Non-perturbative generation of above-threshold harmonics from pre-excited argon atoms in intense mid-infrared laser fields
We experimentally investigate the generation of above-threshold harmonics completely from argon atoms on an excited state using mid-infrared femtosecond laser pulses. The highly nonlinear dependences of the observed signal on the pulse energy and polarization of the driver laser pulses indicate its non-perturbative characteristic.
physics.optics↗