Modeling the coupling between cw lasers and a frequency comb in atomic samples Marco Polo, Daniel Felinto and Sandra Vianna Departamento de Física Universidade Federal de Pernambuco

Index 1 - Introduction 2 - Coherent accumulation and frequency comb 3 - Theoretical model 4 - Results 5 - Conclusions

Introduction Rb vapor Ti:sapphire We use a cw laser to probe the interaction of a frequency comb in an atomic vapor in regime of intense field. Rb vapor Ti:sapphire We are interested in the situation where the repetition rate of fs laser is greater than the atomic relaxation rate, coherent accumulation processes.

Coherent accumulation and frequency comb

Coherent accumulation and frequency comb Two-level sistem: on resonance atoms stopped * * groups of atoms with different velocities * D. Felinto et al, Opt. Comm. (2003)

Theoretical model Model based on the energy levels of Rb, in the transition Rb and fs laser parameters:

Theoretical model Model based on the energy levels of Rb, in the transition Equation of Liouville: Transmission of laser cw: Approaches: 1 – slow envelope Rb and fs laser parameters: 2 – rotating wave approximation

Bloch equations time of flight atoms

fs intensity dependence Change in the transmission of cw field induced by the presence of the fs field:

fs intensity dependence Change in the transmission of cw field induced by the presence of the fs field:

fs pulses of the order of pi Two-level sistem: Bloch sphere

fs pulses of the order of pi Three-level sistem: For a single pulse: periodic behavior with

Open and closed transitions

Open and closed transitions Theory Experiment

Summary We presented theoretical results of the coupling between a cw laser and a frequency comb in atomic vapor where TR < Tij. Effects of coherence and population accumulation are observed in the transmission variation of the cw laser induced by the fs laser. Dependence with: Different atom group velocities fs intensity Open and closed transition – optical pumping process We observe good agreement between theoretical and experimental data. We intend to use the cw laser to study electromagnetic induced transparency by the fs laser.

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