Determination Change In Third Order Nonlinear Refractive Index And Absorption Coefficient Of Gallium Arsenide Using Nonlinear Electron Oscillator Model

Abstract

The optical properties of a semiconductor can be defined as any property that involves the interaction between electromagnetic radiation or light and the semiconductor, including absorption, diffraction, polarization, reflection, refraction, and scattering effects. The main aim of this research work is to understand the nonlinear optical properties of GaAs. In doing so, the third order nonlinear absorption coefficient and refractive index will be analyzed numerically using anharmonic oscillator model.In the Lorentz model the motion of the electrons in the medium is treated as a harmonic oscillator. This can be pictured as electrons attached to their nuclei by springs with resonant frequency ! and damping . An optical wave provides a forcing term through the dipole interaction with the electron and hence the motion of the electron around its equilibrium position can be described by the linear differential equation, Analytical and numerical studies have been made to describe the dependence of third order nonlinear susceptibility on laser frequency and vibrational frequency Gallium Arsenide (GaAs). The frequency response of the real and imaginary part of third order nonlinearity is studied using anharmonic oscillator model. The change in real and imaginary part of third order nonlinear susceptibility of GaAs system is derved with respect to the change in frequency of laser source using classical oscillator model.The result shows that the change in real and imaginary part of third order nonlinear susceptibility increases with decrease in vibrational frequency. The incident optical intensity has a great influence on real and imaginary part of the third order nonlinear susceptibility. Consequently it affects the total change in refractive index and absorption coefficient.Now day’s optical materials with large third order nonlinear susceptibility are the active areas of research for developing devices for optical limiter and all optical switching devices.