Wavelength selective photoexcitation of picosecond acoustic-phonon pulses in a triple GaAs/Al0.3Ga0.7As quantum well structure

Abstract

Ultrashort coherent phonon-pulse generation and detection is investigated in a GaAs-Al 0:3 Ga 0:7 As quantum well structure containing three wells of different widths using an optical pump and probe method. The pump photon energy is tuned to the region of the hh1-e1 transition energies of the wells and the probe photon energy is chosen for detection of the phonon pulses that reach the sample surface. By studying the dependence of the probe reflectance change on the pump photon energy, we demonstrate the possibility of wavelength-selective excitation of picosecond acoustic-phonon pulses in quantum wells. r

Acoustic phonon generation and detection inGaAs∕Al0.3Ga0.7Asquantum wells with picosecond laser pulses

“…2,6 This strain pulse shape can be determined by monitoring the transient surface displacement through interferometric detection or probe beam deflection. 7 Buried semiconductor quantum wells have also been investigated to elucidate the basic physics of phonon generation in confined quantum geometries, 4,[8][9][10] such generation being related to the shape of the electron and hole wave functions and to the strength of the electron-phonon interaction. Preliminary results show that picosecond acoustic phonon pulses can be generated in quantum wells and detected at the sample surface.…”

“…4,9 Moreover, the phonon pulses can be excited selectively in the wells by tuning the optical wavelength. 10 Approximate theoretical treatments using simplified models of the wave function shapes were presented to explain the observed phonon pulse shapes. In this paper we describe the use of a two-color interferometric pump and probe technique with surface probing for the detailed study of picosecond acoustic phonon pulse generation and detection in a triple GaAs/ Al 0.3 Ga 0.…”

Coherent longitudinal acoustic phonons in pyrite

“…Recently, Baumberg et al generated a coherent LA phonon in a GaAs single quantum well to study its relaxation mechanism [2]. Using the coherent LA phonon signal, a detailed evaluation of the optical constants of a superlattice was presented by Matsuda et al [3].…”

Strong Optical-Mechanical Coupling in a Vertical GaAs/AlAs Microcavity for Subterahertz Phonons and Near-Infrared Light

“…We study in this Letter the dynamics of the system through a time-resolved experiment in which the mechanical system is prepared in a given state through the impulsive generation of phonons with an ultrafast laser [28]. A delayed probe monitors the change of reflectivity induced by these phonons, which can be modeled as [29,30] ÁrðtÞ ¼ ik 2 Áðz; tÞ is the variation in the dielectric function induced by the displacement uðz; tÞ, Áðz; tÞ ¼ PðzÞ @uðz;tÞ @z with PðzÞ the photoelastic constant. The first term in Eq.…”