Abstract-Terahertz radiation from an InAs surface due to lateral photocurrent transients

P. Cicėnas, A. Geižutis, V. L. Malevich, and A. Krotkus
https://www.osapublishing.org/ol/abstract.cfm?URI=ol-40-22-5164

We report on terahertz (THz) emission from a (111)-cut InAs crystal in the reflection and transmission directions, excited by femtosecond optical pulses in the direction of its surface normal. THz pulse amplitudes emitted from the crystal surface in this case were only ∼20% smaller than for optimal photoexcitation at a 45° angle. This observation evidences that THz emission from InAs is caused by lateral photocurrent transients appearing due to a crystal anisotropy rather than directly by the photo-Dember effect, which creates fast changing electric polarization perpendicular to the surface. Such a simple geometry of the photoexcitation could greatly enhance the fields of surface THz emitter applications.

© 2015 Optical Society of America

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Abstract-Physical mechanisms of terahertz pulse emission from photoexcited surfaces of tellurium crystals

A. Bičiūnas¹, A. Arlauskas¹, J. Adamonis¹, P. Cicėnas¹ and A. Krotkus¹
http://scitation.aip.org/content/aip/journal/jap/116/9/10.1063/1.4894514
1 Center for Physical Sciences and Technology, A. Goštauto 11, 01180 Vilnius, Lithuania
J. Appl. Phys. 116, 093102 (2014); http://dx.doi.org/10.1063/1.4894514

We report on terahertz (THz) emission from tellurium crystal surfaces excited by femtosecondoptical pulses. Measurements were performed on three differently cut Te samples and with different wavelength optical excitation pulses. THz pulse amplitude dependences on the azimuthal angle measured at various excitation wavelengths have evidenced that three different mechanisms are responsible for THz generation in tellurium: second order nonlinear optical rectification effect, dominating at lower excitation photon energies, as well as transverse and ordinary photo-Dember effects, which emerge at energies larger than 0.9 eV. The shapes of the azimuthal angle dependences were also explained by theoretical model.