Generation of Intense Diffraction-Limited White Light and 4-fs Pulses
Generation of Intense Diffraction-Limited White Light and 4-fs Pulses
复制标题
产生强衍射限制白光和 4-fs 脉冲
DOI：
10.1109/cleoe.1998.718841
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
F. Krausz
中科院分区：
文献类型：
--
作者：
Z. Cheng;G. Tempea;T. Brabec;K. Ferencz;C. Spielman;F. Krausz
自从发现超短激光脉冲产生光谱连续谱以来，由于其对超快光谱学的重要性，引起了人们的广泛兴趣。在本文中，据我们所知，我们首次报告了几乎衍射极限的真正白光飞秒连续谱的产生，在 400-1100 nm 范围内表现出可比的光谱强度。这种性能可以通过通过填充有惰性气体作为非线性介质的毛细管（或空心波导）传播非常短（约 25 fs）的脉冲来获得。波导的主要优点在于，能量转移到高阶横向模式以及因此相关的空间效应累积（例如自聚焦/散焦、成丝）被限制在相对较短的传播长度内，在该传播长度上高阶模式相对于基本模式相移。然而，基模的空间均匀自相位调制（SPM）可以在更长的距离上累积，仅受传播损耗和可能的脉冲展宽效应的限制。因此，与体介质相比，空心波导具有更强的非线性相位积累的潜力，而不会降低光束质量。
Ever since its discovery spectral continuum generation by ultrashort laser pulses has attracted much interest owing to its significance for ultrafast spectroscopy. In this paper we report, for what is to our knowledge the first time, the generation of nearly diffraction-limited truly white-light femtosecond continuum exhibiting comparable spectral intensities all over the range of 400-1100 nm. This performance could be obtained by propagating very short (≈ 25 fs) pulses through a capillary (or hollow waveguide) filled with some noble gas as a nonlinear medium. The key advantage of waveguiding lies in the fact that energy transfer into higher-order transverse modes and hence associated accumulation of spatial effects (e.g. self focusing/defocusing, filamentation) is confined to a relatively short propagation length over which higher-order modes dephase with respect to the fundamental one. Spatially uniform self-phase modulation (SPM) of the fundamental mode, however, can accumulate over much longer distances limited merely by propagation losses and possible pulse broadening effects. As a result, hollow waveguides offer the potential for a much stronger nonlinear phase accumulation without degradation of beam quality as compared to bulk media.