半导体光纤环形激光器输出状态分析与分类

研究了不同注入电流、不同输出偏振度下,半导体光纤环形激光器输出光的混沌特性.分别采用时域观察法、C-C法、Wigner-ville分布时频分析法、最大Lyapunov指数法联合分析输出光的时域、频域统计特性.从而将激光器输出按偏振度划分为三类:偏振度在0%到20%,随着电流的增大,激光器输出偏振混沌激光,其类型发生阶跃性跳变;偏振度在30～80%,激光器输出仍以偏振混沌激光为主,其类型不随电流增大而发生跳变;偏振度趋于90～100%,激光器输出以强度混沌激光为主,偏振混沌光随着偏振度趋向100%而下降为零.利用虚假邻点法计算嵌入维数和回归图法重构吸引子,得到上述三种输出类型的复杂程度依次是:椭圆吸引子(6维)、方形吸引子(7维)、点形吸引子(5维).由此得出,半导体光纤环形激光器用于偏振混沌通信的最佳区域为:偏振度处于30%至80%,注入电流处于330 mA～550 mA.

Analysis and Classification to the Outputs of the Semiconductor Fiber Ring Laser

The chaotic characteristics of the outputs of the semiconductor fiber ring laser at different injected current and different degree of polarization (DOP) were investigated. The statistical properties in the time and frequency domains were studied by time domain watch,C-C method,Wigner-ville distribution (WVD) time-frequency analysis method and the largest Lyapunov exponents respectively. The ring laser outputs are therefore classified into three kinds: DOPs are between 0% and 20% ,the ring laser outputs polarization chaos and step changes theirs sorts, DOP approaches 90%～100%, the polarized chaos decrease into 0% and intensity chaos grow. The outputs change significantly and generate multiple changes in sorts; for the rest of DOPs, the outputs remains polarization chaos and don t change their sorts. With false nearest neighbors (FNN) method computing the embeding dimension and with return map method reconstructing the strange attractor,the complexity of the above-mentioned three kinds of outputs can be obtained,that is: Ellipse (6 dimension), Square (7 dimension) and point (5 dimension). So the suitable range for the polarization chaos communication system is recommended that DOPs are between 30% and 80% and injected currents are between 330 mA and 500 mA.