Selective enhancement of coherent optical phonons using THz-rate pulse train

Selective enhancement of coherent optical phonons in Bi-Sb mixed crystals has been performed using terahertz (THz) rate pulse trains generated by spatial phase modulation of femtosecond pulse with a liquid-crystal spatial light modulator. The profile of the shaped pulse train has a flat-toped shape. The Bi-Bi, Bi-Sb, and Sb-Sb vibrations can be enhanced and canceled selectively for pulse trains with a suitable repetition rate.