Abstract-Ultrafast tunable modulation of light polarization at terahertz frequencies

Vincent Juvé, Gwenaëlle Vaudel, Zoltan Ollmann, Janos Hebling, Vasily Temnov, Vitalyi Gusev, and Thomas Pezeril

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-24-5905

Controlling light polarization is one of the most essential routines in modern optical technology. Since the demonstration of optical pulse shaping by spatial light modulators and its potential in controlling the quantum reaction pathways, it paved the way for many applications as a coherent control of the photoionization process or as polarization shaping of terahertz (THz) pulses. Here, we evidenced efficient nonresonant and noncollinear 𝜒(2)${}^{\mathrm{}}$-type light–matter interaction in femtosecond polarization-sensitive time-resolved optical measurements. Such nonlinear optical interaction of visible light and ultrashort THz pulses leads to THz modulation of visible light polarization in bulk LiNbO3${}_{\mathrm{}}$ crystal. Theoretical simulations based on the wave propagation equation capture the physical processes underlying this nonlinear effect. Apart from the observed tunable polarization modulation of visible pulses at ultrahigh frequencies, this physical phenomenon can be envisaged in THz depth-profiling of materials.

© 2018 Optical Society of America

Abstract-Laser generation of hypersound by a terahertz photo-Dember electric field in a piezoelectric GaAs semiconductor

Gwenaelle Vaudel, Thomas Pezeril, Alexei Lomonosov, Marius Lejman, Pascal Ruello, and Vitalyi Gusev
http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.014302

We experimentally demonstrate the optical generation of hypersound in a piezoelectric GaAs semiconductor through laser excitation of the THz photo-Dember electric field. Such an ultrashort transient Dember electric field is linked to the spatial separation of photoexcited electrons and holes right after above-band-gap femtosecond laser excitation. Through time-domain coherent Brillouin scattering we demonstrate that photoinduced piezoelectric generation of hypersound can dominate even in the absence of preexisting built-in fields and we observe, with increasing laser fluence, a nonlinear optoacoustic excitation process. These results reveal the onset of the THz photo-Dember electric field and highlight the transition from non-ambipolar flow to ambipolar diffusion of the photoexcited electron-hole plasma.

DOI: http://dx.doi.org/10.1103/PhysRevB.90.014302

• 
• 
• 
• 

• Published 9 July 2014
• Received 23 December 2013
• Revised 20 June 201