Coherent A1phonons in Te studied with tailored femtosecond pulses

We tailor the shape and phase of the pump-pulse spectrum in order to study coherent lattice dynamics in tellurium. Employing coherent control by splitting the pump pulse into a two-pulse sequence, we show that the oscillations due to A(1) coherent phonons can be cancelled but not enhanced as compared to single-pulse excitation of the same energy. We further demonstrate that a crucial factor for coherent phonon generation seems to be the bandwidth of the pulse spectrum. We observe that the coherent amplitude for long pump pulses decreases exponentially with pulse duration for both Gaussian and rectangular pulses. Finally, by varying the pulse chirp, we show that the coherent amplitude is independent of the chirp sign while the oscillation lifetime is slightly dependent on the chirp sign.