Conditional femtosecond pulse collapse for white-light and plasma delivery to a controlled distance.

Collisions between ultrashort pulses with different wavelengths are studied numerically. The relative delay, wavelength difference, focusing geometry, and chirp are used to accurately control the distance at which pulses undergo conditional collapse and generate plasma and white light. A wide supercontinuum spectrum is achievable even with pulses that by themselves do not have sufficient power for filament formation.