Intense monochromatic terahertz electromagnetic waves from coherent GaAs-like longitudinal optical phonons in (11 n)-oriented GaAs/ln_(0.1)Al_(0.9)As strained multiple quantum wells

摘要

We demonstrate that, in (11 n)-oriented GaAs/In_(0.1)Al_(0.9)As strained multiple quantum wells, the terahertz electromagnetic wave from the coherent GaAs-like longitudinal optical (LO) phonon is enhanced by a piezoelectric field originating from a tensile strain in the GaAs layer. The presence of the tensile strain is confirmed using Raman scattering spectroscopy. The Fourier power spectrum of the terahertz waveform shows that the intensity of the terahertz band of the coherent GaAs-like LO phonon increases as the index n approaches 1. The amplitude of the GaAs-like LO phonon is proportional to the piezoelectric field in the strained GaAs layer.