石明豐臺灣大學：物理研究所陳宣燁Chen, Shiuan-YehShiuan-YehChen2007-11-262018-06-282007-11-262018-06-282005http://ntur.lib.ntu.edu.tw//handle/246246/54524Vortex is an interesting phenomenon which appears in many branches of physics, including optics, fluid dynamics, and BEC. This dissertation is mainly to present the experimental results of stabilization of the optical vortex in noninstantaneous self-focusing media. The work is focused on the suppression of azimuthal instability (AI) which causes the vortex beam to break into pieces in the nonlinear self-focusing media. From the theoretical analysis of the related phenomenon “modulation instability” (MI), we predict the way to eliminate MI may be applied to annihilate AI. In a series of experiments, the stabilized single charge and double charge vortex beam are observed by increasing the temporal frequency of perturbation and the response time of the nonlinear material. From inspection of interference patterns of these self-trapped stabilized vortex beams, we can confirm their phase information is reserved. That is, these vortex beams are coherent, which are different from earlier observation of the vortex beams stabilized by the partially incoherent light.Abstract..i Chapter 1 Overview of spatial optical solitons..1 1.1 Spatial optical solitons..1 1.2 Self-focusing medium..2 1.3 The forms of nonlinearities..3 1.4 Photorefractive effect..5 Chapter 2 Optical vortex beam and azimuthal instability..8 2.1 Optical vortex beam..8 2.2 Generation of LG beam..11 2.3 Azimuthal instability..15 Chapter 3 Stabilization of the vortex beam..19 3.1 Introduction: From MI to AI..19 3.2 Experimental setup..22 3.3 Experimental results..25 3.4 Conclusion..37 Chapter 4 Summary and future work..38 Bibliography..401802290 bytesapplication/pdfen-US漩渦光非即時自聚焦光孤子VortexNoninstantaneousSelf-focusingsolitonthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/54524/1/ntu-94-R92222025-1.pdf