Pulse fluence noise dynamics at free-space propagation

The dynamics of fluence noise of an optical pulse at free-space (e.g., vacuum) propagation has been studied. It has been shown that the fluence noise with high spatial frequency is effectively cleaned out from the primary smooth pulse either by spatial walk-off or by temporal delay at a relatively small propagation distance. This effect can be referred to as spatial and temporal self-filtering and is of major interest in ultra-high-power and ultra-short-pulse applications. The study comprises a rigorous theory and a few relevant numerical simulation examples.