Progress towards terahertz acoustic phonon generation in doping superlattices

Semiconductor superlattices: a tool for terahertz acoustics.

The properties of optical to acoustic transduction of semiconductor superlattices have been explored for several years in the sub terahertz frequency range. Using femtosecond laser pulses focused on these structures, acoustic modes are excited with a frequency related to the periodicity of the structure stacking. We have shown that these acoustic waves can be extracted and can propagate in the ...

Phonon-pumped terahertz gain in n-type GaAs/AlGaAs superlattices

Monte Carlo simulation of the generation of terahertz radiation in GaN

The conditions for microwave power generation at low temperatures under optical phonon emission are analyzed by Monte Carlo simulations of both smalland large-signal responses in bulk zinc blende and wurtzite GaN. As a result of the high optical phonon energy and the strong interaction of electrons with optical phonons in GaN a general improvement on the transit-time resonance and a considerabl...

High-speed asynchronous optical sampling for high-sensitivity detection of coherent phonons

A new optical pump-probe technique is implemented for the investigation of coherent acoustic phonon dynamics in the GHz to THz frequency range which is based on two asynchronously linked femtosecond lasers. Asynchronous optical sampling (ASOPS) provides the performance of on all-optical oscilloscope and allows us to record optically induced lattice dynamics over nanosecond times with femtosecon...

Coherent phonons in Si/SiGe superlattices

There are several classes of coherent phonons whose generation mechanisms are completely different: impulsive stimulated Raman scattering, Brillouin oscillations, and coherent longitudinal-acoustic-phonon Bragg reflection. All of these are investigated in Si/SiGe superlattices using a picosecond ultrasonics technique at room temperature. Bragg reflection for a single vibrational mode is related...