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We report a family of carbon materials (denoted SFZ8C) prepared from templated carbonization of zeolitic imidazolate framework-8 (ZIF-8) in NaCl–ZnCl2 eutectic salt. The hard-templating effect of the salt is utilized to sustain the framework and maximize the porosity during carbonization. In addition to rich surface nitrogen and oxygen species, SFZ8Cs have large specific surface area. These combined features give rise to excellent adsorption properties for light hydrocarbon gases. SFZ8Cs have both C2H2/CO2 selective and C3/C2 selective adsorption, as well as the ability to selectively remove impurities from methane. Particularly noteworthy is the excellent C3/C2 selective adsorption performance by SFZ8C-900. Its propane/ethane selectivity (7.68) is on par with the best value (7.72) reported so far, yet SFZ8C-900 excels in propane uptake capacity. The multifunctional properties together with the ease for the mass production make SFZ8Cs promising for a number of important applications.

Clinical studies have demonstrated that deep brain stimulation of the anterior nucleus of the thalamus (ANT) is a safe and effective treatment for focal epilepsy and drug-resistant epilepsy. However, the mechanism of action of ANT deep brain stimulation, especially in terms of neuromodulatory circuits, is not fully understood. In this study, we evaluated the anatomical and functional connectivity of the ANT in rats. For anatomical connectivity, herpes simplex virus (HSV) and pseudorabies virus (PRV; Bartha stain) were focally injected into the ANT of rats to label the connected brain structures in the retrograde and anterograde directions, respectively. For functional connectivity, we used c-Fos mapping in conjunction with electrical stimulation of the ANT to map the brain structures functionally connected to the ANT. Circuit connectivity mapping revealed that the ANT was connected to the hippocampus, the nucleus accumbens, the dorsal part of the lateral septal nucleus (LSD), the amygdala, the secondary motor cortex (M2), the cingulate cortex, the substantia nigra, the hypothalamus, and other regions. The ipsilateral connections were stronger than the contralateral connections. Deep brain stimulation of the ANT resulted in c-fos expression in the cortex, hippocampus, amygdala, striatum and hypothalamus, with the strongest activation in the hippocampus. These results suggest that the ANT has a wide range of structural and functional connections, which may underlie the effectiveness of deep brain stimulation in treating epilepsy. DATA AVAILABILITY STATEMENT: The datasets generated for this study are available on request to the corresponding author.

The theoretical expression of the Gaussian beams carried singular Lissajous lines passing through an astigmatic lens is derived, which is used to study evolution behavior of singular Lissajous lines in the presence of an astigmatic lens. The singular Lissajous lines are unstable and disappears after passing through the lens. Being different from the case of a singular Lissajous line in which appearance of no singularities or only one singularity takes place, more singularities may appear in the field. Comparisons with the interaction of two singular Lissajous line in free-space propagation and in the presence of an ideal lens are made.

The TSC1 gene is a tumor suppressor gene that encodes for the growth inhibitory protein hamartin. It was founded clinically relevant to tuberous sclerosis complex (TSC) and related epilepsy. Variants in TSC1 resulted in tuberous sclerosis, focal cortical dysplasia (FCD) Type II, pulmonary lymphangioleiomyomatosis and change in everolimus sensitivity. Here, we generated induced pluripotent stem cells (iPSC) from a normal individual by electroporation of peripheral blood mononuclear cells (PBMC), and further generated TSC1-knockout human iPSC line via CRISPR/Cas9 gene editing. The resulting iPSCs had normal karyotype, free of genomically integrated epitomal plasmids, expressed pluripotency markers, and maintained trilineage differentiation potential.

To improve the optical performance of the large-aperture optical antenna, the Cassegrain splicing receiving antenna consisting of spherical sub-mirrors with different curvatures is designed and optimized based on the three-dimensional (3-D) vector theory of rotation and reflection. Compared with the splicing antenna consisting of spherical sub-mirrors with the same curvatures, the antenna proposed in this paper can decrease the root mean square (RMS) of the spot radius at the receiving plane from 0.0202223 m to 0.0109724 m, and the spot size decreases 45.74%. Besides, the influence of on-axial defocusing and incident ray tilt on the performance of the optical antenna is analyzed. This paper provides not only a new antenna with better performance but also a new idea for designing large-aperture splicing optical antennas.

Optimization of electrocatalysts' geometry structure for making them stabilized and more active sites exposed or accessible is one of keys to design the electrocatalysts with highly active and durable oxygen reduction reaction (ORR) performance. Herein, we designed and reported a novel metal-sulfide-based host-guest electrocatalyst with the apparently-instable Cu2S nanoparticles (NPs) cage-confined into chalcogenide semiconductor zeolite (RWY). Such in-situ-formed composite electrocatalyst was built by diffusing Cu2+ ions into the nanocages of RWY via a facile ion exchange and subsequent etching processes. The obtained composite electrocatalysts with various amount of Cu2S (denoted as Cu2S@RWY-x%, x represents for weight percent of Cu2S) display superior ORR activity, especially for Cu2S@RWY-48.6% showing the best catalytic activities in an alkaline solution with the onset potential of 0.90 V (vs. RHE), quasi-four-electron transfer pathway, and small Tafel slope (69 mV/dec). Importantly, the superior ORR performance from the apparently-inactive guest Cu2S NPs is for the first time explored, which is ascribed to the host-induced stabilization and the optimized balance between catalysts’ loading and their accessibility. This work holds great promising for exploring other cage-confined metal-chalcogenide NPs for the applications in other electrocatalytic fields.

GdTaO4 is a type of excellent materials that can be used as scintillation, laser matrix as well as self-activated phosphor has generated significant interest. Whereas its band structure, electronic structure and optical properties are still need elucidation. To solve this intriguing problem, high-quality GdTaO4 single crystal (M-type) was grown successfully using Czochralski method. Its structure as well as optical properties was determined in experiment. Moreover, a systematic theoretical calculation based on the density function theory methods were performed on M-type and M′-type GdTaO4 and their band structure, density of state as well as optical properties were obtained. Combine with the performed experiment results, the calculated results were proved with high reliability. Hence, the calculated results obtained in this work could provide a deep understanding of GdTaO4 material, which also useful for the further investigation on GdTaO4 material.

The space division multiplexing system is helpful to break through the transmission limitations of traditional optical communication systems. Inter-fiber separation and the number of alternating dielectric layers of Bragg fibers array (BFA) are considered with view to applying BFA to space division multiplexing system. The simulation results indicate that BFA with improper inter-fiber separation will result in topological edge state, thus leading to strong crosstalk and high confinement loss, and its crosstalk is hard to decrease with the increase of alternating dielectric layers. The confinement loss of each Bragg fiber in BFA with proper inter-fiber separation is greatly lower than that of traditional Bragg fiber with the same parameters. Our optimized BFA can be realized with low crosstalk of below −30 dB for 55.4 km propagation. In addition, the arrangement analysis of BFA in this paper provides some constructive suggestions for the application of traditional Bragg fiber in optical devices design such as BFA laser and omnidirectional emitting laser.

The laser beam with asymmetric divergence angle distribution generated by a laser diode (LD) terribly restricts its application in space laser communication. In this paper, an off-axis transmitting antenna with two parabolic cylindrical reflective mirrors is designed to simultaneously shape, collimate and transmit the laser beam. The simulation results demonstrated that the ratio of beam waist (RBW) of the output beam can be reduced from 2.9998 to 1.0003 and the maximum divergence angle of the output light is compressed to 3.98 μ rad. The performance of the system is evaluated under different astigmatism of LD and different transmitting distance. Compared with previous methods, the method proposed in this paper has three main advantages: non-dispersion, fewer reflective mirrors and processing convenience. This paper may not only provide engineers with more practical beam-shaping systems but also provided idea to the designers of off-axis system

In space optical communication system, the beam received by the Cassegrain receiving antenna needs to be coupled into the single-mode fiber before being detected. In this paper, a concave lens and a set of positive–negative angular cone lenses structure are designed to change the hollow beam generated by the Cassegrain receiving antenna into a solid beam. The coupling efficiencies for the hollow beam and solid beam are analyzed and numerically simulated. The simulation results show that the coupling efficiency can be improved and reaches the optimum value 0.808 after the hollow beam is changed into solid beam. Moreover, when the coupling lens and the fiber are not perfectly aligned, the coupling efficiency of the solid beam is larger than the hollow beam. The research results provide a way to improve the coupling efficiency of the Cassegrain receiving system and have practical application in the space optical communication system.

Reported here are two solvothermally synthesized metal selenides, namely [Cu2MSe5][Mn(H+-en)2(en)] (M = Ge (1) and Sn (2), and en=ethanediamine). The two isostructural compounds feature a 1-D anionic chain of [Cu2MSe5]4- with the existence of strong Cu∙∙∙Cu interaction. The estimated optical band gap was determined to be 1.69 eV for 1 and 1.49 eV for 2, indicating their semiconducting nature. Interestingly, 2 exhibits NIR-triggered photoelectric response, which make it potential semiconductor sensor used in photoelectric devices.

In order to investigate the effect of mating type and ploidy on enzymatic activity and fermentation performance in yeast with multiple δ-integrated foreign genes, eight ploidy series strains were constructed. The initial haploid strain BGL-a was shown to contain about 19 copies of the bgl1 gene. In rich media containing 2% (w/v) sugar the specific activities of BGL-aα were lower than those of BGL-aa or BGL-αα, which indicates the existence of mating type effects. While the maximum OD660 decreased with rising ploidy, the biomass yield showed no significant difference between the eight strains and the specific activities (expressed as U/mL or U/mg DCW) showed little to no variation. When cellobiose was used as the carbon source and β-glucosidase substrate, β-glucosidase was expressed more quickly and at higher levels than in glucose-containing media. The maximum specific activitiy values obtained were 19.07U/mL and 19.39U/mL for BGL-αα and BGL-aa, repsectively. The anaerobic biomass and ethanol-producing performance in rich media containing 10% cellobiose showed no significant difference among the eight strains. Their maximal ethanol concentrations and corresponding yields ranged from 40.27 to 43.46g/L and 77.56 to 83.71%, respectively. When the acid- and alkali-pretreated corncob (10% solids content) was used, the diploid BGL-aα fermented the best. When urea was used as the only supplemented nutrient, the ethanol titer and yield were 35.65g/L and 83.69%, respectively, while a control experiment using industrial Angel yeast with exogenous β-glucosidase addition gave values of 37.93g/L and 89.04%. The combined effects of δ-integration of bgl1, ploidy and mating type result in BGL-aa or BGL-αα being the optimal choice for enzyme production and BGL-aα being more suitable for cellulosic ethanol fermentation. These results provide valuable information for future yeast breeding and utilization efforts.

In order to reduce the chromatic aberration problem of the multiple wavelength, reflex cassegrain antenna is widely used in space optical communication system. There are many external factors such as temperature and vibration that may cause defocusing in practice which has influence on Cassegrain antenna. That is to say, the primary mirror's and the secondary mirror's focus cannot be coincided, so it will bring impact greatly on transmission efficiency. This paper studies the effects on the transmission characteristics of the defocused Cassegrain antenna system. While defocused 2.5 cm, the transmission efficiency of Cassegrain antenna will decrease 80% of the initial efficiency. So it is very important to maintain optimum position for high transmission efficiency.

In this paper, a method to suppress the higher-order modes in the negative curvature anti-resonance hollow core fibers (NC-AR-HCFs) by utilizing multiple resonant coupling is proposed. With this method, a hollow core fiber is designed. Based on multiple resonant coupling, the loss of LP11 mode even reaches more than 105 dB/km orders of magnitude over a wide wavelength band, and the loss ratio of LP11 mode to LP01 mode of the proposed fiber remains above 105 orders of magnitude in the range of 1200 ∼ 1550 nm, which shows excellent single-mode operation. The effect of multiple resonant coupling and the effective suppression of further-higher-order modes (LP21 mode and LP02 mode) are analyzed in detail. Moreover, we demonstrate that the extra loss caused by the node effect is reduced by changing the thickness of the outer tube that decreases the fractional optical power of the outer tube wall. And the restrictive relation between the higher-order modes suppression and the reduction of bend loss is discussed. The analysis guides the design of NC-AR-HCFs with effectively suppressing higher-order modes.

Cassegrain antenna is a very important type of optical antenna, which is widely used in space optical communications. However, the secondary mirror barrier may cause lower transmission efficiency in practice. This paper studies the factors affecting the transmission efficiency of the Cassegrain antenna system. Then, a series of optimum structure parameters are obtained, achieving a transmission efficiency of 91.6%. Therefore, this antenna can increase the transmission efficiency to a great extent in optical communication systems.

Cassegrain antenna has excellent transceiver characteristics, it is widely used in inter-satellite communication. Most researchers are only based on the on-focus antenna system. But in fact, some unpredictable factors, like slight impact or thermal deformation may make the primary and secondary mirror cannot be exactly on-focus. Therefore, the off-focus Cassegrain optical antenna system with incident Gaussian beam are researched in the paper. We conclude that the far field transmission gain is more sensitive to the wavelength of the laser than the energy in off-focus system. So in practical application, we must mainly consider the influence of wave length to the transmission gain. If the secondary mirror is set off-focus by 0.05 mm, the gain will change 20.9474 dB with long wave 1550 nm, and 79.8526 dB with short wave 633 nm. So use long wave laser in off-focus system is better.

The propagation constant expression and the field distribution by employing the boundary conditions and QWS condition have been derived. The longitudinal and azimuthal fields have been discussed by the simulation method. We have mainly analyzed the HE 11 mode and figured out the guided flux of the core. By comparing the energy flux of different eccentricity situations, we obtain that the circular waveguide theory may be a particular case of the elliptical one. The process of ellipse tends to split the field into parts, which are in direct proportion to the mode orders.

In this paper, the energy loss caused by the secondary mirror of Cassegrain antenna has been discussed numerically. As the diameter of the secondary mirror is one-fifth of the primary mirror, the loss goes beyond 18.5%. Because of the alignment of the optical system being the significant factor, it influences the transmission quality of the optical antenna system. We analyze and numerically simulate how power attenuation ratio and gain of Cassegrain antenna vary with the antenna deflection, and measure the distance such that the central axis of the receiving antenna deviates from the z -axis in case of occurrence of off-axis space in the system. Finally, an optimum structure is proposed by trepanning the secondary mirror.

A special conical lens and photonic crystal reflector are used to increase transmission efficiency of the Cassegrain antenna. Gauss beam is shaped into a hollow beam which could avoid the loss of energy caused by the subreflector center reflection in the Cassegrain antenna, and the transmission efficiency in the space optical communication system will be greatly enhanced. A one-dimensional (1D) photonic crystal reflector is designed to reduce energy absorption. Thus transmission efficiency of the whole system can be almost close to 100% in theoretical aspects. It is pretty significant for space optical communication of transmission long distances.

A new crystal of Yb-doped gadolinium niobate, 5 at.% Yb:GdNbO 4 , is grown by Czochralski method for the first time. The structure of Yb:GdNbO 4 is determined by Rietveld refinement to the X-ray powder diffraction data and it belongs to the monoclinic space group of I 2/a . With the center of 955 nm, the FWHM of absorption spectra is 57 nm and the absorption cross section is calculated to be 0.97 × 10 −20 cm 2 . Spectral parameters are calculated with absorption spectrum. In emission spectra, the strongest peak is at 1001 nm and the FWHM is 49 nm. In comparison with corresponding emission cross section of Yb:YSO and Yb:GSO, Yb:GdNbO 4 exhibits a relatively larger emission cross section. In addition, a maximal output power of 270 mW is obtained and the slope efficiency is 7.5%.

Recently, we proposed GdTaO4 as a promising high-density scintillator but the scintillation mechanism was still unknown. In this paper, we investigated the temperature-dependent luminescent properties of GdTaO4 crystal. The emission spectra are characterized by a broad band composed of two Gaussian components located at ~2.2 eV and ~2.7 eV of 8–300 K, which are both thermally quenched with the activation energy of 156 meV and 175 meV, respectively. These two bands are believed to be from different luminescent centers, judging from the excitation spectra, thermal activation energy and decay curves. Additionally, it was also found that the annealing atmosphere exerts little influence on the luminescence intensity. Based on the results, we tentatively assigned the high-energy band to self-trapped excitons (STE) localized in TaO 4 3 − groups and the low-energy band to relaxed excitons related to lattice imperfections.

Nd 3+ doped M′-LuTaO 4 phosphor, with high density (9.8 g/cm 3 ) and relatively fast decay time (261 ns), is a potential heavy scintillator. In this work, Nd:LuTaO 4 is codoped with La 3+ or Sc 3+ ion and its structure and luminescent properties as a function of their concentration are studied. The structural parameters are obtained by Rietveld refinement. The strongest emission peak is located at 419 nm which corresponds to the 4 D 3/2 → 4 I 13/2 transition of Nd 3+ . The decay times of 4 D 3/2 → 4 I 13/2 transition in Nd/La:LuTaO 4 and in Nd/Sc:LuTaO 4 are much shorter than that in Nd:LuTaO 4 , which decrease to 211 ns and 163 ns, respectively. It is also found that the decay time of 4 D 3/2 → 4 I 13/2 transition in Nd/La:LuTaO 4 increases with the increase of La content, and the decay time of 4 D 3/2 → 4 I 13/2 transition in Nd/Sc:LuTaO 4 decreases with the increase of Sc content. Besides, the mechanism is discussed respectively.

Based on the analysis of semiconductor laser-diode array (LDA) beam characteristics, a new scheme of beam collimation and focusing is proposed. The elliptical micro-lens shaping the beam of LDA has been analyzed by theoretical and simulated by optical ray tracing. The efficiency for laser beam coupling into the optical fiber is 73.2% of the whole system.

A promising new type of inorganic scintillation material, M′-type Lu 1− x Nd x TaO 4 , was successfully synthesized by a solid reaction method. The structure of the material was determined by Rietveld refinement of X-ray diffraction data. The calculated density of Lu 1− x Nd x TaO 4 is 9.53–9.67 g cm −3 , which is the greatest among current inorganic scintillators. Upon light excitation at 355 nm, the dominant emitting transitions of Nd 3+ were 4 D 3/2 → 4 I 13/2 and 4 D 3/2 → 4 I 15/2 . The concentration dependences of the fluorescence intensity and fluorescence lifetime of the 4 D 3/2 → 4 I 13/2 transition in Lu 1− x Nd x TaO 4 were explored. It was inferred that the optimal doping concentration of Nd 3+ was approximately 5.4% and the fluorescence lifetime of the 4 D 3/2 → 4 I 13/2 transition in the zero-concentration limit was approximately 263.2 ns. The material is suggested to be a potential heavy scintillator due to its high density and fast luminescence decay.

A new Nd 3+ doped GdTaO 4 crystal (having density of 8.83 g cm −3 ) was successfully grown by the Czochralski method. The as-grown crystal was with dimension of Φ 30 mm×50 mm. The structure parameters were refined by Rietveld method to X-ray powder diffraction. The photoluminescence spectra including emission, excitation and decay curves were measured. The photoluminescence decay times were determined to be 20.7 ns (7.73%) and 496 ns (92.27%) monitored at 417 nm, and 463 ns monitored at 453 nm, respectively. In addition, the radioluminescence spectrum was given and discussed. The scintillation decay constants were 46.4 ns (48%) and 1199.7 ns (52%). Compared with GdTaO 4 , the scintillation decay of Nd:GdTaO 4 was faster and the percent of the fast component was remarkably increased. Besides, the light yield of Nd:GdTaO 4 can be estimated to be equal to that of GdTaO 4 . All these results suggest that the Nd:GdTaO 4 crystal can be expected as a potential heavy and fast scintillator.

Three kinds of aspheric collimation lenses for optical antenna have been design by optimization. The aspheric cylinder collimation lenses with aspheric surfaces (such as elliptic, hyperbolic and parabolic marginal profiles) have been researched for the semiconductor laser beam with the characteristic of dot emitting source. Based on genetic algorithm and the optimization toolbox of MTLAB, the divergence angle has been optimized. The collimation divergence angle is less than 115 μrad has been measured by laser beam analyzer. This optimum design laser beam collimation lenses as a pre-collimation system can be used for optical antenna system. And it can be widely used in modern space laser communication.

A new kind of smoothly deformed Bragg fiber structure has been proposed in this paper, and the mode field characteristics about this fiber have been analyzed. By comparing the field at different coordinates along the propagation direction, the evolution of the field for the elliptical transverse faces and the circular one is obtained. The method has also been used to detect the behavior of the elliptical Gaussian beam. This research method can be used to analyze the thermal deformation of fiber.

A new Cr,Yb,Ho,Eu:YAlO3(YAP) laser crystal was successfully grown by the Czochralski method. Thermal properties were investigated along the a, b, and c crystalline axes. Results indicate that the Cr,Yb,Ho,Eu:YAP crystal has large anisotropic thermal expansion and that the suitable crystal growth direction is the b axis. The Debye temperatures were fitted, and the lattice vibration frequencies were calculated. Spectroscopic measurements show that Cr3+ and Yb3+ can be used as sensitizers of Ho3+ ions, and Eu3+ ions can play a role of the deactivator in decreasing the lifetime of laser lower level 5I7 from 8.69 ms to 1.89 ms, which is beneficial in decreasing laser threshold and increasing laser conversion efficiency. All these findings suggest that the Cr,Yb,Ho,Eu:YAP crystal is a new potential candidate for realizing 2.8–3 μm laser output pumped by a 970 nm laser diode or pulsed flash lamp.

Because the energy loss caused by the secondary mirror of Cassegrain antenna is seriously, an optimum structure is designed to improve the transmitting energy of Cassegrain optical system. It is made up of Cassegrain antenna and Double pyramidal system. The parameter of Cassegrain antenna has been analyzed, and it has been revealed that relationship between the Double pyramidal system and Cassegrain antenna. Finally, the relationship between the optimum parameters of Cassegrain and the transmitting efficiency has been researched. Through this optimum structure, the emitting power can be achieved to 91.5%.

The propagation properties of a pair of Lissajous singularities with opposite singularity indexes called the Lissajous singularity dipole (LSD) in free space are studied analytically and illustrated numerically. It is shown that the motion, creation, annihilation and change in the degree of polarization of the LSD, and change in the shape of Lissajous figures take place by suitably varying the waist width, off-axis distance or propagation distance. In particular, the creation and shift to infinity of a single Lissajous singularity may appear. A comparison with the free-space propagation of an optical vortex dipole and a C-dipole is also made.

Strong green upconversion (UC) emissions induced by a 940 nm laser have been observed in a series of Er 3+ , Yb 3+ co-doped LiYMo 2 O 8 samples. The diffuse reflectance absorption spectra show that the co-doped samples can absorb the photons in the range of 900–1050 nm efficiently, demonstrating the excellent sensitization effect of Yb 3+ ions. Based on power switched UC luminescence, UC mechanisms are discussed, and the emission spectra excited by 490 nm are also measured to give additional evidence. The results reveal that application of these phosphors may improve the conversion efficiency of DSSCs.

The propagation of a pair of vortices nested in a Gaussian beam through a tilted lens is studied. It is shown that after passing through the tilted lens, the relation between the transverse position of vortices and the tilt coefficient is linear in the propagation for isopolar vortex pair and vortex dipole, and in the three-dimensional (3D) case the vortex trajectories are sometimes like U or X shapes. With increasing the orientation angle of the vortex pair, the trajectories of vortices are circles for the both cases. The overlap of vortices may take place for the isopolar vortex pair, while the annihilation and revival of vortices occur for the vortex dipole in the propagation.

According to the analysis of different discontinuous images of target, the precision of the images can be increased for lidar imaging, and the deviation of the variation of the vertical and horizontal distance between targets has been analyzed. The laser divergence angle has been briefly analyzed under the laser arrays for realistic measurements and also gave the image restoration of target.

The interaction of the Lissajous singularity and singular Lissajous line in the presence of an astigmatic lens is studied. It is found that the singular Lissajous line is usually unstable, and disappears after passage through the lens. The creation and annihilation of one or two Lissajous singularities may take place by varying the astigmatic coefficient, off-axis parameter, and propagation distance. A comparison with the interaction of the Lissajous singularity and singular Lissajous line in the free-space propagation and in the presence of an ideal lens, and with the vortex–edge dislocation interaction is made. The results are illustrated numerically and interpreted analytically.

Ho:LuGG single crystal was successfully grown by the Czochralski growth method, and its lattice parameter was found to be 12.2371 A. Its thermal conductivity was measured to be 5.29 W mK −1 at 300 K. Meanwhile, transmission spectra were recorded at room temperature, and then its absorption spectra were obtained combining with the transmission spectra of LuGG crystal. The transition intensity parameters Ω t ( t = 2, 4, 6), the oscillator strengths, fluorescence branching ratios, transition probabilities and the lifetimes of Ho 3+ in LuGG crystal were all evaluated by the Judd–Ofelt theory. Furthermore, its emission spectra were also determined and analyzed.

The eigen-beams of orbital angular momentum (OAM) have helical wavefront and can be used to construct the channels for free space optical communication, i.e. orbital angular momentum multiplexing (OAMM). It is similar to time-division multiplexing (TDM) and wave-division multiplexing (WDM). We generate four helical beams with different OAM numbers by fork-like grating and modulates them mechanically. The modulated helical beams are then superposed coaxially into one single complex beam. In the receiver, the complex beam is separated into four helical beams with little mutual interference. The experimental results demonstrate the feasibility of OAMM by using the eigen-beams of orbital angular momentum.

By detailed analysis of Cassegrain optical antenna with inclined optical axis, the receiving antenna power and the curve of power attenuation are obtained for different deflection angles. Three-dimensional images which describe the power distribution of the receive laser beam have been obtained. The coupling efficiency of antenna system is obtained from specific experiment. If the deflection angle is less than 0.1519 rad, the coupling efficiency is beyond 80%. In this case, the optical antenna system can be viewed as in alignment approximately. This research will provide a theoretical base and broad application for achieving precise alignment of optical axis in the field of optical communications and three-dimensional laser radar images.

The propagation characteristics which are influenced by the structures of Bragg fibers have been researched in this paper. Simulation software has been set up to analyze periodic structure, pseudo-periodic structure and non-axial symmetric structure for Bragg fibers. Three dimensional field distributions and the axial propagation flux characteristics which are influenced by the number of radial cladding for high and low refraction index media have been researched by computer simulation. Optimum structure simulation design has an important meaning for the manufacture of Bragg fibers.

A new method based on the Transfer Matrix Theory of Bragg fiber to research a Bragg fiber with defect state has been developed in this paper. The distribution of the electromagnetic field in the Bragg fiber is analyzed, and the loss and efficiency of the Bragg fiber are also estimated based on optical power confinement factor Γ . Thereby, the influence of the defect for transmitting characteristics in Bragg fiber has been researched.

A steady thermal model of photonic-bandgap fiber laser (PBFL) is presented. Temperature distribution in PBFL is analyzed by heat transfer equations and numerical finite-element method (FEM) separately. Thermal stress distribution caused by the temperature difference between the inner and outer claddings is calculated. The results show that the thermal stresses in this fiber structure are low less than the critical tensile stress in fused silica.

Based on vectorial Debye diffraction theory, the focusing properties of stochastic electromagnetic Gaussian Schell-model beams in the focal region of high numerical aperture objective are investigated. Expressions for the intensity distribution and the degree of polarization are derived near the focus. Numerical calculations are performed to analyze the influences of varying corresponding parameters on the changes in the intensity distribution and in the degree of polarization in the focal region.