With the evolution of a laser pulse in water, the formation of a nonlinear X wave during femtosecond filamentation is investigated based on numerical simulations. In particular, we analyze the far-field angularly resolved spectra obtained for different temporal portions of the ultrashort pulse during its propagation. Our result shows that the refocusing of ultrashort pulse leads to the formation of dynamic X wave which essentially manifests itself as conical emission.
© 2010 Chinese Optics Letters
Junjie Xu, Han Xu, Hui Xiong, Ya Cheng, Zhizhan Xu, Weiwei Liu, and See Leang Chin, "The role of refocusing in dynamic X-wave formation during femtosecond laser filamentation in water," Chin. Opt. Lett. 8, 244-247 (2010)