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Ultrafast optically induced dynamics in solids: Non-linear optics on the few-fs timescale

Speaker: 
Dr. Michael Sejer Wismer (Max Plank Institute of Quantum Optics, Germany)
Date: 
Thu, 27/07/2017 - 11:00am to 12:00pm
Location: 
CA2DM Theory Common (S16-06)
Host: 
Prof Vitor M. Pereira
Event Type: 
Seminars

Abstract

The generation of pulses as short as a few cycles at optical frequencies allows for new regimes of nonlinear optics in solid media [1,2]. Few-cycle pulses have been shown to drive currents in insulating materials with large band gaps (~ 9 eV) at electric field strengths on the order of 1 V/Å, without causing structural changes to the medium. 
In this talk I will present results on numerical calculations of few-cycle pulses interacting with electrons in crystalline media. A 5 fs pulse tuned to the fundamental band gap in GaAs exhibits nonlinear dynamics beyond Rabi oscillations, which is due to the significant influence of intraband motion. We argue that the modulation in transition energies caused by intraband motion leads to the appearance of anharmonic resonances.
I will also present results for the optical Faraday effect, which is likewise investigated for ultrashort pulses. Circularly polarised pump pulses with field strength close to the damage threshold are numerically shown to rotate incoming UV probe pulse which would require up to 100 T for the conventional Faraday effect. In addition, pump-probe spectroscopy of the induced ellipticity is predicted to exhibit features that have not yet been measured experimentally. 

[1] “Observation of high-order harmonic generation in a bulk crystal”, Ghimire et al., Nature Phys., 2011.
[2] “Optical-field-induced current in dielectrics Agustin”, Schiffrin et al., Nature, 2013
[3] “Strong-Field Resonant Dynamics in Semiconductors”, Wismer et al., Phys. Rev. Lett. 2016.
[4] “Ultrafast optical Faraday effect in transparent solids”, Wismer et al. arXiv:1612.08433.
 
About the Speaker
Michael Sejer Wismer
Max Plank Institute of Quantum Optics, 
Hans-Kopfermann Straße 1, Garching bei München, Germany

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