Fixed blueshift measurement of focused short laser pulses in the regime of optical field ionization (OFI)

摘要

Fixed blueshifts are observed of a focused intense short pulse laser propagating in a gas chamber. The observed shift is found to be independent of the gas pressure and jumps at threshold intensity. The jump is explained by a 2-step blueshift. The wavelength depends on the leading edge of the laser pulse. If a Gaussian pulse shape is assumed, the laser pulse width is known from measurement of the laser spectrum.