超短激光脉冲在等离子体中的分裂以及类孤子结构的形成

用一维粒子模拟研究了超短脉冲在等离子体中传播时产生的光孤子结构以及由此形成的脉冲分裂现象，比较了不同峰值强度和脉冲宽度对形成光孤子以及脉冲传播方式的影响.研究表明: 脉冲宽度在若干个到十几个振荡周期的超短脉冲在等离子体中可能形成高速传播的光孤子；脉冲宽度增加和强度增大两种方式都可以使得孤子结构的传播速度减慢,且由于高阶孤子的衰变使得初始激光脉冲在等离子体中发生分裂，形成两个以不同速度向前传播的孤子结构.由孤子阶数的理论计算可较好地预言激光脉冲在等离子体中分裂的子脉冲数. 关键词： 光孤子 超短激光脉冲 等离子体 粒子模拟

Splitting of ultrashort laser pulses propagating in plasmas and the generation of soliton-like structures

Using the one-dimensional particle-in-cell simulation, we studied the splitting of ultrashort laser pulses propagating in plasmas and the generation of soliton-like structures, and compared the effect on these phenomenon by changing the duration and intensity of initial laser pulse. It was shown the solitons moving with high group velocities can be formed by the ultrashort laser pulse with in a few cycles of duration. When the pulse duration and intensity of initial laser pulses increase, the group velocities of solitons decrease with greater frequency down-shifts. The decay of high-order solitons are generated by self-steepening and self-frequency shift, so the initial laser pulse splits into several daughter_pulses, and two solitons with different group velocities can be formed and propagate in the plasma. The number of daughter-pulses observed in simulations has been predicted by the theoretical calculation of soliton-orders.