Carrier Envelope Phase Measurement Using a Non Phase Stable Laser

Abstract

Ultrafast laser technologies permit the production of high power, well characterized yet variable optical waveforms in the few cycle regime. Laser systems can easily produce focused intensities in excess of 10¹⁵W/cm², corresponding to electric fields stronger than the atomic Coulomb fields (≈ 10⁹V/cm), leading to strong field ionization. The liberated electrons move quasi- classically in the vicinity of the ion core and can be rescattered (ATI), or recombine after photon emission (HHG), or produce secondary electrons after electron impact (NSDI). Such electron — ion core interactions have been successfully studied in many experiments performed by the community. However, until most recently almost all experiments were conducted using pulses with durations longer than 10fs and therefore consisting of many optical cycles. With such pulses it is not possible to determine at which optical cycle ionization actually takes place or how many cycles later the electron recollides with the ion core. These limitations can be overcome by the use of few cycle pulses. Using techniques developed over the past few years it is now possible to obtain laser pulses with a duration of less than 5fs. In this so-called few cycle regime the carrier envelope phase (CE-phase) becomes an important measure in the description of the instantaneous electric field.