Nonlinear Optics in Coherently-Driven Media

Frequency conversion is at the heart of many research efforts in laser-based science, e.g. to extend the accessible wavelength range of coherent light sources. In particular the regime of short-wavelength, extreme-ultraviolet (XUV) radiation is of significant interest. Applications for XUV radiation range from laser lithography, via high-resolution nonlinear-optical microscopy, towards the generation of ultra-short (sub-femtosecond) light pulses. However, the efficiencies of frequency conversion processes to short XUV wavelengths are typically very small.

We investigate novel mechanisms based on coherent light-matter interactions to enhance the nonlinear optical response of quantum systems and improve frequency conversion processes in atomic media, driven by ultra-fast laser pulses towards the XUV. Among a variety of approaches, we use adiabatic passage processes to prepare atomic coherences and increase the nonlinear polarization in atomic media, or drive quantum interferences between simultaneous excitation pathways to strongly enhance or suppress frequency conversion. Moreover, we investigate the role and potential of multi-photon resonances to improve the harmonic yield also in high-intensity laser-matter interaction. Though at high driving laser intensities (i.e., up to many 10 THz/Gm2) atomic resonances strongly shift and broaden, they are nevertheless still applicable to resonantly enhance harmonic generation by considerable amounts.


[3] Strong quantum interferences in frequency up-conversion towards short vacuum-ultraviolet radiation pulses
P. Ackermann, A. Scharf, and T. Halfmann
Phys. Rev. A 89, 063804 (2014)
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[2] Resonantly-enhanced harmonic generation in Argon
P. Ackermann, H. Münch and T. Halfmann
Opt. Expr. 20, 13824 (2012) 
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[1] Adiabatically driven frequency conversion towards short extreme-ultraviolet radiation pulses
S. Chakrabarti, H. Münch, and T. Halfmann
Phys. Rev. A 82, 063817 (2010)
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Prof. Dr. Thomas Halfmann
Nichtlineare Optik/Quantenoptik
Institut für Angewandte Physik
Fachbereich 05 - Physik
Technische Universität Darmstadt
Hochschulstr. 6
D-64289 Darmstadt

+49 6151 16-20740

+49 6151 16-20741 (Sekretariat)

+49 6151 16-20327


T. Halfmann on ResearcherID

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