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Algorithms for wavefront sensing and error correction from intensity attract great concern in many fields. Here we propose Bayesian optimization to retrieve phase and demonstrate its performance in simulation and experiment. For small aberration, this method demonstrates a convergence process with high accuracy of phase sensing, which is also verified experimentally. For large aberration, Bayesian optimization is shown to be insensitive to the initial phase while maintaining high accuracy. The approach’s merits of high accuracy and robustness make it promising in being applied in optical systems with static aberration such as AMO experiments, optical testing shops, and electron or optical microscopes.

We report the amorphization induced high magneto-caloric effect (MCE) of recently developed Gd55Al15Ni30 bulk metallic glass (BMG). The magnetic properties of the Gd55Al15Ni30 BMG are investigated in comparison with that of its crystalline counterpart. It is found that amorphization can increase the saturation magnetization and decrease the hysteresis of Gd55 Al15 Ni30 alloys, which indicate the possible enhancement of MCE. The magnetic entropy changes and the refrigerant capacity of the BMG as well as the crystalline samples is calculated directly from isothermal magnetic measurements. The results show the amorphization induced high MCE of the alloy and the excellent refrigerant efficiency of Gd55Al15Ni30 bulk metallic glass.

The alteration of atomic absorption via quantum coherence is observed in the degenerate two-level atomic system. It is shown that when the detuning of coupling field equals to that of probe light, i.e. two-photon resonance, the reduction of atomic absorption via electromagnetically induced transparency occurs. However, when we tune the coupling field to two-photon off-resonance, the enhancement of absorption is obtained for the probe field. The influences of one-photon detuning and intensity of coupling field on absorption are also experimentally demonstrated.

We investigate the nanostructure, surface plasmon resonance (SPR) absorption and nonlinear enhancement of Au/Ag alloyed hollow nanoshells prepared by the replacement reaction of Ag nanoparticles in a HAuCl4 aqueous solution. As the volume of HAuCl4 increases from 0mL to 0.5 mL, the SPR band of the Au/Ag alloyed nanoshells is tuned from 430 nm to 780 nm, and the third-order nonlinear optical susceptibility is enhanced nearly by an order of magnitude, which indicates a large enhancement of local field in the Au/Ag alloyed hollow nanoshells with hole defects.

The transition process from steady convection to chaos is experimentally studied in thermocapillary convections of floating half zone. The onset of temperature oscillations in the liquid bridge of floating half zone and further transitions of the temporal convective behaviour are detected by measuring the temperature in the liquid bridge. The fast Fourier transform reveals the frequency and amplitude characteristics of the flow transition. The experimental results indicate the existence of a sequence of period-doubling bifurcations that culminate in chaos. The measured Feigenbaum numbers are δ2 = 4.69 and δ4 = 4.6, which are comparable with the theoretical asymptotic value δ = 4.669.

One- and two-photon absorption and excited fluorescence of the CdSe and the core-shell structure CdSe/ZnS quantum dots (QDs) in n-hexane is investigated. The linear and nonlinear absorption coefficients are measured and the two-photon-absorption cross sections of the QDs are also obtained. For both one-photon fluorescence and two-photon fluorescence, the emission efficiency of CdSe/ZnS is much higher than that of CdSe, originating from the effective surface passivation of the core-shell structure.

We demonstrate a fiber Fabry–Perot cavity in the ultraviolet range, which covers the florescence wavelength for the 2P1/2 to 2S1/2 transition of Yb+ and is designed in the bad cavity limit for florescence collection. Benefiting from both the small cavity mode volume and the large atom dipole, a cavity with moderate finesse and high transmission still supports a good cooperativity, which is made and tested in experiment. Based on the measured experimental parameters, simulation performed on the cavity and ion shows a Purcell factor better than 2.5 and a single-mode fiber collection efficiency over 10%. This technology can support ultra-bright single photon sources based on trapped ions and can provide the possibility to link remote atoms as a quantum network.

We investigate the temperature dependence of the dielectric constant of BaTiO3 ceramic with coarse to nano-grain size under different hydrostatic high pressures up to 5000 bar in the range between room temperature and 200°C. The ferroelectric-to-paraelectric phase transition temperatures Tc are determined from the peak of dielectric constant versus temperature. The values of average grain-size are estimated from the SEM images. It is found that the magnitude of dTc/dp varies considerably from sample to sample depending on grain size. The Curie point Tc of the sample with small grain size decreases more sharply than that of samples with larger one.

We present a time-resolved ultrafast measurement in terahertz (THz) frequency region by means of the free-space electro-optic sampling. The fast delay scan technique is used to suppress the noise with low frequency and to improve the signal-to-noise ratio of the system. The transmission spectra of different materials are obtained. The optical properties of these materials in a THz region are shown. The broadening of spectrum and chirping phenomena are illustrated. We find that polystyrene is an excellent material for the THz application.

The atomic structure of a novel rare earth complex consisting of Nd and the sulfur-containing ligand pipdtc (C5H10NCS2-) has been studied with extended x-ray absorption fine structure (EXAFS) and x-ray diffraction techniques. The complex of formula Nd(pipdtc)4N(CH3)4 crystallizes in the monoclinic space group P21/n with the following lattice parameters, a = 22.685(2), b = 20.332(2), c = 17.1270(10)A, β = 100.570(10)°, Z = 8. The calculated density is 1.47 g/cm3. A new derivative method is used to remove the post-edge absorption background including the multielectron excitation effect. The EXAFS results demonstrate that there are about eight S and four O atoms around Nd with the Nd-S bond length of 2.916 A and the Nd-O bond length of 2.415 A, respectively. This implies that the powder of this complex is not stable and is easy to oxidize in air. The possible change of structure before and after oxidation is discussed.

We investigate the power-dependent luminescence of CdSe/ZnS semiconductor quantum dots closely packed layer-by-layer in the proximity of a silver nanorod array cavity. It is found that the emission peak shifts significantly to the longer wavelengths as the excitation power increases, especially when the longitudinal surface plasmon resonance of the Ag nanorod array cavity is adjusted to be close to the emission wavelength. The equivalent gain varies with the coating layer of CdSe/ZnS semiconductor quantum dots and the excitation power is also studied to explain this interesting spectrum-shifting effect. These findings could find applications in the dynamic information processing of active plasmonic and photonic nanodevices.

The nanostructured Au/AgxO/Ag sandwich multilayer films on quartz substrates are prepared by the magnetron sputtering method. The morphology, plasmon resonance and surface enhanced Raman scattering (SERS) activities of the multilayer films are studied. The resonant absorption wavelength of localized surface plasmon is tuned in a wide range from 618 nm to 993 nm by controlling the density of nanoparticles of Au and Ag. The SERS activity of the Au/AgxO/Ag multilayer films are enhanced over ~10 times compared with those of bare Ag and bare Au films. These properties may find a potential application in biosensor and bioimaging.

The concentration dependence of the fluorescence spectra and lifetimes of chlorophyll a and sodium magnesium chlorophyllin are compared to explore the influences of intramolecular relaxation and intermolecular interaction of chlorophylls on the fluorescence dynamics. With different concentrations of chlorophyll a and sodium magnesium chlorophyllin in the suspensions, three different fluorescence emission bands are observed. Intermolecular interactions increase as the concentrations increase, which lead to redshifts in both fluorescence and lifetime spectra. Additionally, the lifetime is increased by re-absorption in the sodium magnesium chlorophyllin suspensions. These observations increase the understanding of the light harvesting and energy relaxation mechanisms of chlorophyll molecules.

The potential energy surfaces and density distributions of ground states in even-mass Be isotopes are studied by using the point-coupling covariant density functional theory with the PC-F1 effective interaction. The clustering structure is exhibited automatically in most of the Be isotopes. The results indicate that 6Be has an α+2p clustering structure, while 8,10,14Be have the 2α clustering structure. The α—α distances and the corresponding quadrupole deformation parameters have a similar evolution trend against the neutron number.

An ultrasonic energy transference system with a ZnO square piezoelectric thin-film array (SPTFA) structure is presented. The design principle of the system is analyzed, and a device with the SPTFA structure is successfully fabricated based on MEMS processes. The characteristics of the energy transference system are investigated in detail. The experimental results reveal that the resonant frequency of the system is 13 MHz, the maximum voltage of the receiving end reaches 10.87 V when the amplitude of excitation voltage is 10 V, at that time the output power of system is 5.377 mW, and power density is 2.581 mW/cm2. The light emitting diode is lit successfully by the system in a distance of 3 mm.

Photoassociation of ultracold atoms is an important method for producing stable ultracold molecules with extensive applications. Ion spectroscopy technique, which has higher sensitivity compared with trap loss spectroscopy and fragment spectroscopy, plays an important pole in the research of photoassociation spectroscopy. Based on ion spectroscopy technique, a complete experimental system is employed to produce and detect the ultracold ground state molecules, including the equipment of photoionization and time-of-fight mass spectroscopy. Ultra-cold ground state cesium molecules are demonstrated by the ionization detection technique. The number of the ground-state molecules produced in our MOT is measured. In addition, the relationship of the time interval of the cesium atom ion and the cesium molecular ion to the metal grid voltage is studied for the optimization of the experimental parameters.

We investigate theoretically the population dynamics and the second-order correlation functions of photon emissions from the biexciton-exciton system of a single quantum dot with excitation from pulses to continuous wave. The dynamic equations of the correlation functions are deduced by applying quantum regression theorem to optical Bloch equations. The influences of excitation pulse width on the correlation function have been discussed in detail.

We theoretically design a single-mode plasmonic ring nanocavity. Based on the plasmonic cavity, the exciton dynamics between two identical quantum dots (QD-p, QD-q) coupled to the nanocavity are investigated. It is shown that the coupling factors gi (i = p, q) between QD-i and surface plasmons are both equal to 12.53meV in our model and exciton population swap between the two QDs can be realized. The periods and amplitudes of population oscillations can be modified by the coupling factors. Our results may have potential applications in quantum information and quantum computation on a chip.

We prepare Nd doped anodic aluminium oxide (Nd: AAO) template by using Nd doped aluminium foils through two-step anodization processes. Photoluminescence (PL) from the Nd: AAO template with the annealing temperature higher than 400°G is observed, and the PL intensity enhanced with the increasing annealing temperature is found. We investigate the crystallization of Nd: AAO template and the excitation wavelength dependence of PL intensity, showing that the PL results from the Nd doped in the template. The approach presented may probably facilitate the fabricating of AAO with good light-emitting property, which can be used in fabrication of multifunctional nanosized films and may find applications in photonic devices.