Optical control over two-dimensional lattice vibrational trajectories in crystalline quartz

Control over the trajectory of two-dimensional vibrational motion is demonstrated for a degenerate E-symmetry optic phonon mode in crystalline quartz. Pairs of ultrashort optical pulses of different polarizations are used to impart momentum along orthogonal directions of the degenerate mode through impulsive stimulated Raman scattering. Variation of the temporal separation of the two excitation pulses permits various linear, elliptical, or circular trajectories to be selected. More complex two-dimensional trajectories are also possible if arbitrarily shaped excitation waveforms are used.