Masoller Cristina
Instituto de Fisica, Facultad de Ciencias, Universidad de la Republica, Montevideo, Uruguay.
Chaos. 1997 Sep;7(3):455-462. doi: 10.1063/1.166253.
This paper presents a spatiotemporal characterization of the dynamics of a single-mode semiconductor laser with optical feedback. I use the two-dimensional representation of a time-delayed system (where the delay time plays the role of a space variable) to represent the time evolution of the output intensity and the phase delay in the external cavity. For low feedback levels the laser output is generally periodic or quasiperiodic and with the 2D representation I obtain quasiperiodic patterns. For higher feedback levels the coherence collapsed regime arises, and in the 2D patterns the quasiperiodic structures break and "defects" appear. In this regime the patterns present features that resemble those of an extended spatiotemporally chaotic system. The 2D representation allows the recognition of two distinct types of transition to coherence collapse. As the feedback intensity grows the number of defects increases and the patterns become increasingly chaotic. As the delay time increases the number of defects in the patterns do not increase and there is a signature of the previous quasiperiodic structure that remains. The nature of the two transitions is understood by examining the behavior of various chaotic indicators (the field autocorrelation function, the Lyapunov spectrum, the fractal dimension, and the metric entropy) when the feedback intensity and the delay time vary. (c) 1997 American Institute of Physics.
本文给出了具有光反馈的单模半导体激光器动力学的时空特性。我使用延时系统的二维表示（其中延迟时间起到空间变量的作用）来描述外腔中输出强度和相位延迟的时间演化。对于低反馈水平，激光输出通常是周期性或准周期性的，通过二维表示我得到了准周期图案。对于较高反馈水平，出现了相干崩溃 regime，在二维图案中准周期结构破裂并出现“缺陷”。在这个 regime 中，图案呈现出类似于扩展时空混沌系统的特征。二维表示允许识别两种不同类型的向相干崩溃的转变。随着反馈强度增加，缺陷数量增加，图案变得越来越混沌。随着延迟时间增加，图案中的缺陷数量不增加，并且存在先前准周期结构的特征。通过研究当反馈强度和延迟时间变化时各种混沌指标（场自相关函数、李雅普诺夫谱、分形维数和度量熵）的行为，可以理解这两种转变的性质。(c) 1997 美国物理研究所。
