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Reproductive activities of six giant panda females (Ailuropoda melanoleuca) living in the Qinling Mountains of China (Shaanxi Province) were recorded from 1989 into early 1995. Data on mating and birth dates, litter size, cub sex and den use were collected for three of the pandas. At this site, pregnant females migrated to lower elevations in advance of other pandas to seek dens for birthing. One dam was videotaped in the den with her cub from birth to the end of the denning phase at 94 days of age. This cub was repeatedly handled during the dam's absences to obtain data on development and weight. During the early part of the denning phase, the cub was maintained on the dam's body virtually continuously. Postpartum fasting for up to 3 weeks was noted. Dams invariably moved cubs to new dens three or four times during the birth season. By the time cubs left the den at about 3± 4 months, they were fully furred and capable of surviving winter temperatures without further shelter. Reproductive parameters for the wild population fell within the range of values for captive pandas, based on information in the literature and in the giant panda studbook. The combined data on length of gestation, intervals between births, litter size and weight, infant development, and reproductive life span reveal a range of life-history variables that strongly resemble the Ursidae.

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of these perovskite-based photodetectors decreases to almost zero when the incident light wavelength is in the nearinfrared range due to the threshold of the material bandgap width at 760 nm. To improve the optical response of the perovskites in the near-infrared range, many chemical processings were explored, such as mixing of different perovskites [19][20][21][22] and doping of other materials. [23][24][25] Unfortunately, these chemical methods might induce the distortion of perovskite lattice and damage the device performance. [26] Metal nanostructures under light illumination can give rise to localized surface plasmon resonance (LSPR), [27,28] which induces strong light scattering and absorption. [29][30][31][32][33] Randomly inserting metal nanostructures into perovskite-based devices, such as solar cells [34][35][36][37] and photodetectors, [38,39] can improve photoresponse ability at the visible range. However, the response of these perovskite-based devices at the near-infrared range is still very weak.Here, we report a perovskite-based photodetector with high photoresponsivity in the near-infrared range that was fabricated on a well-defined plasmonic-functionalized multilayer substrate that was composed of arrays of Au nanosquares/SiO 2 spacer/ Au film. Due to the strong plasmonic coupling between the substrate and the incident light, a great amount of free carriers are generated in the perovskite film. As a consequence, a wider optical spectrum response and a better external quantum efficiency (EQE) in the near-infrared range were achieved, compared with the perovskite film on a usual Si/SiO 2 substrate. In addition, a sequentially tunable spectral response range of our device can be realized by varying the size of Au nanosquares.The schematic of our photodetector device is shown in Figure 1a, where the plasmonic substrate was designed to consist of three functional layers, arrays of Au nanosquares at the top, a SiO 2 dielectric spacer in the middle, and an Au film at the bottom. The perovskite (CH 3 NH 3 PbI 3 ) and hole-transporting medium (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F 4 -TCNQ)-doped poly [bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) solution, abbreviated as HTM) were spin-coated onto the substrate. The HTM layer, incorporated between the substrate and CH 3 NH 3 PbI 3 layer, serves two functions: harvesting holes from the CH 3 NH 3 PbI 3 layer and insulating the transfer of hot electrons from the decay of LSPR. The incident Organic-inorganic hybrid perovskite photodetectors have been reported to possess superior optoelectronic properties, such as high sensitivity, ultrafast response, and capability of strongly absorbing the light in the visible range. While in the near-infrared range, the performances of these photodetectors deteriorate seriously, originating from the weak coupling of infrared light to the perovskites. In this study, an organic-inorganic hybrid perovskite photodetector on arrays of Au nanostructures is fabricated, which exhibits a remarkable photocur...

It is studied the bright spatial solitons in nonlocal defocusing Kerr media with parity-time (PT) symmetric potentials. We find that these solitons can exist and be stable over a different range of potential parameters. The influence of the degree of nonlocality on the solitons and the transverse energy flow within the stable solitons are also examined. c 2018 Optical Society of America OCIS codes: 190.3270,190.6135. Generally, defocusing Kerr nonlinearity can induce an enhanced beam broadening so that it does not support any localized structures other than vortex and dark solitons, which require background beams [1, 2]. However, the bright solitons, which were thought to exist only for focusing nonlinearity [1], can in fact exist in periodic photonic lattices or waveguide arrays with defocusing nonlinearity [3][4][5]. This means that the strong transverse periodic refractive index potentials can not only suppress the beam broadening due to diffraction but also overcome the broadening effect due to the defocusing Kerr nonlinearity [1]. The nonlocal nonlinear behavior in a system is related to the change of nonlinear refractive index, which depends not only on the intensity of a local beam but also on the intensity of the surrounding region due to a specific distribution [6]. The nature and extent of nonlocality substantially depend on the materials. Principally, new effects attributed to nonlocality have been studied in thermo-optic media [7], photorefractives [8], and liquid crystals [9, 10].The definition of PT potentials and their properties were discussed in the past few years [11][12][13]. The real part of PT symmetric potentials must be a symmetric function of position, while the imaginary component should be antisymmetric. Recently, parity-time symmetric potentials have been introduced into optical field [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. However, thus far all studies focus on bright solitons in self-focusing optical PT symmetric media, and bright spatial solitons in nonlocal Kerr self-defocusing media with a single PT complex potential are never reported.In this paper, we investigate the bright spatial solitons in nonlocal defocusing Kerr media with parity-time (PT) symmetric potentials. It is found that these selftapped states can exist and be stable over a different range of potential parameters. In addition, we show the influence of the degree of nonlocality on the solitons and the transverse energy flow within the stable solitons.In a nonlocal Kerr self-defocusing medium with PT symmetric potentials, the one-dimensional optical beam evolution is governed by the following normalized nonlinear Schrödinger-like equation for q and φ, which are respectively the dimensionless light field amplitude and the nonlinear correction to the refractive index [14][15][16][17][18][19][20][21][22][23][24][25],where z is the propagation distance, V (x) and W (x) are the real and the imaginary components of the complex PT symmetric potential, respectively. V (x) is an even function and W (x) i...

We report the existence and stability of gap solitons in parity-time (PT) complex periodic optical lattices with the real part of superlattices. These solitons can stably exist in the semi-infinite gap. We have studied the effects of different relative strengths of the superlattices and different amplitudes of the imaginary part on soliton propagation. It was found that the relative strength of the superlattices and the amplitude of the imaginary part significantly affect the PT symmetry and the stability of solitons in the PT complex periodic optical lattices.

Manipulation of light-matter interaction is critical in modern physics, especially in the strong coupling regime, where the generated half-light, half-matter bosonic quasiparticles as polaritons are important for fundamental quantum science and applications of optoelectronics and nonlinear optics. Two-dimensional transition metal dichalcogenides (TMDs) are ideal platforms to investigate the strong coupling because of their huge exciton binding energy and large absorption coefficients. Further studies on strong exciton-plasmon coupling by combining TMDs with metallic nanostructures have generated broad interests in recent years. However, because of the huge plasmon radiative damping, the observation of strong coupling is significantly limited at room temperature. Here, we demonstrate that a large Rabi splitting (~300 meV) can be achieved at ambient conditions in the strong coupling regime by embedding Ag-WS 2 heterostructure in an optical microcavity. The generated quasiparticle with part-plasmon, part-exciton and part-light is analyzed with Hopfield coefficients that are calculated by using three-coupled oscillator model. The resulted plasmon-exciton polaritonic hybrid states can efficiently enlarge the obtained Rabi splitting, which paves the way for the practical applications of polaritonic devices based on ultrathin materials.

We numerically study the gray solitons in parity-time (PT) symmetric potentials. Simulated results show that there are two kinds of gray solitons, the dip-shaped gray solitons and the hump-shaped solitons, and both of them can be stable. Hump-shaped solitons can always exist, but the grayness of a stable dip-shaped gray soliton should exceed a threshold value. More interesting, it is discovered that when propagating in PT symmetric potentials, the gray solitons have no transverse deviation, and this is a phenomenon different from the usual gray solitons.