Analysis of photothermal effects and spatial selfphase modulation in Pyrromethene 567

Abstract

Light-matter interactions have enticed strong interest among scientists for newlinedecades significantly advancing our understanding of various optical newlinephenomenon and their practical applications. The invention of the laser in the newline1960s has led to numerous advancements in the field of light-matter newlineinteractions with materials displaying interesting phenomena such as the newlinethermal lens effect and spatial self-phase modulation (SSPM). Photo-induced newlinechanges in the thermal state of a sample often lead to heating of the sample newlinedue to the optical absorption by molecules and the non-radiative relaxation newlineprocesses occurring within the sample. Heating leads to the formation of a newlinerefractive index gradient within the sample which induces the thermal lens newlineeffect and spatial self-phase modulation. newlineThe photothermal effect offers an efficient and sensitive method to analyze newlineand measure the thermal and optical characteristics of a material. The analysis newlineof the photothermal effects is vital in understanding the non-radiative newlinerelaxation process occurring within a material. At higher intensities, the newlineintensity-dependent refractive index gradient formed within the sample newlinemodulates the phase of the laser beam resulting in the formation of spatial selfphase modulation. SSPM has emerged as a novel nonlinear effect that holds newlinegreat potential for applications in optics. This thesis explores the analysis of newlinethe thermal lens effect and spatial self-phase modulation in Pyrromethene 567 newline(PM 567). A dual-beam mode-mismatched thermal lens experiment was newlinecarried out to investigate the thermal lensing behaviour of PM 567. The newlineevolution and dynamics of SSPM in PM 567 including the potential newlineapplications were analyzed. newline