Resolving the build-up of femtosecond mode-locking with single-shot spectroscopy at 90 MHz frame rate
Resolving the build-up of femtosecond mode-locking with single-shot spectroscopy at 90 MHz frame rate
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DOI：
10.1038/nphoton.2016.38
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发表时间：
2016-05-01
期刊：
影响因子：
35
通讯作者：
Solli, D. R.
中科院分区：
文献类型：
--
作者：
Herink, G.;Jalali, B.;Solli, D. R.
锁模激光器已经实现了一些有史以来最精确的测量，从阿秒时域光谱到频率梳计量。然而，这种极端的精度掩盖了潜在的锁模动力学的复杂性。这种复杂性在锁模状态的出现中尤其明显，锁模状态是一种本质上单一的、非重复的过渡。锁模的许多细节都很好地理解，但传统的光谱学不能解决被动锁模的自然纳秒时间尺度，单脉冲周期的新生动力学。在这里，我们捕获了飞秒脉冲序列从初始波动的脉冲分辨光谱演化，记录了类似于900，000个连续周期。我们直接观察到从数十到数千次往返的时间尺度上的关键现象，包括宽带光谱的诞生，伴随的波长偏移和瞬态干涉动力学描述为脉冲锁模。通过时间拉伸变换，结果可能会影响激光设计，超快诊断和非线性光学。
Mode-locked lasers have enabled some of the most precise measurements ever performed, from attosecond time-domain spectroscopy to metrology with frequency combs. However, such extreme precision belies the complexity of the underlying mode-locking dynamics. This complexity is particularly evident in the emergence of the mode-locked state, an intrinsically singular, non-repetitive transition. Many details of mode-locking are well understood, yet conventional spectroscopy cannot resolve the nascent dynamics in passive mode-locking on their natural nanosecond timescale, the single pulse period. Here, we capture the pulse-resolved spectral evolution of a femtosecond pulse train from the initial fluctuations, recording similar to 900,000 consecutive periods. We directly observe critical phenomena on timescales from tens to thousands of roundtrips, including the birth of the broadband spectrum, accompanying wavelength shifts and transient interference dynamics described as auxiliary-pulse mode-locking. Enabled by the time-stretch transform, the results may impact laser design, ultrafast diagnostics and nonlinear optics.