Filamentation formed by self-focusing of intense laser pulses propagating in air is investigated. It is found that the position of filamentation can be controlled continuously by changing the laser power and divergence angle of the laser beam. An analytical model for the process is given.

We report on the generation of millijoules supercontinuum, which covers waveband from ～ 400 nm to ～ 900 nm wavelength, by intense femtosecond laser pulse propagating in 3 mm thick fused silica. The fused silica is placed in front of the geometric focus of incident laser pulse to prevent the breakdown. The dependences of supercontinuum spectrum on incident pulse energy and off-focus distance of medium are investigated in detail. Our work demonstrates that strong supercontinuum can be generated using off-focus pump of solid transparent medium with energetic incident pulses.