Y. Zhang

Dissertation

Friedrich-Schiller-Universität Jena; Physikalisch-Astronomische Fakultät (February 2023)

**Carrier-envelope phase (CEP)-dependent strong-field ionization at infrared (IR) wavelengths**Dissertation

Friedrich-Schiller-Universität Jena; Physikalisch-Astronomische Fakultät (February 2023)

## Abstract:

Intense laser-matter interactions are generally determined by the instantaneous electric field of the laser pulse. For light-matter interactions with few-cycle pulses, the carrier-envelope phase (CEP) plays a critical role as the temporal variation of the electric field depends on the phase. This has a profound impact on many scientific applications. More importantly, controlling the CEP provides an additional degree of freedom to control field-driven processes in atomic, molecular and solid-state systems. In this thesis, we will demonstrate the development and implementation of a single-shot CEP measurement technique, i.e., the so-called carrier-envelope phasemeter based on stereo-above-threshold ionization in Xe and operating at short-wave infrared (SWIR) wavelengths, which allows for simultaneous pulse duration measurement. The experimental results are compared to simulations with two different theoretical models. Next, we will demonstrate the significance of the phase-volume effect, i.e. the reduction of the CEP-dependence due to the spatial distribution of the CEP in focused few-cycle pulsed beams. We formulate a general description of the impact of the focal phase for laser-matter interactions of different nonlinear orders to answer the general question: if, when, and how much should one be concerned about the phase-volume effect? At last, CEP-dependent strong-field ionization of Xe using 3.2um few-cycle pulses as a benchmark will be studied. In order to find an alternative target for a single-shot CEPM at mid-infrared (MIR) wavelengths, Cs will be investigated. We observed an anomalous CEP-dependence in Cs, particularly at high intensities, which can be interpreted as the interference of two backscattered quantum orbits from adjacent optical cycles. Viewed from a higher perspective, this thesis demonstrates a precise characterization of the CEP and an accurate analysis of CEP-dependent light-matter interaction from the NIR, via the SWIR to the MIR range.