Second-harmonic phonon spectroscopy of $\alpha$-quartz

Abstract

We demonstrate midinfrared second-harmonic generation as a highly sensitive phonon spectroscopy technique that we exemplify using $\alpha$-quartz (SiO${}_2$) as a model system. A midinfrared free-electron laser provides direct access to optical phonon resonances ranging from $350{\mathrm{cm}}^{-1}$ to $1400{\mathrm{cm}}^{-1}$. While the extremely wide tunability and high peak fields of an free-electron laser promote nonlinear spectroscopic studies---complemented by simultaneous linear reflectivity measurements---azimuthal scans reveal crystallographic symmetry information of the sample. Additionally, temperature-dependent measurements show how damping rates increase, phonon modes shift spectrally and in certain cases disappear completely when approaching $T_c=846\mathrm{K}$ where quartz undergoes a structural phase transition from trigonal $\alpha$-quartz to hexagonal $\beta$-quartz, demonstrating the technique's potential for studies of phase transitions.

References in corpus (2)

• Effects of Crystal Anisotropy on Optical Phonon Resonances in the Mid-Infrared Second Harmonic Response of SiC
• Infrared reflectivity of the phonon spectra in multiferroic TbMnO3

Cited by in corpus (6)

• Symmetry-Protected Topological Triangular Weyl Complex
• Nonlinear Tunable Vibrational Response in Hexagonal Boron Nitride
• Low-temperature infrared dielectric function of hyperbolic $\alpha$-quartz
• Terahertz high-harmonic generation in gapped antiferromagnetic chains
• Resonantly enhanced polariton wave mixing and Floquet parametric instability
• Sum-Frequency Generation Spectro-Microscopy in the Reststrahlen Band of Wurtzite-type Aluminum Nitride