Design and optimization of with low weakly-coupled few-mode fiber nonlinearity

By investigating the influence of the difference of refractive index between core and cladding （nco - ncl）, normalized frequency （V） and core radius （α） on both the intramodal and intermodal nonlinear coefficients （NCs） respectively, we design a novel weakly-coupled four-mode fiber with low nonlinearity. In general, under the premise of ensuring the low NCs between two non-degenerate modes, this design can reduce the intermodal NCs （〈 0.5 W-l·km^-1） between two degenerate modes and optimizes the parameters of differential group delays （DGDs） and chromatic dispersion. The optimized few mode fiber （FMF） is eligible for transmission and mode de-multiplexing in the receiver.     

Magnetic properties of two-dimensional charged spin-1 Bose gases

Within the mean-field theory, we investigate the magnetic properties of a charged spin-1 Bose gas in two dimensions. In this system the diamagnetism competes with paramagnetism, where the Landé factor g   is introduced to describe the strength of the paramagnetic effect. The system presents a crossover from diamagnetism to paramagnetism with the increasing of the Landé factor. _gc$g_c$ denotes the critical value of the Landé factor. We get the same value of _gc$g_c$ both in the low temperature and strong magnetic field limit. Our results also show that in very weak magnetic field no condensation happens in the two-dimensional charged spin-1 Bose gas.     

Design of dispersive multilayer with particle swarm optimization method

<正>We present a new and efficient method for the design of dispersive multilayer by employing a particle swarm optimization(PSO) technique.Its mathematical background is given and an adaptive PSO is realized with computer code.Two practical designing tasks are solved with this method,and the obtained results are competitive compared with other published structures.The adaptive PSO method demonstrates its merits of fast convergence and powerful global search ability,and could be used as a valuable tool for the optical thin film design.     

Fault tolerant three-party quantum secret sharing against collective noise

We present two robust three-party quantum secret sharing protocols against two kinds of collective noise. Each logical qubit is made up of two physical qubits and is invariant under a collective noise. The two agents encode their message on each logical qubit with two unitary physical operations on two physical qubits. As each logical qubit received by each agent can carry two bits of information and the classical information exchanged is reduced largely, these protocols have a high intrinsic efficiency. Moreover, the boss Alice can read out her agents' information with two Bell-state measurements on each four-qubit system, not four-photon joint measurements.     

Optical responses of dilute anisotropic composites：numerical calculations via Green‘s function formalism

We investigate the linear and nonlinear optical responses of dilute anisotropic networks using Green's function formalism [Gu Y et al 1999 Phys. Rev. B 59 12847]. For different applied fields, numerical calculations indicate that a large third-order nonlinear enhancement and a broad infrared absorption arise from the geometric anisotropy. We also show the overlap and separation between the absorption peak and nonlinear enhancement peak when the applied field is parallel and perpendicular to the anisotropy, respectively. The results can be understood in terms of the inverse participation ratios with q=2 and the spectral distribution of optical responses.     

The coexistence of TE-TM surface waves in uniaxially anisotropic left-handed materials

We investigate theoretically the characteristics of surface waves in uniaxially anisotropic left-handed materials. The constraints for the existence of TE and TM polarized surface waves in uniaxially anisotropic left-handed materials are identified. We discuss mainly whether TE and TM polarized surface modes may coexist in the same frequency domain at the interface between one isotropic regular medium and another uniaxially anisotropic left-handed medium. It is shown that the answer to the coexistence of TE and TM surface modes is really positive. The Poynting vector and the density of energy associated with surface modes are calculated. Depending on the system parameters either TE or TM surface modes has the time averaged Poynting vector directed opposite or same to the mode phase velocity. In the presence of anisotropy, negative refraction does not need to be left-handed. We show that the characteristics of surface waves in uniaxially anisotropic left-handed media are significantly different from that in isotropic left-handed media.     

可调谐二极管激光吸收光谱法测量气体温度

研究了一种新型的非接触式测温技术——可调谐二极管激光吸收光谱(TDLAS)测温技术。介绍了温度测量及调制吸收光谱技术原理,分析了调制幅度对气体温度测量的影响。优选了氧气吸收谱线对13163.78 cm-1和13164.18 cm-1,在搭建的高温实验系统上,实现了气体温度和浓度的同时测量。通过分析实测波形获得了谱线13164.18 cm-1在823~1323 K温度范围内的碰撞展宽系数和温度指数。实验结果表明,在823~1323 K温度范围内,系统温度测量的线性误差为0.65%,最大波动为±15 K。     

莴苣种子的生长与低温保存研究

文中主要介绍高原莴苣种子生长和低温保存时的相关性,为保护保存该种子提供理论和实验依据。种子在低温和适宜温度两种不同情况下培养,进行实验比较,得出低温预培养的种子对于低温保存无作用;快速降温下,DSC曲线出现两个波峰HTE和LTE,当温度低于LTE时,无种子发芽存活;慢速降温下,DSC曲线只有一个波峰HTE;随着温度降低,种子发芽率降低,当温度低于-40℃时,无种子存活。     

Decay of 1.643 h <Superscript>95</Superscript>Ru and its daughter's level structure

The decay of ⁹⁵Ru has been investigated by means of γ-ray spectroscopy. The ⁹⁵Ru nuclei were produced by the reaction ⁹²Mo( α, n) ⁹⁵Ru at a beam energy of 17MeV. High-purity Ge detectors have been used singly and in coincidence to study γ-rays in the decay of ⁹⁵Ru to ⁹⁵Tc. 132 γ-rays are reported, among them, energies and intensities for 127 transitions have been determined. A decay scheme of ⁹⁵Ru with 31 levels is proposed which accommodates 127 of these transitions. Spins and parities for three new levels are proposed from calculated log ft values, measured γ-ray branching ratios, and in-beam experiment results of the daughter nucleus ⁹⁵Tc. Combining with the high-spin states observed by in-beam γ-ray spectroscopy of previous decay works, the structure of the excited states of ⁹⁵Tc is discussed in the framework of the projected shell model.     

Dark energy and neutrino CPT-violation

In this paper we study dynamical CPT-violation in the neutrino sector as induced by the dark energy of the universe. Specifically we consider a dark energy model where the dark energy scalar derivatively interacts with the right-handed neutrinos. This type of derivative coupling leads to cosmological CPT-violation during the evolution of the background field of the dark energy. We calculate the induced CPT-violation of left-handed neutrinos and find that the CPT-violation produced in this way is consistent with the present experimental limit and sensitive to future neutrino oscillation experiments such as the neutrino factory. PACS 95.36.+x; 14.60.St