Lotfi Parvin, Sahrai Mostafa, Siahpoush Vahid, Vafafard Azar
Faculty of Physics, University of Tabriz, Tabriz, Iran.
Sci Rep. 2024 Jul 14;14(1):16234. doi: 10.1038/s41598-024-67019-4.
A nondiffracting propagation of an optical beam through a four-level double-V-type quantum system near a plasmonic nanostructure is investigated. We study the linear absorption and dispersion properties of the quantum system as it interacts with two laser fields. We discuss the effect of the control beam with a Laguerre-Gaussian (LG) profile on the focusing of the probe beam in the presence of a plasmonic nanostructure. An appropriately selected control beam excites one transition of the atomic system and generates a spatially varying refraction index modulation for a weak probe beam that couples to the other transition. We demonstrate that placing a plasmonic nanostructure at a nanometer distance from the atomic system and using a control field with the spatial structure leads to the diffraction-less propagation of the probe beam through the atomic system. Also, it is shown that the optical properties and probe beam focusing can be controlled by adjusting the distance of the plasmonic nanostructure from the atomic system. The proposed all-optical waveguide with high contrast and transmission can be used to implement applications such as image transfer through the medium and image processing.
研究了光束在等离子体纳米结构附近通过四能级双V型量子系统的无衍射传播。我们研究了量子系统与两个激光场相互作用时的线性吸收和色散特性。我们讨论了具有拉盖尔-高斯（LG）分布的控制光束在存在等离子体纳米结构的情况下对探测光束聚焦的影响。适当选择的控制光束激发原子系统的一个跃迁，并为耦合到另一个跃迁的弱探测光束产生空间变化的折射率调制。我们证明，将等离子体纳米结构放置在距原子系统纳米距离处，并使用具有空间结构的控制场，会导致探测光束通过原子系统的无衍射传播。此外，结果表明，可以通过调整等离子体纳米结构与原子系统的距离来控制光学性质和探测光束聚焦。所提出的具有高对比度和透射率的全光 waveguide 可用于实现诸如通过介质进行图像传输和图像处理等应用。
