Search

Waveguiding films of the highly soluble polycarbazolyldiacetylene polyDCHD-HS were prepared by spin coating and characterized at different wavelengths: 5 dB/cm propagation losses were observed at 1321 nm. Measurements of the third order nonlinearity at 1064 nm with the surface plasmon resonance (SPR) method gave the value χ(3)=4.4×10−17+i3.5×10−18 m2/V2.

A large photoinduced reversible change of third-harmonic generation in azo-dye polymer thin films was recently observed. In this work, the microscopic interpretation of this phenomenon is given. The model presented is based on an angular hole burning and molecular reorientation due to trans-cis photoisomerization of azo-dye molecules.

The concentration dependence of the fifth order two-dimensional Raman signal intensity is reexamined. The instantaneous response of the fifth order signal comes from the fifth order susceptibility. The delayed response of the fifth order signal is consistent with a genuine fifth order Raman rather than a cascading process of the third order nonlinearity.

We investigate the third-order nonlinear optical property for 1,6,6a-trithiapentalene (TTP) by using density functional method. A unique spatial contribution of π-electrons to the second hyperpolarizability (γ) is elucidated. Based on our classification rule of γ, the features of γ for other π-conjugated systems involving sulfur (S) atoms are also discussed from the viewpoint of the possibility of combining conductivity and third-order nonlinear optics.

A germano-silicate optical fiber codoped with Pb2+ and Al3+ was developed by modified chemical vapor deposition and solution doping techniques. The non-resonant third-order optical nonlinearity was measured to be 6.9105 × 10−20 m2/W by using the continuous-wave self-phase modulation method. The enhanced non-resonant nonlinearity was ascribed to the increasing number of non-bridging oxygens due to the incorporation of the glass modifiers Pb2+ and Al3+, the large molar refraction from heavy metal ions Pb2+, and the enhanced hyper-polarization from PbO doped into the core of the made fiber.

The optical nonlinearity of Triangular Silver Nanoprism solutions and composites with tuneable absorption wavelength is analyzed using z-scan with 130 fs pulses. A dependence of the nonlinear optical properties on the absorption intensity is observed.

We have studied electroabsorption (EA) in both films and disperssed molecules of C 60 and C 70 . In contrast to a recent model for the third harmonic generation (THG) spectrum, we find that the two-photon states important to the nonresonant χ (3) (0) in molecular C 60 are above the 3.6 eV T 1u state, not below it. We present a model consistent with spectra of EA, THG and degenerate four-wave mixing (DFWM). The lowest-energy resonances in χ (3) ( ω ) are dominated by ‘forbidden’ transitions made allowed by vibronic coupling in the molecule and intermolecular coupling in the solid.

Organic compound of 1-(4-methoxyphenyl)-3-(2-methoxy 5-bromophenyl)prop-2-en-1-one [MMBPP] with molecular formula C16H11BrO3 was synthesized using Schmidt condensation method. A FT-IR spectrum was recorded to identify the various functional groups present in the compound. The single crystals were grown using slow evaporation solution growth technique. The high quality transparent crystals up to a size 10×7×5 mm3 are obtained with in fifteen days. UV-Visible spectrum reveals that the crystal is transparent in the entire visible region. The single crystal XRD study shows that the compound crystallizes in orthorhombic crystal system with a space group P212121 and the observed cell parameters are a =7.6095(13) A, b =13.049(2) A, c = 15.525(3) A, Volume 1541.6(5) A3. The third order Nonlinearity was confirmed by Z-scan technique and non-linear parameters were determined.

The enhancement of frequency mixing and phase-modulation due to cascaded second-order effects is studied in the organic MBA-NP crystal. In a 3 mm-thick sample, we observe a 10 4 increase of the frequency mixing yield, which implies an effective ‘third-order’ susceptibility of 10 -19 m 2 /V 2 .

We investigate the dynamics of the incoherently coupled nonlinear Schrodinger equations describing the propagation of two waves interacting through a third order nonlinearity. We show that the phenomenon of extended modulational instability induced by incoherent coupling is associated with the existence of a new type of solitary wave. This solitary wave consists of a bound state of two interacting semi-infinite symmetric kink waves.

Measurement of nonresonant third order nonlinearity of undoped and silverdoped arsenic sulphide in the near-infrared is reported. A beam distortion (Z-scan) technique was used for the measurements. The method can resolve both the refractive and the absorptive part of the nonlinearity and also their sign. It is shown that silver doping changes the sign of refractive nonlinearity.

Several approaches have been suggested during the past few years for increasing third order nonlinearity in organic compounds. In general, these have focused on manipulation of the effective conjugation length of the pi-electron framework to maximize orbital overlap. It has only recently become apparent that substituent effects, which affect the overall electron density distribution, may be an extremely effective way of enhancing nonlinearity. In this study we review known substituent effects on nonlinearity, and suggest how donor-donor, acceptor- acceptor, and donor-acceptor interaction can be utilized in the design of molecules and polymers with enhanced nonlinearity.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

It is shown that polarization sensitive (optically heterodyned) detection combined with π/2 optical phase biasing between the optical Kerr gate signal and the local oscillator signal provides an effective method for the investigation of dynamics of third‐order nonlinear optical processes. The method permits selective enhancement of either the real or the imaginary component of the nonlinear optical response of the medium under study. Both the magnitudes and the signs of the real and the imaginary components of the complex third‐order optical susceptibility, contributing to the Kerr gate phenomenon, can thus be determined independently. The method is used to investigate the third‐order nonlinear optical response of solutions of canthaxanthin (4,4’‐dioxo‐β‐carotene) in tetrahydrofuran. With the use of ultrafast 60 fs laser pulses at 620 nm, the instantaneous, coherent part of the response is separated from an incoherent, time‐delayed response. The real and the imaginary components of the instantaneous compl...

The concept of interlocked molecules is known from sixties and up to now catenanes and rotaxanes of up to 4 components were synthesized and still the number of components in-crease. These are relatively small molecules when in nature large catenanes are present in DNA molecules. Catenanes and rotaxanes are mechanically interlocked molecules composed of moving parts, held together, where one (or more of them) can move and/or positioning with respect to the other. This unique architecture makes them very interesting as possible candidates for molecular machine-type applications in the field of nonlinear optics particularly in photonics, optoelectronics and optical data storage. In this work we report the results of our studies of nonlinear optical properties of some selected catenanes and rotaxanes. The nonlinear properties were studied by different techniques. The results show important electronic contribution to the third order nonlinear susceptibility confirmed by theoretical calculations at the molecular level. Also, we report the results of nonlinear optical properties of functionalized DNA. The results show high enhancement of nonlinearity when the modified DNA was used. At the same time the best results were observed in holography experiments when DNA-CTMA was used as a matrix for doping of disperse red 1.; La synthèse de caténanes et rotaxanes remonte aux années 60. Aujourd'hui la plupart de ces molécules enchevêtrées, synthétisées comportent jusqu'à 4 éléments et ce nombre continu de croître. Toutefois, ces molécules restent relativement petites, comparées `a celles trouvées dans la nature tels que les caténanes présents dans l'ADN. Les caténanes et rotaxanes sont des molécules mécaniquement assemblées, composées de pièces mobiles, liées, ou non (ou plus d'elles), pouvant se mouvoir et/ou se déplacer par rapport aux autres. Cette architecture unique les rend très intéressants et fait d'eux des candidats potentiels pour les machines moléculaires, ainsi que pour des applications dans le domaine de l'optique non linéaire, en particulier dans la photonique, l'optoélectronique et le stockage de données optique. Dans ce travail, nous exposons les résultats de nos recherches portant sur les propriétés optiques non-linéaires de quelques caténanes et rotaxanes. Ces propriétés non-linéaires ont été abordées par différentes techniques. Les résultats montrent une importante contribution électronique dans la susceptibilité non-linéaire de troisième ordre confirmée par des calculs théoriques au niveau moléculaire. Nous exposons également les résultats des propriétés optiques non linéaires de l'ADN fonctionnalisé. Ces résultats montrent une recrudescence des non linéarités quand l'ADN modifiée est utilisé. Par ailleurs, on a observé les meilleurs résultats dans des expériences d'holographie quand l'ADN-CTMA est utilisé comme matrice pour le dopage du disperse red 1.

The concept of interlocked molecules is known from sixties and up to now catenanes and rotaxanes of up to 4 components were synthesized and still the number of components in-crease. These are relatively small molecules when in nature large catenanes are present in DNA molecules. Catenanes and rotaxanes are mechanically interlocked molecules composed of moving parts, held together, where one (or more of them) can move and/or positioning with respect to the other. This unique architecture makes them very interesting as possible candidates for molecular machine-type applications in the field of nonlinear optics particularly in photonics, optoelectronics and optical data storage. In this work we report the results of our studies of nonlinear optical properties of some selected catenanes and rotaxanes. The nonlinear properties were studied by different techniques. The results show important electronic contribution to the third order nonlinear susceptibility confirmed by theoretical calculations at the molecular level. Also, we report the results of nonlinear optical properties of functionalized DNA. The results show high enhancement of nonlinearity when the modified DNA was used. At the same time the best results were observed in holography experiments when DNA-CTMA was used as a matrix for doping of disperse red 1., La synthèse de caténanes et rotaxanes remonte aux années 60. Aujourd'hui la plupart de ces molécules enchevêtrées, synthétisées comportent jusqu'à 4 éléments et ce nombre continu de croître. Toutefois, ces molécules restent relativement petites, comparées `a celles trouvées dans la nature tels que les caténanes présents dans l'ADN. Les caténanes et rotaxanes sont des molécules mécaniquement assemblées, composées de pièces mobiles, liées, ou non (ou plus d'elles), pouvant se mouvoir et/ou se déplacer par rapport aux autres. Cette architecture unique les rend très intéressants et fait d'eux des candidats potentiels pour les machines moléculaires, ainsi que pour des applications dans le domaine de l'optique non linéaire, en particulier dans la photonique, l'optoélectronique et le stockage de données optique. Dans ce travail, nous exposons les résultats de nos recherches portant sur les propriétés optiques non-linéaires de quelques caténanes et rotaxanes. Ces propriétés non-linéaires ont été abordées par différentes techniques. Les résultats montrent une importante contribution électronique dans la susceptibilité non-linéaire de troisième ordre confirmée par des calculs théoriques au niveau moléculaire. Nous exposons également les résultats des propriétés optiques non linéaires de l'ADN fonctionnalisé. Ces résultats montrent une recrudescence des non linéarités quand l'ADN modifiée est utilisé. Par ailleurs, on a observé les meilleurs résultats dans des expériences d'holographie quand l'ADN-CTMA est utilisé comme matrice pour le dopage du disperse red 1.

The field of nonlinear optics has been characterized by a remarkable increase in research activities during the past decade. We summarize the specific research into nonlinear optical materials prepared by the sol-gel technology. The chapter describes the preparation of glasses doped by semiconductor nanoparticles such as CdS, CuCl, CuBr, Bi2S3 and PbI2, metal nanoparticles and organic dyes. The third order susceptibilities of the various materials are tabulated. Glasses doped by organic dyes, their preparation, and properties of second and third order nonlinearity are discussed. The potential of these materials for industrial and technical applications is stressed.

We demonstrate the third-order nonlinear optical properties of Cr(4+):Y(3)Ga(5)O(12) (Cr(4+):YGG) and Q-switched lasers with Cr(4+):YGG as the saturable absorber for the first time to our knowledge. The third-order nonlinear properties, including the optical Kerr nonlinearity and saturable absorption, were systematically measured and analyzed in detail by using a Z-scan technique. The measured data show that Cr(4+):YGG has a large nonlinear refractive index, ground-state absorption cross section, and excited-state absorption cross section in contrast to Cr(4+):Y(3)Al(5)O(12) (Cr(4+):YAG). With a Nd:YGG crystal as the gain medium and a Cr(4+):YGG crystal as the saturable absorber, the passively Q-switched laser was performed. The shortest pulse width and largest pulse energy were achieved at the absorbed pump power of 8 W with the values of 9.1 ns and 26.1 μJ, respectively, corresponding to the average output power of 0.87 W and peak power of 2.9 kW. The results indicate that Cr(4+):YGG is an available and promising optical switcher for pulsed lasers.

Third-order nonlinearity of optical material has been found to be very useful for group velocity controlling. The velocity of a pulse may be changed by tuning its intensity or using an extra CW pump.

A possibility of tuning the phase of the third-order Kerr-type nonlinear susceptibility in a system consisting of two interacting metal nanospheres and a nonlinearly polarizable molecule is investigated theoretically and numerically. It is shown that by varying the relative inter-sphere separation, it is possible to tune the phase of the effective nonlinear susceptibility \chi^{(3)}(\omega;\omega,\omega,-\omega)$ in the whole range from 0 to $2\pi$., Comment: 10 pages 5 figures

The change of third order nonlinearity in silica fibre caused by poling is stable under UV or thermal erasure. The third order nonlinearity, like the linear refractive index, can be modulated by UV irradiation alone.

The FDTD calculation of light transmission through a 2-D photonic crystal with the third order nonlinearity shows that the photonic band at the second T point allows large enhancement of the nonlinearity with low loss.

Propagation of an intense femtosecond light pulses is investigated by a numerical model which provides the full spatial and temporal description. This is a simulation of pump and probe experiment where the probe pulse is affected by the presence of the pump pulse. Deviation of the plane-wave approximation and its correction to Gaussian beams is studied under variation of several sample parameters. The results give a view to some limitations of use of the approximation.

Quantum-statistical properties of light propagating in a coupler with third order nonlinearity are investigated. The stochastic equations describing the dynamics of the system are derived in positive-P and Wigner representations. The possibility to generate quadrature-squeezed states is shown numerically.

Summary form only given.All optical temporal-spatial conversion techniques using a four-wave-mixing (FWM) process have been developed in the 1990s. The performance of these techniques is determined by the FWM mechanism. The authors demonstrated the serial-to-parallel conversion with large efficiency and fast response time using the excitonic /spl chi//sup (3)/ nonlinearity in ZnSe film. However, the performance was achieved only in low temperature (10 K), because the excitonic nonlinearity of the ZnSe film smears out in room temperature Here we report on serial-to-parallel conversion using a material that has large third order nonlinearity and fast response time in room temperature. The material is a self-organized quantum-well system consisting of inorganic well layers and organic barrier layers. We demonstrate serial-to-parallel conversion of Tbits/s signals with conversion rate of 100 GHz.

We investigate the impact of cascaded third harmonic generation and the intrinsic n4 material nonlinearity on the propagation of ultrashort pulses in noble-gas filled Kagome fibers. We show that the pressure tunability of the cascade allows for the implementation of temporal switching. We also investigate the relative strengths of both effects and show their ratio to be pressure tunable.

Raman Induced Phase Conjugation (RIPC), a form of nondegenerate, backward four-wave mixing is used to measure the ratio of the resonant and non-resonant components of the third order nonlinearity in benzene from the 992 Cm-1 Raman mode. A computer code which models RIPC intensity is used to fit theoretical intensity to those obtained in experiment.

The third-order nonlinear optical susceptibilities χ(3)1111(-3ω; ω, ω, ω) of macrocyclic compounds such as phthalocyanines and porphyrins are determined for the vacuum deposited and spin coated thin films by optical third-harmonic generation measurements at a wavelength of 1907 nm. The enhancements of the χ(3) values are discussed in terms of the central metal substitution, molecular stacking, extended ring size and number of χ-electrons. We firstly describe the results of extended porphyrin systems with 26 delocalized π-electrons.

The third order nonlinear responses for soluble one-dimensional ϕ-conjugated polymers, poly(3-alkylthiophene)s were investigated. Uniaxial stretching of the polymer film was carried out to align the polymer backbone. The stretched film showed large dichroism and crystallinity. Third order nonlinear susceptibility, χ(3)1111 of the stretched film was determined by optical third harmonic generation. A large enhancement of χ(3) due to the main chain alignment was observed.

We report measurements of the nonresonant nonlinear refractive index n2 in antimony glasses at telecom wavelengths. The measurements were performed using the Z-scan technique with a 130fs pulsed laser operating at five wavelengths in the range of 1400–1600nm. Values of n2≈10−15cm2∕W were measured and a negligible two-photon absorption coefficient (

Newpoly(1,4-phenylenevinylene) (PPV) derivative containing Disperse Red 1 (PBDR1PV) was prepared through organic-soluble precursor route. This polymer was characterized by conventional spectroscopic methods (UV-visible, IR, NMR) and the third-order nonlinear optical coefficient was determined by using third harmonic generation (THG) technique. The measured χ (3) value is about 2.5 × 10 −12 esu.

Negative thermal poling introduces second-order nonlinear effects into silica glass. The effects are studied using the charge separation model allowing for the third-order nonlinear effect to be anisotropic. The second-order nonlinear coefficient χ(2) is found to be consistent with the results reported previously by Arentoft et al. (1999), Ren et al. (2002), and Marckmann et al. (2001) and the third-order nonlinear coefficient χ(3) is found to be anisotropic but constant during poling.

It has been demonstrated that an initial phase mismatch in type I second-harmonic generation processes with ultrahigh intensity laser pulses can be used to compensate for third-order nonlinearity not only in temporal profiles but also in spatial distributions of fundamental and second-harmonic pulses. The spatial profile of the second-harmonic pulse shows a good reappearance of the input fundamental pulse throughout the compensation for the third-order nonlinearity.

Second- and third-order optical nonlinearity was measured by second- and third-harmonic generation of the glass, respectively. Second-order optical nonlinearity can be seen in thermally poled SiO2 glass samples. The intensity of the second-harmonic generation depends on the concentration of some additives such as OH or TiO2. On the other hand, third-order optical nonlinearity can be found all kinds of glasses. The magnitude of third-order optical nonlinearity basically depends on the linear refractive index of the glasses.

Nonresonant-type third-order nonlinearity of high refractive index PbO-TiO2-TeO2 and Nb2O5-TiO2-TeO2 glass has been evaluated by means of third-harmonic generation. The PbO-containing glass show higher χ(3) than Nb2O5-containing glass, and the largest χ(3) of 3.7×10-12 esu is obtained for 10 mol%PbO-10 mol%TiO2-80 mol%TeO2 and 25 mol%PbO-10 mol%TiO2-65 mol%TeO2 glass.

The wave-vector dependence of the third-order nonlinearity due to the excitonic polaritons in CuCl is microscopically calculated using the Bloch functions at finite wave vectors obtained from the $\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}\ifmmode\cdot\else\textperiodcentered\fi{}\stackrel{\ensuremath{\rightarrow}}{\mathrm{p}}$ perturbation method. It is found that in the spatially dispersive region the magnitude of the nonlinearity is not so strongly dependent on the wave vector over the range from less than ${10}^{6}$ ${\mathrm{cm}}^{\ensuremath{-}1}$ (upper-branch polariton) up to ${10}^{7}$ ${\mathrm{cm}}^{\ensuremath{-}1}$ (lower-branch polariton).

We study the third order nonlinearity associated with the biexciton resonance in CuCl. The magnitude of X3 is deduced from polarization rotation. A lower limit value X3 ≥ 9.10-6 esu is measured for a light intensity Io ≤ 103W/cm2 in high purity single crystals at T = 2K.

We present a theoretical model of the linear and ring, passively mode locked dye lasers. This simple model gives a clear understanding of the role of the amplifier, the absorber, and the dynamics of the degenerate third order nonlinearity resulting from spatial hole burning [1].

Experimental values of the third-order susceptibility of ultra-thin gold layers are obtained and compared to the values of the third-order susceptibility for bulk gold. The effective enhancement of the third-order nonlinearity depending on the thickness of the gold layers is observed. We discuss possible reason for such enhancement. The two-temperature model is applied to model the nonlinear response of gold waveguides on different time scales. The third-order nonlinear effects in plasmonic waveguides can be used for future developments of optical communication systems.

It is theoretically shown that the variance of fluctuations peaks in the vicinity of threshold of instability in a system having third-order nonlinearity provided the nonlinearity depends on the pumping rate.

A beat signal between longitudinal modes of the laser cavity is detected, amplified and fed back to an electro-optic element inserted in the laser cavity. In this case, if the gain of the beat amplifier is large, this element should have a large equivalent third order nonlinearity. Since this nonlinearity make the modes couple, many types of mode-looking phenomena are expected. In this paper, a theoretical analysis is presented and compared with experiments using a He-Ne 6328 Å laser.