Roland Tomašiūnas

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In this work we have extended the application of a theoretical model describing the processes of all-optical poling of isomerizable molecules while taking into consideration the thermoisomerization related findings presented in the literature. A model describing all-optical poling transients using a three relaxation rate approach was contrasted with the(More)
In this paper, results of investigation of InGaAs quantum dot structure designed as a semiconductor saturable absorber for near-IR are presented. Photoinduced absorption bleaching spectroscopy performed confirm the dedicated wavelength 1070 nm for absorption bleaching of the ground state of quantum dots. Transitions including states from the wetting layer(More)
The synthesis and second order optical features of azophenylcarbazole based monomer 9-(2,3-epoxy)propyl-2-(2,3-epoxy)propoxy-3-(4-nitrophenyl)azo-9H-carbazol and polymeric azo dye AZAP are described. Relative higher optical poling efficiency was measured for the polymer, however, better stability, i.e. less orientational diffusion and thermal relaxation(More)
Summary form only given, as follows. We present methods developed to form two-dimensional photonic crystals for the visible and near IR spectra. Based on aluminium oxide, the photonic crystals comprise column-like periodic structures of triangular lattice configuration. For a perfect structure, two trends of growth - self-ordered and artificially guided -(More)
Second order non-linear optical features of azophenylcarbazole based derivative 9-(2,3-epoxy)propyl-2-(2,3-epoxy)propoxy-3-(4-nitrophenyl)azo-9H-carbazole in polycarbonate investigated at temperature 240 K, which is close to β transition for polycarbonate, are presented. Using all-optical poling technique writing and reading kinetics of second order(More)
A phenomenological model of photoinduced poling dynamics is developed on the basis of the experimental results. Given the intensities of the fundamental field and the second harmonic field used in the poling process, generation and relaxation of &#x03C7;<sup>(2)</sup> and &#x03C7;<sup>(3)</sup> nonlinear susceptibilities are described by this model. The cis(More)
Azo-compounds in polymers will likely play an increasingly important role in engineering of silicon photonics and plasmonic nano-devices for E-O modulation, parametric generation, switching and sensing. In this paper, we present a phenomenological theory of all-optical poling and photo-assisted electric field poling of azo-dye doped polymers and compare(More)
In this paper, semiconductor saturable absorber mirror designed for the near-IR spectra and based on InGaAs quantum dots was investigated. Absorption saturation, absorption femtosecond recovery kinetics measured at various close to resonance quantum energies revealed the wavelength &#x223C; 1050 nm as best performing absorption bleaching (highest value of 2(More)
Second order non-linear optical features of anchor attached azophenylcarbazole based derivative 9-(2,3-epoxy)propyl-2-(2,3-epoxy)propoxy-3-(4-nitrophenyl)azo-9H-carbazole dispersed in polycarbonate was investigated. Using all-optical poling technique writing and reading kinetics of second order susceptibility gratings were measured. Theoretical modelling of(More)
We report on reading process of poled media determined by duration and fluence of reading light. The poled media - oriented azophenylcarbazole molecules - was obtained by all-optical poling using nanosecond YAG laser radiation. While comparing picosecond and nanosecond pulses used for reading, it turned out that the power of light is dominating, if(More)