Measuring the spatiotemporal electric field of ultrashort pulses with high spatial and spectral resolution

Abstract

We demonstrate an experimentally simple and high-spectral-resolution version of spectral interferometry (SEA TADPOLE) that can measure complicated pulses (in time) at video rates. Additionally, SEA TADPOLE can measure spatial information about a pulse, and it is the first technique that can directly measure the spatiotemporal electric field [E(x,y,z,λ)] of a focusing ultrashort pulse. To illustrate and test SEA TADPOLE, we measured E(λ) of a shaped pulse that had a time-bandwidth product of approximately 100. To demonstrate that SEA TADPOLE can measure focusing pulses, we measured E(x,λ) at and around the focus produced by a plano-convex lens. We also measured the focus of a beam that had angular dispersion present before the lens. We have found that SEA TADPOLE can achieve better spectral resolution than an equivalent spectrometer, and here we discuss this in detail, giving both experimental and simulated examples. We also discuss the angular acceptance and spatial resolution of SEA TADPOLE when measuring the spatiotemporal field of a focusing pulse.