Displacement of energy deposition during formation of nanosecond laser plasmas by self-defocusing

The long-term hydrodynamics of laser generated plasma regions are dictated by the spatial distribution of the deposited laser energy. Using an integrated chemical-optical solver to track energy deposition from single and dual nanosecond laser pulses, we show that self-defocusing results in a biased growth of the plasma region towards the focusing lens. This displacement of energy deposition scales with the Rayleigh range and can be reduced by maximizing the beam divergence.