Maker Fringe Research Articles

Synthesis, nanocrystalline morphology, lattice dynamics and nonlinear optics of mesoporous SiO2&LiNbO3 nanocomposite

We demonstrate a hybrid nanocomposite combining mesoporous silica, pSiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document}, as a host medium and guest lithium niobate LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} nanocrystals embedded into tubular silica nanochannels by calcination of the precursor mixed solution of lithium and niobium salts. High-resolution transmission electron microscopy, X-ray diffraction and Raman scattering techniques reveal trigonal LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} nanocrystals within the pSiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document} nanochannels, indicating their random texture morphology. Annealing at high temperatures ( 950∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{\\circ }$$\\end{document}C) during calcination also leads to partial crystallization of the pSiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document} matrix with the formation of trigonal α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document}-SiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document} nanocrystals. The Raman microscopy analysis of the pSiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document}:LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} nanocomposite reveals three structural crystalline phases, α-SiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha -\\hbox {SiO}_2$$\\end{document}, LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} and a mixed phase which involves the α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document}-SiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document} phase of host membrane and LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} nanocrystals embedded into the membrane. The finite size of the LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} nanocrystals results in specific features of the LO-TO phonon frequency splitting, which are investigated by Raman microscopy. In the transmission geometry, the second harmonic generation emission exhibits no Maker fringes and is characterized by a broad angular diagram of diffusely scattered light. The second harmonic generation response is independent of the polarization direction of the incident pump light, thus indicating a spatial isotropy of the nonlinear optical conversion in the pSiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document}:LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} composite, consistent with the randomly oriented textural morphology of the deposited LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} nanocrystals. The contribution of the guest LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} nanocrystals to the second harmonic generation effect was found to be strongly dominant compared to the partially crystallized host pSiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document} matrix. The nanocomposite pSiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document}:LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} membrane, set in the 90∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document} nonlinear optical geometry, shows unusually high diffusely transmitted second harmonic generation light (back-reflected emission), apparently supported by internal light reflection from the tubular nanochannel network. Despite the fundamental interest, the revealed anomalous back-reflected second harmonic generation emission from pSiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {SiO}_2$$\\end{document}:LiNbO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {LiNbO}_3$$\\end{document} nanocomposite membranes expands the prospects for their photonic and nonlinear optical applications.

Second-harmonic generation effect enhanced by Li substitution for Na in Li1(LiXNa5−X)Mo9O30

Large single crystals of the solid-solution series ▪ were grown by the Czochralski method by varying the Li substitution for Na. Structure analyses with X-ray single-crystal diffraction data elucidated statistic disorder of Li with Na at three independent Na sites. The resulting Li substitution X = 0, 1.2, and 2.8 could be confirmed by neutron activation analysis. Second-harmonic generation (SHG) light intensities and non-linear optical (NLO) coefficients were determined in three crystallographic main directions by Maker fringe measurements. DFT calculations delivered absolute NLO magnitudes. UV/Vis optical spectra revealed that the transmission rises from X = 0 to X = 2.8. However, the SHG effect is at largest in ▪ (X = 1.2), so far investigated in this study.

Electric field induced second harmonic generation in arsenic sulfide deposited by thermal evaporation.

Electric field induced second harmonic (EFISH) measurements are performed on thin films of arsenic sulfide deposited on chromium coated fused silica substrates by thermal evaporation of amorphous As2S3 bulk material. EFISH allows to widely tune the second-order optical susceptibility (χ(2)). An observed shift of the minimum of the second harmonic generation (SHG) intensity away from 0 V reveals a non-EFISH bulk χ(2), which is unexpected for amorphous materials. Additional SHG measurements on as-deposited films for investigation of the non-EFISH bulk χ(2) show Maker fringe patterns. Analyzing them and calibrating the SHG response against beta barium borate (BBO) crystal allows us to extract the components of the χ(2) tensor. The main component of this non-EFISH bulk χ(2) has a value of ∼0.22 pm/V. By increasing the χ(2) by applying the dc electric field a maximum value of 3.8 pm/V was achieved in EFISH measurements. This value is comparable to the χ(2) of traditional nonlinear crystals, e.g., BBO, which makes arsenic sulfide an interesting candidate for nonlinear hybrid structures.

Optical second harmonic generation in anisotropic multilayers with complete multireflection of linear and nonlinear waves using ♯SHAARP.ml package

Optical second harmonic generation (SHG) is a nonlinear optical effect widely used for nonlinear optical microscopy and laser frequency conversion. Closed-form analytical solution of the nonlinear optical responses is essential for evaluating materials whose optical properties are unknown a priori. A recent open-source code, ♯SHAARP.si, can provide such closed form solutions for crystals with arbitrary symmetries, orientations, and anisotropic properties at a single interface. However, optical components are often in the form of slabs, thin films on substrates, and multilayer heterostructures with multiple reflections of both the fundamental and up to ten different SHG waves at each interface, adding significant complexity. Many approximations have therefore been employed in the existing analytical approaches, such as slowly varying approximation, weak reflection of the nonlinear polarization, transparent medium, high crystallographic symmetry, Kleinman symmetry, easy crystal orientation along a high-symmetry direction, phase matching conditions and negligible interference among nonlinear waves, which may lead to large errors in the reported material properties. To avoid these approximations, we have developed an open-source package named Second Harmonic Analysis of Anisotropic Rotational Polarimetry in Multilayers (♯SHAARP.ml). The reliability and accuracy are established by experimentally benchmarking with both the SHG polarimetry and Maker fringes using standard and commonly used nonlinear optical materials as well as twisted 2-dimensional heterostructures.

High nonlinear optical efficiency in zinc(II) and copper(I) stilbene based iminopyridine complexes: Absorption, emission analysis and advanced characterization

The novelty of this work lies in the comprehensive studies of the spectroscopic and third-order nonlinear optical properties of zinc(II) and copper(I) stilbene based iminopyridine complexes. Our previous work involved the synthesis as well as the characterization of both the free ligand and these its corresponding metal complexes and conducting quantum chemical calculations on their molecular orbitals, shedding light on their charge transfer and π-π* interactions. This makes these materials promising models for supramolecular assemblies. Thin films, obtained using the spin coating method, are characterized using Atomic Force Microscopy and Ellipsometry methods. These techniques provide valuable information about the physical properties of the layers, such as homogeneity, roughness and linear refractive index. Moreover, we present spectroscopic analysis that involve the absorption and emission of light, along with the decay time of photoluminescence in the thin films. Through advanced techniques like the Maker fringe method for third harmonic generation and the Z-scan method for recording nonlinear absorption and refraction, we demonstrate the high nonlinear optical efficiency of these complexes. This study presents how specific structural elements impacts tailoring in the enhancement of the NLO properties of these complexes. These findings underscore the potential of zinc(II) and copper(I) stilbene based iminopyridine complexes in nonlinear optics and photonics applications.

Optical Setup for Investigating the Hyperpolarizability of Organic Nanostructure Materials in Solutions Using Electric Field Induced Second Harmonic Generation

Abstract: In this paper, an optical setup for electric field-induced second-harmonic generation (EFISH) at 1.9 μm experiment was arranged and used to investigate and determine the hyperpolarizability of some nanostructure organic components in two different solutions. First, a laser beam at 1.9 μm was generated by pumping a hydrogen Raman cell pressurized to 55 bar with 10 Hz Q-switched Nd: YAG nanosecond laser operating at λ = 1.064 μm. Next, the generated laser beam was aligned with all optical components within the assembly. The final step was to optimize the beam’s power and polarization at the center of the EFSH cell. Different nanostructure organic samples in solutions were prepared with nearly the same standard concentration of about 5 mmol/L to be investigated under the optimized system. Two solvents were used in this work, dichloromethane, or DCM (CH2Cl2), and chloroform, or trichloromethane (CHCl3). First, the harmonic order hyperpolarizability of five organic molecules in solutions with different chemical components such as quinolinium groups and organic boron complexes (supplied by the Chemistry Department at Catania University, Italy) were experimentally investigated experimentally. Only component (2-(2-[5′-(N,N-dimethylamino)-(2,2′-bithiophen)-5-yl]vinyl)-1-methyquinolin-1-ium iodide) in chloroform showed a significant difference in Maker fringes amplitude of the applied electrical field in comparison with fringes of its pure solvent. The value ofμfor this component has been calculated as 1320 x 10-48 esu. This value indicates that the component is a suitable candidate for use in second-harmonic generation imaging for biological applications. Keywords: Electric field-induced second-harmonic generation (EFISH), Harmonic light, Organic materials, hyperpolarizability. PACS: Nonlinear optics, 42.65.-k, Electric fields, instrumentation for measurement, 07.50.-e, Organic-inorganic hybrid nanostructures, 81.07.Pr, Organic materials optical materials, 42.70.Jk

Angle Measurement Based on Second Harmonic Generation Using Artificial Neural Network

This article proposed an angle measurement method based on second harmonic generation (SHG) using an artificial neural network (ANN). The method comprises three sequential parts: SHG spectrum collection, data preprocessing, and neural network training. First, the referenced angles and SHG spectrums are collected by the autocollimator and SHG-based angle sensor, respectively, for training. The mapping is learned by the trained ANN after completing the training process, which solves the inverse problem of obtaining the angle from the SHG spectrum. Then, the feasibility of the proposed method is verified in multiple-peak Maker fringe and single-peak phase-matching areas, with an overall angle measurement range exceeding 20,000 arcseconds. The predicted angles by ANN are compared with the autocollimator to evaluate the measurement performance in all the angular ranges. Particularly, a sub-arcsecond level of accuracy and resolution is achieved in the phase-matching area.

Enhanced nonlinearities in hybrid structure based on nanoporous membrane and a metallohelicate with promising application in nanophotonics and NLO.

The main purposes of this work are designing new hybrid structures based on alumina nanoporous membranes with specific metallosupramolecular structure as well as studies of their usefulness in nonlinear optics (NLO). The NLO studies of the hybrid material is performed on the basis of two methods: the first by the Maker fringe technique, where the second harmonic generation (SHG) signal is recorded by rotating the sample; and the second by SHG imaging microscopy, where the SHG signal is collected point by point on the sample surface. The enhanced SHG signals were obtained without the use of the corona poling method needed during the experiment on thin films in our previous works and clearly shows the efficiency of hybrid materials based on nanoporous membranes as promising materials in devices developed based on NLO.

Correlation between Nonlinear Optical Effects and Structural Features of Aurone-Based Methacrylic Polymeric Thin Films.

In this study, new photonics architectures and aurone-based methacrylic polymers were designed and synthesized for their optical and nonlinear optical properties. The studied polymeric thin films were deposited by spin coating method. SHG and THG effects were measured via Maker fringe technique in transmission mode and determined using theoretical models. Investigations involved the theoretical quantum chemical calculation of dipole moments, frontier molecular orbital HOMO and LUMO energies, and first (β) and second (γ) hyperpolarizabilities. We determined the impact of the substitution in the para position of the phenyl ring and at the dipole moment of the chromophore on the nonlinear optical properties of the investigated polymers. The presented theoretical and experimental studies provide important information with respect to the design of methacrylic-based polymeric thin film devices and supplement existing knowledge with respect to their nonlinear behaviour.

Theoretical Investigation for Angle Measurement Based on Femtosecond Maker Fringe

This paper proposes to utilize a femtosecond Maker fringe for angular measurement to expand the measurement range by using the characteristic of the multiple visible peaks in the Maker fringe. Four different z-cut nonlinear materials and three different polarization combinations of SHG were considered in the study, and various theoretical results are calculated for both the intensity-based angle measurement and the frequency-domain angle measurement. As a result, the p-s polarization shows a significant angle dependence in the range of ±20° compared with the other polarization. In addition, the BBO and KDP are superior to the other investigated materials because of the relatively higher sensitivity and visibility. The refractive index difference was introduced in this paper, and it was applied to explain the angle measurement performance of the Maker fringe successfully.

Detailed study of quantum path interferences in high harmonic generation driven by chirped laser pulses

We investigate the electron quantum path interference (QPI) effects during high harmonic generation in atomic gas medium driven by ultrashort chirped laser pulses. To achieve that, we identify and vary the different experimentally relevant control parameters of such a driving laser pulse influencing the high harmonic spectra. Specifically, the impact of the pulse duration (from the few-cycle to the multi-cycle domain), peak intensity and instantaneous frequency is studied in a self-consistent manner. Simulations involving macroscopic propagation effects are also considered. The study aims to reveal the microscopic background behind a variety of interference patterns capturing important information both about the fundamental laser field and the generation process itself. The results provide guidance towards experiments with chirp control as a tool to unravel, explain and utilize the rich and complex interplay between QPIs including the tuning of the periodicity of the intensity dependent oscillation of the harmonic signal, and the curvature of spectrally resolved Maker fringes.

Second harmonic generation by surface of poled glasses: modeling and measurement of Maker fringes

Second harmonic generation by surface of poled glasses: modeling and measurement of Maker fringes

Optical nonlinear, EPR, second harmonic generation and Faraday rotation studies on diamagnetic solid: Influence of thermal poling

The electric field manipulation of magnetic and magneto optical properties is currently of great interest for photonics and spintronics devices. In this study, for the first time, we utilized the thermal poling electric field induced polarization and magnetization to manipulate the magnetic and Faraday rotation performance of heavy metal oxide diamagnetic glass. The influence of poling conditions on second & third nonlinearity, structure and defects, thermal, magnetic and magneto optical properties were studied through varies characterization techniques such as scanning electron microscope, X-ray powder diffraction, Raman, maker fringe, electron paramagnetic resonance, X-ray photoelectron spectroscopy, Z-scan, vibration sample magnetometer and Faraday rotation measurements. 5 µm-thickness layer second harmonic generation intensity increased with the voltages from 1 kV to 3 kV, while at 300°C second harmonic generation the intensity decreased. Third nonlinearity coefficient and nonlinear refractive index were calculated to be much higher than that of un-poled glass through the Z-scan method. X-ray photoelectron spectroscopy, Raman and electron paramagnetic resonance analysis revealed the center-asymmetric network of glass, non-bridging oxygen and defect centers after thermal poling. The modification on glass structure resulted in the enhancement of magnetic moment of glass with electric induced magnetic field changes electric coupling effect as high as 15%. Faraday rotation measurement indicated that polarization dominantly contributed to the enhancement of V, at the same time, the V also was impacted by glass transmittance and crystal scattering. The optimized thermal poling condition was determined to be 3 kVand 260°C for 4 hours, under which thermally poled glass presented the strong second harmonic generation intensity (2.3 pm/V), highest Verdet constant (0.2382 min/G.cm) and improved diamagnetic susceptibility (0.424×10−5 emu/mol). Diamagnetic glass with these properties is attractive for magneto optical sensing and nonlinear applications.

Effect of UV-Irradiation and ZnO Nanoparticles on Nonlinear Optical Response of Specific Photochromic Polymers.

A series of methacrylic styrylquinoline polymers have been synthesized and characterized by spectroscopic and nonlinear optical (NLO) investigations. The NLO properties of studied polymer compounds in the form of thin films prepared by a spin coating method have been investigated by means of second and third harmonic generation via Maker fringe setup with a laser source at 1064 nm and a pulse duration of 30 ps. The results show strong second harmonic signal dependence on polarization configurations. This second harmonic generation (SHG) response was enhanced by UV-irradiation at 366 nm and doping by ZnO nanoparticles (NPs) (100 nm), while the opposite effect was achieved for a third harmonic generation experiment. Thus, values of second and third order nonlinear susceptibilities were determined by theoretical calculations based on comparative models. The remarkable NLO results presented in this paper expose potential optoelectronic and photonic applications.

Determination of nonlinear optical coefficients and efficient type-II second-harmonic-generation for TmCOB crystals

By Maker Fringe (MF) method, all of the nonlinear optical (NLO) coefficients including d11, d12, d13, d31, d32 and d33 of TmCa4O(BO3)3 (TmCOB) crystals were measured to be 0.19, 0.26, −0.61, −0.30, 1.66 and −1.25 pm/V, respectively. Based on which, the second-harmonic-generation (SHG) phase-matching (PM) characteristics of TmCOB crystals in two-dimensional principal planes and three-dimensional non-principal planes (space) were theoretically calculated, such as PM tuning curves, distribution of effective NLO coefficient (deff), beam walk-off angle, and angular acceptance bandwidth. At the fundamental waves of 1064 nm, the type-II optimal PM angles with largest deff for principal planes and space were decided to be (52.8°, 90.0°) (deff = 0.24 pm/V) and (118.0°, 77.2°) (deff = 0.35 pm/V), respectively. The type-II SHG of TmCOB crystals was found to present large acceptance angle bandwidth (~2–12 times of type-I values) and small beam walk-off angle (~0.2–0.4 times of type-I values). At a high input energy of 6.89 mJ (35 ps, 10 Hz, 1064 nm), the SHG transformation efficiency for an uncoated TmCOB crystal sample cut along type-II optimal angle (118.0°, 77.2°) with 12 mm in length was measured to be 55.9%, which achieved the same conversion efficiency grade as type-I optimal PM.

Influence of multi-energy boron difluoride implantation on the second-harmonic generation of thermally poled fused silica

Abstract Multi-energy (10–50 keV) boron difluoride (49BF2+) ions are implanted at a dose of 1015 cm−2 in the fused silica substrate to form a thin layer structure with a thickness of about 120 nm. The refractive index of fused silica substrate increases as a result of BF2 implantation, which applies to optical waveguide fabrication. Moreover, the absorption spectrum of the implanted sample shows two absorption peaks in the photon energy range from 4.0 eV to 6.52 eV, which are likely resulted from the B2β, oxygen divacancy and surface E′ center defects. The sample is thermally poled at the conditions of 5 kV, 60 min, and different temperatures, and the second-harmonic (SH) signal is measured using the Maker fringe technique. At low and moderate poling temperatures, the implanted and non-implanted samples have the same trend of SH signal variation with poling temperature (both increases first, and then reaches a maximum saturation value), and these signals have equivalent strength. At high poling temperature, the SH signal of the implanted sample is enhanced continuously, but the SH signal of the non-implanted sample is attenuated. The charge migration model of mobile ions can qualitatively explain the generation mechanism for second-order optical nonlinearity (SON) of the poled sample. The multi-energy BF2 ion implantation is found, for the first time, that it can enhance about 1.7 times of the SH signal of thermally poled fused silica glass at a high poling temperature.

Transition metals induce control of enhanced NLO properties of functionalized organometallic complexes under laser modulations

The molecular engineering of organometallic complexes has recently attracted renewed interest on account of their potential technological applications for optoelectronics in general and optical data storage. The transition metal which induces control of enhanced nonlinear optical properties of functionalized organometallic complexes versus not only the intensity but also the polarization of the incident laser beam is original and important for all optical switching. This makes organometallic complexes valuable and suitable candidates for nonlinear optical applications. In the present work, we report the synthesis and full characterization of four organometallic complexes consisting of N, N-dibutylamine and azobenzene fragments but differ by auxiliary alkynyl ligands or metal cations. Thus, a ferrocenyl derivative 1 and three ruthenium complexes 2–4 have been prepared. The nonlinear optical properties of the four new azo-based ruthenium and iron organometallic complexes in the solid state, using polymethylmethacrylate as matrix, have been thoroughly studied. This concept is extended to computing the HOMO and LUMO energy levels of the considered complexes, dipole moment, first and second order hyperpolarizabilities using the 6–31 + G(d,p) + LANL2DZ mixed basis set. The second and third nonlinear optical properties of the resulting polymer composites were obtained by measuring SHG and THG response by means of the Maker fringe technique using a laser generating at 1,064 nm with a 30 ps pulse duration. The values of the second and third order NLO susceptibilities of the four organometallic complexes were found to be higher than the common references used. Theoretical calculation shows that the large first and second order hyperpolarizablities are caused by strong intramolecular charge transfer between the transition metal parts and the ligands though a conjugated transmitter. These results indicate that the present organometallic complexes are valuable candidates for optoelectronic and photonic applications.

Penta(zinc porphyrin)[60]fullerenes: Strong reverse saturable absorption for optical limiting applications

Penta(zinc porphyrin)[60]fullerene, in which a fullerene (C60) with attached five electron donating zinc porphyrin moieties was synthesized. The nonlinear optical response was studied together with reference penta(trimethylsilyl)C60 and triazole-zinc porphyrin compounds. The second and third harmonic generation in both guest-host polymeric films deposited by means of spin coating technique and films obtained by physical vapor deposition technique was investigated via Maker fringe technique employing 30 ps laser pulses at 1064 nm. The second and third order susceptibilities as well as second hyperpolarizabilities were determined. Penta(zinc porphyrin)[60]fullerene in solutions and PMMA films demonstrated strong reverse saturable absorption in Z-scan measurements employing the laser double frequency. The nonlinear absorption coefficient and imaginary part of cubic susceptibility were obtained for solutions and films. The second hyperpolarizability and nonlinear absorption cross section were extracted as well. Penta(zinc porphyrin)[60]fullerene shows attractive optical limiting response property suitable for photonic applications.

The effect of the sodium content on the structure and the optical properties of thermally poled sodium and niobium borophosphate glasses

Six niobium rich glasses presenting different sodium contents were synthetized. On the basis of complementary infrared and Raman analysis, the influence of the sodium content and its role on the structure of the glasses prior to and following poling was examined. Correlative second harmonic generation (SHG)/Raman microscopy on the poled glasses cross section has shown a co-localization of the SHG signal and the structural variations. It also evidenced similar structural rearrangements whether sodium is removed through poling (230–300 °C) or through the alkali content defined by the starting glass compositions (melted at 1300–1500 °C). The effect of the sodium content on the optical properties, prior to and after thermal poling, is also discussed. It was found that refractive index variations induced by poling (ranging between 10−3 and 3 × 10−2) are mainly the result of a density decrease in the poled region rather than compositional and structural changes. The electro-optic origin of the poling-induced second order nonlinear response is confirmed by the Maker Fringe SHG analysis, and the evolution of χ(2) (2–2.5 pm/V) with the sodium content is discussed based on a selection of parameters influencing either the third order susceptibility [χ(3)] or the internal electric field strength of the poled layer.

Characterization of all second-order nonlinear-optical coefficients of organic N-benzyl-2-methyl-4-nitroaniline crystal

Full elements of second-order nonlinear optical (NLO) tensor can be completely characterized for an organic NLO crystal for the first time. As-grown bulk N-benzyl-2-methyl-4-nitroaniline (BNA) crystal was processed to expose (100) and (010) crystal orientations with fine optical surfaces by using precision lathe and diamond blade. Then, every five nonvanishing second-order NLO coefficient of BNA can be determined quantitatively using the precisely processed crystals based on 1st-kind Maker fringe measurements. Our method makes it possible to clarify uncertain NLO property of any organic materials and to accelerate application study via precise device fabrications even for fragile organic materials.