Provided is a laser system. The laser system includes: a laser device providing a laser pulse; a pulse compressor decreasing a pulse width of the laser pulse; a pulse stretcher disposed between the compressor and the laser device and dispersing the laser pulse; and a filament portion disposed between the pulse stretcher and the pulse compressor, wherein the filament portion transmits the laser pulse to expand a spectrum of the laser pulse by using self focusing and a filament phenomenon of the laser pulse.