Abstract
Recently we have demonstrated a new nonlinear optical effect in the THz interval of frequencies. The latter is based on the use of femtosecond optical pulses and intense, sub-ps, broadband terahertz (THz) pulses to generate a THz-optical four- and five-wave mixing in the investigated material. The spectrum of the generated signal is resolved in time and wavelength and displays two pronounced frequency sidebands, Stokes and anti-Stokes, close to the optical second harmonic central frequency 2, where is the optical central frequency of the fundamental beam, thus resembling the spectrum of standard hyper-Raman scattering, and hence we named this effect ‘THz hyper-Raman’—THYR. We applied this technique to several crystalline materials, including α-quartz and gallium selenide. In the first material, we find that the THYR technique brings spectroscopic information on a large variety of low-energy excitations that include polaritons and phonons far from the Γ-point, which are difficult to study with standard optical techniques. In the second example, we show that this new tool offers some advantages in detecting ultra-broadband THz pulses. In this paper we review these two recent results, showing the potentialities of this new THz technique.
Highlights
The Terahertz electromagnetic spectrum ranges in the frequency window from ~100 GHz to~30 THz, i.e., in between the microwave and the far-infrared domains
In the absence of resonances, the THz hyper-Raman (THYR) 3D-spectrum may be used under some circumstances for a phase-sensitive detection of the THz optical field, as we have demonstrated in crystalline GaSe [17]
In this paper we reviewed our recent results on a new nonlinear optical effect in the THz interval of frequencies, which we
Summary
The Terahertz electromagnetic spectrum ranges in the frequency window from ~100 GHz to. A great progress for the detection of THz pulses has been achieved by the introduction of the so-called electro-optic sampling (EOS) technique, which uses part of the laser pulse generating the THz field to sample the latter This advancement has led to the development of the so-called THz time-domain spectroscopy (THz-TDS) [1]. We have demonstrated a new nonlinear optical effect in crystalline quartz (α-SiO2 ) that we have named THz hyper-Raman (THYR) [16] It makes use of femtosecond infrared (IR) pulses and intense, sub-ps, broadband THz pulses to generate a four- and five-wave-mixing (FFWM) in the investigated material. When material resonances lie in the THz band of the THYR signal these show up in the THYR 3D-spectrum as temporal oscillations The latter may be solved in the frequency domain by applying a numerical fast Fourier transform (FFT). For a comprehensive review on the latter we remind to Ref. [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
