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Kim, Hyung Taek,Tosa, Valer,Nam, Chang Hee Institute of Physics Publishing Ltd. 2006 Journal of Physics B: Atomic, Molecular and Optica Vol.39 No.13
<P>Bright harmonic generation in a long Ne gas jet achieved using self-guided and chirped femtosecond laser pulses has been analysed. Three-dimensional modelling was performed to look into the details of laser pulse propagation, harmonic generation and attosecond pulse characteristics. The theoretical analysis and the comparison to the experimental results showed emitted harmonics form a bright attosecond pulse train with good synchronization in time. In the space domain the synchronization is especially good in the self-guided region.</P>
Spectral response of chirp-dependent femtosecond laser filamentation in air
Yun Hyeok,Cho Wosik,Sung Jae Hee,Yang Jeong Moon,Choi Jun Hee,Kovács Katalin,Tosa Valer,Kim Hyung Taek 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.83 No.12
Filamentation is a nonlinear optical phenomenon that involves the interplay between Kerr lens self-focusing and plasma defocusing, holding promise for practical applications in open-air environments over long distances. This process signifcantly alters the characteristics of laser pulses, making the control of laser properties a pivotal issue. In this study, we investigated the efects of laser energy and chirp on the spectral modulation of femtosecond laser pulses caused by flamentation in air. Negatively and positively chirped pulses exhibit distinct characteristics in the spectra measured after the flamentation. Negatively chirped pulses have broader spectral broadening and a stronger dependence on initial laser energy than positively chirped pulses, making them suitable for generating few-cycle pulses and applications requiring white light. In contrast, positively chirped pulses can be advantageous for applications requiring long-distance transmission of high-energy laser pulse. Our fndings reveal the fundamental characteristics of femtosecond laser flamentation in air, thereby expanding the scope of possible atmospheric applications.