Abstract-Disturbing the coherent dynamics of an excitonic polarization with strong terahertz fields

M. J. Drexler, R. Woscholski, S. Lippert, W. Stolz, A. Rahimi-Iman, and M. Koch

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.195304

We present a paper based on combining four-wave mixing and strong fields in the terahertz frequency range to monitor the time evolution of a disturbed excitonic polarization in a multiple quantum well system. Our findings not only confirm a lower field-dependent ionization threshold for higher excitonic states, but furthermore provide experimental evidence for intraexcitonic Rabi flopping in the time domain. These measurements correspond to the picture of a reversible and irreversible transfer as previously predicted by a microscopic theory.

DOI: http://dx.doi.org/10.1103/PhysRevB.90.195304

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Abstract-Disturbing the coherent dynamics of an excitonic polarization with strong terahertz fields

M. J. Drexler, R. Woscholski, S. Lippert, W. Stolz, A. Rahimi-Iman, and M. Koch

https://journals.aps.org/prb/accepted/c907aY1bEf71ff4532829ec048ac14177c73bb7f9

We present a study based on combining Four-Wave-Mixing (FWM) and strong fields in the terahertz frequency range (THz) to monitor the time-evolution of a disturbed excitonic polarisation in a multiple quantum well system. Our findings not only confirm a lower field-dependent ionisation threshold for higher excitonic states but furthermore provide experimental evidence for intra-excitonic Rabi flopping in the time domain. These measurements correspond to the picture of a reversible and irreversible transfer as previously predicted by a microscopic theory.

Abstract-Terahertz plastic compound lenses

M. Wichmann, A. S. Mondol, N. Kocic, S. Lippert, T. Probst, M. Schwerdtfeger, S. Schumann, T. Hochrein, P. Heidemeyer, M. Bastian, G. Bastian, and M. Koch  »View Author Affiliations http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-52-18-4186

We present terahertz (THz) lenses made of highly refracting polymeric compounds which provide a better focusing performance and an increased functionality in comparison to conventional THz lenses. Using mixtures consisting of polypropylene (PP) and alumina as well as PP and zinc sulfide allows a significant increase of the refractive index while simultaneously keeping a low extinction and dispersion. With these new material combinations, lenses with an increased focusing capability are realized. This is evaluated by focal plane measurements using a fiber coupled THz time-domain spectrometer.