Control of beam propagation in optically written waveguides beyond the paraxial approximation
Control of beam propagation in optically written waveguides beyond the paraxial approximation
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DOI：
10.1103/physreva.87.043842
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发表时间：
2013-04-30
影响因子：
2.9
通讯作者：
Evers, Joerg
中科院分区：
文献类型：
--
作者：
Zhang, Lida;Dey, Tarak N.;Evers, Joerg
研究了光写入波导结构中光束在近轴近似外的传播。在由非相干泵浦驱动的五能级原子蒸汽和两个相干空间相关控制平面波场组成的介质上，刻印了导致无衍射光传播的波导结构。我们首先研究了光束在单个光写入波导中的传播，并发现傍轴近似不能提供对探针传播的准确描述。然后，我们使用相干控制场，使两个平行和一个倾斜的高斯光束产生分支波导结构。倾斜光束允许有选择地将探针光束导向波导结构的不同分支。通过改变高斯控制光束的宽度和空间相关的非相干泵浦场的强度，可以改善探测光束在特定支路的传输。
Beam propagation beyond the paraxial approximation is studied in an optically written waveguide structure. The waveguide structure, which leads to diffractionless light propagation, is imprinted on a medium consisting of a five-level atomic vapor driven by an incoherent pump and two coherent spatially dependent control and plane-wave fields. We first study beam propagation in a single optically written waveguide and find that the paraxial approximation does not provide an accurate description of the probe propagation. We then employ coherent control fields such that two parallel and one tilted Gaussian beams produce a branched waveguide structure. The tilted beam allows selective steering of the probe beam into different branches of the waveguide structure. The transmission of the probe beam for a particular branch can be improved by changing the width of the titled Gaussian control beam as well as the intensity of the spatially dependent incoherent pump field.