Nonlinear Refractive Index N2 Research Articles

Growth of L asparagine monohydrate doped potassium dihydrogen phosphate semiorganic crystals and its structural, thermal and optical properties

A novel semiorganic crystal is harvested by doping organic amino acid L asparagine monohydrate (LAM) with inorganic compound Potassium dihydrogen phosphate (KDP) by adopting slow evaporation method. Rietveld refinement of the XRD data was performed and the structural study exhibits single phase nature of the LAM doped KDP (LAM-KDP) crystals with a slight decrease in c-axis of the unit cell parameters. Other crystallographic parameters such as crystallite size and strain were also evaluated. The interaction of LAM with KDP was studied from FT-IR analysis by detecting functional groups. The constituting elements of the crystal were identified by energy dispersive X-ray (EDX) analysis. Etching study has been employed to study surface morphology of these crystals. From UV–vis transmittance data, optical band gap and different optical constants like Urbach energy, dielectric constants, electrical and optical conductivities were evaluated. Optical transparency of the LAM-KDP crystals is observed to increase. The third order nonlinear susceptibility χ(3) and nonlinear refractive index n2 of the grown crystals have been predicted using empirical Miller's rule. The value of χ(3) has increased from 1.87 × 10−13 esu to 4.29 × 10−13 esu due to LAM doping. Change in enthalpy (ΔH), change in Gibb's free energy (ΔG) and activation energy Ea during chemical reaction were calculated by thermogravimetric analysis (TGA). Thermal decomposition characteristics of the crystals were analyzed by differential scanning calorimetry (DSC). The high transparency of LAM-KDP crystals in the entire visible spectrum and larger values of nonlinear susceptibility χ(3) and nonlinear refractive index n2 make the synthesized crystal applicable for NLO and optoelectronic devices applications.

Silicon nanocrystal slab optical waveguide by multi-energy ion implantation: linear and nonlinear optical properties

Silicon nanocrystals (Si-nc) have gained attention in optics and photonics research areas in recent years due to their advanced optical nonlinear properties. However, a nonlinear integrated optical platform that allows the fabrication of photonic devices with different Si-nc composition is yet under investigation. In this work, we experimentally demonstrated a nonlinear optical waveguide based on ion implantation that offers advantages in terms of material composition, low propagation losses, and enhanced nonlinear optical properties, such as a high nonlinear refractive index. In this work we present the fabrication of Si-nc containing waveguiding structures, and a study of their linear and nonlinear optical properties. Our nonlinear integrated optical platform presents a two-photon absorption coefficient β = 3.17x10-6 cm·W-1 and a nonlinear refractive index n2 = 1.19x10-10 cm2·W-1, which shows potential applications in all-optical signal processing devices, such as single-photon sources.

Characterizing the properties of Li2O–B2O3–SiO2– P2O5–TiO2 glasses: A multidimensional investigation of their structure, optical properties, and gamma-ray shielding capability

A series of lithium borophosphosilicate glass doped with TiO2 was produced with melt-quenching procedure with empirical formula (20-x) Li2O–40B2O3–20SiO2– 20P2O5–xTiO2, where x can be changed between 0 and 16 mol%. By adding titanate, the bulk density of BSPLT glass increased from 3.61 to 4.812 g/cm3. The amorphous nature of glasses is demonstrated by XRD analysis. Different optical characteristics, including the refractive index and optical band gap (Eopt), were determined by recording optical absorption spectra in the 250–2500 nm range. The observed range (Eopt) values from 3.09 eV to 2.64 eV suggests that the (Eopt) decreases as the content of TiO2 in the BSPLT samples increases. The linear optical susceptibility χ(1), third-order non-linear optical susceptibility (χ(3)), and the non-linear refractive index (n2) were determined. Higher-density glasses provide more effective radiation shielding because they are better at absorbing and slowing down radiation particles. BSPLT-16 glass exhibits the highest FNRCS value among the samples tested, indicating its superior performance in shielding against fast neutrons. It is noted that the BSPLT-16 sample, has the highest density among the glasses tested, shows the greatest effective for radiation shielding applications according to the results.

Novel third order nonlinear optical stilbazolium crystal replaced with 3-methoxy benzaldehyde as donor for optical device applications

A novel organic nonlinear optical stilbazolium group single crystal of 1-methyl-2-[2-(3-methoxystyryl)]-pyridinium iodide (subsequently referred to as MSMI) was grown by the solution growth technique using the method of slow evaporation at ambient temperature. The Single-crystal XRD investigation indicates that the MSMI crystal belongs to a monoclinic crystal system with a centrosymmetric space group. CHN elemental analyser confirms the weight percentage of carbon (C = 51.00 %) hydrogen (H = 4.55 %) and nitrogen (N = 3.94 %) in the MSMI crystal structure. The presence of 16 hydrogen atoms and 15 carbon atoms in the MSMI was affirmed by the Nuclear Magnetic Resonance (NMR) spectroscopic analysis. Fourier Transform Infrared (FTIR) studies confirmed the fundamental vibrations for different functional groups found in the MSMI crystal. The Hirsfeld surface analysis figured out the hydrogen bond interaction and π…π interaction which supports the stability of the crystal structure. The crystal is found to exhibit transmittance of wavelength above 400 nm and has a band gap of 3.05 eV ascertained from UV–Vis-NIR spectroscopic analysis. Photoluminescence (PL) studies reveal that the title crystal has an emission wavelength of 572 nm. The surface characteristics of the title crystal were examined by Atomic Force Microscopy (AFM), and etching studies. The value of Meyer's number is n = 1.8 which is determined by the Vickers microhardness studies. The value of the third-order nonlinear refractive index (n2) is 4.662×10−8 cm2/W, the nonlinear absorption coefficient (β) is 1.305×10−3 cm/W, nonlinear susceptibility (χ(3)) is 9.297×10−5 esu and the optical limiting threshold is 11.43 J/cm2 was ascertained form the Z-scan technique. The results indicate that the MSMI crystal is a potential optical limiter and has promising applications in nonlinear optical devices.

Improvements of multifunctional spintronic and optoelectronic applications of nanostructured Eu-doped ZnS thin films through magnetic and linear, nonlinear optical investigations

This study describes the spintronic and optoelectronic improvements upon Eu substitution in Zn atomic site of the nanostructure ZnS thin films. The electron beam deposition technique has been used to deposit a series of Zn1-xEuxS thin films on a glass substrate with different Eu dopants (x = 0, 0.01, 0.03, 0.05, and 0.08). The nanostructure nature of the Eu-doped ZnS thin film has been confirmed from structural and morphology studies performed by the X-ray diffraction (XRD) and atomic force microscope (AFM) measurements. XRD investigations further show a hexagonal-type structure with no detectable extra phases with the lattice parameter c increasing, while a decrease linearly with increasing Eu-dopant in the ZnS hosted lattice. The microstructures analysis reveals a reduction in the mean crystallite size and increasing in the lattice strain of the films with rising Eu doping. The Fourier transform infrared spectra display the existence of chemical bonds in the thin films whereas photoluminescence reveals near-band edge emission. The linear optical parameters were obtained from the analysis of the transmission data measured by the spectrophotometer technique. The results reveal that the band gap energy (EgOpt) reduces by raising ohe Eu doping ratio, which is ascribed to the structural deformation (strain and/or defects) confirmed from structural analysis, density of localized states and PL measurements. The index of refraction n was calculated using the Swanepoel method. The values were found to increase as the level of Eu doping grows, which is associated with the rise in polarizability. Wemple and DiDomenico's (WDD) model was utilized to compute the dispersive and oscillator energies (Eo, and Ed), the nonlinear absorption coefficient βc, nonlinear refractive index n2, and nonlinear optical susceptibility χ3. The results demonstrate that the adjustability of EgOpt , Eo, and Ed of ZnS: Eu films is conducted to improve the nonlinear optical characteristics, providing it well-suited for optoelectronic device implementations. On the other hand, ZnS doped with Eu film displays inherent ferromagnetic properties at room temperature, as evidenced by the results of the magnetic investigation. This finding could be attributed to the presence of sulphur defects (vacancies), as supported by photoluminescence (PL) measurements, which lead to the creation of the bound magnetic polaron. These discoveries indicate the potential of utilizing Eu-doped ZnS film in the effective development of spintronic devices.

Defects assisted the enhancement of optical and ferromagnetism in Zn1-xCoxS quantum dots: Toward efficient optoelectronic and spintronic applications

Colloidal Co-doped ZnS Quantum dots (QDs) were successfully synthesized through a facile and effective chemical co-precipitation method using polyethylene glycol (PEG) as a capping agent. A comprehensive study on the structure, optoelectronic, and magnetic properties of ZnS: Co2+ QDs was thoroughly carried out using diverse characterization techniques. Transmission electron micrographs reveal spherical QDs with a mean particle size of 5 ± 0.5 nm, whereas the X-ray diffraction (XRD) analysis and Raman spectroscopy confirm the exclusive presence of cubic ZnS phase structure, without any signs of Co-related impurity phases. Energy-dispersive x-ray (EDX) analysis verifies the presence of only three elements: Zinc, Cobalt, and Sulphur, with nearly stoichiometric proportions. X-ray photoemission (XPS) analysis confirmed the presence of Co2+ ions in the divalent oxidation state as well as the fair existence of sulphur vacancies. Optical measurements demonstrate that Co-doping in ZnS leads to a decrease in the optical band gap owing to the presence of defects that create localized states within the band structure. In addition, the refractive index (n) is found to increase with Co-doping level due to the increase in the polarizability. The outcomes of optical properties reveal that the tunability of the optical band gap and dispersive oscillator parameters in Co-doped ZnS QDs results in an enhancement of the non-linear optical parameters, such as third-order non-linear optical susceptibility χ(3), and non-linear refractive index n2, rendering them well-suited for applications in optoelectronic devices. Furthermore, the room-temperature photoluminescence (PL) spectra revealed that the Co-doped ZnS QDs have two broad emission bands, including the blue emission, and the green emission. By varying the level of Co-doping, it becomes possible to effectively control the relative PL intensities of dual-color emissions, highlighting their potential for producing adjustable color outputs. The room temperature ferromagnetic behaviour of the QDs has been observed and analyzed in accordance with the bound magnetic polarons model. These findings suggest that Co-doped ZnS QDs can be utilized effectively in the design of spintronic devices.

Dispersion of two-photon absorption and nonlinear refraction in β -Ga2O3 from 350 to 515 nm

We report the wavelength dependencies of the two-photon absorption coefficients β as well as the nonlinear refractive index n2 of undoped β-Ga2O3 single crystal in the spectral range 350–515 nm (0.51 < Ephoto/Eg < 0.75). Femtosecond Z-scan measurements show that n2 decreases monotonically toward the shortwave side, while the maximum value of n2 is 5.0 × 10−19 m2/W near half of the bandgap, Eg. Interestingly, a second upward trend in β was observed when the incident photon energy is larger than 0.6Eg, indicating the impact of additional inter-band transitions with higher energy. A higher-energy band-to-band transition around 6.0 eV was determined by both femtosecond nondegenerate two-photon absorption spectroscopy and ab initio calculations. Our results could provide guidance for designing nonlinear β-Ga2O3 photonic devices in the UV-visible spectral range.

Ultrafast Dynamics, Optical Nonlinearities, and Chemical Sensing Application of Free-Standing Porous Silicon-Based Optical Microcavities.

The present work demonstrates the ultrafast carrier dynamics and third-order nonlinear optical properties of electrochemically fabricated free-standing porous silicon (FS-PSi)-based optical microcavities via femtosecond transient absorption spectroscopy (TAS) and single-beam Z-scan techniques, respectively. The TAS (pump: 400 nm, probe: 430-780 nm, ∼70 fs, 1 kHz) decay dynamics are dominated by the photoinduced absorption (PIA, lifetime range: 4.7-156 ps) as well as photoinduced bleaching (PIB, 4.3-324 ps) for the cavity mode (λc) and the band edges. A fascinating switching behavior from the PIB (-ve) to the PIA (+ve) has been observed in the cavity mode, which shows the potential in ultrafast switching applications. The third-order optical nonlinearities revealed an enhanced two-photon absorption coefficient (β) in the order of 10-10 mW-1 along with the nonlinear refractive index (n2) in the range of 10-17 m2 W-1. Furthermore, a real-time sensing application of such FS-PSi microcavities has been demonstrated for detecting organic solvents by simultaneously monitoring the kinetics in reflection and transmission mode.

Shielding parameters and optical stability of sodium alumino-borate glasses against gamma rays by iron oxide additives

The development of various industries and technologies necessitates a greater utilization of ionizing radiation, such as gamma rays. Herein, we investigate the shielding parameters and the stability of the optical parameters of sodium alumino-borate glasses against gamma rays by different iron oxide (Fe2O3) additives. We found that the Fe2O3 additives improved the shielding parameters. Moreover, the influence of various doses of γ rays (50, 100, and 150 kGy) on the optical characteristics of the performed glasses was studied. For example, the influence of gamma doses on the optical absorbance (A), optical band gap (Eg), Urbach energy (EU), refractive index (no), electronegativity (X), electron polarizability (αo), and nonlinear refractive index (n2). The optical absorbance of all glass samples increased, particularly in the visible range, with further irradiation.Furthermore, the reduced optical band gap and Urbach energy values grow as the gamma irradiation increases, which are attributed to the increased number of donor centres. Conversely, an investigation was conducted on the ability of the material to protect against radiation. We found that the Fe2O3 additives improved the shielding parameters. Furthermore, the half-value layer results of the glassy samples in question were compared to those of conventional radiation shielding materials and glasses. Therefore, the glass samples work better at blocking radiation than conventional window glass when employed for radiation shielding purposes.

Crystal growth, Hirshfeld analysis, optical, thermal, mechanical, and third-order non-linear optical properties of Cyclohexylammonium picrate (CHAP) single crystal

The organic single crystals of Cyclohexylammonium picrate (CHAP) had been grown using the method of slow evaporation solution growth. A determination was made regarding the solubility of the substance. The crystal's lattice cell parameters and morphology were characterized using single-crystal X-ray diffraction and powder X-ray diffraction techniques. The HRXRD techniques were utilized to assess the crystal quality. The functional groups of CHAP material were identified through the use of FT-IR and FT-Raman analysis. A Hirshfeld surface analysis was performed to investigate the formation of hydrogen bonds between N–H⋯O and C–H⋯O molecules. The grown crystals were examined in optical and thermal investigations utilizing UV–visible and TGA, DSC techniques. Mechanical analysis is used to quantify surface properties, such as work hardening coefficient and void volume. Z-scan analysis was utilized to calculate the non-linear refractive index (n2), nonlinear absorption (β), and third-order non-linear susceptibility (χ3).

Investigating the third-order nonlinear optical properties of a Schiff base (DBAP) and its Co/Cu metal complex using Z-scan and DFT methodology

Utilizing UV-visible, Fluorescence spectroscopic, and Z-scan methods, the optical and structural properties of 2-(4-(dimethyl amino)benzylidene amino) phenol (DBAP) and their Co/Cu metal complexes were studied. The Z-scan method has been used to investigate the nonlinear absorption coefficient (β), nonlinear refractive index (n2), third-order susceptibility (χ(3)), and optical limiting (OL). In dimethyl sulfoxide (DMSO) and methanol (MeOH) solvents, the DBAP and their Co/Cu metal complexes display positive nonlinear absorption and a positive nonlinear refractive index, according to the Z-scan data. Using the Z-scan approach and an 800 nm central wavelength, femtosecond amplified 48 fs pulse, 1kHz repetition rate laser, the compound's third-order nonlinear optical (NLO) properties are measured. According to the Z-scan data, we may modify the structure and bonding of legend with metals to improve the NLO capabilities of metal complexes, making this material a promising choice for upcoming optoelectronic and photonic devices. The geometrical structure of the compound is optimized using theoretical computations at the B3LYP that are functional with 6-31G and the LanL2DZ on a mixed basis, as determined by the density functional theory (DFT) framework. They provide insight into the charge transfer interactions taking place in the molecule through their HOMO-LUMO analysis.

Synthesis, Physicochemical and Third Order Nonlinear Optical Properties of Bis-Chalcone (BBDP) as Donor-pi Acceptor Chromophore in Organize Medium.

Bis-Chalcone (BBDP) has been prepared by condensation of N, N-dimethyl benzaldehyde and 1,1'-([1,1'-biphenyl]-4,4'-diyl) di (ethan-1-one), and structure of BBDP was characterized by Mass Spectra, 13C-NMR, 1H-NMR, and IR. Physicochemical properties including Dipole-moments, Stoke-Shifts, Oscillator-strength, dielectric constant and quantum-yields of fluorescence of BBDP were investigated by the emission and absorbances in different solvents. Compound (BBDP) displayed bathochromic shift upon increasing the solvent polarity (from n-Hexane to DMSO). Furthermore, we have exploited third-order nonlinear optical characteristics of the bisChalone were invigilated by the Z-scan techniques in Chloroform. The measurements were taken with a continuous-wave (CW) diode laser having a wavelength of 520 nm in CHCl3 solvent. The third-order nonlinear optical properties, such as the nonlinear refractive index (NLRI) n2, nonlinear absorption coefficient (NLAC) β, and nonlinear susceptibility χ(3), were measured at various solution concentrations and laser powers. The obtained values of n2, β, and χ(3) were estimated to be high, of the order of 10-7(cm2/W), 10-3 (cm/W), and 10-6 (esu), respectively. As a result, bis-chalcone (BBDP) is considered as a promising candidate for applications in nonlinear optical (NLO) devices and optical limiting (OL).

Enhanced optical third-harmonic generation in phase-engineered nanostructured Zn1−x Cd x S thin films for optoelectronic device applications

A polycrystalline nanostructured thin film of zinc cadmium sulfide was meticulously fabricated on a glass substrate using the thermal evaporation method physical vapor deposition within a vacuum chamber. Different doping concentrations were introduced by varying the cadmium (Cd) content, resulting in Zn1-x Cd x S films with Cd concentrations ranging from x = 0.00–0.20 wt %. The impact of Cd doping on the third-order nonlinear optical (TONLO) properties of these films was thoroughly studied using the Z-scan method, employing a diode-pumped solid-state continuous-wave laser. To gain insight into the structural characteristics, the Zn1-x Cd x S thin films underwent analysis through x-ray diffraction. Optical studies confirmed the tunability of the optical band gap (Eg) in the Zn1-x Cd x S films, ranging from 3.88 eV for undoped ZnS to 2.80 eV for the film fabricated with 20 wt. % of Cd-content. This significant reduction in ‘Eg’ renders the films highly suitable for use as absorbing layers in applications such as solar cells and optoelectronics. Surface morphology analysis, performed via field emission scanning electron microscopy, revealed noticeable alterations with increased Cd doping. Significantly, the doped films exhibited a substantial redshift in the band edge and an increase in transmittance within the visible and near-infrared regions. The investigation of TONLO properties, including the nonlinear absorption coefficient (β), nonlinear refractive index (n 2) and susceptibility χ(3), yielded values ranging from 3.15 × 10−3 to 8.16 × 10−3 (cm W−1), 1.65 × 10−8 to 7.45 x 10–8 (cm2 W−1), and 3.12 × 10−5 to 7.86 × 10−5 (esu), respectively. These results indicate the presence of self-defocusing nonlinearity in the films. Overall, the outcomes underscore the potential of Cd-doped ZnS nanostructures in modifying surface morphology and enhancing NLO characteristics. Zn1-x Cd x S thin films exhibit promise for applications in nonlinear optical devices, as evidenced by these encouraging findings.

The band gap and nonlinear optical susceptibility of SrSn1-xVxO3 films

Perovskite-type oxide SrSn1-xVxO3 thin films with different concentrations x = 0.1–0.9 were fabricated by using pulsed-laser deposition, and the effects of V doping on the structure, optical band gap and the third-order optical nonlinearity were systematically investigated. With the increase of x value, the lattice parameters of SrSn1-xVxO3 decrease from 3.997 to 3.862 Å gradually, while the optical band gaps firstly increase and then decrease with boundary at x = 0.3. The third-order nonlinear optical responses were studied via the z-scan technique. The closed-aperture measurements show a negative nonlinear refractive index n2, and the open-aperture measurements demonstrate a saturable absorption β. Both the n2 and β responses vary with the increase of V doping level. The metal-oxygen chemical bond along with the localized V5+Sn2+V5+ complex contribute to the enhancement of optical nonlinearity, and the highest value of third-order susceptibility χ(3) is observed in SrSn0.5V0.5O3 film.

Effect of zirconium oxide nanoparticles on thermal, optical, and radiation shielding properties of Bi2O3-B2O3-MnO2 glasses

This study has explored the DSC, UV–Vis absorption spectroscopy, gamma ray and neutron shielding properties of Bi2O3-B2O3-MnO2: ZrO2 glasses. It demonstrates a unique approach to photon shielding analysis using JENDL/PD-2016 photonuclear data and employs a validated spherical neutron model for neutron shielding. Five transparent glasses were prepared with the chemical composition (in mol%) of 29Bi2O3-70B2O3-(1-x)MnO2: xZrO2, and labeled as MZ0.00 (for x = 0), MZ0.25 (for x = 0.25), MZ0.50 (for x = 0.5), MZ0.75 (for x = 0.75) and MZ1.00 (for x = 1). The glass ceramic nature of the samples has been characterized by DTA thermograms. The glass forming ability parameters (Kgl, S & H) were found to be highest for the sample MZ1.00. The UV–Visible optical absorption spectra have been interpreted, and hence the cut-off wavelength (λcut-off) and optical band gap (Eo) were evaluated. The absorption spectra have revealed the co-existence of manganese ions in three stable valence states Mn4+, Mn3+ and Mn2+ in the samples. When ZrO2 nanoparticles were added in the composition up to x = 0.50 mol%, the red shift in the cut-off wavelength (λcut-off) with gradual shrinkage in optical band gap (Eo) has been observed. Also, the linear and non-linear optical parameters viz., refractive index (no), non-linear refractive index (n2), linear optical susceptibility (χ(1)) and non-linear optical susceptibility (χ(3)) have been evaluated. These parameters showcased that B-O, Bi-O, Mn-O, Zr-O, etc. bonds could be strengthened by subsequent reduction of polarization of the trivalent ions (B3+ ions, Bi3+ ions and Mn3+ ions) in the glass system at higher concentrations of ZrO2. Photoatomic and photonuclear attenuation studies portrayed that the sample MZ0.50 has the lowest photon shielding capability. The fast neutron effective removal cross section (ΣR) was observed to be the highest for the sample MZ1.00. Thus, these glasses can be used to design the thermally stable transparent glasses, tunable optical elements, and radiation shielding materials.

Properties of nonlinear optical absorption and refraction of rapidly grown KDP crystals

Potassium dihydrogen phosphate (KDP) single crystals grown under different conditions were obtained by the “point seed” technique. Third-order nonlinear optical properties of type-II samples which were prepared from the pyramidal and prismatic sections of crystal, respectively, were systematically investigated using the Z-scan technique at λ = 532 nm. Some heat-treated samples have been studied simultaneously. The results show that the nonlinear optical absorption and nonlinear optical refraction have been reflected, meanwhile, the nonlinear refractive index (n2) is positive, suggesting the generation of self-focusing effect. Furthermore, the results indicate that the nonlinear absorption and nonlinear refraction were associated with the growth conditions of the crystal. The prismatic sample grown under the relatively low growth temperature range (45∼25 °C) and small supersaturation (4 %) possessed a smaller nonlinear absorption coefficient (β) and n2 (β=4.73 × 10−13 m/W, n2=2.82 × 10−13 esu) than that of the others. In addition, the values of nonlinear absorption and nonlinear refraction of the samples can be further reduced after thermal annealing. These results may provide an assist to understand the mechanism of laser-induced damage of KDP crystals.

Third-order nonlinear optical properties of highly electron deficient, nonplanar push-pull porphyrins: β-nitro-hexa-substituted porphyrins bearing bromo, phenyl, and phenylethynyl groups.

β-Heptasubstituted porphyrins [MTPP(NO2)X6; M = 2H, NiII, CuII, and ZnII; X = Br, Ph, and PE] were synthesized and their third-order nonlinear optical (NLO) properties explored using the single-beam Z-scan technique with femtosecond, MHz pulses in the visible range. The three-photon absorption (γ), third-order nonlinear optical susceptibility (χ3), three-photon absorption cross-section (σ3), and nonlinear refractive index (n2) have been determined from theoretical fits with experimental results. The sign and magnitude of the nonlinear refractive index (n2) have been obtained from the closed-aperture experiment while the three-photon absorption coefficient and three-photon absorption cross-section were determined from the open-aperture experiment. The magnitudes of the 3PA and σ3 extended in the range of (2.7-3.4) × 10-23 cm3 W-2 and (5.5-7.0) × 10-78 cm6 s2, respectively. The higher magnitude of the NLO coefficients ensures their utility in optical and photonic applications.

Unraveling the role of superalkalis in modulating the static and dynamic hyperpolarizabilities of emerging calix[4]arenes.

Calixarenes, as novel organic materials, can play a pivotal role in the development of high-performance nonlinear optical materials due to the ease of design and fabrication. In this study, DFT simulations were employed to investigate the geometric, electronic, and NLO responses of calix[4]arene doped with Li3O, Na3O, and K3O superalkalis. The computed values of the vertical ionization energies and interaction energies indicate the chemical and thermodynamic stabilities of the targeted M3O@calix[4]arene complexes. The corresponding energy gaps (2.01 to 3.49 eV) are notably reduced, indicating the semiconductor nature of the materials. Surprisingly, the M3O@calix[4]arene complexes exhibit transparency in the UV/visible range as the absorption peaks are shifted in the near infrared (NIR) region. The highest values of 5.9 × 105 a.u. and 2.3 × 108 a.u. for the respective first and second hyperpolarizabilities are observed for Na3O@calix[4]arene. Furthermore, the Na3O@calix[4]arene complex exhibits maximum values of 2.3 × 105 a.u. for second harmonic generation (SHG) and (K3O@calix[4]arene) 2.3 × 106 a.u. for the electro-optical Pockels effect (EOPE) at 1064 nm. Similarly, approximations are made for the dynamic second hyperpolarizability coefficients (EOKE and EFISHG) at different wavelengths. Notably, the Na3O@calix[4]arene complex demonstrates the highest quadratic nonlinear refractive index (n2) of 9.5 × 10-15 cm2 W-1 at 1064 nm. This research paves the way for the development of stable calix[4]arenes doped with superalkalis, leading to an improved nonlinear optical (NLO) response.

Investigation on the growth aspects and properties of rubidium hydrogen succinate hydrate single crystal for NLO applications.

A novel semiorganic nonlinear optical single crystal of rubidium hydrogen succinate hydrate (RbHSH) was grown at room temperature using the slow evaporation solution growth technique (SEST) with water as a solvent for nonlinear optical applications. The grown crystal is a triclinic system with a centrosymmetric space group of P1̄ and the compound is stabilized by intramolecular O-H-O and C-H-O bonding. FTIR spectral studies were used to determine the various functional groups present in the material. The optical transmission spectra of the grown crystal demonstrated that a transparency of 89%, with a low cut off wavelength of 240 nm and an energy band gap of 5.21 eV, which is beneficial to developing advanced photonic and optoelectronic devices in the solar blind UV area. The grown crystal is thermally stable upto 174 °C. The electrical properties of RbHSH crystal exhibit low dielectric loss and a low dielectric constant at high frequencies tends to have good optical characteristics. Mechanical analysis demonstrated that the grown crystal shows the normal indentation size effect (ISE) and falls into the hard material category with n = 1.4. Photoconductivity measurements revealed negative photoconductivity. Photoluminescence studies showed that RbHSH emits blue light with a wavelength of 484 nm. Hirshfeld surface analysis was used to analyze intermolecular interactions in the RbHSH crystal. The grown RbHSH crystal piezoelectric charge coefficient have been calculated (d33 = 13 pC N-1) and it is suitable for piezoelectric device applications. Under continuous-wave laser excitation, the third order nonlinear refractive index (n2), absorption coefficient (β), and susceptibility (χ(3)) of the RbHSH crystal were found to be 1.6639 × 10-12 (cm2 W-1), 1.1739 × 10-5 (cm W-1) and 4.86331 × 10-9 esu, respectively.

Synthesis, crystal structures, spectroscopy, and quantum chemical studies on the 4-dimethylaminopyridinium-2,4-dinitrophenolate: an organic NLO material for optoelectronics.

In this work, the 4-dimethylaminopyridinium-2,4-dinitrophenolate (4DMAP + 2,4DNP) by slow evaporation solution growth method has been presented. The Fourier transform infrared (FT-IR) (4000-400cm-1) and FT-Raman (4000-50cm-1) spectra were recorded for the grown crystal. The computational calculation has been carried out with density functional theory (DFT) in ground state with Gaussian program package. Optimized geometrical parameters (bond distances, bond angles, and dihedral angles) have been obtained and compared with X-ray crystallography data. The calculated fundamental vibrational frequencies from DFT/B3LYP with 6-311 + + G(d,p) level of theory were scaled so as to agree with the observed results, and the scaling factors were reported. Experimental and computed ultraviolet-visible (UV-Vis) spectra in acetone and methanol solvents were found comparable to each other. Furthermore, the frontier molecular orbitals (FMOs) energies, molecular electrostatic potential (MEP), nonlinear optical (NLO), hirshfeld surface (HS), and global chemical descriptors of the molecule were also calculated. The thermal stability and the melting point of the title compound were analyzed by the thermogravimetric analysis/differential thermal analysis (TGA/DTA) techniques. The mechanical behavior of the organic single crystal was measured by Vickers micro-hardness method. The third-order nonlinear optical properties such as nonlinear refractive index (n2), nonlinear absorption coefficient (β), optical nonlinear susceptibility Reχ(3), and optical nonlinear susceptibility Imχ(3) were calculated by using the open and closed aperture Z-scan technique. The theoretical and experimental NLO values clearly proposed that the nonlinearity of 4DMAP + 2,4DNP molecule could be helped as a potential candidate for optical limiting, frequency doubling, and optical switching applications.