Nonlinear Optical Polymers Research Articles

Styrene monomer as potential material for design of new optoelectronic and nonlinear optical polymers: density functional theory study.

Using density functional theory, we have studied the intrinsic properties of styrene. First, we determine the optimized structures, structural parameters and thermodynamic properties to make our simulations more realistic to experimental results and check the stability. Second, we investigate optoelectronic, electronic and global descriptors, transport properties of holes and electrons, natural bond orbital analysis, absorption and fluorescence properties. Finally, we study nonlinear optical (NLO) properties: first- and second-order hyperpolarizability, second and third-order optical susceptibilities, hyper-Rayleigh scattering hyperpolarizability, electro-optical Pockel effect, direct current Kerr effects and quadratic refractive index. The bandgap energy E g = 5.146 eV and dielectric constant show that styrene is a good insulator with an average electric field value of 4.43 × 108 Vm-1. Thermodynamic findings show that our molecule is thermodynamically and chemically stable. Electron and hole reorganization energies of 0.393 and 0.295 eV, respectively, show that styrene is more favourable to hole transport than electron transport. Styrene is transparent with linear refractive index n = 1.750 and quadratic n 2 = 1.748 × 10-20 m2 W-1. At the NLO, styrene has a non-zero value of which confirms the existence of first-order NLO activity. Globally the study shows that the styrene monomer is suitable for the architecture design of new polymer materials for NLO applications and optoelectronic by functionalization.

Synthesis, electro‐optic properties, and performance of novel fluorinated polyurethaneimide

AbstractUrethane imide anhydride oligomers with terminal groups as anhydride groups were designed and synthesized using second‐order nonlinear optical chromophore molecule, bisphenol AF‐type diethylidene dianhydride, and toluene diisocyanate as monomers. Polyurethaneimide (PUI) second‐order nonlinear optical polymers with the structure of imide and amino ester chain segments were then synthesized by the polycondensation reaction between urethane imide anhydride oligomers and aromatic diamine monomers. The glass transition temperature (Tg) of PUI reached 186°C, and the 5% heat‐loss decomposition temperature was 320°C. The corona‐polarized PUI had an electro‐optic (EO) coefficient (γ33) of 82 pm/V tested by the reflection method. The loss of light transmission of the polymer waveguide prepared with PUI as electro‐optical material was 1.13 dB/cm at 1550 nm. Mach–Zehnder type polymer waveguide electro‐optical modulators have been prepared based on the properties of the electro‐optic material PUI. The fabricated polymer EO modulators had favorable electro‐optic modulation response performance for low‐frequency electrical signals. The good modulation characteristics of the manufactured electro‐optical modulators proved that the synthesized PUI was a waveguide polymer material with good comprehensive performance.Highlights Electro‐optic fluorinated polyurethaneimide was synthesized. Polyurethaneimide as core material, polymer waveguide EO modulators were fabricated. The prepared modulators had good electro‐optic modulation performance.

A Full‐Scale Analysis of Absorption Edges in Dye‐Doped Nonlinear Optical Polymers

AbstractA full‐scale analysis of the absorption edges by modified Tauc‐Lorentz models is essential in determining the optical bandgap and Urbach energy of semiconductors, transparent conductors, ionic compounds, and dielectric materials. This technique has not yet been applied to analyzing organic nonlinear optical (NLO) materials. This problem is tackled by preparing high‐quality films of guest–host NLO polymers with a wide thickness range from sub‐micron to 200 microns, allowing accurate measurement of full‐spectral absorption coefficients of NLO materials over four orders of magnitude by the UV‐VIS‐NIR spectroscopy. The Tauc model and a new Monolog–Lorentz model are used to study the optical absorption edge of guest‐host NLO polymers containing various push‐pull chromophores and the dependence of optical bandgap and Urbach edge on the structure and composition of materials is analyzed. The results reveal the critical transition of the Urbach exponential tail to a low energy tail that overlaps with vibrational overtones of materials at the telecom wavelengths. Determining the fundamental absorption region of organic NLO films in this study provides quantitative insight into the research to harness the resonance‐enhanced nonlinear coefficients of materials by operating at the wavelengths near the band edge with the control of optical loss.

Nonlinear Metal–Organic Framework Crystals for Efficient Multicolor Coherent Optical Emission

AbstractNon‐centrosymmetric metal–organic frameworks (MOFs) have recently emerged as a promising class of coordination polymers for nonlinear optics and light conversion. Nevertheless, achieving high endurance and efficiency for the light conversion within the whole visible range by a single crystal of MOF remains a challenge. This article reports on the design of two non‐centrosymmetric MOFs based on a 1,3,5‐benzenetricarboxylic acid ligand and Er/Co ions, providing an efficient and simultaneous multiple second and third optical harmonic generations (SHG, THG) from 400 to 750 nm with a high endurance (over 100 cycles or 3 h of continuous operation). Optical experiments and quantum chemical modeling of the MOF single crystals confirm the polarization and chemistry‐dependent efficiency of SHG and THG, associated with the varied MOFs' symmetry and dipole moment. The observed coherent light conversion within the whole visible range by MOF single crystals at ambient conditions makes it possible to achieve the multicolor (up to three) coherent emission required for modern laser technologies, making MOFs highly competitive and sustainable materials for nonlinear optics.

Phthalocyanine‐Based 2D Polymer for Ultrafast Nonlinear Optical Application

AbstractStrong ultrafast nonlinear optical (NLO) responses in near‐infrared (NIR) regions and favorable solution processability are two urgent requirements for practical NLO applications, especially for optical limiting (OL) applications. However, simultaneously optimizing these properties remains significant challenging. In this study, the successful synthesis of a phthalocyanine‐based 2D polymer (Pc‐2DP) is reported; its structure features extended π‐electrons delocalization space constructed by topologically integrating the phthalocyanine units into the 2D framework. The as‐prepared few‐layered Pc‐2DP not only exhibits power‐ and wavelength‐dependent NLO properties toward 35 fs ultrafast pulsed laser, but it also demonstrates excellent ultrafast reverse saturable absorption (RSA) responses in NIR regions. The nonlinear absorption coefficients of Pc‐2DP dispersion reach up to 0.12 and 0.19 cm GW−1 at 800 and 1550 nm, respectively, which are much higher than those of the typical MXene (Ti3C2TX) and molybdenum disulfide with hexagonal structure (2H‐MoS2). The obtained NLO devices exhibit remarkable OL performance at 800 nm and, particularly, in the telecommunication region (1300 to 1550 nm), which is highly desired but seldom reported. The study demonstrates that the as‐prepared Pc‐2DP featuring a highly conjugated aromatic framework is a very promising OL material and that this research provides a new strategy for developing high‐performance 2D organic NLO polymers.

Low half-wave voltage polymeric electro-optic modulator using CLD-1/PMMA for electrocardiogram (ECG) signal acquisition.

Electro-optic (EO) modulators are typically made of inorganic materials such as lithium niobate; the replacement of these modulators with organic EO materials is a promising alternative due to their lower half-wave voltage (Vπ), ease of handling, and relatively low cost. We propose the design and fabrication of a push-pull polymer electro-optic modulator with voltage-length parameters (VπL) of 1.28 V·cm. The device uses a Mach-Zehnder structure and is made of a second-order nonlinear optical host-guest polymer composed of a CLD-1 chromophore and PMMA polymer. The experimental results show that the loss is 1.7 dB, Vπ drops to 1.6 V, and the modulation depth is 0.637 dB at 1550 nm. The results of a preliminary study show that the device is capable of efficiently detecting electrocardiogram (ECG) signals with performance on par with that of commercial ECG devices.

Promotion of the second-order nonlinear optical effect by introducing ether linkage into polymer main chains

The lower rotational barrier of ether bond than that of single carbon–carbon one resulted in enhanced d33 values from 94 to 166 pm V−1, providing a new strategy for adjustment of molecular alignment of nonlinear optical polymers under electric field.

Efficient four-wave mixing wavelength conversion in a hybrid silicon slot and polymer microring resonator.

We present a silicon slot microring resonator for efficient frequency conversion via four-wave mixing (FWM). The slot consists of a narrow silicon waveguide pair with a gap of 80 nm, which is filled with a nonlinear optical polymer. The group velocity dispersion for the microring is controlled by engineering the geometry of the slot structure. Because of the large buildup factor of the slot microring, an FWM conversion efficiency of -27.4 dB is achieved with an optical pump power of less than 1.0 mW. From the measured power dependence of FWM generation, a nonlinear refractive index coefficient of 1.31 × 10-17 m2 W-1 is obtained at a wavelength of 1562 nm. This work presents a hybrid silicon slot and polymer microring as a potential nonlinear device for applications in integrated photonic devices.

Thermally crosslinkable second-order nonlinear optical polymer networks: high stability, good transparency, and large second-order nonlinear optical effects

A new in situ thermal crosslinking approach was proposed to design second-order nonlinear optical polymer networks through a simple synthetic route, with the combination of the “isolate chromophore” concept.

Synthesis and copolymerization of new methacrylic monomers for the creation of nonlinear optical polymer materials

Synthesis and copolymerization of new methacrylic monomers for the creation of nonlinear optical polymer materials

Polarization Dependences in Terahertz Wave Detection by Stark Effect of Nonlinear Optical Polymers

Polarization Dependences in Terahertz Wave Detection by Stark Effect of Nonlinear Optical Polymers

A nitrophenyl-carbazole based push-pull linker as a building block for non-linear optical active coordination polymers: A structural and photophysical study

Non-linear optical effects (NLO) such as multi-photon absorption, second harmonic generation (SHG) etc. have a wide range of applications. Nevertheless, the performance of many NLO-active organic dyes is limited by their thermal stability and photobleaching. These problems can be overcome by integrating the dyes into coordination polymers or metal-organic frameworks. Here, we present a structural and photophysical study of dipropyl-9-(4-nitrophenyl)-carbazole-3,6-dicarboxylate, a new “push-pull” organic dye molecule designed as a chromophore linker for NLO-active coordination polymers. Structure determination of a single-crystal showed that it crystallizes in a monoclinic crystal system P 21/c. The solvated chromophore exhibits two aromatic absorption bands at 250 nm and 275 nm as well as broad long wavelength band at 350 nm, which we assign to an intramolecular charge transfer state. Photoluminescence measurements in solvents of different polarities revealed two main effects: In nonpolar solvents, the spectrum shows an emission band at 360 nm, whereas in solvents with a higher polarity, the emission maximum broadens and redshifts. Solid-state emission measurement of sample powder exhibits an emission band at 520 nm which is redshifted compared to the measurements in solution, due to excimer formation in the solid-state. The optical as well as solvation-related properties of the investigated pigment render it to be a versatile ligand in coordination polymers.

The effect of cyano-containing acceptor moieties on the photoisomerisation mechanisms and UV/vis spectra of azochromophores with switchable nonlinear optical activity

The photoisomerisation pathways of substituted aminoazobenzenes with cyano-containing acceptor moieties, AAB-DCV and AAB-TCV, are revealed by TD-DFT at B3LYP/6-31G** level. Stationary and transition points on ground and excited state potential energy surfaces are localised; both inversion and rotation trans- and cis-isomerisation mechanisms are considered and the former is shown to be the preferable for both chromophores in the ground state. UV/vis spectra of isomeric forms of AAB-DCV and AAB-TCV are calculated by TD-DFT in chloroform at CAM-B3LYP/PCM//def2-TZVP level, the effect of acceptors on the spectrum shape and absorption maximum is revealed. It is found that S0→S2 excitation determines the most intensive π-π* band in the case of AAB-DCV trans-isomer, while in the case of AAB-TCV this band is due to S0→S1 excitation. λmax is bathochromically shifted when passing from AAB-DCV to AAB-TCV for trans-isomers. As for cis-isomers, the spectrum shape is determined by several excitations up to S0→S4, corresponding transitions having close intensities. Switching ability of the composite nonlinear-optical polymer material is demonstrated at both molecular and macroscopic levels: first hyperpolarisability of trans- and cis-forms differs three times in favour of the former; estimations of macroscopic quadratic electric susceptibility, χ(2), performed for model PMMA-based doped materials reveal the corresponding almost twofold difference.

Electric Field-Induced Linear Electro-Optic Effect Observed in Silicon-Organic Hybrid Ring Resonator

In this work, we report on the observation of the electric field-induced linear electro-optical effect in a silicon-based slot waveguide ring resonator covered by the nonlinear optical polymer Poly[(methyl methacrylate)-co-(Disperse Red 1 methacrylate)]. The device is fabricated in a photonic integrated circuit technology and intensity modulation is demonstrated to work in a direct-detection setup. As unique feature, the electric field-induced linear electro-optical effect allows to modulate the optical carrier wave with a time-varying electric field, while a static electric field can control its amplitude with no need for additional photonic components. Here, a linear tuning of the modulation-amplitude as function of the applied static electric field is demonstrated. This work paves a way toward novel integrated photonic device concepts.

The influence of different factors on exploitation properties of nonlinear optical polymeric materials based on an epoxy matrix doped with flavonoids

The paper is devoted to investigations of exploitation properties of nonlinear-optical (NLO) polymer film materials based on an epoxy matrix doped with flavonoids. Adhesion of the polymer films to a glass substrate is investigated. Also, the influence of photoinduced destruction on functional properties of these polymer composites by UV–Vis spectroscopy method is studied. Effect of various microorganisms such as mold fungi of Aspergillus niger (A. niger) and Pinicillum chrysogenum (P. chrysogenum) species on the polymer NLO materials are analyzed by evaluation of the fungistatic effect and fungicidal resistance and using the FTIR spectroscopy. As a result it is established that the NLO polymer film materials based an epoxy matrix doped with flavonoids have a very good adhesion to the glass substrate, and they are stable to the photoinduced destruction. These materials do not have the fungistatic effect but they demonstrate some fungicidal resistance. This phenomenon is explained by the presence of flavonoids, which are natural antiseptics.

A TCBD-based AB2-type second-order nonlinear optical hyperbranched polymer prepared by a facile click-type postfunctionalization

A double click-type postfunctionalization strategy was successfully designed to prepare an AB2-type hyperbranched polymer containing highly polarizable tetracyanobutadienyl (TCBD)-based nonlinear optical chromophores.

Double-click synthesis of polysiloxane third-order nonlinear optical polymers with donor–acceptor chromophores

A series of third-order nonlinear polysiloxane polymer materials were prepared by thiol–ene click polymerization and [2 + 2] click chemistry. All the polymers exhibit good electron transfer capabilities and nonlinear optical properties.

Orientation Order of Nonelectrically Poled FTC-Type Chromophores in PMMA on SiO2 Surfaces

Abstract We present the orientation order of push-pull chromophores consisting of phenyl vinylene thiophene vinylene (FTC) bridges between the N,-N-bis-(2-hydroxyethyl)-amine electron donor and phenyl-trifluoromethyl-tricyanofuran (TCF-Ph-CF3) acceptor in poly (methyl methacrylate) (PMMA). The chromophores have attracted great attention as a guest material for nonlinear optical polymers for near-IR applications. Our experimental results demonstrated that the chromophores with relatively large molecular weights were oriented in a polar order with the aid of adsorption onto the surfaces of the SiO2 substrates, even without the conventional electrical poling procedure. The polar order of the chromophores extended approximately 50 nm vertically from the substrate surfaces. Polarized linear absorption and second harmonic generation spectroscopies were performed to determine the orientation distribution function of the chromophores in the PMMA. The average molecular tilt angle Θ, indicating the degree of the orientation order, was wider than the magic angle, and the chromophores were preferably oriented horizontally to the substrate surfaces. A relatively low orientation order was explained in terms of the strong dipole-dipole repulsions among the neighboring guest chromophores.

Dendronized Polymers with High FTC-chromophore Loading Density: Large Second-order Nonlinear Optical Effects, Good Temporal and Thermal Stability

In this study, two new dendronized nonlinear optical (NLO) polymers were synthesized with high FTC chromophore loading density by introduction of high generation chromophore dendrons on the side chains. Due to their suitable molecular weights, both of them possessed good solubility in common solvents. They also inherited the advantages of dendrimers (large NLO coefficient), especially for PG2 whose NLO coefficient d33 value was as high as 282 pm·V-1. Also, PG2 had a good temporal stability with 80% of its maximum value being retained at the temperature as high as 129 °C.

Poly(difluorophosphazene) as the First Deep‐Ultraviolet Nonlinear Optical Polymer: A First‐Principles Prediction

AbstractA novel concept to obtain the deep‐ultraviolet (DUV) nonlinear optical (NLO) materials is proposed based on the assembling of one‐dimensional (1D) polar motifs into quasi‐1D polymer patterns. Based on the first‐principles calculations, we have successfully discovered an excellent DUV NLO polymer, i.e., poly(difluorophosphazene), with the chemical formula of (PNF2)n. Calculations reveal that PNF2 has a larger band gap, a stronger second harmonic generation effect, a larger birefringence, and a shorter phase‐matching cutoff than KBe2BO3F2. These findings not only demonstrate that the PNF2 is the first reported DUV NLO polymer, but also could open a new direction to discover novel DUV NLO materials in polymer systems.