Spatiotemporal Control of Laser Intensity Through Cross-Phase Modulation

Spatiotemporal pulse shaping provides control over the trajectory and range of an intensity peak. While this control can enhance laser-based applications, the optical configurations required for shaping the pulse can constrain the transverse or temporal profile, the orbital angular momentum (OAM), or the duration. Here we present a novel technique for spatiotemporal control that eliminates these constraints by using a "stencil" pulse to spatiotemporally structure a second, primary pulse through cross-phase modulation in a Kerr lens. The temporally shaped stencil pulse imparts a time-dependent focusing phase on to the primary pulse. This technique, the "flying focus X," allows the primary pulse to have any profile, OAM, or duration, expanding the flexibility of spatiotemporal pulse shaping for laser-based applications. As an example, simulations show that the flying focus X can deliver an arbitrary velocity, ultrashort intensity peak with OAM over distances much longer than a Rayleigh range.