Gouy phase compensation in quasi-phase matching

In any focussed nonlinear interaction the focus induced phase shift, known as the Gouy phase shift, provides an imperfection in phase matching for any linearly invariant material. However, using an appropriately designed quasi-phase matched structure it is theoretically possible to compensate for the deleterious effects of the Gouy phase shift, allowing a symmetric frequency response and tighter optimal focussing than in a uniform material.     

Revisiting Gouy phase

The aim of this paper is to highlight the added value of the generalized Gouy phase shift introduced by Siegman. Although suited for optical systems study, including those more complex than free space, we note that it did not meet the use that it deserves so far. The analysis of the whole of the ideas and analytical approaches associated to the important concept of the Gouy phase proves its effectiveness.

Usually, the resonance condition is systematically built on the basis of the equivalent empty cavity. Unfortunately, this approach does not cover some of the useful parameters of the real resonator. By means of the generalized Gouy phase and the self-consistent complex parameter q, we derive here a new approach for the calculation of the resonance condition for the real cavity. Moreover, the use of the generalized Gouy phase clearly simplifies the study of resonators, while making it possible to avoid the use of the Huygens’ Fresnel integral.     

Observation of Gouy phase anomaly with an interferometer

The intensity variation of bright and dark fringes in Young's double slit experiment shows that a light beam propagating through the focus of a lens experiences a phase shift (called the Gouy phase shift [Gouy CR. Acad Sci Paris 1890;110:1251]) with respect to its plane wave counterpart. The additional phase change of π introduced on focusing the light beam and then further propagating it in one arm of the interferometer changes a bright fringe into a dark fringe and vice-versa. We have, thus, made direct visualization of the Gouy phase shift by a simple experiment.     

Propagation of optical vortex solitons due to the Gouy phase in strongly nonlocal nonlinear media

In this paper,we present a study on the propagation of the symmetrical optical vortices formed by two collinear Laguerre-Gauss solitons in strongly nonlocal nonlinear media.The optical vortices,which move along the beam axis as the light propagates,result in a rotation of the beam’s transverse profile.This physical reason of the rotation is the Gouy phase acquired by the component beams.     

Extreme beam attenuation in double-slit experiments: Quantum and subquantum scenarios

Combining high and low probability densities in intensity hybrids  , we study some of their properties in double-slit setups. In particular, we connect to earlier results on beam attenuation techniques in neutron interferometry and study the effects of very small transmission factors, or very low counting rates, respectively, at one of the two slits. We use a “superclassical” modeling procedure which we have previously shown to produce predictions identical with those of standard quantum theory. Although in accordance with the latter, we show that there are previously unexpected new effects in intensity hybrids for transmission factors below a?10⁻⁴$a?10^{-4}$, which can eventually be observed with the aid of weak measurement techniques. We denote these as quantum sweeper effects, which are characterized by the bunching together of low counting rate particles within very narrow spatial domains. We give an explanation of this phenomenology by the circumstance that in reaching down to ever weaker channel intensities, the nonlinear nature of the probability density currents becomes ever more important, a fact which is generally not considered–although implicitly present–in standard quantum mechanics.     

Analysis of period and visibility of dual phase grating interferometer

Dual phase grating interferometer may simultaneously achieve large field of view and high x-ray dose efficiency. Here, we develop a simple theoretical method to better understand the imaging process of the dual phase grating interferometer. The derivation process of fringe period and the optimal visibility conditions of the dual phase grating interferometer are given in detail. Then, we theoretically prove that the fringe period and optimal visibility conditions of the dual phase grating interferometer include that of the Talbot interferometer. By comparing our experimental results with those of other researchers, we find that when the positions of phase gratings are far away from the positions where the fringe visibility is optimal, the fringe period of the dual π -phase grating interferometer is twice the theoretical results under the illumination of polychromatic x-ray. This conclusion may explain the contradictory research results of dual phase grating interferometer among different researchers.     

强非局域介质中基于古依相位的旋转涡旋光孤子

利用强非局域非线性介质中傍轴光束传输的修正Snyder-Mitchell模型讨论了两束共线(即光束中心和传输方向都相同)拉盖尔-高斯型光孤子(CLGS)构成的涡旋光孤子传输过程。在一定条件下,涡旋光束在传输过程中,光束截面光斑发生旋转现象,但光束的束宽保持不变,称之为旋转涡旋光孤子。涡旋光孤子旋转的现象可以通过叠加光场中的古依相位来解释。结果展现了几个旋转涡旋光孤子在传输过程中的旋转现象和强非局域介质中多环形旋转涡旋光孤子的传输。     

超连续谱干涉方法测量古依相移

利用两束超连续光干涉得到的信号,测量了透镜焦点附近飞秒激光脉冲的古依(Gouy)相移。根据得到的光谱干涉信号,利用傅里叶变换得到相对相位值。激光光束在聚焦透镜后的束腰半径可以由成像方法测得。根据测量得到的激光光束束腰半径,用非线性拟合的方法得到了古依相移曲线,拟合曲线与实验结果符合得非常好。给出了古依相位在焦点前后1 mm区域内的移动量。     

杨氏双缝干涉实验中的光谱奇异现象

基于部分相干光的传输理论,研究了杨氏双缝干涉实验中的光谱奇异现象。发现在杨氏双缝干涉实验干涉场区中的某个点的光谱奇异现象,它会随着某些参量(如源光谱宽度Γ′,缝宽参量ε,相对空间相干度Δ0)的变化而改变,指出该现象可应用于信息的编码及自由空间的信息传输。     

光束在左手材料中的强度和相位旋转特性

建立了左手材料中拉盖尔高斯光束传输模型,通过研究拉盖尔高斯光束的相位分布来分析光束的强度旋转特性。具体分析了光束参数模式、Gouy相、频率和色散对光束强度和相位旋转特性的影响。研究发现:方位角相差是导致光束强度旋转的主要原因;负折射率引起的逆的Gouy相移将会导致光束强度反转;在正常色散区左手材料中光束的强度和相位旋转方向是相同的,而在反常色散区,左手材料中光束的强度和相位旋转方向是相反的。     

液体折射率测量实验中提高半荫视场可见度的途径

分析了掠入射法测定液体折射率实验中棱镜角的选择范围,提出了增加半荫视场可见度的途径,讨论了光源位置和棱镜选取对半荫视场分界线可见度的影响,得出了实验室常用棱镜的选择方案.     

夫兰克-赫兹演示实验中工频的相位干扰分析与消除

充氩管夫兰克-赫兹实验装置的示波器显示图像不稳定,其原因是夫兰克-赫兹管输出电流太小,受到环境中的工频电磁波的污染,以及能谱信号受到了噪声相位的干扰.从噪声中提取扫描触发信号,用来同步夫兰克-赫兹管的扫描信号,可以完全消除噪声相位的干扰.本文给出了不稳定图像的数学模型、解决方案及仿真结果.     

De Broglian probabilities in the double-slit experiment

A new probability interpretation of interference phenomena in the double-slit experiment is proposed. It differs from the standard interpretation (based on elementary events happening in complementary, mutually exclusive setups—arrivals of waves to the screen when one of the slits is closed) which encounters the paradox that the law of total probability is violated. This new interpretation is free of such difficulties and paradoxes since it is based on compatible elementary events (events happening in the same setup in which happenall events considered—arrivals of quantons to the screen when both slits are open). Quantum objects—quantons—possess simultaneously particle and wave properties. Compatible statistical interpretation synthesizes in a consistent way the superposition principle for waves and the law of total probability applied to compatible events. Such synthesis is a theoretical expression of de Broglie's observation, now fully confirmed by experiments, that the interference fringes obtained on a photographic plate result from an infinite number of tiny local spots which display arrival of quantons, while the set of fringes is a statistical effect of the wave aspect.     

Parameter estimation by decoherence in the double-slit experiment

We discuss a parameter estimation problem using quantum decoherence in the double-slit interferometer. We consider a particle coupled to a massive scalar field after the particle passing through the double slit and solve the dynamics non-perturbatively for the coupling by the WKB approximation. This allows us to analyze the estimation problem which cannot be treated by master equation used in the research of quantum probe. In this model, the scalar field reduces the interference fringes of the particle and the fringe pattern depends on the field mass and coupling. To evaluate the contrast and the estimation precision obtained from the pattern, we introduce the interferometric visibility and the Fisher information matrix of the field mass and coupling. For the fringe pattern observed on the distant screen, we derive a simple relation between the visibility and the Fisher matrix. Also, focusing on the estimation precision of the mass, we find that the Fisher information characterizes the wave-particle duality in the double-slit interferometer.     

涡旋光束经杨氏双缝干涉后的光谱变化

从完全相干光的传输定理出发,研究了完全相干涡旋光照射在双缝上,干涉场中的光谱变化。研究结果表明,和普通的完全相干光(平面波)经双缝干涉的光谱变化相比较,涡旋光束的光谱变化情况显得更加丰富。研究了相对平均频率的变化,发现相对平均频率将随着源光谱的宽度,拓扑荷数以及观察点位置的变化而变化。给出了对应于不同拓扑荷数,一个固定观察面的相对平均频率的分布情况。     

Young's double-slit experiment in photonic crystals

We present an experimental and numerical study of the transmission of a photonic crystal perforated by two subwavelength slits, separated by two wavelengths. The experimental near-field image of the double-slit design of the photonic crystal shows an interference pattern, which is analogous to Young's experiment. This interference arises as a consequence of the excitation of surface states of the photonic crystals and agrees very well with the simulations.     

Phase anomaly and phase singularities of the field in the focal region of high-numerical aperture systems

The phase behavior of the three Cartesian components of the electric field in the focal region of a high-numerical aperture focusing system is studied. The Gouy phase anomaly and the occurence of phase singularities are examined in detail. It is found that the three field components exhibit different behaviors.     

Feynman path integrals in the young double-slit experiment

An estimate for the value of the nonlinear interference term in the Young double-slit experiment is found using the Feynman path-integral method. In our time-dependent calculation the usual interference term becomes multiplied by 1+e withe proportional to cos(2m L/ T), where is the distance between the two slits (holes) andL is the length of the shortest trajectory of electrons between the source and the observation point.     

计算电容中Fabry-Perot干涉仪测量位移的相位修正方法

计算电容是复现电学阻抗单位的基准装置, 利用计算电容值和量子霍尔电阻值可以准确计算出精细结构常数α. 计算电容的本质是通过高准确度地测量屏蔽电极的位移, 实现对电容量值的测量. 因此, 基于Fabry-Perot干涉仪的精密电极位移测量系统是计算电容装置中最为核心和关键的部分. 在Fabry-Perot干涉仪测位移过程中, 由于高斯激光束存在轴向Gouy相位, 该附加相位将会引起相邻干涉条纹对应位移的变化(大于或者小于λ/2), 导致位移的测量值与实际值存在偏差. 本文阐述了高斯激光场的传播特性, 利用高斯激光束在自由空间和透过薄透镜复振幅的变换关系, 建立了计算电容装置中Fabry-Perot干涉仪透射光束的传输模型; 通过对不同腔长的Fabry-Perot干涉仪透射光场相位的分析, 获得了高斯激光束轴向Gouy相位修正与传输距离的关系. 结果表明, 当腔长从111.3 mm移动至316.3 mm时, 在接收距离为560 mm的情况下, 高斯光束轴向Gouy 相位引起的位移修正的绝对值最小为0.7 nm, 其相对相位修正量|δL|/|ΔL| = 3.4×10^-9.