Optical mode structure of the plasma waveguide
Optical mode structure of the plasma waveguide
复制标题
等离子体波导的光学模式结构
DOI：
10.1103/physreve.61.1954
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Milchberg
中科院分区：
文献类型：
--
作者：
Clark;Milchberg
利用双延迟的端部注入和侧部注入探测脉冲，研究了演化等离子体波导的准声波模式。这些不同的耦合几何形状的使用允许在两个时间制度的波导的光学模式的探测：早期的等离子体通道的发展，其特征在于泄漏的光学约束，和后来的通道流体动力学膨胀的特征在于更强的约束。通过求解波动方程，确定了实验测得的电子密度分布的准波导光学模式及其约束。在波导出口处测量的引导强度图案和光谱成功地解释了这些模式的解决方案。发现宽带端耦合探测脉冲的光谱不受引导过程的影响，主要是因为那些幸存到波导出口的模式是良好束缚的，并且对于强束缚场，横模轮廓与波长无关。相比之下，侧耦合到准声波模式的等离子体波导被认为是高度模式和频率选择性。
The quasibound modes of an evolving plasma waveguide were investigated by using variably delayed end-injected and side-injected probe pulses. The use of these different coupling geometries allowed the probing of the waveguide's optical modes during two temporal regimes: early-time plasma channel development, characterized by leaky optical confinement, and later channel hydrodynamic expansion characterized by stronger confinement. The wave equation was solved to determine the available quasiguided optical modes and their confinement for experimentally measured electron density profiles. The guided intensity patterns and spectra measured at the waveguide exit were successfully explained in terms of these mode solutions. The spectrum of broadband end-coupled probe pulses was found to be unaffected by the guiding process, mainly because those modes which survived to the waveguide exit were well-bound, and for strongly bound fields, the transverse mode profiles are wavelength independent. By contrast, side coupling to the quasibound modes of the plasma waveguide was seen to be highly mode and frequency selective.