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Performance problems observed in production environments that have their origin in program code are immensely hard to localize and prevent. Data that can help solve such problems is usually found in external dashboards and is thus not integrated into the software development process. We propose an approach that augments source code with runtime traces to tightly integrate runtime performance traces into developer workflows. Our goal is to create operational awareness of performance problems in developers' code and contextualize this information to tasks they are currently working on. We implemented this approach as an Eclipse IDE plugin for Java applications that is available as an open source project on GitHub. A video of PerformanceHat in action is online: https://youtu.be/fTBBiylRhag

Plasmonics involves the interaction of light with metallic structures at the nanoscale, which enables in particular the generation of strong reflection and absorption effects in the visible and near infrared range. The fabrication of plasmonic nanostructures using ultra-violet (UV) imprint and thin metallic coatings is reported. Wafer-scale fabrication and process compatibility with cost-efficient roll-to-roll production are demonstrated, which paves the road towards an industrial implementation. The color, phase, polarization and direction of the transmitted light are controlled by tuning the process parameters and the symmetry of the nanostructures. A family of devices is presented, for which the potential for sensing, filtering, anticounterfeiting and optical security is evaluated.

The synthesis and properties of a new ROMP backbone polymer bearing lateral donor–acceptor-substituted (E)-diethynylethene ((E)-hex-3-ene-1,5-diyne) chromophores are described. The polymer with an average of 40 monomeric repeat units is readily soluble in common organic solvents such as tetrahydrofuran, dichloromethane and chloroform. Good optical-quality films were obtained by spin coating. The third-order susceptibility χ(3) at a wavelength of 1907 nm was determined to be 100 times greater than that of fused silica. After electrical poling, the polymer also showed a significant second-order nonlinear optical coefficient (d33) value, which decays by a factor of two over a period of one month at room temperature.

Experiments are reviewed on quadratic solution generation, and soliton interactions between each other and with a nonlinear interface in non-critical birefringence phase-matched KNbO 3 and periodically poled KTP. Spatially symmetric and asymmetric patterns of multiple soliton-like beam generation were observed and interpreted when only a high intensity fundamental beam is used as the input. The nonlinear reflection of quadratic solitons from a nonlinear interface characterized by a half wavelength shift in the poling structure was obtained. Finally the interactions between pairs of solitons were measured in KNbO 3, including the creation of new solitons in non-coplanar geometries.

Piperazine-2,5-diones derived from 2-amino-7-cyano-4-methoxyindan-2-carboxylic acid were prepared in meso, racemic, and enantiomerically pure forms, crystallized from dimethyl sulfoxide (DMSO), and the supramolecular organization in the crystals determined by X-ray crystallography. These molecules were designed to bear two strongly polar p-methoxybenzonitrile moieties either aligned or opposed. In contrast with nonpolar or weakly polar piperazinediones of similar size and shape, which exclude DMSO to form ladder-like tapes by reciprocal intermolecular amide-to-amide hydrogen bonding, these more strongly polar piperazinediones participate in hydrogen bonding with included DMSO. In cocrystals of the enantiomerically pure compounds, the p-methoxybenzonitrile dipoles were aligned in the three-dimensional lattice but opposed by the dipoles of included DMSO. These cocrystals exhibited second harmonic properties comparable to urea. A second cocrystal possessing aligned p-methoxybenzonitrile dipoles was observed ...

Photobleaching of organic optical materials can be used to structure the surface layer for integrated optics applications. Linear optical properties and absorption were studied in 4-N, N-dimethylamino-4′-N′-methyl stilbazolium tosylate (DAST) organic crystals within the absorption band from 260–700 nm in order to determine the depth-range of photobleaching. The results were obtained from reflectivity measurements and bleaching experiments. The depth range of photobleaching can be varied between 0.2 and 2.6 μm by selecting a suitable wavelength.

We propose a microring structure based on non-identical waveguides for the implementation in practical devices. Our design pays attention to aspects such as fabrication tolerances and fiber coupling efficiency. A detailed study has been carried out on the coupling between the non-identical waveguides in the analyzed structure.

We discuss different methods to grow organic single crystalline thin films from solution. Specifically, we address exploratory developments and apply them on the highly nonlinear material DAST (4′-dimethylamino-N-methyl-4-stilbazolium tosylate) in a DAST/methanol system. We describe the nucleation and growth thermodynamics in solution using a solubility diagram and its Ostwald–Meiers metastable region. The important experimental parameters for bidimensional growth are discussed and first promising results are presented. To cite this article: S. Manetta et al., C. R. Physique 3 (2002) 449–462.

A selection of dimeric tetraethynylethenes (TEEs) and perethynylated expanded radialenes, containing different donor/acceptor substitution patterns, have been prepared and fully characterized. The first X-ray crystal structure of an expanded [6]radialene, with twelve peripheral 3,5-di(tert-butyl)phenyl substituents, is presented. This macrocycle, the all-carbon core of which is isomeric with fullerene C60, adopts a non-planar, "chair-like" conformation. Also a TEE dimer, carrying N,N-dimethylaniline donor substituents, has been subjected to an X-ray crystallographic analysis. The electronic properties were studied by UV/Vis spectroscopy and electrochemistry, providing fundamental insight into mechanisms of pi-electron delocalization in the acyclic and macrocyclic chromophores. Donor or donor-acceptor-substituted dimeric TEE derivatives show very strong absorptions extending over the entire UV/Vis region; their longest wavelength absorption bands have high charge-transfer character. Macrocyclic cross-conjugation in the expanded radialenes becomes increasingly efficient with increasing donor-acceptor polarization. A dual, strongly solvent-polarity-dependent fluorescence was observed for a tetrakis(N,N-dimethylaniline)-substituted dimeric TEE; this interesting emission behavior is explained by the twisted intramolecular charge-transfer (TICT) state model. Donor-substituted expanded radialenes display huge resonance-enhanced third-order nonlinear optical coefficients.

A new series of thermally stable heterocyclic imidazole-based nonlinear optical chromophores has been developed. These chromophores possess a thiophene based stilbene conjugation pathway with a nitro acceptor group attached to the phenyl end. This feature leads to robust chromophores with high thermal stability and enhanced molecular nonlinearity

A strongly dipolar piperazine-2,5-dione was synthesized in enantiomerically pure form, crystallized from DMSO, and the supramolecular organization of the crystals determined by X-ray crystallography. In contrast with non-polar or weakly polar piperazinediones of similar molecular topography, which form tapes by reciprocal intermolecular amide-to-amide hydrogen bonding, the strongly dipolar piperazinedione participated in hydrogen bonding with occluded DMSO. The dipoles of the piperazinedione molecules were aligned and were opposed by the dipoles of the DMSO molecules. The cocrystals exhibited second harmonic generation when subjected to pulsed irradiation.

Two series of monodisperse, terminally donor-donor [D-D, D=4-(dimethylamino)phenyl] and acceptor-acceptor [A-A, A=4-nitrophenyl] functionalized poly(triacetylene) (PTA) oligomers ranging from monomer to hexamer were synthesized by oxidative Hay oligomerization under end-capping conditions. The corresponding D-D and A-A end-substituted polymers with an average degree of polymerization (DP) of n approximately 18 and n approximately 12, respectively, were also prepared and served as reference points for the corresponding infinitely long polymers. These terminally functionalized PTA oligomers and polymers are yellow- to orange-colored compounds, displaying excellent solubility in aprotic solvents with melting points above 200 degrees C for the hexamers. For the 4-(dimethylamino)phenyl substituted compounds, a consistent first oxidation potential around +0.42 V versus Fc/Fc+ (ferrocene/ferricinium) was observed, whereas the 4-nitrophenyl functionalized systems underwent a reversible reductive two-electron transfer around -1.40V versus Fc/Fc+. The nature of the end-groups has a dramatic influence on the electronic absorption spectra. Saturation of the linear optical properties in the D-D series occurs at significantly shorter chain-length [effective conjugation length (ECL) of n approximately 4 monomer units] than in the A-A substituted or the previously reported Me3Si- and Et3Si-end-capped PTA oligomer series (ECL: n approximately 10 monomer units). Similar observations with respect to the ECL were made by measurement of the Raman-active v(C triple bound C) stretches. Third-harmonic generation (THG) and degenerate four-wave mixing (DFWM) experiments showed that shorter oligomers of terminally D-D or A-A functionalized PTAs display higher second hyperpolarizabilities gamma than the corresponding R3Si-end-capped series (R=alkyl). Moreover, they disclose a distinct peak of the nonlinearity per monomer unit at intermediate backbone lengths. In THG experiments, the second hyperpolarizabilities for long D/A-functionalized PTA oligomers attained the same saturation values as observed for the corresponding R3Si-end-capped rods. The nonlinearities measured by DFWM of the D-D and A-A substituted PTAs were found to be larger than for the silylated ones, which can be explained by the closeness of the two-photon resonance.

A series of monodisperse Et3-Si-end-capped poly(triacetylene) (PTA) oligomers ranging from monomer to hexadecamer was prepared by a fast and efficient statistical deprotection-oxidative Hay oligomerization protocol. The PTA oligomers exhibit an increasingly deep-yellow color with lengthening of the pi-conjugated backbone, feature excellent solubility in aprotic solvents, and exhibit melting points up to > 22 degrees C for the hexadecameric rod. This new dramatically extended oligo(enediyne) series now enables to investigate the evolution of the physico-chemical effects in PTAs beyond the linear 1/n versus property regime into the higher oligomer region where saturation becomes apparent. We report the results of joint experimental and theoretical studies, including analysis of the 13C NMR spectra, evaluation of the linear (UV/ Vis) and nonlinear [third-harmonic generation (THG) and degenerate four-wave mixing (DFWM)] optical properties, and characterization of the redox properties with cyclic and steady-state voltammetry. Up to the hexadecameric rod, an increasingly facile one-electron reduction step is observed, showing at the stage of the dodecamer, a leveling off tendency from the linear correlation between the inverse number of monomer units and the first reduction potential. The effective conjugation length (ECL) determined by means of UV/Vis spectroscopy revealed a pi-electron-delocalization length of about n = 10 monomeric units, which corroborates well with the oligomeric length for which in the 13C NMR spectrum C(sp2) and C(sp) resonances start to overlap. Third-harmonic generation (THG) and degenerate four-wave mixing (DFWM) measurements revealed for the second-order hyperpolarizability gamma a power law increase gammma-alpha-n(a) for oligomers up to the octamer with exponential factors a= 2.46+/-0.10 and a=2.64+/-0.20, respectively, followed by a smooth saturation around n = 10 repeating units. The power law coefficient a calculated with the help of the valence effective Hamiltonian (VEH) method combined to a sum-over-states (SOS) formalism corroborates well with the values found by both THG and DFWM experiments. Up to the PTA heptamer, INDO (intermediate neglect of differential overlap)-calculated gas-phase ionization potentials and electron affinities obey a linear relationship as a function of the inverse number of monomer units displaying a strong electron-hole symmetry. The onset of saturation for the electron affinity is calculated to occur around the octamer, in accordance with experimentally obtained results from electrochemical measurements.

Potentially photorefractive molecules, which possess both a charge transfer component and a nonlinear optical chromophore, were prepared by the direct N -monoalkylation of Disperse Orange 3 ( 1 ) with a carbazole alkyl bromide ( 2 ) utilizing phase transfer catalysis. Further N -alkylation of the remaining active N–H with alkyl halides with various chain lengths allowed the thermal properties of the Disperse Orange 3 derivatives to be fine-tuned.

We report on a calibration procedure based on third-harmonic generation, which yields absolute values for ${\ensuremath{\chi}}^{(3)}.$ By calibrating the nonlinear susceptibility ${\ensuremath{\chi}}^{(3)}$ of fused silica against the established, quantum chemically calculated second-order hyperpolarizabilities \ensuremath{\gamma} of various gases at different pressures, we determine reliable absolute values for fused silica. We propose a standard third-order nonlinear optical susceptibilities ${\ensuremath{\chi}}^{(3)}$ of fused silica ${\ensuremath{\chi}}^{(3)}(\ensuremath{-}3\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega})=(2.0\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}22}{\mathrm{m}}^{2}{/\mathrm{V}}^{2}$ at the wavelength 1.064 \ensuremath{\mu}m and ${\ensuremath{\chi}}^{(3)}(\ensuremath{-}3\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega})=(1.6\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}22}{\mathrm{m}}^{2}{/\mathrm{V}}^{2}$ at 1.907 \ensuremath{\mu}m. These results are in excellent agreement with the cascading experiments reported by Bosshard et al. [Phys. Rev. B 61, 10 688 (2000)].

Cascaded second-order contributions to third-harmonic generation are analyzed in detail, and are exploited to obtain reliable reference values for third-order nonlinear optical susceptibilities at several wavelengths. We describe the influence of boundary conditions on the measured properties for the case of high nonlinearity crystals such as ${\mathrm{KNbO}}_{3}$ and the organic salt 4-N, N${\ensuremath{-}\mathrm{d}\mathrm{i}\mathrm{m}\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{y}\mathrm{l}\mathrm{a}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{o}\ensuremath{-}4}^{\ensuremath{'}}$-${N}^{\ensuremath{'}}$-methylstilbazolium toluene-p-sulfonate (DAST). Wavelength dispersion relations for the electronic third-order susceptibilities derived from third-harmonic generation experiments are discussed. Our reference standards allow a comparison of the third-harmonic generation results with measurements of the Kerr susceptibility determined with degenerate four-wave mixing and the z-scan technique and shows that ${\ensuremath{\chi}}^{(3)}(\ensuremath{-}\ensuremath{\omega},\ensuremath{\omega},\ensuremath{-}\ensuremath{\omega},\ensuremath{\omega})g~{\ensuremath{\chi}}^{(3)}(\ensuremath{-}3\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega})$ in the investigated wavelength range. The investigation of structure-property relationships between the perovskite crystals ${\mathrm{KNbO}}_{3}$ and ${\mathrm{KTaO}}_{3}$ indicates similar bond nonlinearities in these two compounds.

We show that the organic salt 4- N , N -dimethylamino-4′- N ′-methyl-stilbazolium tosylate (DAST), developed for electro-optic applications, also is an interesting material for phase-matched parametric interactions such as frequency-doubling and optic parametric oscillation in the near infrared. Based on measured refractive indices we predict configurations for phase matched frequency doubling and promising tuning ranges for optical parametric oscillation. We determined experimentally a figure of merit for frequency doubling, d eff 2 / n 3 =230 pm 2 /V 2 at 1313 nm which is almost 30 times the one of KNbO 3 (7.9 pm 2 /V 2 ) or 120 times the one of KTP (1.9 pm 2 /V 2 ).

Push–pull polyenes are of particular interest for nonlinear optics (NLO) as well as model compounds for long-distance intramolecular charge transfer (ICT). In order to tune the ICT phenomenon and control the linear and nonlinear optical properties, we have synthesized and investigated several series of soluble push–pull diphenylpolyenes of increasing length and having various donor (D) and acceptor (A) end groups. Their linear and NLO properties have been studied by performing electro-optical absorption measurements (EOAM) and third-harmonic generation (THG) experiments in solution. Each push–pull molecule exhibits an intense ICT absorption band in the visible characterized by an increase in dipole moment upon excitation (Δ μ ). By lengthening the polyenic chain, linear increases in excited-state dipoles are achieved while the ground-state dipole is maintained constant. The polyenic chain thus allows for long-distance intramolecular charge transfer. In addition, tuning of the magnitude of the ICT phenomenon and of the nonlinear responses is achieved by varying the donor and acceptor end groups: increasing the D/A strength leads to concomitant enhancements of Δ μ , quadratic ( β ) and cubic ( γ ) hyperpolarizabilities values. Giant Δ μ values (up to more than 30 D) and enhanced non-resonant quadratic and cubic NLO molecular responses (i.e. β (0)=500×10 −30 esu and γ (0)=8000×10 −36 esu) have been attained while maintaining suitable solubility, stability and transparency.

We investigated the co-crystallization of merocyanine dyes M ( M : R–N + C 5 H 4 –CHCH–C 6 H 4 O − , M1 : R=CH 3 , M2 : R=HO–CH 2 –CH 2 –) with phenolic and aniline derivatives and show that the short or very short hydrogen bond between the two phenolic oxygen atoms which lead to a self-assembly of the M dyes and phenol derivatives is the key steering force for the co-crystallization process. The co-crystal formation was studied by melting point determination, by second-harmonic generation using the Kurtz and Perry powder test, and X-ray structural analysis. We present detailed results on the growth, polymorphism, and nonlinear optical properties of co-crystals of derivatives of M1 ( M2 ) and m -nitrophenol (mNP) and co-crystals of M2 and methyl 2,4-dihydroxybenzoate (MDB). Three phases of the co-crystal M2 ·mNP and three phases of the co-crystal M2 ·MDB were found. Both M2 ·MDB(I) and (II) have the same crystal structure (space group symmetry Cc determined by X-ray diffraction), but show different linear and nonlinear optical properties. This unusual property in the co-crystals of M2 ·MDB(I) and (II) may be caused by a different proton location of the short hydrogen bond (O–H–O) in the aggregation between M2 and MDB which could not be resolved by X-ray diffraction.

Linear dichroism – the in-plane optical anisotropy – is observed for organic thin films grown on fused silica and glass substrates. The films made of [4-pyrid-4-yl-ethynyl-benzoic acid] and [4-trans-2-(pyrid-4-yl-vinyl) benzoic acid] are deposited from an angle of about 30° with respect to the surface normal under ultra-high vacuum conditions. The film thickness measurements by alpha-step, atomic force microscopy in tapping mode, and in situ ellipsometry as well as transmission spectra are discussed in detail. Moreover, the optical constants of these novel materials are determined using ellipsometry and transmission spectroscopy. The remarkable optical asymmetry is found in the ultra-violet transmission spectra and attributed to oriented molecules which are connected by hydrogen bonds.

Organic thin films made of 4-trans-2-(pyrid-4-yl-vinyl) benzoic acid are produced by molecular beam deposition under ultra-high vacuum conditions. We demonstrate by optical transmission measurements and second harmonic generation that oblique incidence of the molecular beam results in thin films with a preferential orientation of the organic molecules on amorphous substrates. Using Pd(110) as crystalline substrate, our STM images reveal improved ordering due to preferential adsorption at specific lattice sites.

We report on a series of new acentric 4-nitrophenylhydrazone derivatives which bear more than one hydroxy or methoxy electron donating group whose large molecular nonlinear optical properties were characterized with semi-empirical calculations and hyper-Rayleigh scattering. The second harmonic powder test results of several compounds showed large signals, two to three orders of magnitude larger than urea, which make these materials potentially interesting for nonlinear optics. Crystals of one of these new molecules (3,4-dihydroxybenzaldehyde-4-nitrophenylhydrazone, 3,4-DHNPH) are very promising for electro-optics. The properties are discussed in detail and a comparison with some of the best existing crystals for electro-optic applications is given

Polyamides based on 2',5'-diamino-4-(dimethylamino)-4-nitro-stilben (DDANS) and aliphatic diacids represent a well-established class of polymers for nonlinear optical (NLO) applications, in which the NLO units are fixed in the polymer backbone with their dipole moments oriented transversly to the polymer main chain. The introduction of a hole transport (HT) agent, [4((diphenylhydrazono)-methyl)phenyl]diethylamin (DEH) or 4-(bis(2-hydroxyethyl)amino)benzaldehyde 1,1-diphenylhydrazone (BBDH), was found to generate or enhance photorefractivity in these materials. Using appropriate chemical pathways, the NLO and HT moieties were connected in various ways, and polymer systems with dramatically different properties were obtained. Thus, (i) polyamides based on DDANS and aliphatic diacids, (ii) polyamide esters based on DDANS, BBDH, and adipic acid, (iii) polymer blends of the DDANS polyamides and a polyester based on BBDH and adipic acid, and (iv) DDANS polyamides doped with DEH have been prepared. All types of polymer systems were processed into transparent thin films by spin coating and could be oriented at elevated temperatures, applying a corona discharge poling technique. Second-order NLO coefficients (d 33 ) of up to 45 pm/V at a fundamental wavelength of 1542 nm have been measured. The poling efficiency was found to depend strongly on the content of the hydrazone moiety and the polymer system, decreasing with increasing content of hydrazone. Preliminary temperature-dependent two-beam coupling experiments demonstrated photorefractivity for DDANS-based systems, even at temperatures below the glass transition.

A series of new chiral donor-acceptor substituted mono- (1a,b), bi- (2a,b,f) and terthiophenes (3) as well as thienyl- and bithienylpyridinium salts 1d-f and 2i-k with various counterions has been synthesized. This class of thiophenes exhibit excellent molecular nonlinear optical properties such as second-order polarizabilities β or second-order hyperpolarizabilities γ. With respect to an application as nonlinear optical materials, some of these compounds have been investigated by Kurtz powder technique as well as by X-ray crystallographic analysis. The second-harmonic generation (SHG) powder efficiencies are measured at 1.064 μm and 1.3 μm with urea as reference. Furthermore, the influence of the chiral donors prolinol and methoxy-methylpyrrolidine in the thiophene derivatives as well as the variation of counterions in the pyridinium salts on the orientation of the chromophores in the crystalline lattice was investigated.

Scientists have sought for over two decades to incorporate the necessary attributes of transparency, stability, and high nonlinear susceptibilities into optimized organic or organometallic chromophores for third-order nonlinear optical (NLO) applications. These investigations have provided an ever-expanding understanding of structure−function relationships for the second hyperpolarizability γ and the bulk third-order nonlinear optical susceptibility χ(3) in organic materials, which are reviewed herein. Contributing to this understanding are the studies of the third-order NLO properties displayed by an array of structurally related organic chromophores based on the conjugated carbon skeletons of hex-3-ene-1,5-diynes (1,2-diethynylethenes, DEEs) and 3,4-diethynylhex-3-ene-1,5-diynes (tetraethynylethenes, TEEs). A comprehensive series of donor (D) and/or acceptor (A) substituted derivatives of DEEs and TEEs has been measured by third-harmonic generation (THG) experiments, and the investigations on these one-...

Relaxation processes in nonlinear optical (NLO) polymers with glass transition temperatures in the range of 125 °C < T g < 176 °C have been studied. The relaxational mechanisms of these side- and main-chain polymers have been investigated above and below the glass transition by second-harmonic decay, dielectric relaxation, and differential scanning calorimetry measurements, and the results obtained have been compared with a variety of nonlinear optical polymer systems cited in the literature. The nonexponential relaxation in both the time and frequency domain was modeled by the Kohlrausch-Williams-Watts function whereas the nonlinear relaxational behavior of these polymers was modeled in terms of the Tool-Narayanaswamy description of the glassy state using the Adam-Gibbs expression for the relaxation time. This procedure allows for the nonlinear extension of the liquid equilibrium state behavior into and below the glass transition region with an accurate prediction of the relaxation times over more than 15 orders of magnitude in time. Time-temperature scaling of the relaxation times with respect to T g /T as the relevant scaling parameter is observed below the glass transition. The effect of annealing was investigated using differential scanning calorimetry with the result that a single set of parameters is sufficient to describe a wide range of thermal histories with as well as without annealing. Optimum annealing temperatures/annealing times for best orientational stability in NLO polymers were calculated according to the same relaxation scheme.

We review here two new directions in the area of molecular crystal engineering for nonlinear optics where the alignment, tuning and optimization of the acentric orientation of highly extended, dipolar chromophores in the crystalline state will be described. The use of the non-rod-shaped framework-hydrazone skeleton-as a π-conjugation core, due to a high preference for a lambda-shaped packing motif is a very useful tool to acentrically align and optimize chromophoric orientation in the solid state for nonlinear optical effects such as second harmonic generation. The supramolecular synthetic approach based on the short hydrogen bond induced self-assembling of molecular aggregates shows a high tendency to induce an acentric packing and a higher degree of design feasibility in tuning and optimizing the chromophoric orientation within the crystalline lattice. In addition, co-crystals obtained by this approach often show greatly improved crystal and physical properties relative to its starting components.

A series of stilbazolium based zwitterionic chromophores was synthesized. They have very large dipole moment (up to μ = 13x10-29 Cm) and high molecular hyperpolarizability (up to β = 135x10-40 m4V-1). Guest-host polymer thin films of the best molecules were prepared and poled by corona discharge. Values of the nonlinear optical coefficient (d31 = 0.7 pm/V. at γ = 1.545 nm) at molecular concentrations of 5x1019 m-3, comparable to that of Disperse Red 1, were obtained. The good molecular characteristics and macroscopic performance of these chromophores combined with their good thermal stability make them promising candidates for side-chain electro-optic polymers.

An organic nonlinear optical crystal, 5-nitro-2-thiophenecarboxaldehyde-4-methylphenylhydrazone (NTMPH), has been prepared and investigated with regard to polymorphism, growth, and characterization...

Two newly developed 4-nitrophenylhydrazone derivatives, 4-diethylaminobenzaldehyde 4-nitrophenylhydrazone, DEANPH, and 5-bromothiophene-2-carbaldehyde 4-nitrophenylhydrazone, BTNPH, which exhibit very strong second harmonic signals that are three orders of magnitude greater than that of the urea standard were investigated by single crystal X-ray analysis. The structural comparison with three other strongly optically nonlinear hydrazones revealed that the hydrogen bond-directed lambda-shaped supramolecular assemblies are the key and fundamental bases of all these non-centrosymmetric crystal packings. The high occurrence within this class of acentric crystals is likely due to this hydrogen bonded lambda-shaped packing motif. Since the chromophores are preferentially arranged in a lambda-shape, the acentric crystals are generally optimized for second-order nonlinear optical effects such as second harmonic generation.

In this work we show that with strong hydrogen bonds, including a ‘very strong’ hydrogen bond and/or strong hydrogen-bonding networks, highly non-linear optically active chromophores, merocyanine dyes and phenol derivatives, are assembled as salt or semi-salt crystals, leading to improvement in crystallinity and interesting non-linear optical properties. Our approach is discussed in connection with four co-crystal structures.

The development of highly efficient organic nonlinear optical materials for opto-electronic applications, which are promising for high-speed information processing and telecommunications, has drawn considerable attention over the last decade."] Although various prototype optoelectronic devices have been successfully demonstrated, the improvement of practical devices still requires further materials and product device developments.[*] Opto-electronic components based on second-order nonlinear optical effects such as linear electro-optic, nonlinear optical, and photorefractive effects require materials with large second-order optical nonlinearities. The optimization of both the molecular hyperpolarizability /3 and the non-centrosymmetric molecular order in the bulk are essential prerequisites to the design of useful molecular or polymeric materials with large secondorder optical nonlinearitie~.[~] It has been theoretically and experimentally shown that the origin of large optical nonlinearities of a onedimensional, rod-shaped, dipolar molecule such as a donoracceptor disubstituted benzenes, biphenyls, polyenes, stilbenes, and tolanes arises from the highly polarizable charge asymmetry of the n-conjugated system."*31 Although over the last few yearsr4] there has been tremendous progress in the understanding and optimization of the first-order molecular hyperpolarizability of these classical dipolar chromophores, these highly hyperpolarizable chromophores, especially donor-acceptor disubstituted polyenes, are usually limited in practical applications because of their chemical instability. Furthermore, the formation of efficient acentric crystals, and the good orientational order and temporal stability in electrically poled polymers of classical dipolar chromophores, are in general challenging materials

Relaxation processes in nonlinear optical modified polyimide polymers with side-chain azo chromophores having glass transition temperatures in the range of 140 < Tg < 170 °C have been studied. The ...

Optical, nonlinear optical, and electrooptical pg-properties of 4'-nitrobenzylidene-3-acetamino-4-methoxyaniline (MNBA) single crystals have been investigated. The refractive indices were determined in the wavelength range of 514 to 1064 nm using an interferometric method. The electrooptical coefficients r/sub 11/, r/sub 13/, r/sub 31/, and r/sub 33/ were measured using a phase modulation technique. The dispersion of the largest electrooptical coefficient, r/sub 11/ (=29 pm/V at /spl lambda/=633 nm), was seen to follow the theoretical two-level model. Using the standard Maker fringe technique, we determined the nonlinear optical susceptibilities. The largest coefficient was found to be d/sub 11/=175 pm/V at /spl lambda/=1064 nm. Electric-field-induced second-harmonic generation was used for the determination of the molecular second-order nonlinear optical susceptibility yielding a good quantitative agreement when compared with the largest nonlinear optical and electrooptical coefficients in the framework of the molecular gas model with charge transfer along the polar molecular axis. Electroabsorption measurements near the band edge were performed that allowed us to calculate the field-induced frequency shift of the dominant oscillator. This field-induced frequency shift is of the same order of magnitude as the frequency shift calculated from the electric field-induced changes of the refractive indices (electrooptical effect). >

Single-mode-emitting high-power diode laser arrays (SM-HPDLA) are available industrially with more than 50 W emission power per bar. Based on this platform an expandable prototype solution is realized for fiber coupling of a stacked array with more than 100 W to an optical fiber with diameter of 200 micron and NA of 0.11. Advanced methods of controlled assembly of micro-optics by infrared laser-soldering have been developed therefore. We present a compact and scalable concept with scalability on 2 internal and 2 external factors. Internal factors are the increasing beam quality and power stability of high-power single-mode-emitting arrays and the improved assembly accuracy for diode bar and micro-optics. External factors are the interlaced coupling of stacked beam emission from the stacked array and the further option to use optimized polarisation coupling with several diode laser stacks.

We have identified cascading of second-order nonlinear processes as the origin of previously reported, very large nonlinearities measured by self-phase-modulation experiments in organic single-crystal-core fibers of 4-(N, N-dimethylamino)-3-acetamidonitrobenzene.

We experimentally demonstrate all-optical steering of arrays of dark spatial solitons. The arrays are generated by two intersecting plane waves in the regime of adiabatic amplification in a Kerr-like medium. The steering is achieved by changing the relative intensities of the beams. In addition, we show that beams guided in the soliton channels can also be scanned.