Extreme nonlinear optics in atomic multi-level systems

• Applicant: Professor Dr. Uwe Morgner
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 226667858

Single-cycle pulses from laser sources open up a unique viewpoint onto the electronic quantum dynamics on femto- and attosecond time scales. Major pulse parameter is the carrier envelope offset phase (CEO-phase, CEP), describing the relative phase between the optical carrier and the pulse envelope. Subject of this project is the CEO dependence of the population in simple multi-level bound quantum systems illumi-nated by single-cycle pulses. Dependence to the CEP is expected in the case when nonlinear quantum paths of different phase interfere in the exited state. This means that the number of possible quantum path interference experiments increases strongly when spectra beyond one octave of bandwidth can be provided. No CEP effect is expected with multi-cycle pulses. While the theoretical modeling of this situation is well established, we here propose the experimental investigation of the dynamics of bound electrons under the influence of single-cycle laser pulses for the first time. The generation of the pulses is based on a two-color pumped parametric amplifier system, generating reliably single-cycle pulses with high repetition rate. The spectra are spanning one and a half octaves and will be subject of phase manipulation by a LCD based pulse shaper. The adaptive scheme allows for pulse characterization, pulse compression, and finally for detailed phase manipulation to perform coherently controlled multi-photon excitations in simple quantum systems (e.g. atomic jets). Before and in parallel to the experiments the quantum system is subject of theoretical investigation by solving the semi-classical optical Bloch equations under the influence of the single-cycle pulses. The direct access to the underlying theory allows for immediate analysis of the measured data and for deep insight into the rich linear and nonlinear physics of atomic or solid-state quantum systems in a parameter range never investigated experimentally before.

• DFG Programme: Research Grants