Showing papers on "Hyperpolarizability published in 2017"

Spin-polarized Second Harmonic Generation from the Antiferromagnetic CaCoSO Single Crystal.

Abstract: The spin-polarized second harmonic generation (SHG) of the recently synthesized CaCoSO single crystal is performed based on the calculated electronic band structure. The calculation reveals that the spin-up (↑) channel of CaCoSO possesses a direct energy gap (Γv-Γc) of about 2.187 eV, 1.187 eV (Kv-Kc) for the spin-down (↓) channel and an indirect gap (Γv-Kc) of about 0.4 eV for the spin-polarized CaCoSO single crystal. The linear optical properties obtained reveal that the recently synthesized crystal exhibits considerable anisotropy with negative uniaxial anisotropy and birefringence favor to enhance the SHG. We have calculated the three non-zero tensor components of the SHG and found the is the dominat component, one with a large SHG of about (d33 = 6.936 pm/V at λ = 1064 nm), the half value of KTiOPO4 (KTP). As the values of (↑) (↓) 1.187 eV> spin-polarized gap 0.4 eV; therefore, a smaller energy gap gives better SHG performance. Furthermore, the microscopic first hyperpolarizability, βijk, is calculated.

Experimental and computational studies on second-and third-order nonlinear optical properties of a novel D-π-A type chalcone derivative: 3-(4-methoxyphenyl)-1-(4-nitrophenyl) prop-2-en-1-one

Abstract: The present study reports the theoretical and experimental investigations of linear and nonlinear optical (static and dynamic) properties of 3-(4-methoxyphenyl)-1-(4-nitrophenyl)prop-2-en-1-one (MNC). The crystal structure was confirmed from powder X-ray diffraction (PXRD) analysis and evaluated the crystalline quality using high-resolution X-ray diffraction (HRXRD). Linear absorption and fluorescence spectra were recorded and the optical band gap was determined by Tauc’s relation. Third-order nonlinear optical (NLO) characteristics along with optical limiting behavior were explored using the femtosecond (fs) Z-scan technique at 800 and 900 nm wavelengths (Ti: sapphire laser, 150 fs, 80 MHz). The experimental results are supported by theoretical calculations obtained from the density functional theory (DFT). The optimized geometry, linear optical absorption, HOMO-LUMO energy gap, molecular electrostatic potential (MEP), dipole moments and global chemical reactivity descriptors (GCRD) were computed by employing B3LYP/6-311+G(d) level of theory. The static and dynamic linear polarizability (α), first hyperpolarizability (β) and second hyperpolarizability (γ) components were calculated using time-dependent Hartree–Fock (TDHF) method. The computed first hyperpolarizability β(−2ω;ω,ω) at 1064 nm wavelength was found to be 55 times greater than that of urea standard. The experimental and calculated dynamic molecular second hyperpolarizabilities γ(−3ω;ω,ω,ω) are in good accordance at 800 and 900 nm wavelengths.

First principles study for the key electronic, optical and nonlinear optical properties of novel donor-acceptor chalcones.

Abstract: Using first-principle methods, several key electronic, optical and nonlinear optical properties are calculated for two recently synthesized chalcone derivatives i.e. (2E)-3-(4-methylphenyl)-1-(3-nitrophenyl)prop-2-en-1-one (comp.1) and (2E)-3-[4-(dimethylamino)phenyl]-1-(3-nitrophenyl)prop-2-en-1-one (comp.2). The calculation of dipole moment, polarizability , anisotropy of polarizability as well as second hyperpolarizability (usually considered as a signature for two photon absorption phenomenon) are performed using density functional theory methods at PBE0/6-311G** level of theory. The linear average polarizability for comp.1 and comp.2 are found to be 32.15×10-24 and 38.76×10-24esu, respectively. Similarly, the second hyperpolarizability amplitudes of comp.1 and comp.2 are found to be reasonably larger mounting to 79.31×10-36 and 181.36×10-36esu, respectively. The importance of donor end is determined by comparing p-methylphenyl group of comp.1 with that of N,N-dimethylaniline group of comp.2 that results a remarkable increase in its amplitude, which is ∼2 times larger as compared with that of comp.1 owing to the stronger donor-acceptor configuration of comp.2. Interestingly, a comparison of average static third-order nonlinear polarizabilities shows that amplitudes of comp.1 and comp.2 are ∼13 times and ∼29 times larger than that of para-nitroaniline (a typical standard push-pull NLO-phore) at the same PBE0/6-311G** level of theory, which indicates a real time NLO application of our titled compounds. Time dependent density functional theory (TD-DFT) calculations along with frontier molecular orbitals, density of states (DOS), second hyperpolarizability density analysis and molecular electrostatic potential (MEP) diagrams are used to trace the origin of electro-optical as well as structure property relationships.

Second-Order Nonlinear Optical Properties of Multiaddressable Indolinooxazolidine Derivatives: Joint Computational and Hyper-Rayleigh Scattering Investigations

Abstract: The linear and nonlinear optical (NLO) properties of two indolinooxazolidine derivatives acting as multiaddressable switches are reported. The second-order hyperpolarizability contrasts upon commutation between their closed and open forms are characterized using hyper-Rayleigh scattering (HRS) measurements, and rationalized by means of density functional theory and post Hartree–Fock ab initio calculations. It is evidenced that the addition of a withdrawing substituent on the indolinic subunit leads to a more effective photoinduced charge transfer while decreasing the transition energy of the S0 → S1 transition, which induces a significant enhancement of the HRS response of the open form. This substitution is however detrimental to the NLO contrast, due to the concomitant increase of the HRS response of the closed form.

Hyperpolarizability and operational magic wavelength in an optical lattice clock

Abstract: Optical clocks benefit from tight atomic confinement enabling extended interrogation times as well as Doppler- and recoil-free operation. However, these benefits come at the cost of frequency shifts that, if not properly controlled, may degrade clock accuracy. Numerous theoretical studies have predicted optical lattice clock frequency shifts that scale nonlinearly with trap depth. To experimentally observe and constrain these shifts in an ^{171}Yb optical lattice clock, we construct a lattice enhancement cavity that exaggerates the light shifts. We observe an atomic temperature that is proportional to the optical trap depth, fundamentally altering the scaling of trap-induced light shifts and simplifying their parametrization. We identify an \"operational\" magic wavelength where frequency shifts are insensitive to changes in trap depth. These measurements and scaling analysis constitute an essential systematic characterization for clock operation at the 10^{-18} level and beyond.

A theoretical investigation on doping superalkali for triggering considerable nonlinear optical properties of Si 12 C 12 nanostructure

Abstract: In this work, we designed a series of superalkali-doped Si12 C12 nanocage M3 O@Si12 C12 (M = Li, Na, K) with donor-acceptor framework. Density functional theory calculations demonstrated that the HOMO-LUMO gap of the complexes conspicuously narrowed with increase of atomic number of the alkali metal, the value decreased from 5.452 eV of pure Si12 C12 nanocage to 3.750, 2.984, and 2.634 eV of Li3 O@Si12 C12 , Na3 O@Si12 C12 , and K3 O@Si12 C12 , respectively. This finding shows that the pristine Si12 C12 cluster could be transformed to n-type semiconductor by introduction of the superalkali M3 O. We also showed that the superalkali doping remarkably enhanced the first hyperpolarizability of Si12 C12 . Among the studied systems, K3 O@Si12 C12 not only has the narrowest gap but also has the strongest nonlinear optical (NLO) properties, its first hyperpolarizability reached as high as 21695 a.u. The striking results presented in this work will be beneficial for potential applications of the Si12 C12 -based nanostructure in the electronic nanodevices and high-performance NLO materials. © 2017 Wiley Periodicals, Inc.

Synthesis and characterization of a novel indoline based nonlinear optical chromophore with excellent electro-optic activity and high thermal stability by modifying the π-conjugated bridges

Abstract: Two novel second order nonlinear optical (NLO) chromophores based on indoline donors and tricyanofuran (TCF) acceptors linked together via modified polyene π-conjugation bridges have been synthesized in good overall yields and systematically characterized. Thermal stability, optical property and electro-optic property were measured to investigate the effects of the introduced rigid benzene derivative steric hindrance group on the bridge. Besides, density functional theory (DFT) was used to calculate the HOMO–LUMO energy gaps and first-order hyperpolarizability (β) of these chromophores. After introducing the benzene derivative steric hindrance group into the bridge, chromophore CLH-2 showed very good thermal stability with a decomposition temperature of 250 °C, which was 83 °C higher than chromophore CLH-1 without the isolation group on the bridge. In electro-optic activity, the introduction of rigid steric hindrance groups can effectively reduce dipole–dipole interactions to translate the relatively small β values into bulk high EO activities. By doping chromophores CLH-1 and CLH-2 with a high loading of 45 wt% in APC, EO coefficients (r33) of up to 63 and 102 pm V−1 at 1310 nm can be achieved, respectively. The r33 value of the new chromophore CLH-2 was about 1.6 times that of chromophore CLH-1. The high r33 value, good thermal stability and high yield suggest the promising applications of the new chromophore in nonlinear optical areas.

Synthesis, crystal growth, physicochemical properties and quantum chemical investigations of a D–π–A type organic single crystal: 2-amino-5-nitropyridinium p-phenolsulfonate (2A5NPP) for nonlinear optical (NLO) applications

Abstract: Efficient organic nonlinear optical (NLO) 2-amino-5-nitropyridinium p-phenolsulfonate (2A5NPP) single crystals have been grown by slow cooling method using methanol as a solvent. Single crystal X-ray diffraction (SXRD) analysis revealed the unit cell parameters of the grown crystal. The morphology of the grown crystal was identified by single crystal XRD analysis as well. The crystallinity of the title crystal was studied by powder X-ray diffraction (PXRD) analysis. The presence of functional groups was determined by FTIR spectral analysis. The optical transmittance revealed that the grown crystal is transparent in the visible and NIR region with a lower cutoff wavelength of 408 nm. The chemical etching analysis showed that the grown crystal has a lower etch pit density (EPD). The title compound is thermally stable up to 200 °C, as assessed by thermogravimetric (TG) and differential thermal analysis (DTA). The photocurrent (Ip) and dark current (Id) values were found to be 5.3 × 10−11 A and 3.3 × 10−11 A at 50 V, respectively, by photoconductivity analysis. A dielectric study was carried out to find the distribution of charges within the crystal. Theoretical calculations were performed using the B3LYP/6-311++G(d,p) level basis set. The structural parameters of 2A5NPP were studied using the DFT method and the calculated results were compared with the experimental values. The charge transfer characteristic of the title compound was studied by frontier molecular orbital (FMO) analysis. The first-order hyperpolarizability of the 2A5NPP molecule was found to be 2.9 × 10−29 e.s.u, which is 37 times higher compared to the reference urea molecule. The Mulliken charge of the obtained molecule was theoretically analyzed. Hydrogen bonding of the obtained molecule was confirmed by NBO analysis. The Kurtz–Perry powder technique was used to evaluate the second harmonic generation (SHG) efficiency of the title crystal and it was found to be 22 times that of the reference KDP material.