Dresden 2020 – wissenschaftliches Programm
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O 18.10: Vortrag
Montag, 16. März 2020, 17:30–17:45, WIL A317
fluctuation-modulated third harmonic deep ultraviolet emission from randomly disordered Si nanograss — •Juemin Yi1, Dong wang2, Jinhui Zhong1, Peter Schaaf1, Erich Runge3, and Christoph Lienau1 — 1Carl von Ossietzky Universität, Institut für Physik and Center of Interface Science, 26129 Oldenburg — 2TU Ilmenau, Institut für Werkstofftechnik und IMN MacroNano, 98693 Ilmenau — 3TU Ilmenau, Institut für Physik und IMN MacroNano, 98693 Ilmenau
It is well known that Si nanograss or black Si greatly enhances light absorption in a broad spectral range and thus is of relevance for solar cell application. Very little is known about their nonlinear optical properties. For that, we have utilized a broadband and few-cycle ultrafast laser to generate coherent third harmonic (TH) emission from randomly disordered Si nanograss. The TH signal is two-order-of-magnitude stronger than that from bulk Si surfaces. For individual hot spots, the TH enhancement even reaches a factor of the order of 1000. A statistical analysis of the TH intensity fluctuations demonstrates that multiple light scattering within the randomly disorder medium is the cause of those fluctuations. A phase-locked and collinear pulse pair excitation proves the coherent nature of the deep ultraviolet emission. The interferometric frequency-resolved autocorrelation (IFRAC) microscopy shows that the deep ultraviolet pulse is around 10fs. Our findings identify random Si nanograss as the most promising candidates for generating ultrashort deep ultraviolet pulses.