Effects of the Carrier-Envelope Phase in the Multiphoton Ionization Regime

Abstract

We theoretically investigate the effects of the carrier-envelope phase (CEP) in the low-intensity regime where multiphoton ionization is the dominant mechanism for ionization. For atoms with low-ionization threshold such as Cesium, total ionization yield barely exhibits phase dependence. However, population of some bound states clearly shows dependence on the CEP. This implies that the measurement of the CEP would be possible through the photoemission between bound states without energy and angle-resolved photoelectron detection. The proposed scheme could be particularly useful to measure the CEP for a light source without an amplifier, such as a laser oscillator, which cannot provide sufficient pulse energy to induce tunneling ionization. Similar findings are also obtained for hydrogen, which shows stronger phase dependence not only for the bound state population but also for the total ionization yield.