Jahanbakht Sajad
Appl Opt. 2017 Feb 1;56(4):975-984. doi: 10.1364/AO.56.000975.
A frequency domain approach for computing all of the steady state modes of single-loop optoelectronic oscillators (OEOs) corresponding to the exact parameter values, especially the fiber length, is presented. Computing these modes is useful in analyzing their effects on the phase noise performance as well as in designing single-mode OEOs. This computation is also useful in analyzing injection-locked OEO systems where the locking state depends on the values of oscillation frequencies and power levels of the steady state modes of the OEOs involved. The proposed steady state computation approach requires a much smaller amount of run-time compared to time domain methods; however, its results have to be checked for stability. Two stability analysis schemes, one based on the frequency domain Nyquist stability analysis and the other based on solving a slowly varying perturbation system in the time domain, are presented. The validities of these schemes are verified by comparing their results with each other, with full time domain integrations, and with previously published results. It is shown that the modes of a single-loop OEO computed by the presented approach are either stable or unstable, which justifies the need to use the proposed stability analysis schemes. Simulations show that the unstable modes ultimately converge to the dominant mode, i.e., the one with the largest small-signal loop gain. The effect of exciting any mode on the phase noise is also investigated through simulations.
提出了一种频域方法，用于计算与精确参数值（特别是光纤长度）相对应的单环光电振荡器（OEO）的所有稳态模式。计算这些模式对于分析它们对相位噪声性能的影响以及设计单模OEO很有用。这种计算在分析注入锁定OEO系统时也很有用，在该系统中，锁定状态取决于所涉及的OEO的振荡频率和稳态模式的功率水平值。与时域方法相比，所提出的稳态计算方法所需的运行时间要少得多；然而，其结果必须进行稳定性检查。提出了两种稳定性分析方案，一种基于频域奈奎斯特稳定性分析，另一种基于求解时域中的慢变摄动系统。通过将这些方案的结果相互比较、与全时域积分结果以及与先前发表的结果进行比较，验证了这些方案的有效性。结果表明，通过所提出的方法计算得到的单环OEO模式要么是稳定的，要么是不稳定的，这证明了使用所提出的稳定性分析方案的必要性。仿真表明，不稳定模式最终会收敛到主导模式，即具有最大小信号环路增益的模式。还通过仿真研究了激发任何模式对相位噪声的影响。
