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Research On High Nonlinear And Dispersion Flattened Microstructured Fibers

Posted on:2011-07-27Degree:MasterType:Thesis
Country:ChinaCandidate:Y M WangFull Text:PDF
GTID:2178360308462082Subject:Electromagnetic field and microwave technology
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The research works of this paper are supported by the National Basic Research Program of China (973 Project, Grant 2003CB314906), the National 863 High Technology Project of China (2007AA03Z447), the Foundation for the Key Program of Ministry of Education of China (Grant 104046).Microstructured fibers (MFs) show us an amazing and promising application potentiality for their novel properties, such as flexible and controllable dispersion property, controllable nonlinearity, and low confinement loss. In recent years, the design, fabrication and application of MFs have become hot research tropics. Especially, the application research on DWDM light source and all-optical regeneration based on the Supercontinuum (SC) Spectrum in microstructured fibers become more and more valuble. The design of the high-nonlinear and dispersion-flattened microstructured fibers which could generate 1550nm wavelength band, broad and flattened SC spectrum, and the application of multi-wavelegth light source and all-optical regeneration which are based on the SC spectrum in MFs, are studied both theoretically and experimentally. The major contents and achievements are as follows.1. The control law about the properties of MFs by adjusting the structure parameters of MFs is studied theoretically, including dispersion, nonlinearity and confinement loss. One new type of MFs which have two- zero dispersion, flattened dispersion, high nonlinearity and low confinement loss is designed by utilizing the finite-difference beam propogation method (FD-BPM). The dispersion value is between -1.380 and +0.9866 ps/nm/km with the wavelength ranging from 1.45μm to 1.65μm. The nonlinear coefficient is larger than 33.1W-1km-1, and confinement loss is in the order of 10-4dB/km at the wavelength of 1550nm. The proposed MFs also own the advantages of fewer structure parameters and the modest ratio between aperture and pitch of holes.2. Another type of MFs which could generate 1550nm wavelength band, broad and flattened SC spectrum is designed. It has the properties including near-zero nomal dispersion, flattened dispersion, high nonlinearity and low confinement loss. The dispersion value is between-1.65 ps/nm/km and-0.335 ps/nm/km from 1.45μm to 1.65μm. At the telecommunication window of 1550nm, the nonlinear coefficient is larger than 33.7735W-1km-1, and the confinement loss is as low as 3.32×10-4dB/km.3. The influence of parameters on the SC spectrum including the fiber length L, peak power Po and full width at half maximum (TFWHM) of the pulse, and plus-minus chirp (C) is theoretically analyzed by using of the designed MF which has near-zero nomal dispersion. Results indicate that with the same conditions of L=80m and TFWHM =1.5ps, high nonlinear and dispersion flattened MF (NL-1550-NEG-1) from Crystal Fiber Company needs P0>100W to generate lOdB bandwidth of more than 80nm, and the proposed MFs only need P0=30W but could generate 10dB bandwidth of more than 100nm.4. Cooperating with others, the feasibility of applying the supercontinuum (SC) of MFs into DWDM light source is verified. Clock pulses can be filterred out at different wavelength between 1525nm to 1575nm from the SC while the bandwidth of the filter window is changing from 2.5nm to 0.8nm.5. All-optical 2R regeneration of 10 Gb/s signals based on SC spectrum in an 80-m dispersion-flattened microstructured fiber was demonstrated experimentally. The output extinction ratio (ER) of the optimal regenerated signals was improved from 5.6 dB to about 12 dB. The regenerator also could greatly reduce the amplitude jitter. Furthermore, the single-to-multiple-channel wavelength conversion characteristic of the regenerator was also discussed.6. The simulation experiment of all-optical communication system by use of DWDM light source, all-optical regeneration devices and so on. Results indicate that the pulse sequence with 10GHz-repeat frequency and 6ps width is obtained by use of the DWDM light source based on SC spectrum; the moduled optical signal transmits as input signal through 98km length, and the dispersion and dispersion slope are compensated by use of 1km-length broadband dispersion compensation MF.The eye diagram has been improved after compensation. The Q factor of signal's eye diagram has been improved from 11.4 to 12.7 and the height of eye diagram has rised by 8.3%.
Keywords/Search Tags:microstructured fibers, high nonlinear, dispersion flattened, confinement loss, supercontinuum spectrum, all- optical regeneration
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