The basic physics of filamentation is universal and occurs in all transparent media (gases, liquids and solids). After propagating through an optical medium, a femtosecond (fs) Ti-sapphire laser pulse (at around 800 nm) turns into a white light laser pulse whose transverse pattern shows a central white spot surrounded by colored rings. The only difference is that the length of the filament is different in different media while the free electron generation mechanisms inside the filament core are different between gases and condensed matter materials. Figure 2.1a–d show the evolution of the transverse patterns of a 5 mJ/45 fs/800 nm Ti-sapphire laser pulse after propagating and filamenting in air without external focusing. The transform limited pulse from the vacuum compressor propagates into a 10 m vacuum pipeline which is connected directly to the vacuum compressor (see Fig. 2.2). After passing through the 1 cm-thick CaF2 exit window, the pulse enters the corridor next to the author’s laboratory.