Nonlinear optical properties of Ag nanocluster composite fabricated by 200 keV negative ion implantation

Metal nanocluster composite glass prepared by 200 keV Ag ions' implantation into silica with dose of 2 × 10¹⁷ ions/cm² has been studied. The formation of sandwiched nanocluster-nanovoid-nanocluster structures has been evidenced by in situ transmission electron microscopy experiment (TEM). Fast nonlinear optical refraction and nonlinear optical absorption coefficients were measured at 532 nm and 1064 nm of wavelength by the Z-scan technique. The third-order nonlinear susceptibility χ⁽³⁾ of this kind of sample was determined to be 4.0 × 10⁻⁸ esu at 532 nm and 9.0 × 10⁻⁸ esu at 1064 nm, respectively.     

Optical nonlinearities of Au nanocluster composite fabricated by 250 keV ion implantation

Metal nanocluster composite glass prepared by 250 keV Au ions into silica with dose of 1 × 10¹⁷ ions/cm² has been studied. The microstructural properties of the nanoclusters are characterized by optical absorption spectra and transmission electron microscopy (TEM). Third-order optical properties of the nanoclusters are studied by the Z-scan technique under 1064 nm and 532 nm excitations. The nonlinear refraction index, nonlinear absorption coefficient, and the real and imaginary parts of the third-order nonlinear susceptibility are deduced. The results of the investigation of nonlinear refraction using the off-axis Z-scan configuration are presented and the mechanisms responsible for the nonlinear response are discussed. The third-order nonlinear susceptibility χ⁽³⁾ of this kind of sample was determined to be 1.6 × 10⁻⁷ esu at 532 nm and 1.3 × 10⁻⁷ esu at 1064 nm.     

Nonlinear optical properties of laser deposited CuO thin films

In this work we investigate the third-order optical nonlinearities in CuO films by Z-scan method using a femtosecond laser (800 nm, 50 fs, 200 Hz). Single-phase CuO thin films have been obtained using pulsed laser deposition technique. The structure properties, surface image, optical transmittance and reflectance of the films were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and UV-vis spectroscopy. The Z-scan results show that laser-deposited CuO films exhibit large nonlinear refractive coefficient, n₂ = − 3.96 × 10^− 17 m²/W, and nonlinear absorption coefficient, β = − 1.69 × 10^− 10 m/W, respectively.     

Gold nanoparticles incorporated mesoporous silica thin films of varied gold contents and their well-tuned third-order optical nonlinearities

Gold nanoparticles (NPs) incorporated mesoporous silica thin films (MSTFs) of varied gold contents from 4.64 to 29.15 wt.% were synthesized through a refined chemical modification to the mesopore surface using different amounts of silane with amino end group. The microstructures of the composite thin films were characterized and the off-resonant third-order optical nonlinearities of the composite thin films were investigated by Z-scan technique at 1064 nm. The resultant composite thin films showed increased third-order optical nonlinear susceptibility (χ⁽³⁾) from 4.26 × 10⁻¹¹ to 9.24 × 10⁻¹⁰ esu at increased gold contents. The dependence of χ⁽³⁾ on gold content have been discussed, which can be described by an exponent function y = y₀ + Ae^−x/t when the gold contents of the composite thin films were below 30 wt.%.     

Third order optical susceptibilities of the Cu2O thin film

By performing Z-scan method with a femtosecond laser (800 nm, 50 fs, 1 kHz), we investigated the third-order optical nonlinearities of a cuprous oxide (Cu₂O) film. Single-phase Cu₂O film deposited on a quartz substrate was obtained using the pulsed laser deposition technique. The structure properties, surface morphology and optical transmission spectrum were characterized by X-ray diffraction, scanning electron microscopy and double beam spectrophotometer, respectively. The Z-scan results show that the Cu₂O film exhibits large nonlinear refractive index, n₂ = 3 × 10^− 3 cm²/GW, while the two-photon absorption coefficient, α₂ = 40 cm/GW, is relatively small. It implies that the Cu₂O film is a promising candidate for nonlinear photonic devices.     

Large third-order optical nonlinearity of SrBi2Nb2O9 thin films fabricated by pulsed laser deposition

SrBi₂Nb₂O₉ (SBN) thin films with a single phase of layered perovskite structure have been fabricated on fused quartz substrates at room temperature by pulsed laser deposition. The XRD and AFM analysis indicated that the films had better crystallinity, less rough surface morphology, and larger grain size with increasing oxygen pressure. The nonlinear optical properties of the samples were determined using a single beam Z-scan technique at a laser wavelength of 532 nm with laser duration of 25 ps. The real and imaginary parts of the third-order nonlinear optical susceptibility χ⁽³⁾ of the films were measured to be 3.18 × 10^− 8 esu and 5.94 × 10^− 9 esu, respectively.     

Optical properties of Cu and Ag nanoparticles synthesized in glass by ion implantation

Metal nanoparticles synthesized by sequentially ion-implanted Ag and Cu into silica glasses have been studied. The implantation doses (×10¹⁶ ions/cm²) were 5Ag, 5Cu and 5Ag/5Cu, respectively. The optical and microstructural properties of the nanoparticles were characterized by optical absorption spectra and transmission electron microscopy (TEM), respectively. Fast nonlinear optical refraction and nonlinear optical absorption coefficients were measured at 1064 nm of wavelength using Z-scan technique. Results in this paper indicate that the nonlinear refractive index for the Ag/Cu implanted system has a higher value compared to single Ag or Cu implantation nanoparticles.     

Organic and inorganic hybrid film with second-order nonlinear optical and pyroelectric properties

An organic and inorganic hybrid material was prepared from a nonlinear optically active imidazole derivative 4-(nitrophenyl)-2,4-Bis-(4,4′-[N,N-bis-(2-hydroxyethyl)aminophenyl]) imidazole and metal alkoxide of Nb(V) via sol-gel process. The second-order nonlinear optical and pyroelectric properties of the hybrid film were investigated in terms of the second harmonic generation (SHG) and pyroelectric coefficient measurement. The SHG coefficient d₃₃ was found to be 29.3 pm/V at the fundamental wavelength of 1064 nm and the pyroelectric coefficient P was found to be 1.47 × 10^− 6 C/cm² K.     

Synthesis and nonlinear optical properties of Lead Telluride nanorods

Lead Telluride (PbTe) nanorods have been uniformly grown on silicon substrates, using the thermal evaporation technique under high vacuum conditions. The structural and morphological studies are done using X-ray diffraction and scanning electron microscopy. Optical nonlinearity studies using the open aperture z-scan employing 5 ns and 100 fs laser pulses reveal a three-photon type absorption. For nanosecond excitation the nonlinear absorption coefficients (γ) are in the order of 10⁻²² m³ W⁻² and for femtosecond excitation it is in the order of 10⁻²⁹ m³ W⁻². The role of free carriers and excitons in causing the nonlinearity in both excitation time domains is discussed. Results indicate that PbTe nanorods are good optical limiters with potential device applications.     

Enhancement of optical nonlinearity in binary metal-nanoparticle arrays

Periodic binary metal-nanoparticle arrays, comprising of Au and Fe, were fabricated on quartz substrates using nanosphere lithography and pulsed laser deposition technique. The dimension of the obtained triangular Au(Fe) particles was about 80 nm which was defined by the single-layer masks prepared by self-assembly of polystyrene nanospheres with radius R = 100 nm. The structural characterization of the particle arrays was investigated by atomic force microscopy. In the optical absorption spectra, the metal-nanoparticle arrays show a strong absorption peak of ~ 550 nm due to the surface plasmon resonance of metal particles. The nonlinear optical properties of the nanoparticle arrays were determined using a single beam z-scan method at a wavelength of 532 nm with laser duration of 55 ps. By adding Fe, the resonant absorption of Au particles was quenched, and the figure of merit χ⁽³⁾/α (with χ⁽³⁾ being the third-order nonlinear susceptibility, α being the absorption coefficient) was obviously increased. The obtained maximum χ⁽³⁾/α is about 6.15 × 10^− 12 esu cm. The results show that periodic Au + Fe nanoparticle arrays exhibit a large nonlinear optical property with fast response.     

Third harmonic generation in LiKB4O7 single crystal

The third order nonlinear optical properties of the lithium potassium borate (LiKB₄O₇) single crystal have been investigated by means of the rotational Maker fringe technique using Nd:YAG laser at 1064 nm working in picosecond regime. The value of the third order nonlinear optical susceptibility was calculated using the theoretical model of Kajzar et al. and was found to be about 1.4 × 10⁻²¹ m² V⁻² that is one order higher than that of fused silica.     

Crystal structure and third-order nonlinear optical property study of a copper complex constructed by DMIT ligand

A copper complex constructed by the ligand: 1,3-dithiole-2-thione-4,5-dithiolato (DMIT) has been synthesized and its crystal structure has been determined by means of X-ray single crystal diffraction. The central copper(II) ion coordinates with two DMIT which constructed a square environment. Intermolecular C–H?S hydrogen bonds between cation groups and ligands lead to the formation of a two-dimensional supramolecular network. Its third-order nonlinear optical property has been studied using Z-scan technique at different peak laser irradiance with 20 picosecond (ps) pulses at wavelength 1064 nm. Its molecular second hyperpolarizability γ was determined to be 4.03 × 10⁻⁵⁷ m⁴ C V⁻³.     

Fabrication and third-order nonlinearity of an ultrathin film containing perylene derivatives

An ultrathin composite film containing cationic tetra-pyridine perylene tetracarboxylic acid diimide (TPP-I) and an anionic tetra-sulfuric perylene tetracarboxylic acid diimide (TSP-Na) has been fabricated by the electrostatic layer-by-layer self-assembly technique. UV/Vis spectra showed a continuous and uniform deposition process of TPP-I/TSP-Na. The film structure was characterized by the small-angle X-ray diffraction measurement and atomic force microscopy image. We investigated the third-order nonlinearity of the ultrathin film sample at 532 nm. The film exhibited strong saturable nonlinear absorption. The nonlinear absorption coefficient and refractive index of the film sample are − 5.0 × 10^− 7 mW^− 1 and − 1.2 × 10^− 14 m²W^− 1, respectively.     

Intense low threshold nonlinear absorption and nonlinear refraction in a new organic–polymer nanocomposite

Intense reverse saturable absorption is reported for the first time in solid films of a new organic–polymer nanocomposite, cast by doping Biebrich Scarlet dye in a vinyl polymer host polyvinyl alcohol for various concentrations, as studied employing the Z-scan technique at 442 nm under different peak incident intensities ranging from 9.37 × 10² to 104.18 × 10² W cm⁻². The sample also exhibited nonlinear refraction under the experimental conditions. The estimated values of the effective coefficients of nonlinear absorption β_eff(0.27 × 10⁻² to 45.5 × 10⁻² cm W⁻¹) as well as nonlinear refraction n₂ (−1.5 × 10⁻⁷ to −2.75 × 10⁻⁷ cm² W⁻¹) measured up to the highest reported ones for low power continuous wave excitation. The composite films were characterized as nanoclusters consisting of dye molecules encapsulated between larger molecules of the amorphous polymer and having a low average roughness (≈1 nm) for the surface. These results, together with the simple and flexible processing method for the dye–polymer composite, imply that BS–PVA composite films have promising optical properties as an efficient low threshold nanocomposite material for potential applications in nonlinear optical devices.     

Third-order nonlinear optical properties of Bi2S3 nanocrystals doped in sodium borosilicate glass studied with Z-scan technique

The third-order nonlinear optical properties of Bi₂S₃ nanocrystals doped in sodium borosilicate glass are measured by Z-scan technique. The microstructures of the glass are characterized by means of X-ray diffraction, transmission electron microscopy, scanning transmission electron microscopy, energy dispersion X-ray spectra, and high-resolution transmission electron microscopy. The results show that the Bi₂S₃ nanocrystals ranging from 10 to 30 nm are determined to be of the orthorhombic crystalline phase, and the third-order optical nonlinear refractive index γ, absorption coefficient β, and susceptibility χ⁽³⁾ of the glass are determined to be 2.56 × 10⁻¹⁶ m² W⁻¹, 4.13 × 10⁻¹⁰ mW⁻¹, and 1.43 × 10⁻¹⁰ esu, respectively.     

Nonlinear optical properties of p-(N,N-dimethylamino)dibenzylideneacetone doped polymer

A bis-chalcone derivative, p-(N,N-dimethylamino) dibenzylideneacetone was synthesized. Its third-order nonlinear susceptibility was determined to be as high as 10⁻¹² esu by employing single beam Z-scan and degenerate four wave mixing techniques using Nd:YAG 7 ns laser pulses at 532 nm. The compound was doped in to poly(methylmethacrylate) matrix and the third-order nonlinearity was investigated by using Z-scan technique. The nonlinear refractive index of the doped polymer is found to be negative, and its magnitude is of the order of 10⁻¹⁰ esu. The results show that the compound exhibits strong reverse saturable absorption and a good optical limiting property and hence may be used as a promising dopant material. The study on concentration dependence of nonlinear optical parameters has been presented.     

Nonlinear optical properties of an ultrathin film containing porphyrin and poly (phenylenevinylene) units

An ultrathin nanoscopic multilayer film has been fabricated through the electrostatic layer-by-layer self-assembly of water-soluble porphyrin derivative 5,10,15,20-tetrakis-(3,4,5-trihydroxy-phenyl)-porphyrine (DHP) and oppositely charged poly{(2, 5-bis (3-bromotrimethylammoniopropoxy)-phenylene-1, 4-divinylene)-alt-1, 4-(2, 5-bis (2-(2-hydroxyethoxy) ethoxy))phenylenevinylene} (BH-PPV). UV-vis spectra showed a continuous and uniform deposition process of BH-PPV and DHP. The film structure was characterized by small-angle X-ray diffraction measurement. The nonlinear optical property of ultrathin film was characterized by Z-scan technique with laser duration of 8 ns at the wavelength of 532 nm. The BH-PPV/DHP film exhibited nonlinear saturated absorption and strong self-defocusing effect. The nonlinear absorption coefficient and refractive index of the film sample are − 1.9 × 10^− 5 m/W and − 5.57 × 10^− 12 m²/W, respectively.     

Exceptionally large third-order optical susceptibility in Ag:SrBi2Nb2O9 composite films

Thin films of SrBi₂Nb₂O₉ with and without the inclusion of Ag nanocrystals were prepared on MgO (001) substrates by alternative pulsed laser ablation of SrBi₂Nb₂O₉ ceramic and Ag metal in a nitrogen atmosphere. The size of the Ag nanocrystals can be brought down to ca. 5.0 nm, as revealed by transmission electron microscopy and X-ray diffraction. We measured the third-order susceptibility χ⁽³⁾ of the deposits by single beam z-scan technique at a wavelength of 532 nm. It is found that SrBi₂Nb₂O₉ is an effectively nonlinear optical medium, exhibiting a very large χ⁽³⁾. With the inclusion of Ag nanocrystals the χ⁽³⁾ was nearly doubled (Reχ⁽³⁾ = 8.052 × 10^− 7 esu, and Imχ⁽³⁾ = − 1.717 × 10^− 7 esu), which comes very close to the maximum value available in the current time. This indicates that the Ag:SrBi₂Nb₂O₉ composite structure can be an excellent candidate for nonlinear optical applications. A general approach for further enhanced third-order susceptibility by tailoring the dielectric constant of the metal inclusion is briefly discussed.     

Large nonlinear optical response of a Bi1.5Zn1.0Nb1.5O7 thin film fabricated by pulsed laser deposition

The Bi_1.5Zn_1.0Nb_1.5O₇ (BZN) thin film has been fabricated on MgO (001) substrate by pulsed laser deposition. The nonlinear optical properties of the BZN film were investigated using Z-scan technique at a wavelength of 532 nm with 25 ps pulse duration. The two-photon absorption coefficient and the nonlinear refractive index of the BZN film were obtained to be 4.2 × 10^− 6 cm/W and 1.6 × 10^− 10 cm²/W respectively, which are comparable with those of some representative nonlinear optical materials. The large and fast response optical nonlinearities indicated that the BZN film is a promising candidate for future photonics devices.     

Nonlinear optical response of silica doped with copper nanoclusters under 1064 nm laser excitation

Metal nanocluster composite glass was formed by Cu ion implantation into silica using metal vapor vacuum arc (MEVVA) ion source. The microstructural properties of the nanoclusters were analyzed by optical absorption spectra and transmission electron microscopy (TEM). Third-order nonlinear optical properties of the nanoclusters were measured at 1064 nm excitations using Z-scan technique. The nonlinear refraction index, nonlinear absorption coefficient, and the real and imaginary parts of the third-order nonlinear susceptibility were deduced. The mechanisms responsible for the nonlinear response were discussed. Third-order nonlinear susceptibility χ⁽³⁾ of this kind of sample was determined to be (4.2 ± 1.0) × 10⁻⁸ esu.