Filaments of light dynamically isolate a single attosecond pulse

By matching a driving laser’s peak power to the self-focusing threshold in an extended gas cell, a nonlinear light filament is formed that naturally isolates attosecond pulses. As it propagates, the filament autonomously shortens and spatially cleans the driving beam, while simultaneously altering the local medium properties to synchronize the light fields. This dynamic effect restricts the coherent buildup of emitted radiation to a single half-cycle, eliminating the need for complex external optical gating.