A. Karakas

Third-order nonlinear optical properties and structures of (E)-N-(4-nitrobenzylidene)-2,6-dimethylaniline and (E)-N-(4-nitrobenzylidene)-2,3-dimethylaniline.

(E)-N-(4-Nitrobenzylidene)-2,6-dimethylaniline (1) and (E)-N-(4-nitrobenzylidene)-2,3-dimethylaniline (2) have been synthesized. The crystal structures of both compounds have been defined by X-ray diffraction analysis. The maximum one-photon absorption (OPA) wavelengths recorded by quantum mechanical computations using a configuration interaction (CI) method are estimated in the UV region to be shorter than 450nm, showing good optical transparency to the visible light. To provide an insight into the microscopic third-order nonlinear optical (NLO) properties of the investigated molecules, both dispersion-free (static) and also frequency-dependent (dynamic) linear polarizabilities (alpha) and second hyperpolarizabilities (gamma) at lambda=825-1125nm and 1050-1600nm wavelength areas have been computed using time-dependent Hartree-Fock (TDHF) method. According to the ab initio calculation results, the title molecules exhibit second hyperpolarizabilities with non-zero values, implying microscopic third-order NLO behavior.

THE INVESTIGATION OF ELECTRONIC PROPERTIES AND MICROSCOPIC SECOND-ORDER NONLINEAR OPTICAL BEHAVIOR OF 1-SALICYLIDENE-3-THIO-SEMICARBAZONE

To investigate the microscopic second-order nonlinear optical (NLO) behavior of the 1-salicylidene-3-thio-semicarbazone Schiff base compound, the electric dipole moments (μ), linear static polarizabilities (α) and first static hyperpolarizabilites (β) have been calculated using finite field second-order Moller-Plesset perturbation (FF MP2) theory. The ab-initio results on (hyper)polarizabilities show that the investigated molecule might have microscopic NLO properties with non-zero values. To understand the NLO behavior in the context of molecular orbital structure, we have also examined the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and the HOMO-LUMO gap in the same theoretical framework as the (hyper)polarizability calculations. In addition to the NLO properties, the electronic transition spectra have been computed using a semi-empirical method (ZINDO). ZINDO calculation results show that the electronic transition wavelengths have been estimated to be shorter than 400 nm.

THIRD-ORDER NONLINEAR OPTIC AND OPTICAL LIMITING PROPERTIES OF A MN(III) TRANSITION METAL COMPLEX

N,N′-bis(5-bromosalicylidene)propane-1,2-diamine-O,O′,N,N′)-manganese(III) chloride transition metal complex has been synthesized and characterized by elemental analysis and UV-vis spectroscopy. Its crystal structure has been determined using X-ray diffraction analysis. To provide an insight into the optical limiting (OL) behavior of the title compound, the third-order nonlinear optical (NLO) properties, one-photon absorption (OPA) and two-photon absorption (TPA) characterizations have been theoretically investigated by means of the time-dependent Hartree–Fock (TDHF), AM1 and configuration interaction (CI) methods, respectively. According to ab initio calculation results, the examined molecule exhibits second hyperpolarizabilities (γ) with non-zero values at the positions of TPA peaks, implying microscopic third-order optical nonlinearity. The maximum OPA wavelengths recorded by linear optical experiment and quantum mechanical computations are estimated in the UV region to be shorter than 400 nm, showing good optical transparency to the visible light. The TPA cross-sections (δ(ω)) at values indicate that the synthesized compound might possess OL phenomena, which are in accord with the experimental observations on the manganese complexes in the literature.

SYNTHESIS, CRYSTAL STRUCTURE, SPECTROSCOPIC STUDIES AND AB-INITIO CALCULATIONS ON THIRD-ORDER OPTICAL NONLINEARITY OF A FIVE-COORDINATE CHLOROIRON(III) COMPLEX

A five-coordinate chloroiron(III) complex has been synthesized and characterized by X-ray diffraction analysis and UV-Vis spectroscopy. The maximum one-photon absorption (OPA) wavelengths recorded by both linear optical measurements and quantum mechanical computations using the configuration interaction (CI) method are estimated to be shorter than 400 nm in the UV region, showing good optical transparency to visible light. To investigate the microscopic third-order nonlinear optical (NLO) behavior of the title compound, we have computed both dispersion-free (static) and also frequency-dependent (dynamic) linear polarizabilities (α) and second hyperpolarizabilities (γ) at λ = 825–1125 nm and 1050–1600 nm wavelength areas using the time-dependent Hartree–Fock (TDHF) method. The ab-initio calculation results with non-zero values on (hyper)polarizabilities indicate that the synthesized molecule might possess microscopic third-order NLO phenomena.

Synthesis, Structure, Spectroscopic Studies And Ab-Initio Calculations On First Hyperpolarizabilities Of N,N’-Bis(2-Hydroxy-1-Naphthylmethylidene)- 1-Methyl-1,2-Diaminoethane-N,N’,O,O’-Copper(Ii)

N,N’-Bis(2-hydroxy-1-naphthylmethylidene)-1-methyl-1,2-diaminoethane-N,N’,O,O’-copper(II) has been synthesized, and characterized by FT-IR and UV/vis spectroscopies. Its crystal structure has been determined by X-ray diffraction analysis. The maximum absorption wavelengths recorded by linear optical experiments are estimated in the UV region to be shorter than 450 nm, showing good optical transparency to the visible light. It may thus possess first hyperpolarizabilities with non-zero values for nonlinear optical (NLO) applications. Ab-initio quantum chemical calculations of the electric dipole moments (μ) and the first static hyperpolarizabilities (β ) were carried out. The computational results suggest that the complex may indeed have microscopic NLO behavior with non-zero values

Ab-initio calculations on static and dynamic third-order optical nonlinearity of azo-azulenes

The paper presents the way that colour can serve solving the problem of calibration points indexing in a camera geometrical calibration process. We propose a technique in which indexes of calibration points in a black-and-white chessboard are represented as sets of colour regions in the neighbourhood of calibration points. We provide some general rules for designing a colour calibration chessboard and provide a method of calibration image analysis. We show that this approach leads to obtaining better results than in the case of widely used methods employing information about already indexed points to compute indexes. We also report constraints concerning the technique. Nowadays we are witnessing an increasing need for camera geometrical calibration systems. They are vital for such applications as 3D modelling, 3D reconstruction, assembly control systems, etc. Wherever possible, calibration objects placed in the scene are used in a camera geometrical calibration process. This approach significantly increases accuracy of calibration results and makes the calibration data extraction process easier and universal. There are many geometrical camera calibration techniques for a known calibration scene [1]. A great number of them use as an input calibration points which are localised and indexed in the scene. In this paper we propose the technique of calibration points indexing which uses a colour chessboard. The presented technique was developed by solving problems we encountered during experiments with our earlier methods of camera calibration scene analysis [2]-[3]. In particular, the proposed technique increases the number of indexed points points in case of local lack of calibration points detection. At the beginning of the paper we present a way of designing a chessboard pattern. Then we describe a calibration point indexing method, and finally we show experimental results. A black-and-white chessboard is widely used in order to obtain sub-pixel accuracy of calibration points localisation [1]. Calibration points are defined as corners of chessboard squares. Assuming the availability of rough localisation of these points, the points can be indexed. Noting that differences in distances between neighbouring points in calibration scene images differ slightly, one of the local searching methods can be employed (e.g. [2]). Methods of this type search for a calibration point to be indexed, using a window of a certain size. The position of the window is determined by a vector representing the distance between two previously indexed points in the same row or column. However, experiments show that this approach has its disadvantages, as described below. * E-mail: A.Nowakowski@ire.pw.edu.pl Firstly, there is a danger of omitting some points during indexing in case of local lack of calibration points detection in a neighbourhood (e.g. caused by the presence of non-homogeneous light in the calibration scene). A particularly unfavourable situation is when the local lack of detection effects in the appearance of separated regions of detected calibration points. It is worth saying that such situations are likely to happen for calibration points situated near image borders. Such points are very important for the analysis of optical nonlinearities, and a lack of them can significantly influence the accuracy of distortion modelling. Secondly, such methods may give wrong results in the case of optical distortion with strong nonlinearities when getting information about the neighbouring index is not an easy task. Beside this, the methods are very sensitive to a single false localisation of a calibration point. Such a single false localisation can even result in false indexing of a big set of calibration points. To avoid the above-mentioned problems, we propose using a black-and-white chessboard which contains the coded index of a calibration point in the form of colour squares situated in the nearest neighbourhood of each point. The index of a certain calibration point is determined by colours of four nearest neighbouring squares (Fig.1). An order of squares in such foursome is important. Because the size of a colour square is determined only by the possibility of correct colour detection, the size of a colour square can be smaller than the size of a black or white square. The larger size of a black or white square is determined by the requirements of the exact localisation step which follows the indexing of calibration points [3]. In this step, edge information is extracted from a blackand-white chessboard. This edge information needs larger Artur Nowakowski, Wladyslaw Skarbek Institute of Radioelectronics, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warszawa, A.Nowakowski@ire.pw.edu.pl Received February 10, 2009; accepted March 27, 2009; published March 31, 2009 http://www.photonics.pl/PLP

Third-order Nonlinear Optical Properties and Crystal Structures of N-(2-Nitrobenzalidene)-2,4-dimethylaniline and N-(3-Nitrobenzalidene)- 2,4-dimethylaniline

N-(2-nitrobenzalidene)-2,4-dimethylaniline (1) and N-(3-nitrobenzalidene)-2,4-dimethylaniline (2) have been synthesized and characterized by X-ray diffraction analysis. Linear optical characteristics have been evaluated theoretically using the configuration interaction (CI) method. The maximum one-photon absorption (OPA) wavelengths of the studied compounds are shorter than 450 nm, giving rise to good optical transparency in the visible and near IR regions. To provide an insight into the third-order nonlinear optical (NLO) behavior of the title molecules, both dispersion-free (static) and frequency-dependent (dynamic) linear polarizabilities (α) and second hyperpolarizabilities (γ) at λ = 825 - 1125 nm and 1050 - 1600 nm wavelength ranges have been computed using the time-dependent Hartree-Fock (TDHF) method. The ab initio computational results on (hyper)polarizabilities reveal that both compounds exhibit second hyperpolarizabilities with non-zero values, implying microscopic third-order NLO behavior.

Study on the Second Order Optical Properties of N-(2,4-Dichloro)-salicylaldimine

N-(2,4-Dichloro)-salicylaldimine was synthesized, characterized by elemental analysis, FT-IR, and UV-visible spectroscopy, and its crystal structure was determined. The title compound is almost planar and contains short intramolecular O-H. . .N hydrogen bonds [O1-N1 2.601(1) A° ]. It remains transparent in the visible region and has solvatochromic behavior in the UV region in the range 198 - 349 nm, implying non-zero microscopic first hyperpolarizability. The ab-initio quantum mechanical calculations (finite field second-order Møller Plesset perturbation theory) of the studied compound have been carried out to compute the electric dipole moment (μ) and the first hyperpolarizability (β ) values. The ab-initio results also show that this ligand might have microscopic nonlinear optical behavior with non-zero values.

Theoretical calculations of second and third-order nonlinear susceptibilities and their corresponding hyperpolarizabilities of a styrylquinolinium dye

The second (Xexp(2)) and third-order (Xexp(3)) susceptibilities of a styrylquinolinium dye (1) have been determined utilizing second-harmonic generation (SHG) and third-harmonic generation (THG) techniques, respectively. The reported measurement findings on Xexp(2) and Xexp(3) have been compared with the theoretical data evaluated here by means of ab-initio quantum mechanical calculations. The electric dipole moments (μ), static dipole polarizabilities (a) and first hyperpolarizabilities (β) have been computed by density functional theory (DFT) at B3LYP/6-311+G(d, p) level. To reveal the frequency-dependent second and third-order microscopic nonlinear optical (NLO) behavior of the title compound, the dynamic dipole polarizabilities, first and second (γ) hyperpolarizabilities have been theoretically investigated using time-dependent Hartree-Fock (TDHF) method. According to the experimental and theoretical results, the values of susceptibilities and the corresponding microscopic coefficients with large non-zero responses make the examined dye promising candidate for NLO applications.

Second-order hyperpolarizability and susceptibility calculations of a series of ruthenium complexes

The ab-initio quantum mechanical calculations (time-dependent Hartree-Fock (TDHF) method) of a series of ruthenium complexes have been carried out to compute electric dipole moment (μ), dispersion-free and frequency-dependent first hyperpolarizability (β) values. The one-photon absorption (OPA) characterizations have been also theoretically investigated by means of configuration interaction (CI) method. Our calculated results on the maximum OPA wavelengths and second-order hyperpolarizabilities are in good agreement with the observed values in the literature. According to the results of the TDHF calculations, the investigated molecules exhibit non-zero β values, and they might have microscopic second-order nonlinear optical (NLO) behaviour. We also give the computational results of the frequency-dependent second-order susceptibilities (χ(2)) for the examined compounds. The calculated results on dynamic (χ(2)) are quite consistent with the previous experimental observations.