Cipura, Fabian (2020)
Coherent frequency conversion towards ultrashort VUV pulses enhanced by dressed states and adiabatic quantum dynamics.
Technische Universität Darmstadt
doi: 10.25534/tuprints-00012868
Ph.D. Thesis, Primary publication
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Item Type: | Ph.D. Thesis | ||||
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Type of entry: | Primary publication | ||||
Title: | Coherent frequency conversion towards ultrashort VUV pulses enhanced by dressed states and adiabatic quantum dynamics | ||||
Language: | English | ||||
Referees: | Halfmann, Prof. Dr Thomas ; Walther, Prof. Dr. Thomas | ||||
Date: | July 2020 | ||||
Place of Publication: | Darmstadt | ||||
Date of oral examination: | 20 July 2020 | ||||
DOI: | 10.25534/tuprints-00012868 | ||||
Abstract: | In this work, we thoroughly investigated frequency conversion towards ultrashort picosecond (ps) laser pulses in the vacuum ultraviolet (VUV) spectral regime via nonlinear optics in coherently-driven quantum systems at high intensities. We applied approaches of adiabatic quantum dynamics relying on coherent light-matter interactions, which modify the "bare" eigenstates of a quantum system to "dressed" states and exploit slow (i.e., adiabatic) population evolutions via such dressed states. This enables enhancement of typically low-order, low-intensity nonlinear optics (at MW/cm², GW/cm²), where the light field perturbs the atomic level structure only weakly. On the other hand, aiming at nonlinear optics at higher orders, e.g., high-harmonic generation, strong light fields are applied (100 TW/cm², PW/cm²), which modify the Coulomb potential of the atom strongly. In this case, resonances play no role anymore and adiabatic quantum dynamics via atomic resonances will not work. With this work, we demonstrated the implementation of adiabatic quantum dynamics and coherently prepared media for nonlinear optics in an intermediate intensity regime (TW/cm²), i.e., at Keldysh parameters approaching γ≈1. The fundamental question was, whether the high intensities still permit us to drive and exploit coherent-adiabatic dynamics via dressed states for enhancement of frequency conversion processes. We investigated two approaches to enhance the frequency conversion yield applying nonlinear optics in coherently-driven quantum systems (rare gases). In the first approach, we resonantly enhanced harmonic generation via dressed states with large Autler-Townes splittings. With this approach, we demonstrated how to make atomic resonances available for an initially far detuned fixed-frequency pump laser and showed a compensation for inevitable, perturbing Stark shifts. In the second approach, we investigated frequency conversion, enhanced by coherent population return (CPR) and preparation of maximal atomic coherences at high intensities. With this approach, we showed how to maximally benefit from an atomic resonance via adiabatically driven frequency conversion, i.e., by detuning the strong pump laser slightly from the resonance. |
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URN: | urn:nbn:de:tuda-tuprints-128689 | ||||
Classification DDC: | 500 Science and mathematics > 530 Physics | ||||
Divisions: | 05 Department of Physics > Institute of Applied Physics 05 Department of Physics > Institute of Applied Physics > Nonlinear Optics/Quantum Optics |
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Date Deposited: | 06 Aug 2020 12:08 | ||||
Last Modified: | 06 Aug 2020 13:25 | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/12868 | ||||
PPN: | 467944113 | ||||
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