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Nd-doped GdVO4(Nd:GdVO4) films with a-axis preferred orientation were fabricated on SiO2/Si substrate by pulsed-laser deposition. Fluorescences at around 1065.0 and 1342.5 nm, corresponding to 4F3/2→4I11/2 and 4F3/2→4I13/2 transitions, respectively, were excited simultaneously with an 808 nm diode laser. Waveguide behaviors in the film were investigated by using the prism coupling technique at the wavelength of 632.8 nm. Both TE and TM mode spectra revealed that favorable light confinements were achieved within the Nd:GdVO4 waveguide layer. Additionally, the optically anisotropic properties of the film were studied in detail. [ABSTRACT FROM AUTHOR]

An efficient generation of red light in a periodically-poled nearly-stoichiometric LiTaO3 (PPSLT) by extracavity single-pass frequency doubling of a diode-pumped, Q-switched Nd:YVO4 laser at 1342 nm was realized. An average power of 1.4 W of the 671 nm red light is obtained at the fundamental power of ∼2.8 W with the conversion efficiency of 50%. The high conversion efficiency and steady output of red light indicate that the thick PPSLT is a competitive candidate for frequency conversion in order to construct a compact all-solid-state red laser. [ABSTRACT FROM AUTHOR]

We demonstrate simultaneous quasi-continuous wave generation of red, yellow, green and blue coherent radiation based on quadruple quasi-phase matching (QPM) frequency upconversion from a single, aperiodically poled LiTaO[sub 3] (APPLT) crystal with a diode-pumped Nd:YVO[sub 4] dual-wavelength laser oscillating at 1342 and 1064 nm. We designed and prepared an APPLT crystal, which can provide four pertinent reciprocals for simultaneous quadruple QPM processes. Namely, frequency doubling of 1342 nm generates red light at 671 nm, sum-frequency mixing of 1342 nm and 1064 nm produces yellow light at 593 nm, frequency doubling of 1064 nm achieves green light at 532 nm and sum-frequency mixing of 1342 nm and 671 nm obtains blue light at 447 nm. [ABSTRACT FROM AUTHOR]

To explore the physiological response characteristics of plant photosynthesis under acid precipitation stress (A stress), snow-melting agent stress (S stress), and freeze-thaw stress (F stress) as well as their various combinations, the net assimilation rate (NAR), intercellular CO2 concentration (Ci), stomatal conductance (Gs) and water use efficiency (WUE) of tall fescue (Festuca arundinacea Schreb.) under these three stresses respectively and four kinds of combined stresses were measured. The effects of these different kinds of stresses on the photosynthesis parameters were then evaluated, and the major mechanisms of main factors affecting the interactions between stresses were speculated. The experimental results indicated that both NAR and WUE decreased significantly in response to all stresses and Ci increased dramatically in response to all stresses, while Gs ascended under F stress but descended in response to A stress and S stress. The photosynthetic efficiency significantly decreased as the temperature decreased and did not clearly recover as the temperature increased. Moreover, the combination of A stress and S stress had fewer effects on photosynthesis than did the S stress alone, while the effects resulting from F stress were similar at low temperature. The major controlling mechanism is most likely the strong inhibition of photosystem II and the promotion of antioxidant enzymes resulting from acid precipitation as well as NaCl may strengthen the freezing tolerance of plants. [ABSTRACT FROM AUTHOR]

We report a compact all-solid-state mid-infrared optical parametric oscillator with wide tunability using periodically poled 5 mol % MgO-doped LiNbO3 with a multiple-channel structure design and pumped by a compact diode-pump solid-state laser operating at 1.064 μm. Wide tunability from 1.44 to 1.58 μm at the signal beam wavelength and from 3.28 to 4.11 μm at the idler beam wavelength was achieved by both varying the temperature and translating the crystal through the resonator and the pump beam with no realignment required. The tuning performance and its related factors were analyzed, and at the same time the output performance as well as the effect of mid-infrared absorption of idler beam was investigated. [ABSTRACT FROM AUTHOR]

A scatheless visualization has demonstrated that the engineered and spontaneous domains of lithium niobate (LiNbO3) crystal can be delineated by means of the nanoparticle decoration. These nanoparticles were monodispersed in nonpolar solvent and negatively charged under the existence of aerosol-OT (AOT or sodium di-2-ethylhexylsulfosuccinate). This method was based on the process of electrostatic interaction, in which the LiNbO3 crystal wafers were heated in the presence of decorating colloid solvent. The charged nanoparticles deposited preferentially on the surfaces of those domains with the opposite charges. The delineated patterns corresponded with the polarization property of domain structures and consequently provided a domain contrast image with resolution down to micron scale. This decoration technique is effective, easily operated, nondestructive for sample, noninvasive for human body, and especially, is more suitable for the domain mapping of oxide ferroelectric crystals. In addition, the initial exploration of the model of such decoration process is also presented in this article. [ABSTRACT FROM AUTHOR]

In this letter we report the experimental result on the study of light scattering in a one-dimensional quasiperiodically poled LiTaO3 crystal. The infrared scattering signal in the crystal was upconverted into visible band by sum frequency with incident light, forming a set of coaxial conical second harmonic beam with a quasiperiodic ratio at the radius. The quasi-phase-matching significantly enhanced such a nonlinear interaction. The angular distribution of scattering light in crystal was extracted from the experimental result. This reveals a possible application of quasiperiodic structure on the study of light scattering. [ABSTRACT FROM AUTHOR]

Background: The choice of general anaesthetics may affect postoperative cognitive outcomes. This study was designed to compare the potential impact of propofol-based vs sevoflurane-based general anaesthesia on the development of delayed neurocognitive recovery in older adults early after major cancer surgery.Methods: Older adults (aged ≥65 and <90 yr) who were scheduled to undergo major cancer surgery (≥2 h) were randomised to receive either propofol- or sevoflurane-based general anaesthesia. Cognitive function was assessed before and 1 week after surgery with a battery of neuropsychological tests. Age- and education-matched non-surgical controls were recruited, and their cognitive functions were tested at comparable time intervals in order to adjust for learning effects from repeated tests. Delayed neurocognitive recovery was diagnosed according to the International Study of Postoperative Cognitive Dysfunction 1 definition.Results: From April 1, 2015 to October 15, 2016, 392 patients were enrolled and randomised. Of these patients, 387 completed the intervention and 30-day follow-up, and 379 completed 1-week neuropsychological tests. Fifty-nine control subjects were enrolled and completed repeated neuropsychological tests. The incidence of delayed neurocognitive recovery at 1 week was significantly lower in the propofol group [14.8% (28/189)] than in the sevoflurane group [23.2% (44/190); odds ratio=0.577; 95% confidence interval, 0.342-0.975; P=0.038]. Safety outcomes did not differ between the two groups.Conclusions: When compared with sevoflurane-based general anaesthesia, propofol-based general anaesthesia might decrease the incidence of delayed neurocognitive recovery in older adults after major cancer surgery.Clinical Trials Registration: NCT02662257; Chinese Clinical Trial Registry (identifier: ChiCTR-IPR-15006209). [ABSTRACT FROM AUTHOR]

We report a quasi-white-light laser, which was generated by an all-solid-state laser technique. The approach is to use a cascaded optical superlattice in a LiTaO3 crystal to directly frequency double and triple a diode-pumped, Q-switched dual-wavelength Nd:YVO4 laser. Three primary color lights, red at 671 nm, green at 532 nm, and blue at 447 nm, were simultaneously generated in a proper proportion, forming a quasicontinuous, quasi-white-light laser with a maximum output power of 530 mW under a pump power of 18 W. From the result, a more effective quasi-white-light output can be anticipated if the superlattice is fabricated in a stoichiometric LiTaO3 crystal and the double resonant technique is further optimized. [ABSTRACT FROM AUTHOR]

MgO-doped congruent Lithium Niobate (MgO:CLN) is widely used in a variety of nonlinear optical processes, while its Sellmeier equation has only been derived from experiments under 200°C. Here we extend the temperature range for the Sellmeier equation study to as wide as 60 °C to 510 °C. This work is important to extend the operation temperature range of MgO:CLN crystal. [ABSTRACT FROM AUTHOR]

Nonlinear frequency conversion is promising for manipulating photons with orbital angular momentum (OAM). In this letter, we investigate the second harmonic generation (SHG) of light beams carrying fractional OAM. By measuring the OAM components of the generated second harmonic (SH) waves, we find that the integer components of the fundamental beam will interact with each other during the nonlinear optical process; thus, we figure out the law for topological charge transfer in frequency doubling of the fractional OAM state. Theoretical predictions by solving the nonlinear coupled wave equations are consistent with the experimental results. [ABSTRACT FROM AUTHOR]

In this letter, we demonstrate the realization of nonlinear Cherenkov difference-frequency generation (CDFG) exploiting the birefringence property of KTiOPO4 (KTP) crystal. The pump and signal waves were set to be along different polarizations, thus the phase-matching requirement of CDFG, which is, the refractive index of the pump wave should be smaller than that of the signal wave, was fulfilled. The radiation angles and the intensity dependence of the CDFG on the pump wave were measured, which agreed well with the theoretical ones. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate multiple copies of optical orbital angular momentum (OAM) states through quasi-phase-matched (QPM) second-harmonic (SH) generation in a 2D periodically poled LiTaO3 (PPLT) crystal. Since the QPM condition is satisfied by involving different reciprocal vectors in the 2D PPLT crystal, collinear and noncollinear SH beams carrying OAMs of l2 are simultaneously generated by the input fundamental beam with an OAM of l1. The OAM conservation law (i.e., l2 = 2l1) holds well in the experiment, which can tolerate certain phase-mismatch between the interacting waves. Our results provide an efficient way to obtain multiple copies of the wavelength-converted OAM states, which can be used to enhance the capacity in optical communications. [ABSTRACT FROM AUTHOR]

A consequent tendency toward high-performance quantum information processing is to develop the fully integrated photonic chip. Here, we report the on-chip generation and manipulation of entangled photons based on reconfigurable lithium-niobate waveguide circuits. By introducing a periodically poled structure into the waveguide circuits, two individual photon-pair sources with a controllable electro-optic phase shift are produced within a Hong-Ou-Mandel interferometer, resulting in a deterministically separated identical photon pair. The state is characterized by 92.9 ± 0.9% visibility Hong-Ou-Mandel interference. The photon flux reaches ∼ 1.4 × 107 pairs nm-1mW-1. The whole chip is designed to contain nine similar units to produce identical photon pairs spanning the telecom C and L band by the flexible engineering of nonlinearity. Our work presents a scenariofor on-chip engineering of different photon sources and paves the way to fully integrated quantum technologies. [ABSTRACT FROM AUTHOR]

One of the most fascinating predictions of the theory of general relativity is the effect of gravitational lensing, the bending of light in close proximity to massive stellar objects. Recently, artificial optical materials have been proposed to study the various aspects of curved spacetimes, including light trapping and Hawking radiation. However, the development of experimental 'toy' models that simulate gravitational lensing in curved spacetimes remains a challenge, especially for visible light. Here, by utilizing a microstructured optical waveguide around a microsphere, we propose to mimic curved spacetimes caused by gravity, with high precision. We experimentally demonstrate both far-field gravitational lensing effects and the critical phenomenon in close proximity to the photon sphere of astrophysical objects under hydrostatic equilibrium. The proposed microstructured waveguide can be used as an omnidirectional absorber, with potential light harvesting and microcavity applications. [ABSTRACT FROM AUTHOR]

An integrated realization of photonic entangled states becomes an inevitable tendency toward integrated quantum optics. Here we report the compact engineering of steerable photonic path-entangled states from a monolithic quadratic nonlinear photonic crystal. The crystal acts as a coherent beam splitter to distribute photons into designed spatial modes, producing the heralded single-photon and appealing beamlike two-photon path entanglement. We characterize the path entanglement by implementing quantum spatial beating experiments. Such a multifunctional entangled source can be further extended to the high-dimensional fashion and multiphoton level, which paves a desirable way to engineering miniaturized quantum light sources. [ABSTRACT FROM AUTHOR]

We worked out a new group of collimated plasmon beams by the means of in-plane diffraction with symmetric phase modulation. As the phase type changes from 1.8 to 1.0, the beam undergoes an interesting evolution from focusing to a straight line. Upon this, an intuitive diagram was proposed to elucidate the beam nature and answer the question of whether they are nondiffracting or linear focusing. Based on this diagram, we further achieved a highly designable scheme to modulate the beam intensity (e.g., "lossless" plasmon). Our finding holds remarkable generality and flexibility in beam engineering and would inspire more intriguing photonic designs. [ABSTRACT FROM AUTHOR]

We report a direct observation of guided-mode interference in polymer-loaded plasmonic waveguides by the technique of leakage radiation microscopy (LRM). Spatial beating patterns of the interferences were clearly characterized with respect to different structural parameters, and the interference properties were analyzed in detail. Besides, the capability of LRM for characterizing the multiple modes was also discussed extensively. Our finding not only offers an efficient technique in analyzing the guided modes and their interference, but also provides a definite guideline in evaluating the validity of LRM and deepens further studies on the dielectric-loaded hybrid waveguide system. [ABSTRACT FROM AUTHOR]

We observe multiple simultaneous cascaded-χ(2) Cˇerenkov conical radiations in radially poled nonlinear photonic crystals. By using two incident fundamental waves ω1 and ω2, a variety of cascaded nonlinear up-conversion processes occur which result in high-frequency Cˇerenkov radiations at 2ωi+ωj(i,j=1,2) exhibiting as multicolor conical beams. Two types of phase-matching geometries with different emission angles are demonstrated for each kind of cascaded-χ(2) Cˇerenkov radiation. The external angle of the Cˇerenkov radiation exhibits strong dependence on the fundamental wavelengths. The experimental results agree well with the theoretical calculations. [ABSTRACT FROM AUTHOR]

We demonstrate that both linear and nonlinear Fano resonances can be realized on two dimensional magnetic metamaterials. The Fano resonance comes from the interference between localized magnetic plasmon resonance and propagating surface plasmon polaritons. When studying the linear optical response of the metamaterial structure, this interference phenomenon was observed in the ellipsometric spectrum. By finely tailoring the geometrical parameters of the magnetic metamaterial device, the nonlinear Fano response was tuned to a near-infrared wavelength (1.61-1.8 µm) of femtosecond pump laser, and Fano-type modulation of the third harmonic generation was found and agrees well with our theoretical model. [ABSTRACT FROM AUTHOR]

We report an experimental realization of a plasmonic Airy beam, which is generated thoroughly on a silver surface. With a carefully designed nanoarray structure, such Airy beams come into being from an in-plane propagating surface plasmon polariton wave, exhibiting nonspreading, self-bending, and self-healing properties. Besides, a new phase-tuning method based on nonperfectly matched diffraction processes is proposed to generate and modulate the beam almost at will. This unique plasmonic Airy beam as well as the generation method would significantly promote the evolutions in in-plane surface plasmon polariton manipulations and indicate potential applications in lab-on-chip photonic integrations. [ABSTRACT FROM AUTHOR]

In this paper, the plasmon coupling effect between two gold nanospheres on a gold slab is investigated. At plasmon resonance frequencies, electrons on the surface of the slab are absorbed into spheres and contribute to plasmon oscillation. This effect can enhance the local electric field and optical coupling force between the two spheres. [ABSTRACT FROM AUTHOR]

The pathophysiology of post-operative cognitive dysfunction remains unclear and there is no widely accepted animal model that can simulate its occurrence. The purpose of this study was to explore the effects of surgical stress on long-term post-operative memory function in mice of different ages. Healthy C57Bl/6J male mice, of either 4- or 16-month-old, were each randomly divided into three subgroups. (1) Control group: neither anesthesia nor surgery was performed; (2) Anesthesia group: general anesthesia was administrated, surgery was not performed; (3) Surgery group: two-thirds partial hepatectomy was completed in about 15 min under general anesthesia. Morris water maze test was performed after 30 days. In mice of both month-ages, the escape latencies as well as the swimming distances decreased significantly across training days ( P<0.001). In 4-month-old mice, there were no significant differences among three subgroups. In 16-month-old mice, the escape latency was significantly less in the surgery group than in the control group ( P=0.001), and the swimming distance was significantly shorter in the surgery group than in the control and the anesthesia groups ( P=0.001 and 0.047, respectively). In the spatial probe test, time spent in the target quadrant was significantly longer in the surgery group than in the combined control and anesthesia group ( P=0.037). Partial hepatectomy did not produce significant long-term effects on memory function in 4-month-old mice. However, it significantly improved long-term memory function in 16-month-old mice. [ABSTRACT FROM AUTHOR]

This study is to assess the difference between IV-G and IV-S in a large cohort of Chinese patients with lupus nephritis. The detailed data of patients with subclass IV-G and IV-S were retrospectively analyzed. Serum ANCA and anti-C1q antibodies were detected. A total of 172 cases were classified as class IV, including 152 cases with IV-G and 20 cases with IV-S. In IV-S, the level of haemoglobin was significantly higher (P = 0.024), proteinuria was milder (P = 0.003), serum creatinine was lower (P = 0.021), serum C3 was higher (P = 0.045) and the ratio of positive serum anticardiolipin antibodies was higher (P = 0.014). On pathological evaluation, the ratio of glomerular fibrinoid necrosis was significantly higher (P = 0.006) and the score of endocapillary hypercellualrity, interstitial inflammation and total activity indices was significantly lower (P < 0.001, P = 0.01, P = 0.006, respectively) in IV-S. The frequency of serum ANCA was significantly higher in IV-S than that in IV-G (20 vs 4.6%, P = 0.008). The frequencies of anti-C1q IgG1 and IgG3 subclass were significantly higher in IV-G (P = 0.006, P = 0.011, respectively). There are significant differences in clinical and pathological manifestations between IV-S and IV-G lupus nephritis which need further investigation. [ABSTRACT FROM AUTHOR]

The three-color continuous-variable entanglement directly produced by a cascaded nonlinear process in an optical superlattice was investigated theoretically. This cascaded nonlinear process can be realized by using quasi-phase-matching technique in a quasiperiodic superlattice. In the first step, signal- and idle-beams can be generated by a parametric down-conversion. Then, the third beam can be obtained through sum-frequency of idle and pump. The degree of quadrature phase amplitude correlations between the three modes was discussed by a sufficient inseparability criterion with a single inequality for continuous-variable entanglement. [ABSTRACT FROM AUTHOR]

High power red light was generated from a periodically-poled stoichiometric LiTaO3 (PPSLT) by single-pass frequency doubling of a diode-side-pumped, Q-switched Nd:YAG laser at 1319 nm. An average power of 2.4 W of the 660 nm red light was obtained at the fundamental power of ∼5.4 W with the conversion efficiency up to 44.4% and with low fluctuation down to 2%. The high efficiency and stability at the red output indicate that it is a practical method to construct a reliable compact red laser. [ABSTRACT FROM AUTHOR]