On the cut-off in two dimensional guiding center plasmas

We derive a thermodynamically extensive expression for the energy of the two dimensional guiding center plasma. The energy value for onset of “negative temperature” states is evaluated and its physical meaning in terms of the long wavelength cut-off is elucidated.     

Continuous transfer and laser guiding between two cold atom traps

We have demonstrated and modeled a simple and efficient method to transfer atoms from a first Magneto-Optical Trap (MOT) to a second one. Two independent setups, with cesium and rubidium atoms respectively, have shown that a high power and slightly diverging laser beam optimizes the transfer between the two traps when its frequency is red-detuned from the atomic transition. This pushing laser extracts a continuous beam of slow and cold atoms out of the first MOT and also provides a guiding to the second one through the dipolar force. In order to optimize the transfer efficiency, the dependence of the atomic flux on the pushing laser parameters (power, detuning, divergence and waist) is investigated. The atomic flux is found to be proportional to the first MOT loading rate. Experimentally, the transfer efficiency reaches 70%, corresponding to a transfer rate up to 2.7×10⁸ atoms/s with a final velocity of 5.5 m/s. We present a simple analysis of the atomic motion inside the pushing–guiding laser, in good agreement with the experimental data.     

Coupling of two parallel multimode parabolic index waveguides: An exact analysis in the weakly guiding approximation

A model analysis of a guiding structure consisting of two parallel multimode parabolic-index waveguides in the weakly guiding approximation has been presented. Such structures are expected to play an important role as directional couplers in data bus systems, etc. The modes thus obtained have been used to study the power exchange between the two waveguides and a simple analytical expression has been obtained for the coupling length in a case of practical importance.     

Antiresonant guiding optofluidic biosensor

We propose a novel optofluidic biosensor in which detection is based on a shift in the transmission spectrum due to the contrast in refractive index between the carrier fluid and the target biomaterial. The sensor can function using focused illumination without the need for fiber or waveguide coupled input/output signals. We study the spectral response of the sensor using 2D full-wave time-harmonic field analysis and perform parametric analysis of detection sensitivity as a function of material and device parameters. Our analysis demonstrates that detectible shifts in the transmission spectrum can be achieved with nanoscale accumulation of biomaterial within the sensor. We show that the transmission minima and detection sensitivity can be estimated using analytical expressions based on a 1D antiresonant waveguide model.     

The Hamiltonian of the guiding centre in the electromagnetic field

The Hamiltonian of the guiding centre in an adiabatically variable electromagnetic field (for the relative variations of the field 1/H. dH/dt _c , 1/E. dE/dt _c ) is derived in the present paper.The solution of the corresponding canonical equations is given for an axially symmetric stationary electromagnetic field.     

Effect of guiding filters on the behavior of dispersion-managed solitons

We show that guiding filters fundamentally alter the behavior of dispersion-managed soltions by making the pulse energy nearly independent of path-average dispersion (D?) in the neighborhood of D?=0 . This fact enables one to design maps permitting adequate pulse energy with narrow-bandwidth, temporally broad pulses for the attainment of high spectral efficiency and reduced nonlinear penalties in wavelength-division multiplexing.     

Microwave guiding of electrons on a chip

We demonstrate the transverse confinement and guiding of a low energy electron beam of several electron volts in a miniaturized linear quadrupole guide. The guiding potential is generated by applying a microwave voltage to electrodes fabricated on a planar substrate, which allows the potential landscape to be precisely shaped on a microscopic scale. We realize transverse trapping frequencies of 100 MHz and guide electrons along a circular section of 37 mm length. A detailed characterization of the guiding properties in terms of potential depth and dynamic stability is given. This new technique of electron guiding promises various applications in guided matter-wave experiments such as electron interferometry.     

Evidence of light guiding in ion-implanted diamond

We demonstrate the feasibility of fabricating light-waveguiding microstructures in bulk single-crystal diamond by means of direct ion implantation with a scanning microbeam, resulting in the modulation of the refractive index of the ion-beam damaged crystal. Direct evidence of waveguiding through such buried microchannels is obtained with a phase-shift micro-interferometric method allowing the study of the multimodal structure of the propagating electromagnetic field. The possibility of defining optical and photonic structures by direct ion writing opens a range of new possibilities in the design of quantum-optical devices in bulk single-crystal diamond.     

光学制导及其稳像技术

本文论述了光学制导中的两个重要问题,导弹光学寻的器稳像新技术和发射导弹时导弹瞄准系统的稳像技术。     

Strong guiding of light in hollow nanowire Structures

We have theoretically investigated the guiding mode patterns of hollow nanowires. Two types of nanowires,round shape and hexagonal shape, are examined with different combination of outer and inner radii.Because of electric field discontinuity at hollow interfaces and evanescent modes overlap in low refractive index region, strong light guiding and confinement are achieved in both hollow wire structures.     

Drift model of ion beam guiding using capillaries

It is shown that the major role during capillary charging and discharging is played by the charge drift, rather than diffusion. The charge mobility on the capillary surface in a polyethylene terephthalate film is determined.     

高频原子波导中冷原子的磁导引

建立了高频原子波导模型,分析了铷冷原子在该波导内与磁场的相互作用势。高频波导线圈输入电流,在线圈中心轴线区域的势阱深度为mK量级,在线圈的径向能对温度为100 K左右的冷原子实现囚禁。通过分析可知改变输入波导线圈的输入电流大小,可改变势场的大小。计算了进入高频原子波导的冷原子和波导磁场产生相互作用束缚力的大小。在波导轴线中心区域,原子受到的束缚力较大,最大为1.710－23 N,为原子所受重力的10倍。     

Determining the cutoff frequencies of weakly guiding optical fibres by the Laplace transform

We investigate the Laplace transform of the reduced radial Helmholtz equation for the electromagnetic fields in weakly guiding optical fibres. In the Laplace transform space we derive an integral condition for the cutoff frequencies of the LP modes. We apply our equation to several refractive index profiles of practical interest.     

一种重复频率脉冲导引磁场的设计

介绍了一种重复频率脉冲磁场作为高功率微波源的导引磁场的设计,该磁场电源具有功耗低、发热量小、结构紧凑等优点,符合高功率微波朝重复频率方向发展的需求。从产生脉冲磁场的电流表达式出发,根据涡流损耗不能太大、品质因数要高和电容储能要小的原则,给出了脉冲磁场产生系统的储能电容和充电电压的优化设计方法。最后将此方法应用于Ka波段返波振荡器导引磁场的设计,确定出产生脉冲磁场电路的电容和充电电压的值,并进行了仿真和实验研究,结果与理论要求吻合较好,在重复频率10 Hz条件下能稳定运行,验证了设计的合理性。     

Ion guiding through a flat insulating channel

Guiding of beams through flat insulating capillaries has been investigated. A flat capillary guides a beam at inclination of the capillary plane with respect to the beam direction. It is found that a beam can be guided by rotation of a flat capillary around the axis oriented perpendicularly to its plane, i.e., without changing the plane orientation. This effect has been referred to as double guiding. Theoretical models are proposed to explain guiding and double guiding of an ion beam through a flat capillary.     

Channel plasmon-polariton guiding by subwavelength metal grooves

We report on realization of channel plasmon-polariton (CPP) propagation along a subwavelength metal groove. Using imaging with a near-field microscope and end-fire coupling with a tapered fiber connected to a tunable laser at telecommunication wavelengths (1425-1620 nm), we demonstrate low-loss (propagation length approximately 100 microm) and well-confined (mode width approximately 1.1 microm) CPP guiding along a triangular 0.6 microm-wide and 1 microm-deep groove in gold. We develop a simple model based on the effective-index method that accounts for the main features of CPP guiding and provides a clear physical picture of this phenomenon.