Völkel Alexandra, Nimmesgern Luca, Mielnik-Pyszczorski Adam, Wirth Timo, Herink Georg
Experimental Physics VIII-Ultrafast Dynamics, University of Bayreuth, 95440, Bayreuth, Germany.
Theoretical Physics III, University of Bayreuth, 95440, Bayreuth, Germany.
Nat Commun. 2022 Apr 19;13(1):2066. doi: 10.1038/s41467-022-29649-y.
Ultrafast atomic vibrations mediate heat transport, serve as fingerprints for chemical bonds and drive phase transitions in condensed matter systems. Light pulses shorter than the atomic oscillation period can not only probe, but even stimulate and control collective excitations. In general, such interactions are performed with free-propagating pulses. Here, we demonstrate intra-cavity excitation and time-domain sampling of coherent optical phonons inside an active laser oscillator. Employing real-time spectral interferometry, we reveal that Terahertz beats of Raman-active optical phonons are the origin of soliton bound-states - also termed "Soliton molecules" - and we resolve a coherent coupling mechanism of phonon and intra-cavity soliton motion. Concurring electronic and nuclear refractive nonlinearities generate distinct soliton trajectories and, effectively, enhance the time-domain Raman signal. We utilize the intrinsic soliton motion to automatically perform highspeed Raman spectroscopy of the intra-cavity crystal. Our results pinpoint the impact of Raman-induced soliton interactions in crystalline laser media and microresonators, and offer unique perspectives toward ultrafast nonlinear phononics by exploiting the coupling of atomic motion and solitons inside a cavity.
超快原子振动介导热传输，是化学键的指纹特征，并驱动凝聚态物质系统中的相变。短于原子振荡周期的光脉冲不仅可以探测，甚至可以激发和控制集体激发。一般来说，这种相互作用是通过自由传播的脉冲来实现的。在这里，我们展示了有源激光振荡器腔内相干光学声子的腔内激发和时域采样。利用实时光谱干涉测量法，我们揭示了拉曼活性光学声子的太赫兹拍频是孤子束缚态（也称为“孤子分子”）的起源，并且我们解析了声子与腔内孤子运动的相干耦合机制。同时存在的电子和核折射非线性产生了不同的孤子轨迹，并有效地增强了时域拉曼信号。我们利用固有的孤子运动自动对腔内晶体进行高速拉曼光谱分析。我们的结果明确了拉曼诱导的孤子相互作用在晶体激光介质和微谐振器中的影响，并通过利用腔内原子运动与孤子的耦合，为超快非线性声子学提供了独特的视角。
