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Experimental Investigations On Photo-written 3-D Waveguides In Iron-doped Lithium Niobate Crystals

Posted on:2007-11-07Degree:MasterType:Thesis
Country:ChinaCandidate:H L XuFull Text:PDF
GTID:2178360182979097Subject:Optics
Abstract/Summary:PDF Full Text Request
Optical waveguide is the basic element of an optical integrated system, and it is playing an important role in the applications of optical computations, optical dynamic interconnections and information processing. Proton exchange, ion implanting, and etching are some traditional waveguide fabrication techniques in a two-dimensional plane. But all of these methods are complicated in technics. Recently, light-induction methods attract much research interest. In this thesis, three methods to form 3-D waveguide structures in lithium niobate (LiNbO3) crystals, including laser micromachining, structure-light illuninating, and photovoltaic spatial optical soliton induction technique are investigated experimentally in detail. The main work is as follows:(1) By solving the photorefractive dynamic equations, the optimal intervals for waveguide fabrications in LiNbO3 crystal are numerically specified when the focused laser beams scan along different directions. Curved and Y-branches waveguides are experimentally formed in an iron doped LiNbO3 crystal. The near field pattern and the results of the guiding tests show that the waveguide are successfully fabricated.(2) Index changes in LiNbO3 crystals induced by writing beams with different intensity profiles are theoretically analyzed and numerically simulated. For the one-dimensional cases, analytic relations between the intensity profiles of writing beams and the index distributions are obtained. While for the two-dimensional cases, numerical solution methods are employed to obtain the intensity profiles of the writing beams corresponding to the desired index changes with distributions of gaussian, square law, or ring type. These are experimentally demonstrated in an iron doped LiNbO3 crystal.(3) Fabricating a 2×2 light coupler employing structure-lights formed by a binary optical mask is investigated experimentally in an iron doped LiNbO3 crystal. Mach-Zehnder waveguide employing structure lights formed by an LCLV is obtained in an iron doped LiNbO3 crystal.(4) Formations of 1-D dark photovoltaic spatial optical solitons are numerically simulated and experimentally demonstated in an iron doped LiNbO3 crystal. Planar, Y-branches and channel waveguides are successfully fabricated in LiNbO3: Fe crystal by introducing phase perturbations and amplitude perturbations in uniform incident beams, respectively.
Keywords/Search Tags:iron doped LiNbO3 crystal, 3-D optical waveguides, laser micromaching, structure-lights illuminating, spatial optical solitons
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