左手介质椭圆光波导基模传播特性

在椭圆柱坐标系中,采用分离变量方法,得出了左手介质椭圆光波导本征方程的近似解,通过数值计算,分析了椭圆波导偏心率、左手介质的电容率、磁导率对椭圆光波导基模传播特性的影响,并将左介质光波导与右手介质光波导基模特性进行对比,得出左手介质光波导的基模特性与右手介质光波导基模特性差别不大的结论.     

Highly Luminescent One-Dimensional Organic–Inorganic Hybrid Double-Perovskite-Inspired Materials for Single-Component Warm White-Light-Emitting Diodes

Double perovskites (DPs) are one of the most promising candidates for developing white light-emitting diodes (WLEDs) owing to their intrinsic broadband emission from self-trapped excitons (STEs). Translation of three-dimensional (3D) DPs to one-dimensional (1D) analogues, which could break the octahedral tolerance factor limit, is so far remaining unexplored. Herein, by employing a fluorinated organic cation, we report a series of highly luminescent 1D DP-inspired materials, (DFPD)₂M^IInBr₆ (DFPD=4,4-difluoropiperidinium, M^I=K⁺ and Rb⁺). Highly efficient warm-white photoluminescence quantum yield of 92 % is achieved by doping 0.3 % Sb³⁺ in (DFPD)₂KInBr₆. Furthermore, single-component warm-WLEDs fabricated with (DFPD)₂KInBr₆:Sb yield a luminance of 300 cd/m², which is one of the best-performing lead-free metal-halides WLEDs reported so far. Our study expands the scope of In-based metal-halides from 3D to 1D, which exhibit superior optical performances and broad application prospects.     

An additive function on a ring of integers in the imaginary quadratic field Q(√d) with class-number one

LetB (a) be an additive function on a ring of integers in the quadratic number fieldQ(d) given byB (a) = _p|a *N (p) with a fixed > 0, where the asterisk means that the summation is over the non-associate prime divisorsp of an integera inQ(d), N(a) is the norm ofa. In this paper we obtain the asymptotic formula of _N(a)x *B (a) in the case where the class-number ofQ(d) is one.Project supported by the National Natural Science Foundation of China.     

Fluorescent probe gold nanodots to quick detect Cr(VI) via oxidoreduction quenching process

A method is described here for the quickly(30 s) accurate determination of Cr(VI)(Cr_2O_7~(2-)), based on fluorescent probes gold nanodots(AuNDs, excitation/emission peaks at 395/604 nm) coated with glutathione(GSH). The fluorescence of the AuNDs responses linearly to Cr(VI) concentrations, ranging widely from 1 nM to 10 m M with detection limit as low as 0.35 nM. At the same time, the AuNDs is demonstrated highly selective for Cr(VI) detection over other acid group ions and metal ions without any masking reagent. These make probability for practical use. The quenching mechanism is investigated deeply via fluorescent lifetime, XPS and TEM analysis. Different from most reported quenching explanation of aggregation derived from charge attraction, these results verify the redox reaction between Cr_2O_7~(2-)and sulfhydryl(–S) of GSH. The Au(I)–S bonds of AuNDs broke, accompanies with the oxidation of –S to form S–S bonds. As a result, AuNDs cross linked to each other. In the end, the fluorescence quenched. Attractively, the present study provides a new strategy for pollutant detection, such as from harmful Cr(VI) of Cr_2O_7~(2-)to nontoxic Cr(III).     

Sensing Mechanism of Excited-State Intermolecular Hydrogen Bond for Phthalimide:Indispensable Role of Dimethyl Sulfoxide

Main observation and conclusion Excited-state hydrogen bond strongly affects the intramolecular charge conversion process,which is very suitable for the design ...     

飞秒脉冲展宽器的设计

以群速度色散展宽脉冲理论和基尔霍夫－菲涅耳积分为基础，合理地设计了一种紧凑有效的飞秒脉冲展宽器，不仅获得了较大的脉冲展宽比，而且光束通过展宽器后其空间特性也得到恢复。     

用光束脉冲矩阵研究多色光学谐振腔

用光束脉冲矩阵法分析了多色光学谐振腔的稳定条件；给出了计算腔内净群速度色散的准确表达式。具体分析了一种新型自锁模谐振腔，计算了它的腔内净群速度色散数值，为研究它的锁模机理提供了可靠的数据。     

High gain low noise L-band preamplifier with cascade double-pass structure

An optimized two-stage-cascade double-pass structure L-band preamplifier was proposed and experimentally studied to overcome the shortcomings of low gain coefficient and high noise figure of L-band erbiumdoped fiber amplifier (EDFA). The fiber lengthes of 6.5 and 32.5 m, pump powers of 130 and 119 mW for the first and second stages respectively are used in the experiment. When input signal power is-30 dBm, the amplifier can provide gain above 38.84 dB in a wavelength range of 34 nm (1568-1602 nm), gain ripple less than 2.04 dB (40.88-38.84 dB), and noise figures lower than 5.29 dB with the lowest value of 3.95 dB at 1590 nm. Experimental and simulation results show that this low cost and high pump efficiency amplifier is suitable for the application as an L-band preamplifier in the broadband fiber communication system.     

A generalization of a curious congruence on harmonic sums

Zhao established a curious harmonic congruence for prime :

In this note the authors extend it to the following congruence for any prime and positive integer :

Other improvements on congruences of harmonic sums are also obtained.

     

n-Tuples of positive integers with the same second elementary symmetric function value and the same product

In this paper, by using the theory of elliptic curves, we prove that for every k, there exist infinitely many primitive sets of k n-tuples of positive integers with the same second elementary symmetric function value and the same product.