Abstract
We investigated the damping of phonon polaritons in congruent lithium tantalate (LiTaO3) single crystals by measuring spontaneous Raman spectra of the low-frequency wing of the A(1) phonon line, the dependence of the linewidth of the stimulated Raman scattering gain curves on polariton frequency and the spatial damping of propagating phonon-polariton pulses by nonlocal time-delayed coherent ...
Abstract
We investigated the damping of phonon polaritons in congruent lithium tantalate (LiTaO3) single crystals by measuring spontaneous Raman spectra of the low-frequency wing of the A(1) phonon line, the dependence of the linewidth of the stimulated Raman scattering gain curves on polariton frequency and the spatial damping of propagating phonon-polariton pulses by nonlocal time-delayed coherent anti-Stokes Raman scattering. The damping and the dispersion curve of the lowest-frequency A, phonon polaritons were determined from 10 to 200 cm(-1) at room temperature and at 77 K. The observed frequency dependence of the damping is discussed in the context of low-frequency excitations and a Debye relaxational mode.
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