Coherent optical phonons in diamond

The authors report femtosecond dynamics of the coherent optical phonon of single crystal diamond. Sub-10fs, 395nm laser pulses excite 40THz coherent phonons with an extremely small damping rate (0.15ps−1). Linear power dependence of the phonon amplitude under off-resonant excitation condition gives a direct evidence for an eletric-field-driven generation mechanism. The coherent phonon generation is noticeably suppressed by doping with nitrogen impurities, in spite of their absorption in the near ultraviolet. The present study demonstrates that a simple pump-probe technique can be a powerful tool for evaluating the ultrafast coherent electronic and lattice dynamics of diamond materials.