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We consider nanopatterning of dielectric substrates by harmonics of single powerful femtosecond pulses from a Ti:Sapphire laser. The nanopatterning is mediated by closely packed monolayers of polystyrene microspheres that act as microlenses at the surface. Observed modification of the material proceeds via ionization. By our theory, the second harmonic is more effective in multi-photon ionization and is better focused than the fundamental frequency which is effective in multiplying of the amount of free electrons via impact ionization. Experiments show that conversion of a part of the pulse energy into the second harmonic decreases the modification threshold and improves the localization of the structures. Optimization of the time offset between the harmonics could further improve the efficiency and quality of nanostructuring.

Colloidal particle lens array (CPLA) proved to be an efficient near-field focusing device for laser nanoprocessing of materials. Within CPLA, spherical particles do not act as independent microlenses. Due to the coupling of the spherical modes, the field near the clusters of spherical microparticles cannot be calculated by means of the superposition of Mie solutions for individual spheres. In the paper, the electromagnetic field distributions near laser-irradiated clusters of dielectric microspheres with configurations that match the fragments of the close-packed CPLA are studied. It is shown that some practically important mode coupling effects can be understood in terms of an effective immersion medium formed for the spherical particle by its surrounding.

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We study the thermo-physical and photoluminescence (PL) properties of cadmium-(bis)dodecylthiolate (Cd(C12H25S)2). Significant attention is drawn to characterization of Cd(C12H25S)2 by different methods. The laser-induced PLs of Cd(C12H25S)2 and Cd(C12H25S)2/(polymethyl methacrylate) (PMMA) composites are studied. Samples of Cd(C12H25S)2/PMMA are synthesized by the polymerization method. Ultraviolet (UV)-pulsed laser irradiation of the samples under relatively small fluences leads to the formation of induced PL with the maximum near the wavelength of 600 nm. This process can be attributed to the transformation of Cd(C12H25S)2 within the precursor grains. Another PL peak at 450–500 nm, which appears under the higher fluences, relies on the formation of CdS complexes with a significant impact of the polymer matrix.