Geints Yuri E, Minina Olga V, Geints Ilia Yu, Seleznev Leonid V, Pushkarev Dmitrii V, Mokrousova Daria V, Rizaev Georgy E, Shipilo Daniil E, Nikolaeva Irina A, Kurilova Maria V, Panov Nikolay A, Kosareva Olga G, Houard Aurélien, Couairon Arnaud, Ionin Andrey A, Liu Weiwei
V.E. Zuev Institute of Atmospheric Optics, 1 Acad. Zuev Square, Tomsk 634021, Russia.
Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia.
Sensors (Basel). 2022 Aug 23;22(17):6322. doi: 10.3390/s22176322.
High-intensity (∼1 TW/cm2 and higher) region formed in the propagation of ∼60 GW, 90 fs Ti:Sapphire laser pulse on a ∼100 m path in air spans for several tens of meters and includes a plasma filament and a postfilament light channel. The intensity in this extended region is high enough to generate an infrared supercontinuum wing and to initiate laser-induced discharge in the gap between the electrodes. In the experiment and simulations, we delay the high-intensity region along the propagation direction by inserting metal-wire meshes with square cells at the laser system output. We identify the presence of a high-intensity region from the clean-spatial-mode distributions, appearance of the infrared supercontinuum wing, and occurrence of the laser-induced discharge. In the case of free propagation (without any meshes), the onset of the high-intensity zone is at 40-52 m from the laser system output with ∼30 m extension. Insertion of the mesh with 3 mm cells delays the beginning of the high-intensity region to 49-68 m with the same ∼30 m extension. A decrease in the cell size to 1 mm leads to both delay and shrinking of the high-intensity zone to 71-73 m and 6 m, respectively. Three-dimensional simulations in space confirm the mesh-induced delay of the high-intensity zone as the cell size decreases.
在空气中约100米路径上传播的约60吉瓦、90飞秒钛宝石激光脉冲形成的高强度（约1太瓦/平方厘米及更高）区域跨度达几十米，包括一个等离子体细丝和一个细丝后光通道。在这个扩展区域内的强度足以产生红外超连续谱翼，并在电极之间的间隙引发激光诱导放电。在实验和模拟中，我们通过在激光系统输出端插入具有方形单元的金属丝网，使高强度区域沿传播方向延迟。我们从清晰的空间模式分布、红外超连续谱翼的出现以及激光诱导放电的发生来确定高强度区域的存在。在自由传播（无任何丝网）的情况下，高强度区域的起始位置在距激光系统输出端40 - 52米处，扩展约30米。插入3毫米单元的丝网会使高强度区域的起始位置延迟到49 - 68米，扩展仍约为30米。单元尺寸减小到1毫米会导致高强度区域延迟并缩小，分别变为71 - 73米和6米。空间三维模拟证实，随着单元尺寸减小，丝网会导致高强度区域延迟。
