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Unlike traditional symmetrical vortex beams, we demonstrate one kind of asymmetric spatial modes, namely Lommel-Gaussian (LMG) mode carrying orbital angular momentum (OAM) for optical communications, which possesses higher channel capacity through orthogonal multiplexing process. Some unique properties, such as better detection probabilities of high-order modes compared with low-order modes, are experimentally observed and well explained using theoretical models based on Rytov approximation method. An efficient scheme to generate LMG superposition states for OAM mode multicasting and multiplexing is proposed. Also, some critical issues, such as mode mismatching, still need further investigations. This work inspires us to explore more spatial multiplexing approaches, whose distinctive properties may open up new prospects for future communications systems.

In vitro culture is employed as a means of producing plant materials from medicinal plants to meet the increasing demands of the market. Herein, we focused on an efficient protocol for organogenesis through two pathways in six explant types from Caryopteris terniflora Maxim (C. terniflora), a medicinal and ornamental plant. For direct organogenesis, the maximum number of shoots per internode explant (62.5) was achieved on Murashige and Skoog (MS) medium containing 3.0 mg L−1 thidiazuron (TDZ) and the maximum number of shoot tips per explant (45.5) was obtained by 1.5 mg L−1 TDZ, with 100% response. A protocol was also developed for indirect organogenesis from leaf, leaf-petiole, petiole, and root explants on MS basal medium containing a range of TDZ concentrations. Leaf-petiole explants induced more adventitious shoots (57.6 per explant) and leaves (31.4 per explant) than petioles (37.5 per explant) or roots (25.0 per explant), and the differentiation rate ranged from 87.2 to 100%. The regenerated shoots were elongated on MS medium containing 0.3 mg L−1α-naphthaleneacetic acid (NAA) and 1.0 mg L−1 gibberellic acid (GA3). The elongated shoots developed roots on ½ MS medium containing 0.3 mg L−1 NAA. Successful acclimatization of rooted plantlets in a greenhouse was achieved with 100% survival. Furthermore, the embryogenic-like structure was observed and the morphological characteristics of C. terniflora assessed at different stages of in vitro development. Our protocol offers, for the first time, an efficient, scalable propagation procedure for C. terniflora useful for large-scale cultivation for the purposes of conservation and genetic manipulation.

An important technology to realize human computer interaction is the technology of converting a given text into natural speech, that is speech synthesis. This paper succinctly expounds the development process of speech synthesis, analyzes the shortcomings of traditional speech synthesis technology, and highlights the advantages and disadvantages of various vocoders. Due to the overwhelming contribution of deep learning to the field of speech synthesis, this paper introduces several pioneering research results in the field of speech synthesis, expounds its main ideas, advantages and disadvantages, and inspires new ideas on this basis. Finally, it objectively discusses and analyzes the problems of speech synthesis technology and puts forward the direction that can be further studied.

Thin-film lithium niobate (LN) has been proved to be an excellent platform for building compact active and nonlinear photonic components on a chip. The coupling of a sub-micron sized LN waveguide and a single-mode fiber remains as one challenging issue. An efficient grating coupler made of Au stripes on an LN ridge waveguide is demonstrated here. The fabrication of the grating is convenient, using just a standard lift-off process of metal films. The peak coupling efficiency of an optimized structure reaches 50.4%, i.e., −3 dB coupling loss, at 1.55 µm wavelength for the fundamental transverse-electrical mode, where the 1-dB coupling bandwidth is 58 nm. Experimentally, fabricated devices, with buried oxide layer thicknesses slightly off the optimal values, exhibit coupling efficiencies of 43.8% and 33.7% for 400 nm and 600 nm thick LN layers.

Background: As a highly valued medicinal plant, Salvia plebeia R. Brown belongs to the Lamiaceae family that has been subjected to over exploitation in its natural habitat for phytochemical and pharmacological studies. Alternative collection methods need to be developed for the large-scale propagation of Salvia plebeian. Results: Here, efficient and simple, direct organogenesis (from shoot tips and cotyledonary nodes explants) and Globular bodies (GBs) induction (from hypocotyl explants) systems were developed for the in vitro propagation of Salvia plebeia. The highest and number of regenerated shoots (7.0±0.82) per shoot tips was obtained on Murashige and Skoog (MS) medium supplemented with a combination of 0.1 mg L-1 indole-3-acetic acid (IAA) and 1.0 mg L-1 6-benzyladenine (6-BA), the proliferation of shoots and shoots rooted were carried out on the same medium treatments almost synchronously. Similarly, MS medium supplemented with 0.1 mg L-1 IAA and 1.0 mg L-1 thidiazuron (TDZ) yielded the maximum number of shoots (37.5±1.34) with 100% shoot sprouting frequency. Simultaneously, a protocol was developed for GBs induction from hypocotyl explants, and it produced 17.4 GBs per explant with 82.7% response on MS medium supplemented with TDZ (1.0 mg L-1) and IAA (0.1 mg L-1), and produced GBs that were morphologically similar to globular embryos and successfully germinated on hormone-free MS medium. The acclimatized plantlets with well-developed root systems were successfully shifted to the natural soils with a 100% survival rate. Conclusions: Taken together, this protocol can be efficiently used for mass propagation, germplasm preservation and likely also for gene transfer of Salvia plebeia.

Two-dimensional grating couplers are important components for silicon photonic circuits to achieve light coupling from/to a fiber for both polarizations. A two-dimensional grating coupler structure with a high coupling efficiency and a low polarization dependent loss is demonstrated. Using two crossing ellipses as the grating scatter and a diamond-like grating lattice, the polarization dependent loss of the grating coupler can be reduced. The coupling loss is further decreased with a metal mirror, which reaches −1.73 dB theoretically at 1310 nm wavelength. Experimentally, −2.37 dB coupling loss is achieved with an 1 dB coupling bandwidth of 29 nm. The corresponding PDL was measured lower than 0.2 dB in a wavelength range of 78 nm. The proposed configuration for the metal mirror also facilitates a robust wafer-scale post-processing as well as an easy fiber alignment.

Unlike traditional symmetrical vortex beams, we demonstrate one kind of asymmetric spatial modes, namely Lommel-Gaussian mode carrying OAM for optical communications, which possesses higher channel capacity through orthogonal multiplexing process.

We demonstrate the first high-speed LiNbO3 thin-film optical modulators operating at 2 μm wavelength. The measured L is 3.67 V·cm, and the electro-optic bandwidth is > 22 GHz (beyond the measurement limit of photodetector).

Alnus cremastogyne is a broad-leaved tree species with fast-growing and promising nitrogen-fixing capacity. Its plantation is under steady growing due to the commercial and restoration importance in China. However, little is known about the effects of projected climate change on its adaptability and future distribution. In the present study, we simulated the ecological suitability of A. cremastogyne under three climate change scenarios (CCS) (i.e., SSP1-2.6, SSP2-4.5 and SSP5-8.5) in 2050 s and 2070 s using geographic information technology (GIS) and maximum entropy model (MaxEnt). The results demonstrated that under current climate situation, the highly suitable areas were mainly located in central and eastern Sichuan, most of Hunan, central and northern Jiangxi, central and eastern Guizhou, most of Chongqing and southeast Hubei, with a total area of 52.1 × 104 km2. The areas of the moderately and poorly suitable areas were 65.52 × 104 km2 and 92.99 × 104 km2, respectively. Under the future CCS, both the highly suitable area and the total suitable area of A. cremastogyne showed increasing trends, 1.22-fold and 1.57-fold higher for highly suitable area by 2050, 1.27-fold and 1.41-fold by 2070, respectively. While the areas of the poorly suitable areas would decline. Moreover, a northwestward migration of the geometric center of the total suitable area was projected. Annual precipitation (5.9–1314.5 mm), the minimum temperature of coldest month (-0.2–16.8 ℃) and the mean temperature of coldest quarter (0.7–11.7 ℃) were the three most important environmental variables determining the distribution of A. cremastogyne. Our results highlight the plasticity of A. cremastogyne to climate change and also the feasibility of intercropping with this species to improve soil nitrogen availability.

Neoseiulus californicus McGregor is a specialized predator of Tetranychidae mites. Recently, commercially produced N. californicus have been shown to be effective in the integrated management of pest mites in scientific trials, and this has attracted the attention of both entomologists and the agricultural industry. In this study, we collected geographic location information on N. californicus, used MaxEnt to simulate its potential suitable distribution in China, and discussed the dominant environmental variables restricting its geographical distribution. The highly suitable areas were mainly located in Hunan, Sichuan, Zhejiang, Fujian, Guangxi, Jiangsu, Anhui, Guangdong, Guizhou, Chongqing, Yunnan and Jiangxi, and the total area was 106.82 × 104 km2. Moderately and lowly suitable areas were 91.44 × 104 km2 and 19.04 × 104 km2, respectively. The key climatic variables affecting the distribution of N. californicus were the maximum temperature in November (11.31–25.7 °C), maximum temperature in the warmest month (25.02–33.91 °C), precipitation in the coldest quarter (125.17–586.87 mm), precipitation in April (48.67–472.71 mm), precipitation in October (60.8–378.18 mm) and temperature seasonality (97.79–836.85).

The thin-film lithium niobate structure has been used recently to construct compact and high-performance electro-optical modulators. Due to the moderate electro-optical coefficient of the lithium niobate material, the device length of such a modulator is still long, a few centimeters usually. Here, a folded Mach–Zehnder interferometer based modulator on x -cut thin-film lithium niobate is demonstrated. An effective poling procedure is developed to activate the device. The proposed modulator structure can shorten the device length without affecting its performance. The measured V π L product of a fabricated and completely poled folded modulator is about 2 .74 V ⋅ c m , and the 3 dB electro-optical bandwidth is about 55 GHz. They are close to those of a conventional Mach–Zehnder modulator with a straight modulation section.

We propose a novel orbital angular momentum (OAM) space division multiplexing system based on Lommel–Gaussian (LMG) beam, which utilizes different transverse wavenumbers under the same topological charge. Using the random phase screen method and diffraction theory, the evolution of light field and mode crosstalk are effectively analyzed during transmission. Owing to the non-diffracting feature, LMG beams are more robust than traditional Laguerre–Gaussian (LG) beams through spatial spectrum analysis under the same intensity. More importantly, the results show that the shape of demultiplexed spot is related to the symmetry of original OAM-carrying beam and LMG beams with smaller scaling factor are better for detection. This work is anticipated to open up new perspectives for future high-capacity communication missions.

Optical communication wavelength is being extended from the near-infrared band of 1.31/1.55 µm to the mid-infrared band of 2 µm or beyond for satisfying the increasing demands for high-capacity long-distance data transmissions. An efficient electro-optic (EO) modulator working at 2 µm is highly desired as one of the indispensable elements for optical systems. Lithium niobate (LiNbO3) with a large second-order nonlinear coefficient is widely used in various EO modulators. Here, we experimentally demonstrate the first Mach-Zehnder EO modulator working at 2 µm based on the emerging thin-film LiNbO3 platform. The demonstrated device exhibits a voltage-length product of 3.67 V·cm and a 3-dB-bandwidth of >22 GHz which is limited by the 18 GHz response bandwidth of the photodetector available in the lab. Open eye-diagrams of the 25 Gb/s on-off keying (OOK) signals modulated by the fabricated Mach-Zehnder EO modulator is also measured experimentally with a SNR of about 14 dB.

The sex-related spatial heterogeneity of gas exchange rates over the leaf surface under salt stress was investigated in the dioecious species, Populus cathayana Rehd. Cuttings were subjected to two salt regimes: 0 and 75 mM NaCl added to the Hoagland solution, the control and the treatment group, respectively. Measurements of gas exchange parameters were taken from over 40 sites on the surfaces of representative ‘non-stressed’ and ‘salt-treated’ leaves which had the same insertion point for two sexual cuttings. Compared to the control group, the treatment group showed a significant decrease in the mean values of the following: water use efficiency (WUE), Chlorophyll a (Chl a) concentration, chlorophyll b (Chl b) concentration, concentration of carotenoids (Caro), total chlorophyll concentration (TC) in two sexes, and net photosynthesis rate (P n), stomatal conductance (g s), and stomatal length/width ratio (SR) in females. Also, in the treatment group, females exhibited lower WUE, P n, g s, E, Chl a, Chl b, TC, and SR than males. Comparison of contour maps showed that the net photosynthesis rate decreased gradually from apical to basal zones over the leaf surface occurred in the two sexes under natural conditions, but under salt stress, the opposite trend was found in females only. The results suggest that the heterogeneity pattern of the gas exchange parameters in response to salt stress between the two sexes is quite different due to different strategies employed by males and females to maintain the photosynthesis rate under salt stress. This heterogeneity phenomenon under salt stress may mainly be attributed to the chlorophyll pigments in males and the stomatal apertures in females.