Nonlinear refraction and absorption investigation for all optical switching applications

Abstract

newline The present thesis deals with the investigation of nonlinear refraction and nonlinear aband#65534;sorption of material which is further utilized for all-optical switching (AOS) applications. The newlineresearch work is mainly divided into three parts: introduction to ultrafast and nonlinear opand#65534;tics, linear/nonlinear characterizations and AOS development. The first part corresponds to newlinethe background and fundamentals of nonlinear optics. The various second and third order newlinenonlinear optical processes owing to the presence of and#967;2 and and#967;3 under the influence of strong newlinelight pulses are elaborated. The origin of the different kind of nonlinearities such as electronic, newlinemolecular reorientation and nuclear contribution posses different temporal dynamics is investiand#65534;ated which is useful for different nonlinear optical applications with respect to their temporal newlinedynamics. Nowadays, optical fiber and other optical transmission lines are used in various comand#65534;munication systems. If the irradiance of the incident signal is high, the nonlinear effects such newlineas self-focussing and nonlinear absorption can be observed. The losses of signal in transmission newlinemedium increases due to the nonlinearity. In this case the nonlinear refraction (NLR) and nonand#65534;linear absorption (NLA) values of the materials are essentially required to minimize the losses. newlineFurther, we have discussed the linear and nonlinear experimental techniques such as spatial newlineand temporal profile of the ultrashort pulsed laser investigation by using the knife-edge and newlinethe autocorrelation techniques, respectively. Also the experimental techniques to determine the newlinenonlinear optical susceptibility values of the materials are discussed. To calculate the nonlinand#65534;earity of particular material one must know the linear optical properties of the material such as newlinelinear absorption coefficient and linear index of refraction because the one photon absorption newline(1PA) energy levels can hinder the progress of the nonlinear absorption. The 1PA spectrum of newline1 newlinematerial is determined with the help of UV