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Studies On The Characters Of Large Chirped Fiber Grating

Posted on:2005-06-01Degree:DoctorType:Dissertation
Country:ChinaCandidate:L XiaFull Text:PDF
GTID:1118360152468047Subject:Electronic Science and Technology
Abstract/Summary:PDF Full Text Request
The research on large chirped fiber Bragg grating (LCBG) is an important part of researches about the fiber grating devices. This thesis gives a detailed discussion on the design and fabrication of LCBG. Conventional small chirped fiber Bragg grating (SCBG) usually has narrow bandwidth and large dispersion for the chirp coefficient restriction, thus is unsuitable for acting as broadband filtering device. But for the LCBG, it has large bandwidth and small dispersion, thus is easy to be applied to broadband filtering, amplifier noise suppressing, gain flattening and fiber sensing, etc. The thesis analyzes the relation of wavelength reflectivity and refractive index modulation zone, the relation of wavelength reflectivity and coupling coefficient under different chirp coefficient, and the relation of wavelength reflectivity and coupling coefficient on different grating position, which are the special characters of LCBG. Moreover, an interpolative inquiry algorithm to design the broadband controllable filtering profile is proposed. Through discrete layer peeling algorithm introduction, the reconstructions of several kinds of grating structure are realized. Through constructing a special refractive index modulation distribution, it is easy to obtain other filtering profiles when the large chirp coefficient and phase mask length are constant. Some special profile filters are produced using this new simple controllable filtering profile design method. Different refractive index modulation distributions along the grating length have been achieved by controlling the pulse number from the excimer laser and beam width during the grating writng process. The reason about non-uniform channel reflectivities existed in the broadband multi-channel filter is also explained in the thesis. Two feasible approaches, non-linear chirp phase mask and constant sample period method as well as changeable sample period and constant chirp coefficient method, are proposed to resolve this problem. The multi-channel equalization filter is designed and manufactured for the first time through the refractive index modulation distribution in the condition of large chirp coefficient. At last in the thesis, a novel grating period sampling design method is demonstrated firstly. The characters of this kind of grating are multi-channel structure and different dispersion at opposite side of the central channel. It is designed and simulated to use in the system dispersion compensation. The effects which may be confronted in the fabrication are also analyzed. All the above results are positive to promote the research and development of the area about FBG.
Keywords/Search Tags:Fiber, Bragg grating, Large chirp, Filter, WDM
PDF Full Text Request
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