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標題: | 非立即反應之反自聚焦介質中非同調共振腔裡的調變不穩定現象 Modulation Instability in Non-instantaneous Self-defocusing Medium in the Incoherent Cavity |
作者: | Meng-Chieh Tsai 蔡孟杰 |
指導教授: | 石明豐 |
關鍵字: | 反自聚焦,非同調共振腔,調變不穩定現象, Modulation Instability,Self-defocusing,Incoherent Cavity, |
出版年 : | 2006 |
學位: | 碩士 |
摘要: | Modulation instability is one of mechanisms which results in pattern formation in nonlinear wave system. The incident wave with small amplitude perturbation passes through the nonlinear system. The perturbation with some special frequencies may have the highest gain and grows up. Then it will form patterns in the output. This phenomenon is often seen in nonlinear wave system, for example, nonlinear Kerr medium, nonlinear elastic medium, optical fiber, BEC, etc. To form MI, Lighthill criterion must be satisfied. It means that the nonlinearity of refractive index must work against the natural dispersion during wave propagation. For example, a cw laser beam propagates in self-focusing medium.
On the other hand, in self-defocusing medium no pattern can be formed spontaneously. But we have reported that induced modulation instability is possible in noninstantaneous self-defocusing medium. That is, a time-varying modulation produced by interference will grow up in the self-defocusing medium because of the delayed response in the change of the refractive index. Furthermore, in this paper we want to show that patterns will form spontaneously in self-defocusing medium with incoherent feedback. Some special frequency will be picked up and experience the highest gain automatically because of the boundary condition. We will show both the experimental result and theoretical analysis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/33290 |
全文授權: | 有償授權 |
顯示於系所單位: | 物理學系 |
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