Yee K J, Lee K G, Oh E, Kim D S, Lim Y S
Department of Physics, Seoul National University, Seoul 151-747, Korea.
Phys Rev Lett. 2002 Mar 11;88(10):105501. doi: 10.1103/PhysRevLett.88.105501. Epub 2002 Feb 19.
We report on generation of coherent optical phonon oscillations in 150 microm thick bulk GaN. With photon energy far below the band gap, the generation mechanisms of coherent phonon modes of A1(LO), high- and low-frequency E2 are revealed to be the impulsive stimulated Raman scattering. We find that one among the two degenerate E2 modes is selectively detected with a proper choice of probe polarization. Dephasing times range from 1.5 to 70 ps for different modes, and phonon-three-photon absorbed carrier interactions are compared between the A1(LO) and the E2 mode.
我们报道了在150微米厚的块状氮化镓中产生相干光学声子振荡的情况。在光子能量远低于带隙的情况下，A1(LO)、高频和低频E2相干声子模式的产生机制被揭示为脉冲受激拉曼散射。我们发现，通过适当选择探测偏振，可以选择性地检测到两个简并E2模式中的一个。不同模式的退相时间在1.5到70皮秒之间，并且比较了A1(LO)模式和E2模式之间的声子 - 三光子吸收载流子相互作用。
