线性布里渊慢光系统中SBS补偿的局限:牺牲与优化

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本文探讨了在基于线性布里渊慢光系统中,利用受激布里渊散射(SBS)诱导的慢光和快光传播在级联光纤中的色散补偿限制。研究者Zhiyao Zhang、Xiaojun Zhou、Lan Lan 和 Yong Liu 来自中国电子科技大学的光电子信息学院,他们提出了一个理论模型,旨在量化SBS引起的等效色散对脉冲形状的影响。该模型分析了一种利用快速光传播来抵消非均匀增益导致的等效群速度色散的线性布里渊慢光系统。 模型的关键发现是,尽管通过这种方式可以有效地消除非均匀增益带来的等效群速度色散问题,但这一方法是以引入更显著的高阶等效色散效应作为代价的。这意味着在设计和优化这种系统时,必须权衡色散补偿的效率与信号质量的保持,因为过高的高阶色散可能导致信号失真和脉冲展宽,从而降低信号传输的稳定性。 作者强调,设计者在实际应用中需谨慎考虑这些限制,可能需要通过优化光纤参数、选择合适的泵浦功率或者采用其他补偿技术,如相位调制或非线性滤波器,来进一步减小高阶色散的影响。此外,研究还可能对光纤通信系统的设计者提供有价值的指导,尤其是在追求超高速数据传输和长距离信号传输时,如何平衡色散管理与系统复杂性的挑战。 这项研究揭示了在利用SBS和快光技术进行色散补偿时,需要深入理解并控制色散特性,以实现高效、低失真的信号传输,这是当前光通信领域的一个重要进展。

翻译This SiO2 shell is a key component in the mechanism for reversible actuation, as illustrated by finite element analysis (FEA) in Fig. 1C. An increase in temperature transforms the SMA (nitinol) from the martensitic to the austenitic phase, causing the 3D structure to flatten into a 2D shape. The responses of the SMA elements at the joints act as driving forces to deform the PI skeleton. This process also elastically deforms the SiO2 shell, resulting in a counter force that limits the magnitude of the deformation. The change in shape ceases when the forces from the shell balance those from the joints (right frame in Fig. 1C). Upon a reduction in temperature, the SMA changes from the austenitic back to the martensitic phase, thereby reducing the force produced by the SMA at the joints to zero. The elastic forces associated with the shell then push the entire system back to the original 3D geometry (left frame in Fig. 1C). Figure S3A simulates the moments generated by the SMA and the SiO2 shell. In the FEA model, the SiO2 shell appears on both the outer and inner surfaces of the 3D robot, consistent with experiments (fig. S3B). Although a single layer of the SiO2 shell at the outer or inner surface can also provide restoring force, the double-layer shell structure follows naturally from the conformal deposition process. This actuation scheme allows for reversible shape transformations using a one-way shape memory material. Without the shell, the structure only supports a single change in shape, from 3D to 2D, as illustrated in fig. S3C. Figure 1D shows optical images of a freestanding 3D peekytoe crab on the edge of a coin, highlighting the preserved 3D geometry enabled by the SiO2 shell after release from the elastomer substrate. Other 3D structures in geometries that resemble baskets, circular helices, and double-floor helices also exhibit high shape storage ratios (>85%) after cycles of heating and cooling (fig. S4). This ratio (s) is defined as s = 1 − |L1 − L0|/L0 × 100%, where L0 and L1 are the distances between the bonding sites at both ends at the initial stage and subsequent stages, respectively

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