In this work, a novel experimental investigation of photoluminescence properties of Znq
2
thin films co-doped with different concentrations of DCM were performed. The thin films were successfully ...deposited on glass substrates with different compositions, under high vacuum, by using the vacuum evaporation technique. For all compositions, the photoluminescence was measured at room temperature and also at low temperature in a wide range from 77 to 300 K with a step of 25 K in a high vacuum. The lifetime of the sample studied in real time was also measured using the decay time technique. The results obtained confirm that the doping influences the intensity of the DCM photoluminescence and also shows a complete energy transfer occurred from Znq
2
to DCM which may have shifted the photoluminescence peak from Znq
2
to the orange wavelength region which is related to DCM. The lifetime of the sample studied in real time was about 4.47 ns for Znq
2
and while all the other samples showed two decay time components. As a result, the doping influences the optical properties of Znq
2
and makes it a potential candidate for optoelectronic applications.
Graphical abstract
In this paper, we present a series of thiophene derivatives (ThD) with a schematic structure of D-π-A, in which we investigated the impact of the acceptor moiety design on nonlinear optical (NLO) ...properties. All molecules contain benzothiophene as an electron-donating group covalently bonded to the thiophene, which plays a role of a π-conjugated bridge. Ten different acceptor moieties were attached to the main core using the Knoevenagel reaction scheme to achieve novel rod-like derivatives. The UV-VIS absorption analysis supported by DFT calculations revealed that molecules enclosing prolonged conjugation length and nitro or dicyano groups as acceptors display the most profound intramolecular charge transfer (ICT) in the THF solution. Furthermore, samples were prepared as guest-host systems, where each ThD was embedded in a poly(methyl methacrylate) matrix and deposited on the glass substrate. By the means of second and third harmonic generation (SHG/THG), along with the optical Kerr effect (OKE) we established the most significant nonlinear optical parameters. The compounds with highly conjugated structures have shown SHG response of the 10−11 m/V order, which is a noteworthy result for purely organic systems. Moreover, the time of trans-cis-trans isomerization was recorded in the range of tens of microseconds, which may be competitive with commercially available azobenzenes. Presented results indicate that designed thiophene derivatives are promising candidates for optoelectronic and photonic applications, such as all-optical switchers or nonlinear microscopy. We clearly demonstrate that by applying small changes in the design of the acceptor moiety, it is possible to efficiently control and tailor the nonlinear response.
Display omitted
•The intramolecular CT of the D-π-A thiophene derivatives can be precisely tailored by the acceptor moiety chemical structure.•The estimated second and third-order susceptibility are over 60 times greater than used reference materials (quartz/silica).•The trans-cis-trans isomerization was recorded in the range of tens of microseconds, which is competitive with azobenzenes.•It has been proved that even small structural changes can have a significant impact on the photophysical and NLO properties.
This Article describes the effect of the excitation wavelength on the spectra of random laser emission obtained in a dye-doped polymeric system, composed of a PMMA layer and a laser dye exhibiting a ...bichromatic gain profile, the 3-(2,2-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (DCNP). We are showing that the change of pumping wavelength can be used to switch the laser emission between particular lasing bands and control the relative intensity between them if the bichromatic light amplification is achieved. We present that the random lasing phenomenon can strongly influence the resulting bichromatic emission, randomly selecting the dominating lasing band. Mentioned random band switching behavior was investigated using a statistical approach, indicating that the obtained distribution is dependent on the excitation wavelength. This feature can be used to design new types of laser-based optical random number generators that can find applications in integrated optical logic devices. To the best of the authors’ knowledge, this is the first demonstration of an optical random number generator based on the bichromatic laser dye described in the literature.
•Synthesis of a two derivatives of pyrazolone dyes.•Nonlinear optical multifunctionality of the organic chromophores dedicated for opto-electronics.•All-optical switching investigation of the two ...pyrazolone-based dyes.•Second and third harmonic generation of the NLO chromophores.•Organic dyes functionalization vs spectroscopic features.
Materials engineering plays a pivotal role in the modern technologies and individual solutions for various applications. In this contribution we describe two pyrazolone-based organic chromophores that differ slightly in structure, but represent a significantly various spectroscopic response. Based on the quantum-chemical calculations, namely TD-DFT model, HOMO-LUMO maps estimation, we have implemented both derivatives in the 2nd and 3rd order nonlinear optical (NLO) experiments. Pyrazolone-based organic systems occurred to be sensitive and appealing all-optical modulators as well as SHG and THG signals generators. The presence of a small methoxy group or its lack in the dye structure directly affects the kinetics of photoinduced birefringence, and its magnification. Moreover, it allows to determine the ease modulation of higher harmonic of the light induction according to the provided experimental polarization spatial conditions. Such approach enables to design and implement individually adjusted organic components to the complex opto-electronic networks and highly effective photonic architectures.
A series of Cu(II), Co(II), Cd(II), Hg(II), Mn(II), and Zn(II) complexes (1–6) of (1-methyl-1H-imidazol-2-yl)(phenyl)methanone ligand (L) have been prepared and structurally characterized ...using single-crystal X-ray diffraction. A study of electrochemical properties has been conducted by cyclic voltammetry. Transition metal coordination complexes are known to have promising optical nonlinearity behavior. So, to explore the quadratic and cubic nonlinear optical (NLO) phenomena of title transition metal coordination structures, several experimental and theoretical investigations have been introduced, and their results have been evaluated. The second-harmonic generation (SHG) and third-harmonic generation (THG) techniques by means of the Maker fringe setup have been performed to analyze and evaluate the quadratic (χ(2)) and cubic (χ(3)) susceptibilities on thin films of 1–6 at 1064 nm. The maximum one-photon absorption (OPA) wavelengths (λmax) of 1–6 have been measured utilizing UV–vis spectral analysis. To acquire the electric dipole moment (μ), static dipole polarizability (α), and first hyperpolarizability (β) values of 1–6, we have taken advantage of the density functional theory (DFT) at the B3LYP level. The time-dependent Hartree–Fock (TDHF) that is known as a very productive quantum mechanical procedure has been chosen to achieve the static second hyperpolarizabilities (γ) and dynamic α, β, γ, χ(2), and χ(3) for 1–6. The measured data on the χ(2), χ(3), and (λmax) results for 1–6 have been confronted with their corresponding calculated values from the TDHF approach and the configuration interaction (CI) method including all doubly occupied molecular orbitals (MOs). Our calculation results of microscopic dipole polarizabilities and hyperpolarizabilities for 1–6 have also been crosschecked with similar structures given in the previous works and outcomes of several reference samples. The second- and third-order NLO efficiencies produced theoretically and experimentally of the title materials have been outlined, revealing that the complexes with closed-shell electronic states have turned out increments of second- and third-order susceptibility responses. This work has also elucidated that the substitutions of metallic cations (Cu2+, Co2+, Cd2+, Hg2+, Mn2+, and Zn2+) have created favorable impacts upon χ(2) and χ(3) conclusions. Furthermore, we have surveyed the first and second frontier MOs and their energy gap values via DFT.
In the present work the third-order nonlinear optical (NLO) properties of the complex-oxides crystals, including nonlinear absorption (NLA) and nonlinear refraction (NLR) are performed by the Z-scan ...technique. The non-centrosymmetric lithium niobate (LiNbO3) and lithium tantalite (LiTaO3) and centrosymmetric cadmium tungstate (CdWO4), calcium tungstate (CaWO4) and calcium molybdate (CaMoO4) single crystals were used for experimental investigation. The main nonlinear optical parameters, such as the two-photon absorption coefficient β, the nonlinear refractive index n2 and third-order nonlinear susceptibility for all investigated crystals are evaluated at different wavelengths λ: 1064 nm and 532 nm. Herein, the influence of λ and crystal orientation of third-order NLO properties on complex-oxides crystals is discussed.
•Growth of new complex oxide crystals and their spectroscopic properties.•Investigation of the nonlinear optical effects by the Z-scan technique.•Strong saturable absorption and reverse saturable absorption of complex oxide crystals.•Self-focusing and self-defocusing properties determined by positive and negative refractive index n2 of studied crystals.
The synthesis of high-quality thin films through spin coating deposition on meticulously cleaned glass substrates is presented. Optical band gaps Eg of both samples using the Kubelka–Munk function ...are determined. The data analysis uncovers the presence of optical allowed direct transition for A2ZnGeO4 (A = K, Li). Spectroscopic ellipsometry measurements on A2ZnGeO4 (A = K, Li) thin films and an analysis of their optical properties using the Cauchy model are presented. Furthermore, the increase of the thickness of the thin film results in improvements in their optoelectrical parameters, such as electrical conductivity, optical mobility, and optical conductivity. Using the Kubodera and Kobayashi comparative model, the third order nonlinear susceptibility (χ(3)) was estimated based on the compounds' high linear absorption of the generated third harmonic wavelength (355 nm). This paper presents remarkable NLO results that reveal potential uses in optoelectronics and photonics.
•Z-scan technique was used to characterize the NLO response in laccaic acid dye.•Nonlinear optical parameters β2, n2, and γ, were evaluated.•Optical limiting behaviour was investigated.•Multiphoton ...absorption was consistent to describe the nonlinearity.
We have investigated the nonlinear optical properties, including the optical limiting behaviour for five different concentrations of laccaic acid dye in solution and a thin film obtained through doping in poly (methyl methacrylate) (PMMA) polymer. The experiments were performed by using single beam Z-scan technique at 532nm with 10ns, 10Hz Nd:YAG laser pulses excitation. From the open-aperture Z-scan data, we derived that the laccaic dye samples exhibit strong two photon absorption (2PA). The nonlinear refractive index was determined through the closed aperture Z-scan data. The estimated absorption coefficient β2, nonlinear refractive index n2 and second order hyperpolarizability γ were found to be of the order of 10−10m/W, 10−9esu and 10−32esu, respectively. The Z-scan study reveals that the natural laccaic acid dye emerges as a promising material for third order nonlinear optical devices application.
PDF
