Using phase diversity for the measurement of the complete spatiotemporal electric field of ultrashort laser pulses

Abstract

Even so-called “complete” ultrashort laser pulse-measurement techniques actually have ambiguities and so are not truly complete. In particular, the spectral-interferometry technique called scanning SEA TADPOLE measures the “complete” spatiotemporal intensity and phase of arbitrary ultrashort pulses (using a previously characterized spatially uniform reference pulse), but the difficulty of maintaining the stability of the required interferometer to submicron resolution while scanning in space usually blurs the frequency-independent spatial component of the pulse phase. We show here, however, that this information is actually still contained in the measured SEA TADPOLE data, and using a simple Gerchberg–Saxton-like phase-diversity algorithm, it can be recovered from measurements in only two planes, yielding a truly complete spatiotemporal measurement of the pulse field, limited only by any possible ambiguities present in the reference pulse.