Abstract-Terahertz pulse emission from GaInAsBi

Journal of Applied Physics

V. Pačebutasa, S. Stanionytė,  R. Norkus,  A. Bičiūnas, A. Urbanowicz,  A. Krotkus

https://aip.scitation.org/doi/abs/10.1063/1.5089855

Quaternary GaInAsBi alloy epitaxial layers were grown on InP substrates with 6% Bi. It was found that the thick layers remain fully strained. The measured carrier lifetimes were of the order of a few picoseconds. The terahertz (THz) emission was investigated using a GaInAsBi layer as an unbiased surface emitter and as a substrate for photoconductive antenna. It was observed that fabricated THz emitters were sensitive to the optical pulses with wavelengths longer than 2 μm. The demonstrated spectral characteristics of THz pulses obtained when using an Er-doped fiber laser for photoexcitation were comparable with those observed in other emitters used for THz-time-domain spectroscopy systems.

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.