of incident light; Faraday rotator mirror 7 is the polarization direction half-twist with respect to incident light by catoptrical polarization direction, make that two quadrature components of light are subject to single-mode fiber 4 birefringent affect identical, the polarization direction of light after by time delay light path 8 keeps vertical with the polarization direction of incident light all the time, and the output polarisation of light state of time delay light path 8 keeps stablizing; From the depolarized light that closes beam port stable output of the second polarization beam apparatus 6b.
Claims (1)
1. utilize the Fibre Optic Depolarizer of single-mode fiber as delay line, it is characterized in that: Fibre Optic Depolarizer is made up of optical fiber splitter (5), the first polarization beam apparatus (6a), single-mode fiber (4), faraday rotator mirror (7) and the second polarization beam apparatus (6b) as delay line; Form time delay light path by the first polarization beam apparatus (6a), single-mode fiber (4) and faraday rotator mirror (7); The two ends of closing beam port, faraday rotator mirror (7) and be connected to single-mode fiber (4) of the first polarization beam apparatus (6a), two points of beam ports of the first polarization beam apparatus (6a) are respectively as input port and the output port of time delay light path; An output port of optical fiber splitter (5) connects the input port of time delay light path, another output port of optical fiber splitter (5) connects a point of beam port of the second polarization beam apparatus (6b), and another point of beam port of the second polarization beam apparatus (6b) connects the output port of time delay light path; The input port of optical fiber splitter (5) is as the input port of Fibre Optic Depolarizer, the second polarization beam apparatus (6b) close the output port of beam port as Fibre Optic Depolarizer; Described faraday rotator mirror (7) is the polarization direction half-twist with respect to incident light by catoptrical polarization direction; Optical fiber splitter (5) is to close beam port to adopt 45 ° of polarization beam apparatus that axle is coupled of polarization maintaining optical fibre.
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| CN104143761A (en) * | 2013-05-07 | 2014-11-12 | 维林光电(苏州)有限公司 | Low-polarization semiconductor laser based on low coherent technology and manufacturing method thereof |
| CN109579972A (en) * | 2018-12-19 | 2019-04-05 | 深圳供电规划设计院有限公司 | A kind of pipeline vibration early warning positioning device and method |
| CN110987146B (en) * | 2019-11-03 | 2022-02-08 | 武汉光谷航天三江激光产业技术研究院有限公司 | Optical fiber sensing self-difference receiving device |
| CN111854802B (en) * | 2020-07-28 | 2021-05-18 | 武汉长盈通光电技术股份有限公司 | Optical path contrast detection method for fiber-optic gyroscope |
| CN114964203B (en) * | 2022-08-01 | 2022-10-11 | 中国船舶重工集团公司第七0七研究所 | Depolarization method and system for hollow-core microstructure fiber optic gyroscope |
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| CN102023337B (en) * | 2009-09-22 | 2012-01-18 | 北京大学 | Double polarized light polarization-preserving fiber polarization eliminator |
| CN102519492A (en) * | 2011-12-26 | 2012-06-27 | 复旦大学 | Distributed single core feedback interference optical path structure having low background light |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102023337B (en) * | 2009-09-22 | 2012-01-18 | 北京大学 | Double polarized light polarization-preserving fiber polarization eliminator |
| CN102519492A (en) * | 2011-12-26 | 2012-06-27 | 复旦大学 | Distributed single core feedback interference optical path structure having low background light |
Non-Patent Citations (2)
| Title |
|---|
| A High-Performance Optical Time-Domain Brillouin Distributed Fiber Sensor;Silvia Diaz等;《IEEE SENSORS JOURNAL》;20080731;第8卷(第7期);正文第1263页左栏第2-3段，图1 * |
| Silvia Diaz等.A High-Performance Optical Time-Domain Brillouin Distributed Fiber Sensor.《IEEE SENSORS JOURNAL》.2008,第8卷(第7期),正文第1263页左栏第2-3段，图1. * |
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