Ultrafast white-light continuum generation and self-focusing in transparent condensed media
Ultrafast white-light continuum generation and self-focusing in transparent condensed media
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DOI：
10.1364/josab.16.000637
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发表时间：
1999-04-01
影响因子：
1.9
通讯作者：
Chin, SL
中科院分区：
文献类型：
--
作者：
Brodeur, A;Chin, SL
报道了140飞秒掺钛蓝宝石激光脉冲在扩展透明介质中产生白光连续谱和自聚焦的研究。研究发现，连续谱的产生是由自聚焦触发的，并且这两种现象都依赖于介质的带隙。连续谱的产生存在带隙阈值。在该阈值以上，连续谱宽度随着带隙的增大而增大。此外，光束的自焦直径在阈值上是不连续的。为了解释这些观测结果，提出了一种机制，该机制涉及多光子激发电子进入自聚焦处的导带；产生的自由电子导致光谱超展宽并限制自焦直径。然后研究了连续光束出奇的低发散度，并用克尔透镜效应对其进行了解释。(C)1999年美国光学学会[S0740-3224(99)00204-0]OCIS编码：320.7110、320.7120、320.2250、190.5940、190.4180、190.2620。
We report an investigation of white-light continuum generation and self-focusing by 140-fs Ti:sapphire laser pulses in extended transparent media. It is found that continuum generation is triggered by self-focusing and that both phenomena depend on the medium's bandgap. There is a bandgap threshold for continuum generation. Above that threshold the continuum's width increases with increasing bandgap. Furthermore, the beam's self-focal diameter is discontinuous across the threshold. To explain the observations a mechanism is proposed that involves multiphoton excitation of electrons into the conduction band at the self-focus; the generated free electrons cause spectral superbroadening and limit the self-focal diameter. The continuum beam's surprisingly low divergence is then investigated and explained in terms of a Kerr lensing effect. (C) 1999 Optical Society of America [S0740-3224(99)00204-0] OCIS codes: 320.7110, 320.7120, 320.2250, 190.5940, 190.4180, 190.2620.