CN101140338A - Method for making optical fiber grating by Moire fringe shake amplitude stencil-plate - Google Patents
Method for making optical fiber grating by Moire fringe shake amplitude stencil-plate Download PDFInfo
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- CN101140338A CN101140338A CNA2006101220555A CN200610122055A CN101140338A CN 101140338 A CN101140338 A CN 101140338A CN A2006101220555 A CNA2006101220555 A CN A2006101220555A CN 200610122055 A CN200610122055 A CN 200610122055A CN 101140338 A CN101140338 A CN 101140338A
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Abstract
The present invention belongs to the technical field of fiber raster production, which comprises superposition of two transparent/reflecting cyclic structures and production of Moire fringe amplitude to make a stencil-plate cling to a fiber. A raster will be produced for the fiber. A light source capable of generating photosensitive effects is adopted as read-in light. After passing through the stencil-plate, the light source casts onto a fiber to be read in. After a certain period of exposure, 'a cyclic modulation structure' with a specific refractive index is formed in the fiber. The present invention has the advantages of easy, feasible and cheap fiber raster production and conveniently changes raster read-in period. The stencil-plate can be repeatedly used with stable fringe distribution and lower price. The present invention is suitable for production of long-raster amplitude stencil-plates.
Description
Technical field
The optics that the invention belongs to fiber grating writes technology, making and applied technical field.
Background technology
The making principle of fiber grating is to utilize diverse ways, makes to write the periodic intensity that light inlet produces vertically distribute in fiber cores, and the periodic distribution of this light intensity will cause that the refractive index of fiber optic materials produces periodic modulation vertically, thereby form grating.Along with the fast development of Fiber Bragg Grating technology, the fiber grating manufacturing technology has also been produced more and more urgent demand.As all industrial technologies, preparing grating also wishes to have a kind of convenient use, and inexpensive method: also more will be suitable for large batch of making simultaneously.
Existing fiber grating method for making can be divided into two big classes: interior wrting method and outer wrting method.Interior wrting method is to utilize the fl transmission light of inside of optical fibre and the light of the transmission dorsad coherence stack that the reflection of optical fiber exit end produces, and forms the periodic distribution of light intensity in optical fiber vertically.
Outer wrting method is to utilize diverse ways in optical fiber side outside formation light intensity periodic distribution vertically, and utilizes optical instrument that this mould spot is projected on the optical fiber, thereby forms the periodic distribution of light intensity in optical fiber vertically.Wherein comprise phase place masterplate method, amplitude masterplate method and point-to-point writing method three classes again:
(1) phase place masterplate method (Phase Mask): the light intensity periodic modulation that the diffracted wave coherence stack that this method utilizes the phase place masterplate to produce forms is made grating.Advantage is to write precision height, stable; Shortcoming is to involve great expense, and general length is not suitable for making long grating at 1cm, and in case to make its cycle immutable, uses inconvenience.
(2) amplitude masterplate method (Amplitude Mask): the method directly utilizes the periodic structure of masterplate or optical imaging to be projected in the periodic distribution that forms light intensity on the optical fiber.Advantage is simple, inexpensive, can extend its length greatly to make long grating; But owing to directly utilize the periodic structure of masterplate, to get well (especially for short-period FBG) so require the precision in masterplate cycle, and in the existing amplitude mode platemaking technology, the grating, other accurate periodic structure that adopt the fixed cycle usually are as masterplate.In addition, masterplate must be close to the optical fiber placement.
(3) point-to-point writing method (Point.by.Point): point-to-point writing method is actual to belong to a kind of of amplitude masterplate method.It is to place the wide slit that equals the grating cycle of a seam in the light source front of assembling, and by controlling moving axially along optical fiber of optical fiber or light source regularity, pointwise optical fiber is exposed then.The accumulation become along fiber axis to the refractive index cycle modulation.Advantage is that required optical element is few, and device is simple, convenient, and can onlinely write: shortcoming is to the mechanically moving structure accuracy requirement height in (direct relation grating cycle), writes time-consumingly, is subject to environmental factor and disturbs.
Summary of the invention
The objective of the invention is to for overcoming the weak point of prior art, utilize the advantage and the popularization of Moire fringe, dissolve in the design feature of amplitude masterplate, make the making fiber grating simple and easy to do, with low cost, can change the cycle of the grating that writes easily, masterplate is reusable, striped distributional stability, price are low, and is applicable to the amplitude masterplate of making long grating.
The present invention proposes a kind of method that adopts Moire fringe amplitude stamp fabrication fiber grating, it is characterized in that, may further comprise the steps:
1) utilize two transmissions/reflective periodic structure overlapping, and rotate the stripe direction that makes in two structures mutually around a certain fixed point and be mutually a minute angle 0, make Moire fringe amplitude masterplate, and θ satisfies the wherein artificial grating cycle that writes of A=d/2sin (θ/2), and d is the cycle of former grating;
2) this Moire fringe amplitude masterplate is close to wait the optical fiber of making grating to be placed; Employing can produce the light source of light sensitive effect as writing light inlet:
3) with after this light source process Moire fringe amplitude masterplate, just in time be incident upon on the optical fiber to be written, the periodic intensity of amplitude masterplate distributes and just is incident upon on the optical fiber like this:
4) in this optical fiber, form the periodic modulation structure of refractive index behind the exposure certain hour.
The method for making of the said Moire fringe amplitude of the present invention masterplate can be that two transmission-type periodic structures by exposure of optics egative film or glass etching formation are overlapping, and rotate the stripe direction that makes in two structures mutually around a certain fixed point and be mutually a minute angle, so just formed Moire fringe amplitude masterplate.
The method for making of said Moire fringe amplitude masterplate also can be to utilize the picture of one or two reflective periodic structure to be superimposed upon on the same picture plane, and makes the stripe direction in two structures be mutually a small angle, forms Moire fringe amplitude masterplate.Said two transmissions/reflective periodic structure is overlapping, and the minute angle that is mutually is generally less than 10 degree and uses, with the fringe contrast that obtains; Gap between said Moire fringe masterplate and the optical fiber is preferably less than 1mm, and because of in bigger zone, because the influence of factors such as diffraction, interference and imaging, the cycle of striped will change, and the interference of interference is arranged.When said light source power enough big, and the length of the grating of writing is during less than 1cm, can directly use the write light source of mould spot diameter: as light source power less relatively (about tens mw) greater than 1cm, and the grating length＞Icm that writes, at this moment just pointolite need be expanded bundle and is focused into length/width than suitable line source (as wide 0.$mm, length can be controlled).
The said Moire fringe principle of the present invention is summarized as follows in conjunction with Fig. 1:
Utilize two transmission-type gratings that form by exposure of optics egative film or glass etching (to be used to form the grating A of Moire fringe, (call in the following text: the cycle former grating) should be as far as possible little for B, so that the angle of two gratings is less relatively, formed like this striped has good contrast) overlapping, or the picture that utilizes one or two reflective periodic structure (grating) is superimposed upon on the same picture plane, and rotates the stripe direction that makes in two structures mutually around a certain fixed point and be mutually a minute angle.
If two grid line angles are 0, the cycle of former grating is d, then if this minute angle satisfies according to Moire fringe formula result calculated, resulting Moire fringe just meets the periodic structure of making the fiber grating requirement just for A=d/2sin (θ/2) the Moire fringe cycle (being the grating cycle that is write).
For example: when the cycle of former grating is 20 lines/mm, when the grating cycle request of writing is 370mp, can calculates angle 0 by following formula and approximate 7.8 °.Be that two former gratings of 20 lines/mm form Moire fringe promptly, when the angle between them equals 7.8 when we in the cycle of adopting.The time, through the cycle that writing fiber grating made after the light source irradiation be exactly 370p.
The present invention has following characteristics:
(1) Moire fringe form easy, price is extremely cheap.
(2) adjust within the specific limits as required, reuse, make the grating of different cycles.
(3) both can be used for long-period gratings, can be used for making again than short-period grating.
(4) be fit to make long grating (mainly considering the restriction of light source power factor): be fit to produce in enormous quantities.
Brief Description Of Drawings
Fig. 1 is the Moire fringe schematic diagram.
Fig. 2 is embodiments of the invention one synoptic diagram.
Fig. 3 is embodiments of the invention two synoptic diagram.
Embodiment
The present invention proposes to adopt two kinds of embodiment of the method for Moire fringe amplitude stamp fabrication fiber grating to be described in detail as follows respectively in conjunction with the accompanying drawings:
Case study on implementation one writes grating for adopting two overlapping Moire fringe amplitude masterplates of making of transmission grating in sulfide optical fiber, as shown in Figure 2.The specific implementation method step:
Write light source 11: because 12 pairs of visible range specific wavelengths of sulfide optical fiber have photosensitivity, thereby employing wavelength 6328A, power write light source greater than the He-Ne laser instrument conduct of 30mw in ablation process.
Monitoring light source 13: the effect for the real-time monitored grating writes needs a monitoring light source.Consider that the fibre loss of present employed single mode sulfide is bigger, and very high with the coupling loss of ordinary optic fibre, therefore required monitoring light source should possess wide live width, and sufficiently high power is arranged again.Select for use Erbium-Doped Fiber Amplifier (EDFA) (EDFA) as monitoring light source in the present embodiment: the monitoring light source utilizes centre wavelength at 1540nm, the ASE spectrum of the Erbium-Doped Fiber Amplifier (EDFA) (EDFA) of 3dB spectrum width 35rim and power 14row.
Two identical transmission gratings of Moire fringe amplitude masterplate 14 usefulness constitute.For eliminating diffraction effect, two light are at interval less than 1mm.The grating that adopts the egative film exposure to make in the present embodiment, the cycle is 20 lines/mm.Form principle and required grating cycle according to Moire fringe, calculating two grating grid line angles is 7.8 °.
Write the 30mw light that light source He-Ne laser instrument sends, become the rectangular light spot that 30X 0.5mm is parallel to fiber axis, laterally incide on the sulfide optical fiber 12 by Moire fringe masterplate 14 again by beam expanding lens 15 and post lens 16 expansion bundles with after focusing on.Equally for the filtering diffraction effect, Moire fringe masterplate and optical fiber near, the gap is less than 1mm.The light that monitoring light source one EDFA light source sends is received by spectrometer 17 behind persulfide optical fiber.
ASE spectral line curve of spectrum after the persulfide Optical Fiber Transmission before writing grating of the EDFA that shows from spectrometer is with contrast writes institute as can be seen and causes that optical fibre refractivity periodic modulation one is the grating effect through the curve of spectrum after the exposure of a few hours.
Embodiment two adopts ultraviolet light to make quartz optical fiber grating as writing light source for the picture that uses common reflection grating forms Moire fringe amplitude masterplate, as shown in Figure 3.Concrete implementation step:
Write light source 21: because silica fibre do not have photosensitivity to the visible range, and to the ultraviolet light sensitivity of specific band, thereby general ultraviolet light one wavelength that adopts is that the excimer laser of 248nm is as writing light source in ablation process.
Monitoring light source 23: comparatively speaking, low, the convenience that continues of silica fibre loss, therefore required monitoring light source should be that the light source that possesses wide spectrum width gets final product.Especially in the ablation process of FBG, also can loosen the requirement of light source spectrum width.Select common broadband LED as monitoring light source in the present embodiment: the 3dB live width is 30nm, and fiber power is about: 1mw.
The Moire fringe amplitude mode is pulled two identical reflection gratings 241,242 of 24 usefulness, and scioptics 251,252 resemble on same picture plane and constitute.By meticulous adjusting, the picture of two gratings can be fully at grade overlapping.Adopt the reflection grating that aluminizer is made on the substrate of glass in the present embodiment, if the cycle is 50 lines/mm (or more high density grid line so that use) under as far as possible little grid line angle.Form principle and required grating cycle according to Moire fringe, calculating two grating grid line angles is about 3 degree.Write the Uv light that light source 21 sends, at first be divided into the light beam that two bundles (size can be controlled) are parallel to fiber axis, laterally shine on the silica fibre 22 through imaging Moire fringe masterplate 24 again by beam splitter prism 26.For the filtering diffraction effect, Moire fringe masterplate and optical fiber near, the gap is less than Imm.Owing to be picture, can reach between Moire fringe masterplate and the optical fiber continuously every.The light that monitoring light source one wide range led light source sends is received by spectrometer 27 through behind the silica fibre.From the curve of spectrum of LED spectral line before writing grating that spectrometer shows, can see that with exposure curve of spectrum contrast afterwards writing institute causes that optical fibre refractivity periodic modulation one is the grating effect through certain hour.
Claims (7)
1. adopt the method for Moire fringe amplitude stamp fabrication fiber grating, it is characterized in that, may further comprise the steps:
1) utilizes two transmissions, reflective periodic structure is overlapping, and rotate the stripe direction that makes in two structures mutually around a certain fixed point and be mutually a minute angle θ, make the Moire fringe amplitude, and 0 to satisfy A=red, in the artificial grating cycle that writes among its A=d/2sin (θ/2), d is the cycle of former grating;
2) this Moire fringe amplitude masterplate is close to wait the optical fiber of making grating to be placed;
3) employing can produce the light source of light sensitive effect for writing light inlet;
4) with after this line source process Moire fringe amplitude masterplate, just in time be incident upon on the optical fiber to be written, the periodic intensity of amplitude masterplate distributes and just is incident upon on the optical fiber like this:
5) in this optical fiber, form the periodic modulation structure of refractive index behind the exposure certain hour.
2. the method for employing Moire fringe amplitude stamp fabrication fiber grating as claimed in claim 1, it is characterized in that, the method for making of said Moire fringe amplitude masterplate is: utilize two transmission-type periodic structures (grating) by exposure of optics egative film or glass etching formation overlapping, and rotate the stripe direction that makes in two structures mutually around a certain fixed point and be mutually a minute angle, so just formed Moire fringe amplitude masterplate.
3. the method for employing Moire fringe amplitude stamp fabrication fiber grating as claimed in claim 1, it is characterized in that, the method for making of said Moire fringe amplitude masterplate is: utilize the picture of one or two reflective periodic structure to be superimposed upon on the same picture plane, and make the stripe direction in two structures be mutually a small angle, form Moire fringe amplitude masterplate.
4. the method for employing Moire fringe amplitude stamp fabrication fiber grating as claimed in claim 1 is characterized in that said two transmissions/reflective periodic structure is overlapping, and the minute angle θ that is mutually is less than 10 degree, with the fringe contrast that obtains;
5. the method for employing Moire fringe amplitude stamp fabrication fiber grating as claimed in claim 1 is characterized in that the gap between said Moire fringe masterplate and the optical fiber is less than 1mm.
As claim 1 ' method of described employing Moire fringe amplitude stamp fabrication fiber grating is characterized in that, when said light source power is enough big, and the length of the grating of writing can directly be used the write light source of mould spot diameter greater than 1cm during less than 1cm:
7. the method for employing Moire fringe amplitude stamp fabrication fiber grating as claimed in claim 1 is characterized in that, less relatively when light source power, and the grating length＞1cm that writes then needs said light source is expanded bundle and be focused into length/width than suitable line source.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2006101220555A CN101140338A (en) | 2006-09-08 | 2006-09-08 | Method for making optical fiber grating by Moire fringe shake amplitude stencil-plate |
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| CNA2006101220555A CN101140338A (en) | 2006-09-08 | 2006-09-08 | Method for making optical fiber grating by Moire fringe shake amplitude stencil-plate |
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| CN101140338A true CN101140338A (en) | 2008-03-12 |
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| CNA2006101220555A Withdrawn CN101140338A (en) | 2006-09-08 | 2006-09-08 | Method for making optical fiber grating by Moire fringe shake amplitude stencil-plate |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102374844A (en) * | 2010-08-20 | 2012-03-14 | 上海微电子装备有限公司 | Device for measuring vertical position of workpiece bench |
| CN105334567A (en) * | 2015-11-26 | 2016-02-17 | 宁波大学 | Manufacturing device and method of chalcogenide fiber grating |
-
2006
- 2006-09-08 CN CNA2006101220555A patent/CN101140338A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102374844A (en) * | 2010-08-20 | 2012-03-14 | 上海微电子装备有限公司 | Device for measuring vertical position of workpiece bench |
| CN105334567A (en) * | 2015-11-26 | 2016-02-17 | 宁波大学 | Manufacturing device and method of chalcogenide fiber grating |
| CN105334567B (en) * | 2015-11-26 | 2018-06-19 | 宁波大学 | A kind of producing device of sulphur system fiber grating and preparation method thereof |
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