We have designed and fabricated a novel nonlinear optical superlattice of LiTa${\mathrm{O}}_{3}$ in which two antiparallel 180\ifmmode^\circ\else\textdegree\fi{} domains building blocks A B were arranged as Fibonacci sequence. measured the quasi-phase-matched second-harmonic spectrum superlattice. The blue, green, red, infrared light generation, with energy conversion efficiencies $\ensuremath{\sim}5%--20%$, was demonstrated experimentally, are comparable those periodic Destruction...

We develop a fluorinated phenyl-tolane based nematic mixture NJU-LDn-4 and evaluate its frequency-dependent birefringence utilizing terahertz time domain spectroscopy (THz-TDS). A large mean of 0.306 is obtained in broad range from 0.4 to 1.6 THz, with maximum 0.314 at THz. Furthermore, relation between molecular structures property discussed. This work reveals new insights for tailing liquid crystal molecules desirable THz range, which extremely meaningful the design fabrication fast,...

The slow oxygen evolution reaction (OER) limits water splitting, and external fields can help improve it. However, the effect of a single field on OER is limited unsatisfactory. Furthermore, mechanism by which unclear, particularly in presence multiple fields. Herein, strategy proposed for enhancing activity catalyst using combined an optical-magnetic field, catalytic enhancement studied. Under Co3 O4 reduces resistance increasing temperature. Meanwhile, CoFe2 further via negative...

The concept of volume holography is applied to the design an optical superlattice for nonlinear harmonic generation. generated wave can be considered as a holographic image caused by incident fundamental wave. Compared with conventional quasi-phase-matching method, this new method has significant advantages when complicated processes such generation special beams. As example, we experimentally realized second-harmonic Airy beam, and results are found agree well numerical simulations.

We have developed a facile and compatible method to in situ fabricate uniform metal nanowire networks on substrates. The as-fabricated show low sheet resistance high transmittance (2.2 Ω sq–1 at T = 91.1%), which is equivalent that of the state-of-the-art networks. demonstrated becomes homogeneous from deep-ultraviolet (200 nm) near-infrared (2000 when size wire spacing increases micrometer size. Theoretical experimental analyses indicated we can improve conductivity as well keep their by...

Wave-front engineering for nonlinear optical interactions was discussed. Using Huygens-Fresnel principle we developed a general theory and technique domain with conventional quasi-phase-matching (QPM) structures being the special cases. We put forward concept of local QPM, which suggests that QPM is fulfilled only locally not globally. Experiments agreed well theoretical prediction. The proposed scheme integrates three functions: generating, focusing, beam splitting second-harmonic wave,...

We report on the fabrication of domain-reversed structures in LiNbO3 by means direct electron beam lithography at room temperature without any static bias. The crystals were chemically etched after exposure and then, patterns domain inversion characterized atomic force microscopy (AFM). In our experiment, an interesting phenomenon occurred when wrote a one-dimensional (1-D) grating negative c-face: two-dimensional (2-D) dotted array was observed positive c- face, which is significant for its...

The promotion of magnetic field on catalytic performance has attracted extensive attention. However, little research been reported the oxygen evolution reaction (OER) for modulating intrinsic magnetism catalyst under a field. Herein, we adjusted CoxNi1–xFe2O4-nanosheet by adjusting ratio Co and Ni, researched relationship between OER activity magnetism. results indicate that CoFe2O4-nanosheet most increases in due to optimal required overpotential CoFe2O4-nanosheet@NF reach current density...

Nonlinear volume holography is employed to realize arbitrary wave-front shaping during nonlinear processes with properly designed 2D optical superlattices. The concept of a polarization wave in investigated. holographic imaging irregular patterns was performed using LiTaO3 crystals fundamental propagating along the spontaneous direction, and results agree well theoretical predictions. This Letter not only extends application area superlattices, but also offers an efficient method for technology.

Coupling of optical parametric processes in an superlattice through quadratic nonlinearity was analyzed theoretically. Solving the coupled equations, we found that efficient quasi-phase-matched third-harmonic (TH) generation depends not only on magnitude coupling coefficients but also their ratio. Theoretically, all fundamental energy can be transferred to TH at a particular In other cases, there exists optimum condition corresponds maximum conversion efficiency. The result is practical...

Quasi-phase matching facilitates the phase of any parametric interaction by setting an appropriately modulated period. We propose a dual-periodic structure that is used in construction frequency-conversion device. For example, we have designed and fabricated such LiTaO3 crystal. Using fundamental source at 1.064 µm, obtained ultraviolet radiation 355 nm green 532 simultaneously frequency tripling doubling source. Theoretically, this idea can be further extended to design multiperiodic for...

This article analyzes theoretically the ‘‘in-line field’’ scheme and ‘‘crossed-field’’ for acoustic excitation of an superlattice both resonators transducers. The electrical impedance admittance are deduced electromechanical coupling coefficients calculated.

We propose a method to realize perfect quasi-phase matching (QPM) for nonlinear optical interactions involving Gaussian beams. Using this method, both the wave-vector mismatching and Gouy phase shift can be compensated. Numerical simulations third-harmonic generation show that conversion efficiency near 100% realized even if fundamental wave is tightly focused, which difficult or impossible with conventional QPM method.

We propose a universal and practical scheme to realize polarization-free second-order nonlinear frequency-conversion processes, including sum-frequency generation, difference-frequency optical parametric amplification. This is based on the superlattice with noncritical phase-matching condition, which suitable for integration. A chirped dual-period structure proposed ensure efficiency stability of conversions.

Harmonic generation in a three-component Fibonacci optical superlattice (3CFOS) is analysed theoretically. The Fourier spectrum of the structural function 3CFOS numerically calculated. positions reciprocal vectors are good agreement with theoretical prediction. intensities second harmonic (SH) and third-harmonic (TH) calculated relative to depletion fundamental. dependence SH TH intensity on parameters discussed. Numerical calculation shows that, compared two-component (2CFOS), there more...

A finite difference method in real space is presented for calculating nonlinear optical processes two-dimensional superlattices. The focused second-harmonic generation under the local quasi-phase-matched condition calculated as an example. field distribution of both fundamental and harmonic wave can be simulated well using this method, result agrees with previous theoretical predictions experimental studies. It shown that a simple rapid technique to analysis

High-efficiency electrocatalytic water splitting requires high intrinsic activity of catalysts and even more importantly favorable mass transfer. However, gas bubbles adhering to the surface limit re-expose catalytic active sites electrolyte reduce activities. The efficient desorption can be facilitated by a hierarchical multiscale structure electrode surface. Herein, we report an opened periodic three-dimensional composed iron (Fe)-cobalt (Co)-nickel (Ni) (oxy)hydroxide nanorods (NRs) grown...

We propose a dual-periodically domain-inverted structure for realizing an efficient third-harmonic generation at arbitrary fundamental wavelength. The allows to couple two separate optical parametric processes, frequency doubling and adding, through cascaded quasi-phase-matched interaction, therefore, generate directly from superlattice sample. As example, we designed fabricated such in LiTaO 3 crystal. Using LD pumped 1.064 µm quasi-cw Nd:YVO 4 laser as source, considerable ultraviolet 355...

The interactions between electromagnetic wave and photonic quasicrystals are investigated. A terahertz (THz) source with multi-frequency modes in an optical LiTaO(3) superlattice produced by quasiperiodic (Fibonacci) domain-inverted ferroelectric material is demonstrated experimentally. Using the canonical pump-probe experimental technique, THz radiations both forward backward propagations in-situ detected simultaneously. Four pronounced frequencies at 1.18, 0.78, 0.59 0.37 Fourier transform...

Second-harmonic generation is used experimentally for the nonlinear imaging of two-dimensional irregular domain structures. Analytical solutions and simulation results Fresnel distribution walls are obtained. The show that wall plays an important role in process corresponding diffraction effect greatly suppressed (we call it a nearly diffraction-free effect), thus providing simple way to realize high-resolution ferroelectric domains.

We propose a new method for detecting small defects on the surface of semiconductor by analyzing transmission spectrum terahertz plasmon polaritons. The field distributions caused detection different sizes are simulated. Experimentally, using time domain spectrometer, we measure polaritons passing through particles an intrinsic InSb wafer. Our results show that measured temporal waveform and frequency spectra distinctly changed due to presence particles, thereby confirming effectiveness this...

Theoretical and numerical solutions of the nonlinear coupling-wave equations second-harmonic (SH) third-harmonic (TH) converters are investigated for both phase-matched phase-mismatched configurations. For TH generation, several kinds schemes [the phase mismatch in either SH generation or sum-frequency (SFG) as well SFG] considered analyzed. The optimal converting properties generalized phase-mismatching operation discussed studied. It is found that efficient depends not only on magnitude...

In conventional frequency conversion based on chi(2)-induced nonlinear optical effects, a number of phase-matching techniques have been deployed to resolve the phase mismatch between interacting waves. this work, we report that in quasi-phase-matching scheme, accumulation can induce quasi-phase-mismatch effect. And contrary, instead eliminating mismatch, modulating effect lead bandwidth enhancement and multiple-wavelength conversion. Both these are essential factors for applications As...

The cascaded parametric processes, i.e. optical oscillation (OPO) and difference frequency generation (DFG), can be used to induce efficient CW mid-infrared radiation at 4–5 µm in a single superlattice obtained by aperiodically poling ferroelectric crystal. consists of basic building blocks modulated spatial function. We numerically solve the coupling equations considering pump depletion mid-IR absorption realize optimal condition for frequency-down-conversion processes. Simultaneously, it...

Quasi-phase-matched parametric downconversion via cascaded optical nonlinearities in an aperiodically poled MgO:LiNbO3 superlattice was studied theory and experiment. Due to the cascading effect abundant reciprocal structure aperiodic superlattice, multiple-wavelength a wide spectrum range can be obtained. Enhancement of conversion efficiency output stability through coupling two nonlinear processes is demonstrated. The result also reveals that process used efficiently downconvert...