Propagation of femtosecond terawatt laser pulses in N{sub 2} gas including higher-order Kerr effects
- HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China)
Propagation characteristic of femtosecond terawatt laser pulses in N{sub 2} gas with higher-order Kerr effect (HOKE) is investigated. Theoretical analysis shows that HOKE acting as Hamiltonian perturbation can destroy the coherent structure of a laser field and result in the appearance of incoherent patterns. Numerical simulations show that in this case two different types of complex structures can appear. It is found that the high-order focusing terms in HOKE can cause continuous phase shift and off-axis evolution of the laser fields when irregular homoclinic orbit crossings of the field in phase space take place. As the laser propagates, small-scale spatial structures rapidly appear and the evolution of the laser field becomes chaotic. The two complex patterns can switch between each other quasi-periodically. Numerical results show that the two complex patterns are associated with the stochastic evolution of the energy contained in the higher-order shorter-wavelength Fourier modes. Such complex patterns, associated with small-scale filaments, may be typical for laser propagation in a HOKE medium.
- OSTI ID:
- 22107648
- Journal Information:
- AIP Advances, Vol. 2, Issue 4; Other Information: (c) 2012 Copyright 2012 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License.; Country of input: International Atomic Energy Agency (IAEA); ISSN 2158-3226
- Country of Publication:
- United States
- Language:
- English
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