Huang Changming, Ye Fangwei, Kartashov Yaroslav V, Malomed Boris A, Chen Xianfeng
Opt Lett. 2014 Sep 15;39(18):5443-6. doi: 10.1364/OL.39.005443.
The concept of the PT symmetry, originating from the quantum field theory, has been intensively investigated in optics, stimulated by the similarity between the Schrödinger equation and the paraxial wave equation governing the propagation of light in guiding structures. We go beyond the paraxial approximation and demonstrate, solving the full set of the Maxwell's equations for the light propagation in deeply subwavelength waveguides and periodic lattices with balanced gain and loss, that the PT symmetry may stay unbroken in this setting. Moreover, the PT symmetry in subwavelength guiding structures may be restored after being initially broken upon the increase of gain and loss. Critical gain/loss levels, at which the breakup and subsequent restoration of the PT symmetry occur, strongly depend on the scale of the structure.
源自量子场论的宇称-时间（PT）对称概念，受薛定谔方程与描述光在波导结构中传播的傍轴波动方程之间的相似性启发，已在光学领域得到深入研究。我们超越傍轴近似，通过求解麦克斯韦方程组来描述光在具有平衡增益和损耗的深亚波长波导和周期性晶格中的传播，证明在这种情况下PT对称可能保持不破缺。此外，亚波长波导结构中的PT对称在增益和损耗增加时最初被打破后可能会恢复。PT对称发生破缺及随后恢复的临界增益/损耗水平强烈依赖于结构的尺度。
