Gu Linlin, Guo Dengchu, Dong Liangwei
Opt Express. 2015 May 4;23(9):12434-43. doi: 10.1364/OE.23.012434.
We address two closely related problems: diffraction management and soliton dynamics in parity-time ( ℙT) symmetric lattices with a quadratic frequency modulation. The normal, anomalous, or zero diffraction is possible for narrow beams with a broad band of spatial frequencies. The frequency band of nondiffraction beams can be enlarged by increasing the chirp rate of lattices. Counter-intuitively, the gain-loss component plays the same role as the real part of lattice on the suppression of diffraction, which leads to an effective reduction of critical lattice depth for nondiffraction beams. Additionally, we reveal the existence of a novel type of "bright" solitons in defocusing Kerr media modulated by chirped ℙT lattices. We also demonstrate that lattice chirp can be utilized to suppress the instability of solitons. Our results expand the concept of ℙT symmetry in both linear and nonlinear regimes, and may find interesting optical applications.
具有二次频率调制的奇偶时间（ℙT）对称晶格中的衍射管理和孤子动力学。对于具有宽带空间频率的窄光束，正常、反常或零衍射都是可能的。通过增加晶格的啁啾率，可以扩大无衍射光束的频带。与直觉相反，增益-损耗分量在抑制衍射方面与晶格的实部起着相同的作用，这导致无衍射光束的临界晶格深度有效降低。此外，我们揭示了在由啁啾ℙT晶格调制的散焦克尔介质中存在一种新型的“亮”孤子。我们还证明了晶格啁啾可用于抑制孤子的不稳定性。我们的结果扩展了ℙT对称性在线性和非线性区域的概念，并可能找到有趣的光学应用。
