Abstract-Phase-Insensitive Scattering of Terahertz Radiation

Mihail Petev ^1,2

,NiclasWesterberg ¹,Eleonora Rubino ¹

,Daniel Moss ^1,3

,Arnaud Couairon ⁴

,François Légaré ⁵

,Roberto Morandotti ^5,6,7

,Daniele Faccio ^1,*  andMatteo Clerici ^8,* 

¹

School of Engineering and Physical Sciences, SUPA, Heriot-Watt University, Edinburgh EH14 4AS, UK

²

Max Planck Institute for the Science of Light (MPL), D-91058 Erlangen, Germany

³

Department of Physics and Solid State Institute, Technion, Haifa 32000, Israel

⁴

Centre de Physique Théorique CNRS, École Polytechnique, F-91128 Palaiseau, France

⁵

INRS-EMT, 1650 Blvd. Lionel-Boulet, Varennes, QC J3X 1S2, Canada

⁶

Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China

⁷

National Research University of Information Technologies, Mechanics and Optics, St. Petersburg 197101, Russia

⁸

School of Engineering, University of Glasgow, Glasgow G12 8LT, UK

http://www.mdpi.com/2304-6732/4/1/7

The nonlinear interaction between Near-Infrared (NIR) and Terahertz pulses is principally investigated as a means for the detection of radiation in the hardly accessible THz spectral region. Most studies have targeted second-order nonlinear processes, given their higher efficiencies, and only a limited number have addressed third-order nonlinear interactions, mainly investigating four-wave mixing in air for broadband THz detection. We have studied the nonlinear interaction between THz and NIR pulses in solid-state media (specifically diamond), and we show how the former can be frequency-shifted up to UV frequencies by the scattering from the nonlinear polarisation induced by the latter. Such UV emission differs from the well-known electric field-induced second harmonic (EFISH) one, as it is generated via a phase-insensitive scattering, rather than a sum- or difference-frequency four-wave-mixing process

Abstract-Terahertz beat oscillation of plasmonic electrons interacting with femtosecond light pulses

• 
• Xinping Zhang
• , Jianfang He
• , Yimeng Wang
•  & Feifei Liu

• Scientific Reports 6, Article number: 18902 (2016)
• doi:10.1038/srep18902
• http://www.nature.com/articles/srep18902
• 
  

Plasmon resonance in nanostructured metals is in essence collective oscillation of free electrons, which is driven by optical electric fields and oscillates at nearly the same frequency as the excitation photons. This is the basic physics for the currently extensively interested topics in optical metamaterials, optical switching, and logic optical “circuits” with potential applications in optical communication and optical computation. We present here an interference effect between photons and plasmon electrons, which is observed as multi-cycle beat-oscillation. The beat frequency is in the range of 3~4 THz, which is equal to the difference between optical frequency of the photons and oscillation frequency of the plasmon electrons. Such beat oscillation evolves in a time scale of more than 1 ps, which is much longer than the optical pulse length, implying interaction between photons and pure damping plasmon-electrons. The discovered mechanisms might be important for exploring new approaches for THz generation.