Excited State Relaxation in Vacuum Deposited and Solution Processed Films of Merocyanine/Fulerene Blends

Exciton dynamics in merocyanine/fulerene blend films made by vacuum deposition and solution processing techniques were investigated by means of steady-state and time resolved fluorescence and absorption spectroscopy. Intermolecular charge transfer states are formed during several ps in neat merocianine films, which determine their fluorescence properties. Fullerene additives cause formation of new heterogeneous charge transfer states. Even a small fullerene concentration significantly influences the exciton dynamics by quenching inherent merocianine fluorescent states and causing appearance of new fluorescence bands caused by the charge transfer states between merocyanine and fullerene molecules. All fluorescence bands are quenched in films with high fulerence concentration due to the charge carrier generation, and the quenching effect is stronger in vacuum deposited films. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3529

SYNTHESIS OF METAL NANOPARTICLES AND THEIR INFLUENCE ON FLUORESCENCE OF ORGANIC MATERIAL

In this work, synthesis of spherical AgNPs and their influence on optical properties of highly fluorescent organic dye rhodamine 6G (R6G) and low fluorescent conjugated polymer (RZ11) was investigated. Fluorescence changes of R6G was studied in solutions when concentration of AgNPs was increasing and fluorescence changes of RZ11 conjugated polymer was studied in thin films when layer of AgNPs was presented. Absorption and fluorescence spectra, and fluorescence decay kinetics of solutions and thin films were recorded by using steady-state and time-resolved spectroscopy. Fluorescence decay kinetics revealed that no energy transfer occur in solutions of R6G (10-6 M) and AgNPs (2.5x10-4÷7.5x10-4 M). In thin films with conjugated polymer, quenching of fluorescence with AgNPs was detected because of the energy transfer from fluorophore to metal due to short distances

Spatial Filters on Demand Based on Aperiodic Photonic Crystals

Photonic Crystal spatial filters, apart from stand-alone spatial filtering function, can also suppress multi-transverse-mode operation in laser resonators. Here it is shown that such photonic crystals can be designed by solving the inverse problem: for a given spatial filtering profile. Optimized Photonic Crystal filters were fabricated in photosensitive glass. Experiments have shown that such filters provide a more pronounced filtering effect for total and partial transmissivity conditions.Peer ReviewedPostprint (published version

Spatial light structures in linear and nonlinear mini-resonators

This Ph.D. thesis contains experimental and theoretical analysis of nonlinear optical pattern formation in monolithic mini-cavity optical parametrical oscillators and spatial properties of linear photonic crystal resonators. The thesis consists of introduction, literature review and two chapters. In the first chapter experimental investigation of optical parametrical oscillation (OPO) in broad aperture monolithic (5x5x1.5 mm) BBO type I crystal mini-cavity is described. OPO was pumped by second harmonic (532 nm) 13 ns duration, 7 15 mJ energy pulses, of Nd:YAG laser. Optical patterns were registered in a near and far field of OPO emission. Experiments and theoretical interpretation revealed that emission of such resonator can be conical and multiconical and direction of signal and idler waves can be controlled by changing the mini-cavity orientation with respect to pump beam. It was also showed, that the stabilization of stripes (or roll) pattern can be achieved by a weak seed injection at subharmonic frequency and temporal spectrum of the stripe pattern degenerate OPO emission is 1/f – like noise spectrum . In the second chapter plane-mirror Fabry-Pérot resonators filled with a single period of photonic crystal (PhC) are introduced and analyzed. PhC resonators are realized by adding periodical 2 µm, 4 µm and 15 µm refraction index modulation on a resonator mirror surfaces (i.e. fabricating 1D or 2D phase diffraction grating). PhC resonator angular transmission measured by using broad spatial spectrum of 532 nm wavelength CW laser. Mode expansion and scattering matrix methods were used for the theoretical analysis of PhC resonator. The results show that diffraction properties of PhC resonators can be manipulated, resulting in sub- and superdiffractive dynamics of light in the resonator

Erdviniai šviesos dariniai tiesiniuose ir netiesiniuose mini rezonatoriuose

This Ph.D. thesis contains experimental and theoretical analysis of nonlinear optical pattern formation in monolithic mini-cavity optical parametrical oscillators and spatial properties of linear photonic crystal resonators. The thesis consists of introduction, literature review and two chapters. In the first chapter experimental investigation of optical parametrical oscillation (OPO) in broad aperture monolithic (5x5x1.5 mm) BBO type I crystal mini-cavity is described. OPO was pumped by second harmonic (532 nm) 13 ns duration, 7 15 mJ energy pulses, of Nd:YAG laser. Optical patterns were registered in a near and far field of OPO emission. Experiments and theoretical interpretation revealed that emission of such resonator can be conical and multiconical and direction of signal and idler waves can be controlled by changing the mini-cavity orientation with respect to pump beam. It was also showed, that the stabilization of stripes (or roll) pattern can be achieved by a weak seed injection at subharmonic frequency and temporal spectrum of the stripe pattern degenerate OPO emission is 1/f – like noise spectrum . In the second chapter plane-mirror Fabry-Pérot resonators filled with a single period of photonic crystal (PhC) are introduced and analyzed. PhC resonators are realized by adding periodical 2 µm, 4 µm and 15 µm refraction index modulation on a resonator mirror surfaces (i.e. fabricating 1D or 2D phase diffraction grating). PhC resonator angular transmission measured by using broad spatial spectrum of 532 nm wavelength CW laser. Mode expansion and scattering matrix methods were used for the theoretical analysis of PhC resonator. The results show that diffraction properties of PhC resonators can be manipulated, resulting in sub- and superdiffractive dynamics of light in the resonator