Časově rozlišená laserová spektroskopie nanomateriálů

Abstract

This diploma thesis is oriented to study of nonlinear properties of semiconductor nanocrystals using ultrashort femtosecond pulses. There is a detailed description of theory and experimental setup of the z-scan method, which can be used to measure the nonlinear refractive index and the two-photon absorption coefficient. In theoretical part we describe the influence the quality of laser beam, quality and thickness of the sample on measurements. There are numerical simulations of the measurements influenced by these parameters. This theory is used for processing of the measured dates by a program, which is attached to this thesis on CD. In experimental part we measured nonlinear refractive indeces of diamond nanocrystals fabricated by the PECVD method, silicon and CdS nanocrystals in glass matrices. One part of this thesis deals with the preparation and optimalization of the experimental setup and increasing the signal/noise ratio.