CN102092937A - Method and system for rapidly optimizing drawing technology of photonic crystal fiber - Google Patents
Method and system for rapidly optimizing drawing technology of photonic crystal fiber Download PDFInfo
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Abstract
The invention relates to a method for rapidly optimizing the drawing technology of the photonic crystal fiber. The method comprises the following steps in the drawing process of the photonic crystal fiber: cutting off a drawn and uncoated bare fibre, collecting the cross-sectional image of the drawn bare fibre; performing edge detection to the cross-sectional image of the bare fibre, reconstructing the geometrical structure of the cross section of the bare fibre; meshing the inside area of the cross section according to the reconstructed geometrical structure; adopting the numerical simulation method to analyze the photonic crystal fiber characteristics of the bare fibre; and comparing the analytical characteristics of the bare fibre with the design characteristics of the photonic crystal fiber to obtain a comparison result; adjusting the drawing technological parameters of the photonic crystal fiber according to the comparison result; and repeating the steps to ensure that the differences between the analytical characteristics of the drawn bare fibre and the design characteristics can be ignored and obtain a group of the optimized technological parameters for drawing the photonic crystal fiber.
Description
Technical field
The present invention relates to the optical fiber fabrication method and system, particularly optimize photonic crystal fiber drawing process method and system.
Background technology
Photonic crystal fiber, since succeeding in developing from being in the news in 1996, structure design and novel characteristic receive much concern flexibly because of it.By designing different airport structures, photonic crystal fiber can obtain the incomparable characteristics of many general single mode fibers such as endless single mode, high birefringence, high non-linearity, super large mode field area, super smooth chromatic dispersion, makes it have very big application potential in fields such as opticfiber communication, fiber optic gyro, Fibre Optical Sensor, optical fiber lasers.
The flexile complex construction of photonic crystal fiber has also increased the difficulty of pulling process when bringing various novel characteristics.In pulling process, need by control comprise such as in feeding speed, pulling speed, the kapillary between inflation pressure, capillary gap drawing process parameters such as suction pressure, Heating temperature control the ad hoc structure of the photonic crystal fiber that draws.The pulling process of photonic crystal fiber more than traditional fiber pulling process complexity many, much also time-consuming to the drawing process Parameter Optimization.The photonic crystal fiber of different structure, the drawing process parameter is also inequality.A kind of New-type photon crystal optical fiber of every making all needs processing parameter is optimized.Research to photonic crystal fiber drawing process parameter optimization at present still is in the theoretical analysis stage.Being entitled as of Tieying Guo " Control of the fabrication parameters during the fabrication of Photonic Crystal Fibers ", Chin. Phys. Soc, 58 (9), in the article of 412-419 (2009), disclose a kind ofly by setting up temperature field and the hydromechanical physics field model that mixes by the N-S equation, analyzed between feeding speed, pulling speed, kapillary internal pressure, capillary gap drawing process parameters such as pressure, Heating temperature the method for the influence of optical fiber structure.Because being difficult to simulate fully actual fiber, the physical field model draws environment, and in to the analytic process of model, this equation a lot of simplification have been carried out for finding the solution complicated N-S equation, so this analytical procedure only is a kind of theoretical method, be not enough to analyze the slight deformation that photonic crystal fiber often occurs in the drawing environment of complexity.This theoretical analysis method still can not instruct actual drawing process Parameter Optimization.
Therefore, in photonic crystal fiber making field, need to provide a kind of and optimize the drawing process parameter immediately, be met the method for the photonic crystal fiber of design performance fast by the structure that in fiber draw process, detects resulting optical fiber.
Summary of the invention
The objective of the invention is to overcome the problem that exists in the above-mentioned photonic crystal fiber drawing process optimizing process.The present invention proposes a kind of based on digital image processing techniques and numerical simulation technology, to the method for photonic crystal fiber drawing process rapid Optimum.The method according to this invention, the photonic crystal fiber cross sectional image is carried out picture processing extract fiber geometric, analyze optical fiber property by method for numerical simulation, the performance that obtains according to this analysis and the different adjustment between the design performance draw the processing parameter of photonic crystal fibers, and finally obtain to determine the drawing process of photonic crystal fiber through optimized parameters.
The invention provides a kind of method of rapid optimization photonic crystal fiber drawing process, in the photonic crystal fiber pulling process, further may further comprise the steps:
Block pulling into and uncoated bare fibre, gather the cross sectional image that draws the bare fibre that obtains;
The bare fibre cross sectional image is carried out rim detection, and reconstruct bare fibre cross section geometry;
According to the bare fibre cross section geometry of described reconstruct, bare fibre cross section inner compartment is carried out grid divide;
Use method for numerical simulation to analyze the photonic crystal fiber characteristic of bare fibre;
The analytical characteristics of bare fibre and the design characteristics of photonic crystal fiber are compared, obtain comparative result;
According to comparative result, adjust photonic crystal fiber drawing process parameter;
Repeat above-mentioned steps, can ignore, obtain one group of optimization processing parameter that draws this photonic crystal fiber until the analytical characteristics of drawing bare fibre and the difference of its design characteristics.
Preferably, photonic crystal fiber drawing process method of the present invention is a kind of tube bank farad system processing method.
The present invention further provides a kind of photonic crystal fiber and draw system, comprising:
Optical fiber drawing apparatus comprises pay-off, towing mechanism, heating unit and pressure regulating device, is used to draw photonic crystal fiber;
Image collecting device is used to gather the photon optical fiber crystalline cross sectional image that is drawn;
Image Edge-Detection device, the image that is used for that image collecting device is gathered carry out rim detection to obtain the cross section of optic fibre geometry of reconstruct;
The optic fibre characteristic simulator comprises that the cross section of optic fibre geometry to reconstruct carries out the grid classification apparatus of grid division and uses method for numerical simulation to analyze the simulated behavior device of the photonic crystal fiber characteristic of this drawing;
The optic fibre characteristic comparison unit is used for the analytical characteristics of bare fibre and the design characteristics of photonic crystal fiber are compared, and the output comparative result;
Processing parameter controlled feedback device is regulated the processing parameter of optical fiber drawing apparatus according to the comparative result of optic fibre characteristic comparison unit.
Technical scheme of the present invention is that it takes following steps in the photonic crystal fiber pulling process:
Step 1: block that pull into and uncoated bare fibre, carry out the cross section of optic fibre IMAQ.Described IMAQ is for example to use film camera or digital camera or digital microscope that uncoated naked photonic crystal fiber cross section is carried out IMAQ.The image that film camera is gathered can be for example be converted to each pixel such as storing with 256 looks of 8 storages or with the RGB mode digital image of the more high luminance relay of higher memory more through scanner, and the image of digital camera or digital microscope collection is stored as with 256 looks of 8 storages or with the RGB pattern color image of the more high luminance relay of higher memory more.
Step 2: the bare fibre cross sectional image is carried out rim detection, the border in the identification photonic crystal fiber between air and background material, and reconstruct bare fibre cross section geometry.Described rim detection for example is to adopt the conventional algorithm such as Sobel algorithm, Roberts algorithm, Laplacian algorithm or Canny algorithm to obtain marginal information, or adopt the two-value Mathematical Morphology Method to obtain marginal information again according to the bianry image that gray threshold is converted to 1 storage the color cross-section image earlier, or adopt the gray scale Mathematical Morphology Method to obtain marginal information.Coloured image is converted to the required gray threshold of bianry image can be according to the manual assignment of cross sectional image grey level histogram artificial selection, or uses iterative algorithm to calculate according to bare fibre cross sectional image gray scale to obtain.The computation process that in the article that is entitled as " the statistics iterative algorithm that image thresholding is cut apart " of Wang Yaoming, discloses iterative algorithm be at first add up with
nEach gray-scale value in the bare fibre cross sectional image of position storage
iPixel number
h i , wherein
i=0,1,2 ..., 2
n -1.Calculate the interim gray threshold that obtains according to previous iteration
T K-1 Calculate [0,
T K-1 ] and [
T K-1 , 2
n -1] the weighted mean gray-scale value between two gray areas, the mean value of the weighted mean gray-scale value between two gray areas is the interim gray threshold of next iteration
T k , its core expression formula is:
Iterative computation until
T k No longer change gained
T k Be coloured image and be converted to the optimal threshold of bianry image.The initial threshold of iteration wherein
T 0 Can be 2
n / 2, or the weighted mean gray-scale value of coloured image.In the formula 1
nBe the storage bit number of image, for example adopt 8,16,24,32,64 or seniority number memory image more, this depends on the output figure place of image pick-up card,
kBe iterations, its size depends on computation process, when
T k =
T K-1 In time, can stop calculating.
Step 3:, bare fibre cross section inner compartment is carried out grid divide according to the boundary shape between air and the background material.Described grid is divided, and is to carry out triangular unit or the division of rectangular element grid the size of triangular unit or rectangular element grid and the edge shape decision of orientation by regional air of living in hole, background material.
Step 4: use the method for numerical simulation analysis photonic crystal fiber characteristic that bare fibre had.Described method for numerical simulation for example is a finite element algorithm, or seamed edge unit method, or the numerical method that can be used to find the solution the optical fiber secular equation, calculate the optical characteristics of optical fiber such as method of finite difference.
Step 5: photonic crystal fiber characteristic and its design characteristics of the bare fibre that analysis is obtained compare, according to the discrepancy adjustment photonic crystal fiber drawing process parameter between the two.This drawing process parameter is the one or more parameters in the internal pressure of slit between prefabricated rods feeding speed, optical fiber pulling speed, furnace temp, prefabricated rods kapillary internal pressure, prefabricated rods rod pipe.
Repeat above-mentioned steps one to five, reach and to ignore, promptly obtain one group of preferred drawing process parameter that draws this kind photonic crystal fiber until the photonic crystal fiber characteristic of drawing bare fibre and the difference of its design characteristics.
The method according to this invention, can analyze the characteristic of the photonic crystal fiber that is drawn quickly and accurately by the photonic crystal fiber that digital image processing techniques and numerical simulation technology are applied to be drawn, and adjust the drawing parameter of photonic crystal fiber on this basis, optimize the drawing process of photonic crystal fiber.The beneficial effect of method of the present invention is:
(1) method of the present invention adopts digital image processing techniques and numerical simulation technology that the photonic crystal fiber that drawing obtains is analyzed, utilize advantage such as have the precision height in the computer processing procedure, speed is fast, can under the situation that the unbroken light photonic crystal fiber draws, in time adjust the drawing process parameter;
(2) method of the present invention only need be gathered one little section photonic crystal fiber, just can gather the cross sectional image of bare fibre and utilize the characteristic of this this bare fibre of image analysis, need not traditional fiber measures required complex apparatus, expensive expense and to the requirement of measured fiber size, has saved R﹠D costs and shortened the research and development time;
(3) method of the present invention is by adjusting the drawing process parameter with reference to the analytical characteristics and the difference between the DESIGNED FEATURE that obtain based on the actual fiber cross sectional image, whether the photonic crystal fiber that instant judgement draws meets the expected requirements, progressively optimize the drawing process parameter, can shorten the lead time of New-type photon crystal optical fiber greatly;
(4) method of the present invention utilizes the cross sectional image of the actual photonic crystal fiber that obtains to adjust controlled variable in the actual pulling process of photonic crystal fiber, optimizes the photonic crystal fiber drawing process.Method of the present invention has avoided simple theoretical analysis and actual pulling process to disconnect, and has stronger practicality;
(5) draw system according to photonic crystal fiber of the present invention, utilize existing photonic crystal fiber drawing device, only add image collecting device and data processing equipment, just can analyze acquisition and draw the characteristic of photonic crystal fiber and be used to instruct adjustment, realize improvement existing installation with lower cost to the drawing process parameter.
Description of drawings
Fig. 1 illustrates the schema according to drawing photon optical fiber crystalline method of the present invention;
Fig. 2 illustrates the block diagram according to drawing photon optical fiber crystalline of the present invention system;
Fig. 3 illustrates the project organization cross sectional representation according to the photonic crystal fiber of the embodiment of the invention 1;
Fig. 4 illustrates the CCD micro-image according to the initial bare fibre cross section of the embodiment of the invention 1;
Fig. 5 illustrates two-value mathematical morphology rim detection schema;
Fig. 6 illustrates image shown in Figure 4 is converted into grey level histogram behind the gray level image;
Fig. 7 illustrates the optical fiber structure border of using two-value mathematical morphology edge detection operator to obtain to image shown in Figure 4;
Fig. 8 illustrates the structure iron after the photonic crystal fiber border reconstruct shown in Figure 4;
Fig. 9 illustrates the photonic crystal fiber cross-sectional structure that reconstruct structure iron shown in Figure 8 is divided into triangle element mesh;
Figure 10 illustrates the power spectrum isogram of initial bare fibre in 1550nm wavelength limitation loss second order mode hour;
The power spectrum isogram of the second order mode when Figure 11 illustrates the bare fibre limitation loss of optimizing the embodiment 1 that obtains behind the processing parameter and reaches 21dB/m;
Figure 12 illustrates the project organization cross sectional representation according to the photonic crystal fiber of the embodiment of the invention 2;
Figure 13 illustrates the micro-image of taking according to the digital camera of the initial bare fibre cross section of the embodiment of the invention 2;
Figure 14 illustrates the photonic crystal fiber cross-sectional view that utilizes the reconstruct of gray scale mathematical morphology algorithm according to the embodiment of the invention 2;
Figure 15 illustrates the dispersion characteristic curve that utilizes the computational analysis of seamed edge unit method to obtain according to the embodiment of the invention 2;
Figure 16 illustrates the dispersion property of photonic crystal fiber curve of optimizing the embodiment 2 that obtains behind the processing parameter;
Figure 17 illustrates the cross sectional image of the negative dispersion photonic crystal fiber that draws according to controlled variable after the utilization optimization of the use digital camera shooting of the embodiment of the invention 2.
Embodiment
In conjunction with the embodiments the present invention is done further detailed description below with reference to accompanying drawings.Should be appreciated that embodiments of the invention are illustrative but not determinate.Protection scope of the present invention is not limited to following embodiment.
Fig. 1 illustrates the schema according to drawing photon optical fiber crystalline method of the present invention, and Fig. 2 illustrates the block diagram according to the drawing system of photonic crystal fiber of the present invention.The drawing system 1000 of photonic crystal fiber comprises photonic crystal fiber drawing device 1001, image collecting device 1002, Image Edge-Detection device 1003, optic fibre characteristic simulator 1004, optic fibre characteristic comparison unit 1005 and processing parameter controlled feedback device 1006.This photonic crystal fiber drawing device 1001 further comprises pay-off, towing mechanism, heating unit and pressure regulating device.Image collecting device 1002 is used to gather the photon optical fiber crystalline cross sectional image that is drawn.The image that Image Edge-Detection device 1003 is used for that image collecting device is gathered carries out rim detection to obtain the cross section of optic fibre geometry of reconstruct.Optic fibre characteristic simulator 1004 comprises that the edge shape according to the cross section of optic fibre geometry of reconstruct carries out the grid classification apparatus of grid division and uses method for numerical simulation to analyze the simulated behavior device of the photonic crystal fiber characteristic of this drawing this geometry.Optic fibre characteristic comparison unit 1005 is used for optic fibre characteristic that analysis is obtained and the optic fibre characteristic of design compares.Processing parameter controlled feedback device 1006 carries out feedback regulation according to the comparative result of optic fibre characteristic comparison unit to each processing parameter of optical fiber drawing apparatus.When the optic fibre characteristic that obtains when analysis satisfies design characteristics, obtain one group of fibre-optical drawing processing parameter of optimizing.
The present invention will specifically describe by embodiment 1 and 2 pairs of drawing photon optical fiber crystalline method and systems according to the present invention of embodiment.
Fig. 3 shows the project organization cross sectional representation according to the photonic crystal fiber of the embodiment of the invention 1.The photonic crystal fiber of embodiment 1 is that background material is the five circle airport optical fiber of 125mm for the diameter of pure quartz for example, and its design characteristics is for there to be and only to have basic mode effectively to transmit in transmission.
Adopt and for example manage the prefabricated rods that excellent method of piling is made photonic crystal fiber, the prefabricated rods diameter is 18 mm.Prefabricated rods one end is fixed on the pay-off of optical fiber drawing apparatus 1001, and the prefabricated rods the other end is heated in heating unit.Puddle at the heating unit inner preform is pulled device traction formation bare fibre.At first, rule of thumb choose processing parameter, for example: 1950 ℃ of furnace temps, feeding speed 0.3mm/min, pulling speed 5.2m/min, the slit suction pressure is about 0.03 crust of negative pressure between the thin rod of tubule.What pulled out this moment is uncoated initial naked photonic crystal fiber.In initial bare fibre, may exist defective such as airport expands, subsides, dislocation and optic fibre characteristic not to meet the problem of design requirements.Need be optimized the photonic crystal fiber that adheres to specification to obtain to the drawing process parameter.
Method according to drawing photonic crystal fiber of the present invention further may further comprise the steps.
Step 101: intercepted length is the bare fibre of just having exported from towing mechanism of about 5cm for example.Measuring its diameter is that 136 mm are placed on microscopically with this section optical fiber, make its axially and the micro objective central shaft point-blank.The CCD imaging system that use links to each other with computer is gathered the CCD micro-image of this cross section of optic fibre, as shown in Figure 4.Cross sectional image for example is kept in the computer with the RGB pattern of 8 256 looks.
Step 102: use the two-value mathematical morphology algorithm of for example writing that the cross section of optic fibre image is carried out rim detection, the border in the identification photonic crystal fiber between air and the background material, and reconstruct bare fibre cross section geometry with Matlab 7.0.
Fig. 5 shows the method for reconstruct bare fibre cross section geometry, may further comprise the steps:
Step 501: be carried in the cross section of optic fibre image that collects in the step 102;
Step 502: and will be converted to the gray level image of representing with gray-scale value Gray with the coloured image of 8 256 look RGB pattern storage, conversion formula is:
Gray=0.3R+0.59G+0.11B ... formula 2
The scope of gray-scale value Gray is 0 to 255, and discretize is expressed as when calculating in computer
i,
i=0,1,2 ..., 255;
Step 503: the statistics gray level image with gray-scale value is
iThe number of all pixels be recorded as
h i With gray-scale value
iBe X-coordinate, the pixel number of each gray-scale value correspondence that statistics obtains
h i For the ordinate zou mapping obtains grey level histogram shown in Figure 6;
Step 504: the gray-scale value threshold value of calculating image shown in Figure 4 with iterative method.Initial threshold T
0Be chosen as max (i)/2, utilize the formula iterative computation shown in the formula 1 to obtain gray threshold T=172.2;
Step 505: is bianry image according to gray threshold with the greyscale image transitions of 256 looks, and gray-scale value is converted to 1 more than or equal to the gray values of pixel points of gray threshold, is 0 less than the grayvalue transition of gray threshold;
Step 506: utilize two-value mathematical morphology edge detection operator to detect marginal information;
In being entitled as of Li Gang " based on the rim detection of the bianry image of mathematical morphology ", reliability and environmental compatibility theoretical investigation, 6, in the article of 35-37 (2004), disclose and a kind ofly obtained edge detection operator, this bianry image has been carried out the method for rim detection by mathematical morphology fundamental operation conversion.For example represent bianry image with A, B represents structural element.When B comprises true origin, there is A ⊕ B ≧ A ≧ A Θ B and AB ≧ A ≧ A zero B to set up.Gou Zao boundary operator is thus: A ⊕ B-A, A-A Θ B, AB-A, A-A zero B.Use edge detection operator A-A Θ B in the present embodiment and detect the border between the air and quartz in the bianry image, the result as shown in Figure 7;
Step 507: the marginal position information that obtains according to rim detection, the use method of least squares re-constructs the border between air and the background material, and be contracted to and the initial identical size of bare fibre according to the image of the ratio between the diameter of the diameter of optical fiber among Fig. 7 and initial bare fibre with reconstruct, and the cross section of optic fibre structure centre of reconstruct moved to the initial point of system of coordinates, the result is as shown in Figure 8.
Get back to Fig. 1, step 103: use the grid maker of matlab 7.0 that the cross-sectional structure of photonic crystal fiber shown in Figure 8 is divided grid, the result as shown in Figure 9, the cross section of photonic crystal fiber is divided into triangle element mesh, central zone and boundary position mesh-density are big, to increase computational accuracy.
Step 104: use for example method for numerical simulation analysis photonic crystal fiber characteristic of full vector finite element algorithm in the present embodiment.According to the gridding information that obtains in the step 103, cooperate the Perfect Matchings final condition to calculate effective refractive index, the limitation loss isotype characteristic of all effective models when the optical communications wavelength 1550nm of photonic crystal fiber with full vector Finite Element Method in this step.Figure 10 shows initial bare fibre shown in Figure 4 power profile in the second order mode of 1550nm wavelength.The effective refractive index of this optical fiber second order mode is 1.4343-i8.6368 * 10
-13, limitation loss is 0.00003dB/m.
Step 105: will compare with design characteristics at the optic fibre characteristic that step 104 obtains.Can be known that by comparative result the limitation loss of the second order mode of optical fiber shown in Figure 4 is less, the second order mode energy can effectively transmission on optical fiber very length.This does not satisfy the design requirements of single-mode fiber.
Step 106: adjust photonic crystal fiber drawing process parameter according to the comparative result of step 105.For making second order mode in the 1550nm wavelength cut-off, can for example reduce feeding speed by adjusting the drawing process parameter, increase pulling speed, reduce the temperature of heating unit, reduce the diameter of fibre diameter and airport, improve the performance of drawing optical fiber.
Preferably, after whether the optic fibre characteristic that judge to obtain adheres to specification, further judge optic fibre characteristic, intensity for example, whether characteristics such as outward appearance are stable.If unstable, need come the stable optical fiber of obtained performance by adjusting the drawing process parameter equally.
After each adjusting process parameter, repeat above-mentioned steps 101 to step 106.Analytical results passes through adjusting process parameter as mentioned above as can be known, and obtaining the second order mode limitation loss of photonic crystal fiber at optical communications wavelength 1550nm place will increase.When being reduced to 125mm, fibre diameter stops to adjust feeding speed and pulling speed.It is 1850 ℃ that Figure 11 illustrates the process furnace Heating temperature, the diameter of acquisition be the second order mode of photonic crystal fiber of 125mm at the Power Spectrum Distribution figure at 1550nm place, its effective refractive index is 1.4381-i6.2440 * 10
-7, limitation loss is 21.99dB/m, and loss is very big, and second order mode is difficult to effective transmission in optical fiber.The optical characteristics of the photonic crystal fiber of this moment satisfies the demands substantially, stop parameter adjustment, and obtain one group of the photonic crystal fiber drawing process parameter of optimizing of the embodiment of the invention 1 thus, feeding speed 0.28mm/min, pulling speed 6m/min, 1850 ℃ of furnace temps, about 0.03 crust of suction pressure negative pressure.
Optical fiber applied to obtain the finished product photonic crystal fiber.
The negative dispersion centre wavelength that Figure 12 shows according to the embodiment of the invention 2 is the project organization cross sectional representation of the dispersion compensation photonic crystal fiber of 1550nm, and this optical fiber designs requires to have bigger negative dispersion performance near 1550nm.The background material of photonic crystal fiber adopts for example pure quartz, and the central zone is adopted and for example mixed the quartz of germanium as the high refractive index fuse.Make prefabricated rods with the excellent method of piling of pipe, the diameter that presets rod is 18mm, in pulling process is bled in slit between the thin rod of tubule, inflates in tubule simultaneously.Prefabricated rods one end is fixed on the pay-off of drawing optical fibers equipment, and the other end enters the heating unit heating, and the puddle of prefabricated rods is pulled the device traction and forms bare fibre.At first, rule of thumb choose controlled variable, for example: 1930 ℃ of furnace temps, feeding speed 0.3mm/min, pulling speed 3m/min, the slit suction pressure is about 0.03 crust of negative pressure between the thin rod of tubule, inflation pressure is about 0.03 crust in the tubule.What pulled out this moment is uncoated initial naked photonic crystal fiber.Defective such as this initial bare fibre for example exists, and airport expands, subside, dislocation and optic fibre characteristic do not meet the problem of design requirements, need be optimized the photonic crystal fiber that adheres to specification to obtain to the drawing process parameter of this photonic crystal fiber.
Method according to drawing photonic crystal fiber of the present invention further may further comprise the steps.
Step 101: intercepted length is the bare fibre of just having exported from towing mechanism of about 5cm for example, and measuring its diameter is 172 mm.This section optical fiber is placed on microscopically, make its axially and the micro objective central shaft point-blank and be adjusted to proper focal length, use digital camera to take its cross sectional image by microscopical eyepiece, show as Figure 13, and the cross sectional image of the JPG form of 8 the 256 look RGB patterns that digital camera is generated is input in the computer.
Step 102: use be entitled as " a kind of gray scale image edge detection method " based on mathematical morphology at Fu Yongqing, Southwest Jiaotong University's journal, 31 (5), disclosed a kind of gray scale mathematical morphology edge detection method carries out rim detection to cross section of optic fibre image shown in Figure 13 in the article of 555-559 (1996), the air of identification photonic crystal fiber and the border between background material, and reconstruct bare fibre cross section geometry.The geometry of reconstruct as shown in figure 14.
Step 103: the cross-sectional structure of the photonic crystal fiber of the grid maker that uses matlab 7.0 after to reconstruct is divided grid, and the cross section of photonic crystal fiber is divided into triangle element mesh, obtains the nodal information and the seamed edge information of triangular unit.
Step 104: use for example characteristic of the numerical analysis method analysis photonic crystal fiber of seamed edge unit method in the present embodiment.According to the gridding information in the step 103, between wavelength 1000nm-2000nm, be the effective refractive index of basic mode in the initial bare fibre of step size computation, and analyze dispersion property that its dispersion curve as shown in figure 15 according to effective refractive index with 10nm.
Step 105: will compare with design characteristics at the optic fibre characteristic that step 104 obtains.By comparative result as can be known, the centre wavelength of negative dispersion this moment is partial to long wavelength region about the 1920nm place.Simultaneously, fibre diameter is not easy to welding greatly than the diameter of general single mode fiber.
Step 106: adjust photonic crystal fiber drawing process parameter according to the comparative result of step 105.Can for example reduce inflation pressure in the tubule by adjusting the drawing process parameter, reduce feeding speed, methods such as increase pulling speed reduce the diameter of optical fiber and negative dispersion centre wavelength are moved to short wavelength's direction, improve the performance of drawing optical fiber.
Repeat above-mentioned steps 101 to 106, the diameter adjustment of bare fibre to 125mm, is stopped to regulate feeding speed and pulling speed, continue to adjust inflation pressure in the tubule until the CHROMATIC DISPERSION IN FIBER OPTICS characteristic that is obtained.As shown in figure 16, negative dispersion this moment centre wavelength adheres to specification at optical communications wavelength 1550nm place.Obtain one group of drawing process parameter of optimizing of the embodiment of the invention 2 thus: feeding speed 0.25mm/min, pulling speed 5m/min, 1930 ℃ of furnace temps, the slit suction pressure is about 0.03 crust of negative pressure between the thin rod of tubule, inflation pressure is about 0.01 crust in the tubule.Shown in Figure 17 being with this organized the photonic crystal fiber cross sectional image that preferred processing parameter control pulling process obtains.
Below invention has been described in conjunction with specific embodiments, but should be understood that, the invention is not restricted to above-mentioned specifically described embodiment, on the contrary, under the prerequisite that does not depart from the scope of the present invention with spirit, can carry out various distortion, replacement, correction to the present invention, these distortion, replace, revise the scope of the present invention that all belongs to appended claims and limited.
Claims (10)
1. a method of optimizing the photonic crystal fiber drawing process rapidly is characterized in that, may further comprise the steps in the photonic crystal fiber pulling process:
Step 1: block pulling into and uncoated bare fibre, gather the cross sectional image that draws the bare fibre that obtains;
Step 2: the bare fibre cross sectional image is carried out rim detection, and reconstruct bare fibre cross section geometry;
Step 3:, bare fibre cross section inner compartment is carried out grid divide according to the bare fibre cross section geometry of described reconstruct;
Step 4: use method for numerical simulation to analyze the photonic crystal fiber characteristic of bare fibre;
Step 5: the analytical characteristics of bare fibre and the design characteristics of photonic crystal fiber are compared, obtain comparative result;
Step 6:, adjust photonic crystal fiber drawing process parameter according to comparative result;
Repeat above-mentioned steps one to step 6, can ignore, obtain one group of optimization processing parameter that draws this photonic crystal fiber until the analytical characteristics of drawing bare fibre and the difference of its design characteristics.
2. the method for rapid optimization photonic crystal fiber drawing process according to claim 1, wherein said IMAQ, comprise and use film camera or digital camera or digital microscope that uncoated bare fibre cross sectional image is gathered, and be stored as RGB pattern color image with n position storage, n=8,16,24,32,64.
3. the method for rapid optimization photonic crystal fiber drawing process according to claim 1, wherein said rim detection, be to adopt the Sobel algorithm, or Roberts algorithm, or Laplacian algorithm, or the Canny algorithm obtains marginal information, or adopts the two-value Mathematical Morphology Method to obtain marginal information after the color cross-section image is converted to bianry image according to gray threshold, or adopts the gray scale Mathematical Morphology Method to obtain marginal information.
4. the method for rapid optimization photonic crystal fiber drawing process according to claim 1, wherein said grid is divided, be to carry out triangular unit or the division of rectangular element grid, the size of triangular unit or rectangular element grid and orientation are determined by the boundary shape between regional air of living in and background material.
5. the method for rapid optimization photonic crystal fiber drawing process according to claim 1, wherein said method for numerical simulation is a finite element algorithm, or seamed edge unit method, or method of finite difference.
6. the method according to the described rapid optimization photonic crystal fiber drawing process of claim 1 is a kind of tube bank farad system processing method.
7. the method for rapid optimization photonic crystal fiber drawing process according to claim 1, wherein said adjustment photonic crystal fiber drawing process parameter are to adjust the one or more parameters in the internal pressure of slit between prefabricated rods feeding speed, optical fiber pulling speed, Heating temperature, prefabricated rods kapillary internal pressure, prefabricated rods pipe rod.
8. the method for rapid optimization photonic crystal fiber drawing process according to claim 3, wherein said gray threshold uses iterative algorithm to calculate according to bare fibre cross sectional image gray scale and obtains, or according to the manual assignment of cross sectional image grey level histogram artificial selection.
9. the method for rapid optimization photonic crystal fiber drawing process according to claim 8, wherein said iterative algorithm, be the statistics with
nEach gray-scale value in the bare fibre cross sectional image of position storage
iPixel number
h i , and according to iterative formula 1 calculating gray threshold
T k ,
The initial threshold of iteration wherein
T 0 Be 2
n / 2, or the weighted mean gray-scale value of coloured image, n=8,16,24,32,64,
kBe iterations, iterative computation until
T k No longer change gained
T k Be converted to the optimal threshold of bianry image for coloured image.
10. a photonic crystal fiber draws system, comprising:
Optical fiber drawing apparatus comprises pay-off, towing mechanism, heating unit and pressure regulating device, is used to draw photonic crystal fiber;
Image collecting device is used to gather the photon optical fiber crystalline cross sectional image that is drawn;
Image Edge-Detection device, the image that is used for that image collecting device is gathered carry out rim detection to obtain the cross section of optic fibre geometry of reconstruct;
The optic fibre characteristic simulator comprises that the cross section of optic fibre geometry to reconstruct carries out the grid classification apparatus of grid division and uses method for numerical simulation to analyze the simulated behavior device of the photonic crystal fiber characteristic of this drawing;
The optic fibre characteristic comparison unit is used for the analytical characteristics of bare fibre and the design characteristics of photonic crystal fiber are compared, and the output comparative result;
Processing parameter controlled feedback device is regulated the processing parameter of optical fiber drawing apparatus according to the comparative result of optic fibre characteristic comparison unit.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103613272A (en) * | 2013-11-12 | 2014-03-05 | 杭州电子科技大学 | Optimized production method for glass optical fiber wire drawing equipment |
| CN104751161A (en) * | 2015-04-03 | 2015-07-01 | 燕山大学 | Photonic crystal fiber property simulation system based on precise end face extraction and finite element method and simulation method thereof |
| CN104794475A (en) * | 2015-04-03 | 2015-07-22 | 燕山大学 | End face structural feature extraction method for photonic crystal fiber |
| CN112094050A (en) * | 2020-09-14 | 2020-12-18 | 江苏南方光纤科技有限公司 | Optical fiber preform rod tail wire drawing control system and method |
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| CN1083449A (en) * | 1992-08-03 | 1994-03-09 | 美国电话电报公司 | Comprise fiber optic articles with low polarization mode dispersion and the method for making this optical fiber |
| JP2005008452A (en) * | 2003-06-17 | 2005-01-13 | Shin Etsu Chem Co Ltd | Apparatus and method for sintering optical fiber preform |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1083449A (en) * | 1992-08-03 | 1994-03-09 | 美国电话电报公司 | Comprise fiber optic articles with low polarization mode dispersion and the method for making this optical fiber |
| JP2005008452A (en) * | 2003-06-17 | 2005-01-13 | Shin Etsu Chem Co Ltd | Apparatus and method for sintering optical fiber preform |
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| 《电子学报》 20040531 任国斌 等 光子晶体光纤的有效面积 1-10 第32卷, 第5期 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103613272A (en) * | 2013-11-12 | 2014-03-05 | 杭州电子科技大学 | Optimized production method for glass optical fiber wire drawing equipment |
| CN103613272B (en) * | 2013-11-12 | 2015-07-29 | 杭州电子科技大学 | A kind of glass optical fiber wire-drawing equipment optimization production method |
| CN104751161A (en) * | 2015-04-03 | 2015-07-01 | 燕山大学 | Photonic crystal fiber property simulation system based on precise end face extraction and finite element method and simulation method thereof |
| CN104794475A (en) * | 2015-04-03 | 2015-07-22 | 燕山大学 | End face structural feature extraction method for photonic crystal fiber |
| CN104794475B (en) * | 2015-04-03 | 2018-04-27 | 燕山大学 | A kind of end face structure feature extracting method of photonic crystal fiber |
| CN112094050A (en) * | 2020-09-14 | 2020-12-18 | 江苏南方光纤科技有限公司 | Optical fiber preform rod tail wire drawing control system and method |
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| CN102092937B (en) | 2012-10-31 |
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