Oligoetheracrylate Photopolymer Research Articles

Intrinsic hyperpolarizability of 3-dicyanomethylene-5,5-dimethyl-1-[2-(4-hydroxyphenyl)ethenyl]-cyclohexene nanocrystallites incorporated into the photopolymer matrices

Second-order optical properties of anionic 3-dicyanomethylen-5,5-dimethyle-1-[2-(4-hydroxyphenyl)ethenyl)]-cyclohexene ( 1) with crystalline sizes from 10 nm to 300 nm were studied. An electric field enhancement of effective second-order susceptibility at 1064 nm for the crystallites incorporated into the oligoetheracrylate photopolymer matrices from 3.1 pm/V to 7.8 pm/V was discovered corresponding to hyperpolarizability increase from 0.12 × 10 −30 esu to 0.21 × 10 −30 esu. The evaluated intrinsic hyperpolarizability achieves value about 0.037, which is comparable with the best organic molecule. Principal possibility of enhancing the intrinsic hyperpolarizability was achieved by applying an external electric field and decrease of the nanocrystallite sizes without an increase of the π-conjugated bond numbers.

UV-induced optical features of oligoetheracrylate photopolymers

Variation of principal optical parameters (absorption and refractive indices) in complex oligoetheracrylate photopolymers under influence of nanosecond pulsed nitrogen laser ( λ = 337 nm ) at wavelengths of low-power semiconducting lasers ( λ=694 nm and 1040 nm) was studied. Two principal mechanisms of the observed changes are discussed: reorientation of the non-solidified liquid composites and topochemical photopolymerization reactions. Besides substantial anisotropy of the transmitted polarized laser light with respect to the polarization of the photoinducing laser beam was found. This effect may be used for creation of UV-operating switchers.

Electrogyration in CHBrClF chromophores stimulated by circularly polarized light

We have found that the CHBrClF chiral-like racemic molecule incorporated into oligoetheracrylate photopolymer matrices demonstrates considerable photoinduced linear electrogyration (EG) caused by circularly polarized bicolour coherent light. The maximally achieved value of the EG, described by the third-order axial tensor for the circularly polarized light of the probe at a wavelength of 633 nm, was equal to about 12°mm−1 at an applied electric field strength equal to 250 V cm−1. We have established that the maximal EG coefficient is achieved for 5.10 wt% of CHBrClF chromophores. The investigated composites possess a long-lived screw-like helicoidal EG decreasing less than 18% after laser treatment for 100 min by the circularly polarized coherent frequencies of an ND-doped yattric aluminium garnet laser. Application of non-circular pump light leads to a decrease in the observed EG.

Comment on ‘Optical poling of oligoether acrylate photopolymers doped by stilbene-benzoatederivative chromophores’

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Reply to Comment on ‘Optical poling of oligoether acrylate photopolymers doped bystilbene-benzoate derivative chromophores’

Optical poling in photopolymers has several principal differences compared to otherguest–host composites. There exists a principal difference between aligning the DC electricfield presented in the article and interior DC electric strength. Also, the use of thehyperpolarizabilities of different orders is clarified.

Circularly light-induced electrogyration in the arylethynyl derivatives incorporated within the oligoetheracrylate photopolymer matrices

We have found that the arylethynyl chromophore molecule incorporated into oligoetheracrylate (OEA) photopolymer matrices might be considered like promising materials for optically induced linear electrogyration (EG) excited by circularly polarized bicolor coherent light. The maximally achieved value of the EG susceptibility described by third-order axial tensor caused by probe circularly polarized light at the wavelength 633 nm was equal to about 1.12 deg/mm at 200 V/cm electric field strength. We have revealed that the maximal EG coefficient is achieved for 4.80% of chromophores in weighting units. The investigated composites possess long-lived EG grating, which decreases no more than 36% after 100 min of laser treatment. Applying of a non-circular pump light leads to diminishing of the observed EG.

Optical poling of oligoether acrylate photopolymers doped by stilbene-benzoate derivativechromophores

A large second harmonic generation (SHG) excited by an Nd:YAG laser(λ = 1.32 µm) has been observed during the investigation of the optical poling process in2-(stilbene-4-yl)benzoxazole derivatives chromophores incorporated within oligoetheracrylate photopolymer matrices. We have revealed that the maximum outputSHG is observed for the chromophore derivatives molecule possessing the highestsecond-order hyperpolarizabilities and corresponding dipole moments. Due tothe incorporation of the chromophore into photopolymer matrices, second-ordermicroscopic susceptibilities of the composites substantially increase (from 0.24 up to1.89 pm V−1). The investigated composites possess long-lived polarized states and after more than106 laser pulses the output SHG did not decrease below 75% compared with the initial SHG one. Optimalconditions for optical poling corresponded to a power density of the doubled frequency beam of about0.07 GW cm−2 and chromophore content about 6.5% (in weighting units).

Optical poling of oligoether acrylate photopolymers doped by 1- H-pyrazolo[3,4-b]quinolines derivative chromophores

Second harmonic generation excited by Nd:YAG laser ( λ=1.32 μ m) was observed during the investigation of second-order optical poling process in 1- H-pyrazolo[3,4-b]quinolines chromophores incorporated within the oligoether acrylate (OEA) photopolymer matrices. We have found that the observed SHG output is correlated well with the values of corresponding dipole moments. Due to incorporation of the chromophore into photopolymer matrices second-order microscopic hyperpolarizabilities of the composites substantially increase (up to 3.01 pm/V). The investigated composites possess long-lived photopolarized states and after about 10 5 laser pulses the output SHG output signal did not decrease below 75% compared to the SHG signal in the beginning of the treatment. Optimal conditions of the optical poling corresponded to power density of the doubled frequency beam about 0.024 GW/cm 2 and chromophore content about 5.2% (in weighting unites).

Non-linear optical anomalies near the phase transitions in polysiloxane chromophore incorporated within an oligoetheracrylate photopolymer matrix

The photoinduced optical second-harmonic generation (PISHG) in polysiloxane (PX) chromophore incorporated within an oligoetheracrylate photopolymer matrix was investigated as a function of temperature within the 4.2–300 K temperature range. The addition of PX chromophore leads to an enhancement of the local non-centrosymmetric charge density distribution determining optical second-harmonic generation. Two maxima of the PISHG signals were observed at temperatures of ~ = 20 and 126 K. The DSC data give the positions of the maxima at 36 and 132 K. This temperature discrepancy may be a consequence of different contributions of the electron–vibration sub-system to the observed phase transformations. An explanation of the observed temperature anomalies is given within a quantum chemical approach.

SiOxC1−xN large-sized nanocrystals in the photoinduced SHG

Photoinduced second harmonic generation (SHG) has been revealed in SiOCN nanocrystallites incorporated into the oligoetheracrylate photopolymers. Increasing photoinducing Q-switched nitrogen laser pulses (λ=337nm) leads to an increase of the SHG signal. The SHG achieves its maximum at pump photon flux of about 1.83GW/cm2. The maximum photoinduced SHG is achieved for C/N ratio of about 0.92 and is equal to (3.82±0.11) pm/V. Optimal concentration of the embedded SiOCN nanopowders lies between 4.2% and 6.3%. Decreasing temperature favours increase of the SHG. Substantial contribution of nanocrystallite interfaces is expected in observed nonlinear optical phenomena.

Non-linear optical phenomena in the large-sized nanocrystallites

Photoinduced second harmonic generation (PISHG) in SiC nanocrystallites (with sizes ranging from 10 to 30 nm) incorporated into an oligoetheracrylate photopolymer matrix was studied using an experimental photoinducing non-linear optical technique and ab initio molecular dynamics simulations. PISHG measurements were made using a pulse YAG:Nd laser ( λ=1.06 μm ; duration time varying from 4 to 850 ps, laser power about 14 MW) as the probing beam and a nitrogen pulse laser ( P=25 MW; λ=0.377 μm ) as the pumping beam synchronized with a probing beam. We found that with an increase in the nitrogen laser power, the PISHG output signal increased and achieved its maximum value at nitrogen laser photon flux of about 2.6 GW/ cm 2 . Maximum output PISHG signals were observed for parallel polarization of the photoinducing and probing light beams. The second order non-linear optical susceptibility observed at the maximum PISHG was about 1.2 pm/V. The PISHG signals increased as the sample temperature decreased. This increase became marked when the temperature fell below 30 K. Time-dependent probe-pump measurements showed the existence of a PISHG maximum at a time delay of about 20–25 ps. As a result of total energy structure optimization, a good correlation between the size dimensions and the degree of hexagonality within the nanocrystallites was observed. An increase in the degree of hexagonality was also found to cause an increase in the PISHG signal. At a temperature of about 4.2 K, and with a time delay of 25 ps, the maximum PISHG was observed for a degree of hexagonality of approximately 0.76. Our calculations suggest that hexagonal substructures play a key role in the photoinduced effects observed. Several discrepancies between theoretical and experimental data may be caused by specimen in-homogeneity which is usually present in such kinds of materials.

Contribution of Hexagonal-like Structure to the Nonlinear Optics in Large-sized SiC Nanocrystallites

Contribution of the hexagonal-like structure to the optically poled (photoinduced) second harmonic generation (SHG) in SiC large-sized nanocrystallites (with sizes within the 10-30 nm) incorporated into the oligoetheracrylate photopolymer matrices is found. The SHG measurements have been carried out using pulsed YAG:Nd laser ( @ duration time ‰ = 1550 ps, laser power about 30 MW) as probing ones and a nitrogen pulse laser ( P = 10 MW; u; = 0.377 w m; ‰ = 515 ps) as a photoinducing beam. We have found that with increasing pumping power the SHG output signal increases and achieves its maximum value at the pump photon power about 2.6 GW/cm 2 per pulse. The maximal output photoinduced SHG signals have been observed for parallel polarization between the pumping and probing light beams and the observed maximal value of the SHG is equal about 4.02 pm/V. With decreasing temperature the SHG signal considerably increases below the 30 K. Probe-pump measurements show an existence of the photoinduced SHG maximum at th...

Photoinduced anisotropy of push–pull chromophores incorporating 5-(1,3-benzodithiol-2-ylidene)-1-(4-nitrophenyl) penta-1,3-diene embedded into photopolymer oligoetheracrylate matrices

Photoinduced (PI) birefringence (Δ n) and phototransparency ( T) have been studied for a wavelength of 633 nm (He–Ne laser) under photoillumination by doubled-frequency YAG:Nd pulse laser polarized beam ( λ=0.53 μm; pulse duration τ=10–50 ps). The push–pull chromophore 5-(1,3-benzodithiol-2-ylidene)-1-(4-nitrophenyl) penta-1,3-diene was incorporated into an oligoetheracrylate photopolymer matrix in a concentration of about 2.5 wt.%. Special properties of the molecule are connected with substantial role played by electron-vibration interactions in the observed PI effects. The Δ n decreases with decreasing temperature. Optical density D depends non-linearly on the PI beam power. With increasing photoinducing power (up to 0.41 GW/cm 2), the PI birefringence Δ n and the optical density D approaches (1.4–1.7)×10 −3 and 1.5%, respectively. The intensity dependence of intramolecular (669 cm −1) and intermolecular (89.5 cm −1) vibration mode has a maximum and a broad minimum (at a PI power of about 0.45 GW/cm 2), respectively. Such behavior correlates well with the PI dependencies of the Δ n and the optical density D. Description of the obtained results is based on quantum chemical calculations with taking into account an electron-vibration anharmonicity of the chromophore. Essential role of the PI electrostatic potential redistribution under influence of the PI polarized light beam has been demonstrated. Possible mechanisms of the observed phenomena are discussed within a phenomenological as well as microscopic approach.

Modulated superstructures in oligoetheracrylate photopolymers

Abstract Acoustooptical quality coefficient in amorphous oligoetheracrylate photopolymers of different chemical compositions was investigated depending on temperature. It was observed that the quality coefficient increases with decreasing temperature and saturates below 4.2 K. An external electric field strongly influences acoustooptical properties of the mentioned photopolymers. It was found that increasing number of aromatic rings leads to an increase of the acoustooptical quality coefficient. A strong influence of the C=O bonds distance on the quality coefficient was observed as well. Such a behaviour points out at a very essential role of a noncentrosymmetric disorder which contributes to the acoustooptical constants. The oligoetheracrylates are therefore more promising than traditional photopolymer materials (e.g., polyurethanes) because of their better elastic and optical transparency properties.