Measuring the complete spatio-temporal field of focused ultrashort laser pulses for multi-photon microscopy

Abstract

ABSTRACT We present two complementary interferometric techniques for measuring the complete spatio-temporal intensity and phase, E (x,y,z,t), of ultrashort pulses. The first technique, called SEA TADPOLE, allows for the first time the complete measurement of pulses near a focus, while the second technique, called STRIPED FISH, allows the complete measurement of mostly collimated pulses, but on a single-shot basis. Keywords: Ultrashort pulse, spatio-temporal profile, in terferometry, multi-photon microscopy. 1. INTRODUCTION Most applications of ultrashort pulses, such as multi-photon microscopy or ultrafast micro-machining, invo lve focusing the pulse. In order to optimize the pulse at the focus, it is important to be able to directly measure the electric field as a function of space and time. While techniques for characterizing the temp oral or spatial field alone e xist, measuring the complete spatio-temporal field is much more difficult, especially at or near a focus or on a single shot. So we intr oduce, to our knowledge, the first method that measures the complete E (x,y,z,t) at and near a focus and the first technique to measure E (x,y,z,t) on a single shot . One technique is based on spectral interf erometry (which measures a pulse vs. time or frequency), and we call it SEA TADPOLE