光反馈半导体激光器产生低频起伏与高维混沌信号及其演化过程

Dynamics of semiconductor laser with optical feedback:Evolution from low-frequency fluctuations to chaos

利用光反馈半导体激光器产生了低频起伏及关联维数为12.2的高维混沌状态.实验研究了低频起伏到高维混沌的演变过程.实验表明,当偏置电流Ib<1.03Ith时,随着反馈强度的降低,低频起伏的峰峰值先增大后减小,平均周期一直减小,直至进入稳定状态,但不能转化为混沌.当偏置电流Ib>1.03Ith时,随着反馈强度的降低,低频起伏的峰峰值一直增大,平均周期一直减小,直至进入无周期的高维混沌状态.确立了光反馈半导体激光器在反馈强度及偏置电流改变下将会经历稳定激发、低频起伏和混沌三个区域.数值模拟分析了偏置电流和反馈强度对低频起伏及混沌载波的制约关系.模拟结果与实验结果相符.

The low-frequency fluctuations and high-dimensional chaos with 12.2 correlation dimensions were generated experimentally by a semiconductor laser with optical feedback. Extensive experimental and numerical studies were performed to reveal the evolution process from low-frequency fluctuations to chaos. Our results showed that there exists a obvious critical point for the semiconductor laser＇s bias current. When the bias current lb is set below 1.03Ith, the peak-to-peak value of the low-frequency fluctuations increases at first and then decreases with the feedback strength decreasing, while its average period keeps decreasing. In this process, the output of the semiconductor laser never goes chaos. However, when the bias current Ib is set beyond 1.03Ith, chaos appears and is persistent in this range. Moreover, the peak-to-peak value of the low-frequency fluctuations increases eontinuouslly and its duration decreases with the decrease of the feedback strength. Three stages experienced in the process leading from stable emission and low-frequency fluctuation to chaos are established. Numerical simulations are well consistent with the experimental results.