Influence of Nonlinear Electron Mobility on Response Time in Photorefractive Semiconductor Quantum Wells

Abstract

Nonlinear transport of hot electrons in semi-insulating GaAs / AlGaAs quantum wells significantly affects their photorefractive properties. In case of two waves mixing, this influence consists, among others, in an increased shift of photorefractive grating relative to light intensity distribution. The influence of nonlinear transport on grating recording time is less examined experimentally and theoretically. This study compares numerical and analytical solutions describing grating dynamics in approximation of small fringe contrast. The influence of nonlinear electron mobility on space-charge field was examined depending on external electric field intensity and on the grating constant. It was found that in the electric field range below 20 kV/cm, the nonlinear transport of electrons does not shorten the grating generation time.

Effects of geometry and doping level on dispersion and spectrum in GaAs/AlGaAs quantum well waveguide for the near-IR region

“…11,12 The main focus of this work is to numerically study the optical nonlinear pulse propagation in an MQW waveguide made of doped Al x Ga 1Àx As, where x is the doping fraction, this type of structure can be used to fabricate photodetector since they exhibit high sensitivity and short time esponse. 6,8 We show that this type of structure has great potential as a (SC) source, which can be integrated to a photonic circuit because of its small size. We study an MQW structure composed of 40 layers, each measuring 30 nm in width for a total of 1.2 m. We focus on wavelength dependent refractive index variations, valid for wavelengths over 1.1 m alike.…”

“…3 Additionally, both numerical and experimental analysis have been widely carried out to characterize and optimize the lineal and nonlinear optical properties of AlGaAs. 4,6 Semiconductor structures have found applications in the¯eld of photo-detectors and light sources, of particular interest is the use of a two-photon to characterize the pulses produced by mode-locked quantum cascade lasers. 5,7 Some of these devices can be made out of multiple quantum well (MQW) structures since in this kind of structure charged particles are con¯ned in layers as a consequence of the di®erence in bandgaps between external layers, which creates interesting nonlinear optical e®ects that can be easily studied in real devices and simulations alike.…”