From the general polariton dispersion theory it can be shown that in an uniaxial crystal the frequencies of optical phonons * which are identical to those of the short wavelength polaritons depend on the angle 0 between the optic axis and the phonon wave vector. For <9=0 and &=jx/2 the phonons are exactly transversal or longitudinal so that they can be assigned to be of totally symmetric or two...

We have performed molecular dynamics simulations with phonon spectral analysis to predict the mode-wise phonon relaxation times (RT) of suspended and supported graphene at room temperature, and the findings are consistent with recent optical measurements. For acoustic phonons, RTs reduce from up to 50 ps to less than 5 ps when graphene is put on silicon dioxide substrate. Similarly, optical pho...

Using confocal micro-Raman and photoluminescence spectroscopy, we studied bending effects on optical properties of individual ZnO nanowires. Raman spectroscopy shows that local tensile strain can be introduced by bending the nanowire. The strain is expected to reduce the band gap on the bent part and modify the local phonon-exciton interaction. The corresponding micro-photoluminescence spectra ...

We explore the physics of optomechanical systems in which an optical cavity mode is coupled parametrically to the square of the position of a mechanical oscillator. We derive an effective master equation describing two-phonon cooling of the mechanical oscillator. We show that for high temperatures and weak coupling, the steady-state phonon number distribution is nonthermal (Gaussian) and that e...

Structural, vibrational, and lattice dielectric properties of CdCu3Ti4O12 are studied using the densityfunctional theory within the local spin-density approximation, and the results are compared with those computed previously for CaCu3Ti4O12 . Replacing Ca with Cd is found to leave many calculated quantities largely unaltered, although significant differences do emerge in zone-center optical ph...

Using two optical techniques, we have studied the hot electron–optical phonon interactions in GaAs/AlxGa12xAs multiplequantum wells. Raman scattering measurements at 15 K are presented for the Al composition of xˆ 0.3, 0.5, 0.7 and 1.0. The GaAs-like and AlAs-like phonon frequencies of the first-order modes are also measured as a function of Al composition. The optical phonon energies emitted b...

The manipulation of transverse-optical TO -phonon polaritons and the associated terahertz THz light field by means of an ultrasound acoustic wave is proposed and illustrated by calculating the TO-phonon-mediated THz response of acoustically pumped CuCl and TlCl crystals. We show the high-contrast acoustically induced change in the THz reflectivity and multiple THz Bragg replicas, which are asso...

Electron transport characteristics of GaN crystals in high electric fields are shown to be essentially influenced by different optical phonon modes inherent to the hexagonal and cubic phases of these compound crystals. Additional optical phonon modes (≈ 26 meV) competing with the higher-energy ones (≈ 92 meV) in hexagonal GaN, together with the low-lying satellite valley (Γ3), dramatically redu...

This work develops a Monte Carlo (MC) simulation method for calculating the heat generation rate in electronic nanostructures. Electrons accelerated by the electric field scatter strongly with optical phonons, yet heat transport in silicon occurs via the faster acoustic modes. The MC method incorporates the appropriate energy transfer rates from electrons to each phonon branch. This accounts fo...