CN201754194U - Bandwidth-tunable filter based on single-fiber grating - Google Patents
Bandwidth-tunable filter based on single-fiber grating Download PDFInfo
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- CN201754194U CN201754194U CN2010202559402U CN201020255940U CN201754194U CN 201754194 U CN201754194 U CN 201754194U CN 2010202559402 U CN2010202559402 U CN 2010202559402U CN 201020255940 U CN201020255940 U CN 201020255940U CN 201754194 U CN201754194 U CN 201754194U
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- fiber grating
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Abstract
The utility model relates to a bandwidth-tunable filter based on single-fiber grating, which is characterized by comprising a fiber grating 1, polymer 2, two metal sleeves 3 and a metal hose 4. The fiber grating 1 coaxially penetrates into the two metal sleeves 3, the polymer 2 is filled among the fiber grating 1 and the two metal sleeves 3, interfaces of the two ends of the fiber grating 1 linked with the polymer 2 are sleeved by the metal hose 4 for protecting tail fibers of the fiber grating, the inner diameters of the two metal sleeves 3 range from 16mm to 20 mm, the lengths are 15mm, and the spacing is 10 mm. When part of middle points in a grating area of the fiber grating are packaged at a zero strain position, central wavelength of reflection spectrum of the fiber grating is unchanged, and the bandwidth is widened along with increasing of pressure. The bandwidth-tunable filter has the advantages of wide bandwidth tuning range, simple and smart structure, easy system integration and the like, and can be widely applied to fiber communication and fiber sensing systems.
Description
Technical field
The utility model relates to a kind of bandwidth tunable optic filter, belongs to the optical fiber filter field, particularly a kind of bandwidth tunable optic filter based on single fibre grating.
Background technology
Fiber grating is because of its excellent selecting frequency characteristic and realize Full Fibre Network easily, is widely used at fiber optic communication field.Because the temperature of external environment and the drift that strain all can cause fiber grating centre wavelength, therefore, fiber grating can be used as the tunable wave length filter applies in optical fiber communication and sensing network.In addition,, also can realize bandwidth tuning, can obtain the bandwidth tunable optic filter, and the tuning range of bandwidth is directly proportional with the gradient in strain or temperature field fiber grating by setting up strain or temperature gradient field in the grid region of fiber grating.Utilize the uneven chirped fiber grating of index modulation cycle or depth of modulation,, can realize the adjustable filtering of bandwidth equally, but chirped fiber grating is more more complex than the manufacture craft of uniform fiber grating by chirp rate tuning.At present, many relevant warbling of fiber grating realization bandwidth tunable optic filters that utilize have been arranged, these filter applies methods such as mechanics, electromagnetics, calorifics, comprising multiple beam type structure, in order to produce the gradient Strain Distribution, usually need be made into special beam type structure, so its manufacture craft is relatively complicated; Plate the not metallic film of uniform thickness in addition outside fiber grating, make fiber grating produce chirp phenomenon by the electric current that changes metallic film, its coating process itself is with regard to more complicated, and cost is higher, and centre wavelength also can change in bandwidth tuning; Adopt the chirped fiber grating bandwidth tuning of step motor drive two ends compression column with fixed,, need to adopt high-precision step motor drive, its price comparison costliness if will obtain high-precision bandwidth tuning.Therefore, the fiber grating bandwidth tuning wave filter that adopts above various structures to make, some manufacture craft is had relatively high expectations, and some complicated operation or cost are higher, and perhaps centre wavelength also can change in bandwidth tuning, thereby has limited its practical application.
Summary of the invention
The technical matters that solves
For fear of the deficiencies in the prior art, the utility model proposes a kind of bandwidth tunable optic filter based on single fibre grating, act on pressure on the polymkeric substance by change, cause that fiber grating produces chirp, thereby reach the tunable purpose of fiber grating reflectance spectrum bandwidth, finally realize the bandwidth tunable optic filter that a kind of centre wavelength is constant.
Thought of the present utility model is: fiber grating is encapsulated on the central axis of polymkeric substance, the polymkeric substance side closely is connected with two sections metal sleeves, extraneous equally distributed pressure acts on polymkeric substance and metal sleeve, because polymer moieties is subject to metal sleeve, therefore axially can produce the gradient strain along fiber grating, and the strain value size is successively decreased by middle mind-set both sides, thereby makes the fiber grating reflectance spectrum produce the broadening of chirp phenomenon and bandwidth.When the grid region of fiber grating part mid point was encapsulated in the zero strain place, the centre wavelength of fiber grating reflectance spectrum was constant, and bandwidth is broadening along with the increase of pressure.
Technical scheme
A kind of bandwidth tunable optic filter based on single fibre grating is characterized in that: comprise fiber grating 1, polymkeric substance 2, two sections metal sleeves 3 and metal hoses 4; Fiber grating 1 coaxial penetrating among two sections metal sleeves 3, filled polymer 2 between fiber grating 1 and the two sections metal sleeves 3, the interface suit that fiber grating 1 two ends are connected with polymkeric substance 2 is used to protect the metal hose 4 of fiber grating tail optical fiber; The internal diameter of described two sections metal sleeves 3 is 16～20mm, and length is 15mm, at a distance of 10mm.
The grid region of described fiber grating is apart from the end face 10～20mm of polymkeric substance one end.
Described fiber grating is a uniform Fiber Bragg Grating FBG of index modulation cycle, and its grid region length is 10mm, and reflectivity is greater than 90%.
Described polymkeric substance is polyurethane, acrylate or silicon rubber.
Beneficial effect
A kind of bandwidth tunable optic filter that the utility model proposes based on single fibre grating, when ambient temperature one timing, along with the increase of pressure only can cause the broadening of fiber grating reflectance spectrum bandwidth, and centre wavelength can not change, and has improved the stability and the accuracy of filtering.Adopt two different fiber gratings of centre wavelength to be encapsulated in the polymkeric substance, the effect that can be implemented in uniform pressure produces the bandwidth tunable optic filter of dual wavelength passage down.Simultaneously, easily this structural extended is subject in the multistage same metal sleeve of constant distance to polymkeric substance, and select centre wavelength to be encapsulated in the polymkeric substance, thereby realize the bandwidth tunable optic filter or the comb filter of multi-wavelength passage at a distance of the fiber grating of certain value.In addition, it is big that this wave filter has the bandwidth tuning scope, simple in structure small and exquisite, is easy to advantages such as the system integration, can be widely used in optical fiber communication and the optical fiber sensing system.
Description of drawings
Fig. 1 is based on the bandwidth tunable optic filter structural profile synoptic diagram of single fibre grating.
Fig. 2 adopts finite element method for simulating emulation based on Fig. 1 median filter structure, and the central shaft of encapsulation polymkeric substance under the even distribution pressure effect in the external world is to the Strain Distribution curve, and fiber grating is in strain zone between a point and the b point.
Fig. 3 is encapsulated in fiber grating between the strain zone a point and b point shown in Figure 2 the broadening situation synoptic diagram of the fiber grating reflectance spectrum bandwidth that numerical simulation obtains.
Wherein: the 1-fiber grating; The 2-polymkeric substance; The 3-metal sleeve; 4-capillary metal tube; The 5-single-mode fiber.
Embodiment
Now in conjunction with the embodiments, accompanying drawing is further described the utility model:
Consult accompanying drawing 1 and accompanying drawing 2, fiber grating adopts Fiber Bragg Grating FBG, fiber grating is encapsulated on the central axis of polymkeric substance, and polymkeric substance sliding phenomenon can not occur with two periods tight connections of metal sleeve, extraneous evenly distribution pressure acts on polymkeric substance and the metal sleeve, because polymkeric substance is subject to two sections metal sleeves, therefore on the central axis of polymkeric substance, can present Strain Distribution situation as shown in Figure 2, a kind of strain gradient promptly appears, fiber grating is encapsulated between the regional a point and b point of gradient maximum, and then make fiber grating produce chirp phenomenon, the final bandwidth tunable optic filter of realizing based on fiber grating.Polymkeric substance adopts polyurethane, acrylate or silicon rubber.
For uniform Fiber Bragg Grating FBG of index modulation cycle, its central wavelength lambda
BCan be expressed as
λ
B＝2n
effΛ
In the formula, n
EffBe the fibre core effective refractive index, Λ is a grating pitch.Under the effect of uniform temperature or strain field, its reflection spectrum bandwidth is constant, but centre wavelength drifts about, and drift value Δ λ
BCan be expressed as
Δλ
B＝[(1-P
e)ε+(α+ξ)ΔT]·λ
B
In the formula, ε is a dependent variable, and Δ T is a temperature variation,
Effective elasto-optical coefficient (P for fiber optic materials
IjFor being respectively the bullet light component of tensor and the Poisson ratio coefficient of fiber optic materials with μ), α and ξ are respectively the thermal expansivity and the thermo-optical coeffecient of fiber optic materials.When temperature-resistant, fiber grating is under the effect of heterogeneous strain field ε (z), because the grid of each position, grating grid region is (as pitch Λ and index modulation depth delta n
Eff) corresponding non-uniform change will take place with the non-uniform Distribution of strain field, thereby cause the centre wavelength at fiber grating diverse location place inequality, because the function of strain curve is continuous, finally form the reflectance spectrum of warbling of the whole broadening of a fiber grating reflectance spectrum shape.The broadened bandwidth amount Δ λ of the spectrum of warbling
ChirpedWith maximum strain difference Δ ε
MaxThe pass be
Δλ
chirped＝λ
B(1-P
e)·Δε
max
In addition, when the grid region of fiber grating part mid point is encapsulated in the zero strain place, the fiber grating both sides are subjected to normal strain and negative strain respectively, therefore the fiber grating reflectance spectrum is that mid point launches to two ends with the central wavelength, the centre wavelength that is reflectance spectrum is constant, and bandwidth along with the increase of pressure broadening.The grid region part of fiber grating is encapsulated in the strain zone, adopts numerical simulation to obtain the reflectance spectrum broadened bandwidth situation of fiber grating under different pressures.
Embodiment consults accompanying drawing 1, and fiber grating is encapsulated in part and is subject on the polyurethane central axis of metal sleeve, and two sections metal sleeves are at a distance of 10mm, so the pressure practical function is at two end faces and the middle exposed part of polymkeric substance.The tail optical fiber of fiber grating is adopting the protection of capillary metal tube near polymkeric substance end face place, in order to avoid under the pressurized situation, the optical fiber phenomenon that fractures occurs.Under the effect of ambient pressure, it is maximum and present the symmetry distribution of successively decreasing to two ends that strain appears in the midpoint on the polymkeric substance central axis.The mid point of fiber grating is encapsulated in the zero strain place, to guarantee that fiber grating bandwidth tuning process centre wavelength is not drifted about when environment temperature one timing.
Claims (4)
1. the bandwidth tunable optic filter based on single fibre grating is characterized in that: comprise fiber grating (1), polymkeric substance (2), two sections metal sleeves (3) and metal hose (4); Fiber grating (1) is coaxial to be penetrated among two sections metal sleeves (3), filled polymer (2) between fiber grating (1) and the two sections metal sleeves (3), the interface suit that fiber grating (1) two ends are connected with polymkeric substance (2) is used to protect the metal hose (4) of fiber grating tail optical fiber; The internal diameter of described two sections metal sleeves (3) is 16～20mm, and length is 15mm, at a distance of 10mm.
2. the bandwidth tunable optic filter based on single fibre grating according to claim 1 is characterized in that: the grid region of described fiber grating is apart from the end face 10～20mm of polymkeric substance one end.
3. any bandwidth tunable optic filter based on single fibre grating according to claim 1 and 2 is characterized in that: described fiber grating is a uniform Fiber Bragg Grating FBG of index modulation cycle, and its grid region length is 10mm, and reflectivity is greater than 90%.
4. the bandwidth tunable optic filter based on single fibre grating according to claim 1 is characterized in that: described polymkeric substance is polyurethane, acrylate or silicon rubber.
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| CN2010202559402U CN201754194U (en) | 2010-07-12 | 2010-07-12 | Bandwidth-tunable filter based on single-fiber grating |
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| CN2010202559402U CN201754194U (en) | 2010-07-12 | 2010-07-12 | Bandwidth-tunable filter based on single-fiber grating |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101907744A (en) * | 2010-07-12 | 2010-12-08 | 西北工业大学 | Filter for realizing bandwidth tuning based on optical fiber grating self-chirping effect |
| CN107687817A (en) * | 2017-07-20 | 2018-02-13 | 北京航天控制仪器研究所 | One kind miniaturization flexible optical fibre grating strain transducer |
| CN112033445A (en) * | 2020-08-17 | 2020-12-04 | 桂林电子科技大学 | Large dynamic range optical fiber sensor based on programmable optical fiber grating |
-
2010
- 2010-07-12 CN CN2010202559402U patent/CN201754194U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101907744A (en) * | 2010-07-12 | 2010-12-08 | 西北工业大学 | Filter for realizing bandwidth tuning based on optical fiber grating self-chirping effect |
| CN107687817A (en) * | 2017-07-20 | 2018-02-13 | 北京航天控制仪器研究所 | One kind miniaturization flexible optical fibre grating strain transducer |
| CN107687817B (en) * | 2017-07-20 | 2019-11-29 | 北京航天控制仪器研究所 | A kind of miniaturization flexible optical fibre grating strain transducer |
| CN112033445A (en) * | 2020-08-17 | 2020-12-04 | 桂林电子科技大学 | Large dynamic range optical fiber sensor based on programmable optical fiber grating |
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Granted publication date: 20110302 Termination date: 20120712 |