Lineshape dependence of ultrafast saturation of absorption and fluorescence
Anil K. Patnaik, Sukesh Roy, James R. Gord
Ultrafast saturation of signals from an optical process occurs when intense laser pulses, with the duration of the driving laser pulse shorter than the effective decay timescales, interact with the target system. Recently, it has been shown that such saturation is marked by transition from transient-absorption to the transient-gain regime, unlike in continuous-wave or long-duration excitations where saturation occurs once the underdamping regime is achieved. The threshold intensities of the drive pulse that drives the optical signal to saturate can be estimated by calculating the area of the pulse. We demonstrate that depending on the shape of the pulse, the saturation behavior differs. The lineshape dependence of ultrafast saturation of absorption and fluorescence is studied for a variety of pulse shapes. We demonstrate that the saturation threshold is lower for super-Gaussian pulses and almost an order of magnitude lower for sech pulses compared to a Gaussian pulse.
Physica Scripta•Oct 1, 2015•7 citations