Interference of optical phonons in diamond studied using femtosecond pulses of polarized near-infrared light

The phononic interference of optical phonons in diamond is studied via transient transmittance change measurements using the double pump-probe protocol with polarized pump pulses. With orthogonal-polarized pulses, the phonon amplitude is enhanced/suppressed if the second pump pulse is irradiated by a halfinteger/integer multiple of the phonon period. This is contrary to the usual phononic interference (enhancement at integer multiples of the phonon period) observed when using parallel-polarized pulses. These observed results are well explained using a quantum-mechanical model in calculations involving the Raman tensor of the diamond lattice structure. The amplitude of the optical phonons generated via the off-diagonal term of Raman tensor is proportional to the product of the x- and y-components of the optical electric field. The phase of the phonon oscillations is dependent on the angle between the crystal orientation and the polarization of the pump pulse.

Automated summary

The phononic interference of optical phonons in diamond is investigated using polarization-based pump-probe measurements. It is found that the phonon amplitude can be enhanced or suppressed depending on the polarization of the second pump pulse. These observations are explained using a quantum-mechanical model involving the Raman tensor of the diamond lattice structure. The results provide important insights into the behavior and characteristics of phonons in diamond.