Radial phased-locked Laguerre-Gaussian correlated schell-model beam array.

A new beam array called radial phased-locked Laguerre-Gaussian correlated Schell-model (LGCSM) beam array is presented, the beamlet of this beam array is partially coherent beam with Laguerre Gaussian-Schell model correlation. The propagation expression of a radial phased-locked LGCSM beam array in free space is derived. It is aimed to give the effect of beam parameters on evolutions of beam array composed by LGCSM beam. The radial phased-locked LGCSM beam array has unique properties on propagation, the intensity of such beam array will evolve from a beam array composed of Gauss beams into a beam array formed of LGCSM beams. Furthermore, the intensity evolutions of such beam array are modulated by coherence length and beam order of beamlets. The obtained results are important in areas such as light field shaping, and free space optical communication.

Propagation of partially coherent Lorentz-Gauss vortex beam through oceanic turbulence.

The partially coherent Lorentz-Gauss vortex beam generated by a Schell-model source has been introduced. Based on the extended Huygens-Fresnel principle, the cross-spectral density function of a partially coherent Lorentz-Gauss vortex beam propagating in oceanic turbulence is derived. The influences of coherence length, topological charge M, and oceanic turbulence on the spreading properties and position of the coherence vortex for a partially coherent Lorentz-Gauss vortex beam are analyzed in detail. The results show that a partially coherent Lorentz-Gauss vortex beam propagating in stronger oceanic turbulence will evolve into a Gaussian-like beam more rapidly as the propagation distance increases, and the number of coherent vortices will change.

Propagation properties of a partially coherent Lorentz beam in uniaxial crystal orthogonal to the optical axis.

The cross-spectral density function of a partially coherent Lorentz beam propagating in uniaxial crystal orthogonal to the optical axis is obtained, and the evolution properties and the spectral degree of coherence for a partially coherent Lorentz beam in uniaxial crystal are illustrated by using numerical examples. The influence of coherence length and the ratio of refractive index ne/no on the normalized intensity and spectral degree of coherence for a partially coherent Lorentz beam are analyzed in detail.

Evolution properties of partially coherent four-petal Gaussian vortex beams propagating in uniaxial crystals orthogonal to the optical axis.

The analytical propagation equations for partially coherent four-petal Gaussian vortex beams propagating through uniaxial crystals orthogonal to the optical axis are derived, and the propagation properties are analyzed by numerical examples. The influence of beam order n, topological charge M, the coherence length, and the ratio of refractive index n(e)/n(o) on the normalized intensity distribution of partially coherent four-petal Gaussian vortex beams is discussed.

Evolution properties of partially coherent flat-topped vortex hollow beam in oceanic turbulence.

Employing the theory of coherence, the partially coherent flat-topped vortex hollow beam is first introduced. The analytical propagation equation for a partially coherent flat-topped vortex hollow beam in oceanic turbulence is derived by using the extended Huygens-Fresnel diffraction integral and the spectrum of oceanic turbulence. The influences of coherence length, beam order N, the topological charge M, and the parameters of oceanic turbulence on evolution properties of partially coherent flat-topped vortex hollow beams propagating in oceanic turbulence are obtained by using the numerical examples.

Photocatalytic overall water splitting promoted by an α-ß phase junction on Ga2O3.

When Alpha met Beta: a tuneable α-ß surface phase junction on Ga(2)O(3) can significantly improve photocatalytic overall water splitting into H(2) and O(2) over individual α-Ga(2)O(3) or ß-Ga(2)O(3) surface phases. This enhanced photocatalytic performance is mainly attributed to the efficient charge separation and transfer across the α-ß phase junction.

Fused perylenebisimide-carbazole: new ladder chromophores with enhanced third-order nonlinear optical activities.

A series of ladder chromophores featuring planar structures of fused perylenebisimide and carbazole have been efficiently synthesized via photocyclization under sun light. Compared to N,N'-bis(3-pentyl) perylenebisimide (PBI-1), they show remarkably enhanced nonlinear properties.

Starburst triarylamine donor-acceptor-donor quadrupolar derivatives based on cyano-substituted diphenylaminestyrylbenzene: tunable aggregation-induced emission colors and large two-photon absorption cross sections.

In this work, we have developed a new class of aggregation-induced emission (AIE) active compounds, in which three electron-donating diphenylamine, phenothiazine, or carbazole groups are connected to the 1, 4-positions of the benzene through bis(α-cyano-4-diphenylaminostyryl) conjugation bridges to form three triarylamine quadrupolar derivatives (3 a-c). Their one- and two-photon absorption properties have been investigated. The two-photon absorption (2PA) cross sections measured by the open-aperture Z-scan technique were determined to be 1016, 1484, and 814 GM for 3 a-c, respectively. From this result, the high 2PA properties of these molecules are attributed to the extended π system and enhanced intramolecular charge transfer from the starburst triarylamine to the cyano group. Moreover, cyano-substituted diphenylamine styrylbenzene (CNDPASB)-based compounds are very weakly fluorescent in THF, but their intensities increase by almost 230, 70, and 5 times, respectively, in water/THF (v/v 90 %) mixtures, in which they exhibit strongly enhanced red, orange, and deep yellow fluorescence emissions, respectively. This result indicates that the intramolecular vibration and rotation of these dyes is considerably restricted in nano-aggregates formed in water, leading to significant increases in fluorescence. It was found that the color tuning of the CNDPASB-based compounds could be conveniently accomplished by changing the starburst triarylamine donor moiety. Multilayer electroluminescence devices with TPBI (2,2',2''-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole)) electron-transporting layers have been made, with 3 a and 3 c as a non-doping red-yellow emitter. The preliminary results for these multilayer devices show a maximum efficiency of 0.25 %, and electroluminescence (EL) wavelengths around 568 nm. The excellent 2PA and AIE properties of these compounds make them potential materials for biophotonic applications.

Synthesis, two-photon absorption and optical limiting properties of multi-branched styryl derivatives based on 1,3,5-triazine.

Five new multi-branched two-photon absorption triazine chromophores (T1-T5) with different donor strength, conjugation length, and direction of charge transfer have been designed and synthesized. The one-photon fluorescence, fluorescence quantum yields, and two-photon properties have been investigated. The two-photon absorption (2PA) cross sections measured by the open aperture Z-scan technique were determined to be 447, 854, 1023, 603, and 766 GM for T1, T2, T3, T4, and T5, respectively. This result indicates that their 2PA cross section values (σ) increase with increasing electron-donating strength of the end group, extending the conjugation length of the system, and introducing electron-withdrawing perfluoroalkyl as side groups to the end donor. In addition, the σ value of T5 is also larger than that of T1, which provides evidence that the σ value is relative to the direction of charge transfer (from the ends to the center of the molecule or from the center to the ends). Moreover, significant enhancement of the two-photon absorption cross section was achieved by introducing a thiophene moiety to a conjugated C==C bond. At the same time, the optical limiting behavior for these chromophores was studied by using a focused 800 nm laser beam with pulses of 140 fs duration. It was found that these molecules also exhibit good optical limiting properties. These initial results clearly demonstrate that multi-branched triazine chromophores are a highly suitable class of two-photon absorbing materials.

Star-shaped donor-pi-acceptor conjugated oligomers with 1,3,5-triazine cores: convergent synthesis and multifunctional properties.

Monodispersed oligomers have been widely developed and used in different optoelectronic areas due to their well-defined molecular structures, high purity, and solution processability. Star-shaped oligomers are especially interesting for OLED application because of their antiaggregation abilities and stable electroluminescence. In addition, star-shaped donor-pi-acceptor conjugated molecules are known to afford good nonlinear optical and two-photon absorption properties due to the intramolecular charge transfer and cooperative enhancement effects. In this context, three generations of highly soluble 1,3,5-triazine based donor-pi-acceptor compounds, TFT1, TFT2, and TFT3, were prepared through a convergent synthetic strategy and their optoelectronic properties were fully studied, which showed distinct correlations with the structures. Closed-aperture and open-aperture Z-scan methods were employed to measure the nonlinear refractive index and two-photon absorption properties of the oligomers, respectively. TFT1 showed a high nonlinear refractive index of 4.14 x 10(-12) esu in THF solution with an excitation wavelength of 800 nm. Also, TFT1 exhibited a large two-photon absorption cross section of 234 GM and a frequency up-converted two-photon excited fluorescence with a lambda(TPEF)(max) value of 527 nm under 800 nm laser irradiation with a pulse duration of 140 fs. OLED devices using the spin-coated films of these oligomers as an active layer showed intensive blue electroluminescence with a maximum luminance of 3093 cd/m(2) at a current efficiency of 1.47 cd/A from TFT1.

Multibranched triarylamine end-capped triazines with aggregation-induced emission and large two-photon absorption cross-sections.

Multibranched triarylamine derivatives with a 1,3,5-triazine core have been synthesized and exhibit aggregation-induced emission and a large two-photon absorption cross section (8629 GM).