Shift Of Interference Pattern Research Articles

Shift of the surface plasmon polariton interference pattern in symmetrical arc slit structures and its application to Rayleigh metallic particle trapping.

In symmetric nano/micro metal slit structures, interference patterns are produced by counter-propagating surface plasmon polaritons (SPPs) in the the center of structures, which can be employed to improve the resolution of microscopy and surface etching and to realize particle trapping. This paper focuses on the shift of the SPP interference patterns in the symmetric arc slit structures. The excitation models with one incident beam and two incident beams are established and analyzed respectively, and methods to shift the SPP interference patterns via adjusting the tilt angle and initial phase of the excitation beams are compared. The FDTD simulation results show that these methods can precisely shift the SPP interference patterns in the symmetrical arc slits. Compared to the linear slits, the SPP waves arising from arc slits are more strongly focused, resulting in a stronger gradient force. The characteristics of stronger focus and dynamic shifting of the focal spot give the symmetric arc slit structure unique advantages in the capture and transfer of the Rayleigh metallic particle.

Reviewing Michelson Interferometer Experiment and Measuring the Speed of Starlight

The wave-aether model was proposed long time ago. We study Michelson interferometer experiment and find that its theoretical calculation erroneously neglected the aether drag effect. We take the drag effect into account and reanalyze the theoretical interference pattern shift. The result is null because the drag coefficient of aether is zero. Such that the wave-aether model fulfills all light propagation characteristics. We design and implement a system to measure the starlight speed by comparing to that from a local source. We observe that the arrival times are different. It implies the apparent speeds of starlights are not equal to c.

The Aharonov-Bohm effect, controversial features of a long-standing debate

En el fenomeno denominado efecto magnetico Aharonov-Bohm, se produce un desplazamientodel patron de interferencia cuantico cuando los electrones se mueven en una region libre de campo magneticoy, por lo tanto, en ausencia de fuerzas. Tambien se observan cambios analogos en experimentos de interferenciacuando los electrones viajan a traves de un campo magnetico, siendo afectados por fuerzas magneticas.Debido a la vasta literatura especializada sobre este tema, se requiere un esfuerzo no trivial para abarcarel panorama completo. As, en este artculo se ha concentrado la atencion en los siguientes aspectos: i)rediscutir los fundamentos teoricos, ii) describir los aspectos basicos de los principales experimentos realizadoshasta ahora y, iii) revisar el ya largo debate sobre la interpretacion del cambio de fase en el efectoAharonov-Bohm como un fenomeno topologico cuantico sin analoga en la teora clasica, o como un retardorelativo a la energa causado por la accion de fuerzas clasicas.

Optical Pdms Microfibre Sensor For Displacement Determination

We prepared and demonstrated the usage of an optical polydimethylsiloxane (PDMS) microfibre sensor for displacement measurement. The sensor consists of PDMS microfibre placed between two conventional single-mode optical fibres. For proper bend of the microfibre the structure forms Mach-Zehnder interferometer. In that case, one arm of the interferometer consists of the microfibre and second one of the air. In addition, it is possible to resize the air arm in a range of several tens of micrometres with sufficient ratio of intensities between lights transmitted through the interferometer arms. For optical paths difference smaller than optical coherence of light source one can observe the interference of light. Determination of the displacement was done based on the spectral shift of interference pattern for particular lengths of air arm. The sensitivity of the sensor was 2.5 nm/μm.

Multi-terminal multi-junction dc SQUID for nanoscale magnetometry

Miniaturization of superconducting quantum interference devices (SQUIDs) is of major importance for the development of sensitive scanning nanoscale magnetometry tools. The high sensitivity of nanoSQUIDs is restricted, however, to only particular periodic values of the applied magnetic field, making accurate measurements at intermediate values of the field impossible. We present a theoretical investigation of a multi-terminal, multi-junction SQUID (mSQUID) that lifts this limitation by providing electrical means for a continuous shift of the quantum interference pattern with respect to the applied field. Analysis of 4-terminal, 4-junction and 3-terminal, 3-junction mSQUIDs shows that operation at maximum sensitivity can be obtained at any value of the magnetic field by applying control current to the extra terminals. The model describes the variation and the shift of the interference pattern as a function of the control currents, junction asymmetries, and the mSQUID inductance. The mSQUID is also shown to provide a direct measurement of the current–phase relations of superconducting junctions. The derived model provides a quantitative description of the recently developed multi-terminal nanoSQUID-on-tip.

Temperature insensitive PCF interferometer coated with graphene oxide tip sensor

We report a simple, compact, and robust photonic crystal fiber (PCF)-based Mach–Zehnder modal interferometer coated with graphene oxide (GO) for monitoring refractive index (RI) of analyte (sucrose). GO is prepared by Hummers method, and the fabrication of sensing probe is achieved by splicing single-mode fiber with solid core PCF followed by collapsing of air holes at the end face of PCF. The PCF along with the collapsed region is functionalized and then coated with GO. The proposed tip sensor in reflection mode can be used for the detection of RI of a small quantity of sucrose in either intensity or/and wavelength interrogation. Our experimental results show that the sensor has wavelength sensitivity as high as 230-nm/RIU along with very high intensity sensitivity of 130 dB/RIU with negligible shift in interference pattern with rise temperature.

Photonic crystal fiber interferometric vector bending sensor.

A compact and highly sensitive interferometric bending sensor (inclinometer) capable of distinguishing the bending or inclination orientation is demonstrated. The device operates in reflection mode and consists of a short segment of photonic crystal fiber (PCF) inserted in conventional single-mode optical fiber (SMF). A microscopic collapsed zone in the PCF-SMF junction allows the excitation and recombination of core modes, hence, to build a mode interferometer. Bending on the device induces asymmetric refractive index changes in the PCF core as well as losses. As a result, the effective indices and intensities of the interfering modes are altered, which makes the interference pattern shift and shrink. The asymmetric index changes in the PCF make our device capable of distinguishing the bending orientation. The sensitivity of our sensor is up to 1225pm/degree and it can be used to monitor small bending angles (±2°). We believe that the attributes of our sensor make it appealing in a number of applications.

Reflectometric measurement of n-hexane adsorption on ZnO2 nanohybrid film modified by hydrophobic gold nanoparticles

Zinc-peroxide/poly(styrenesulfonate) nanohybrid thin films (containing 20 bilayers: [ZnO2/PSS]20, d∼500nm) were prepared using layer-by-layer (LbL) method. The thin film surface was functionalized by different surface modifying agents (silanes, alkylthiols and hydrophobized nanoparticles). Based on the experimental results of quartz crystal microbalance (QCM) and contact angle measurements (as prequalifications) the octanethiol covered gold nanoparticles (OT-AuNPs) were selected for further vapour adsorption studies. Reflectometric interference spectroscopy (RIfS) was used to measure n-hexane vapour adsorption on the original and modified nanohybrid films in a gas flow platform. The thin film provides only the principle of the measurement (by interference phenomenon), the selectivity and hydrophobicity is controlled and enhanced by surface functionalization (by dispersion interaction between the alkyl chains). The interference pattern shift (Δλ) caused by the increase of the optical thickness of the thin film due to vapour adsorption was investigated. It was found that due to the surface functionalization by hydrophobic nanoparticles the effect of water vapour adsorption decreased significantly, while for n-hexane opposite tendency was observed (the effective refractive index and thus the interference pattern shift increased drastically). The correlation between QCM technique and optical method (RIfS) was specified: linear specific adsorbed amount vs. wavelength shift calibration curves were determined in the pr=0–0.4 relative vapour pressure range. The thin film is suitable for sensorial application (e.g. volatile organic compound/VOC sensor).

ZnO2 nanohybrid thin film sensor for the detection of ethanol vapour at room temperature using reflectometric interference spectroscopy

Reflectometric interference spectroscopy (RIfS) was used to detect ethanol vapour in 10–100ppm concentration on the surface of original and modified ZnO2 thin films in a gas flow platform. The interference pattern shift (Δλ) caused by the increase of the effective refractive index (in general terms the optical thickness) of the thin film due to vapour adsorption into the pores was investigated. The effect of noise level was reduced by polynomial fitting, hence the limit of detection (LOD) was improved significantly (by half an order of magnitude). Similarly, by surface functionalization (with butyltrichlorosilane, BTS) the sensitivity to ethanol vapour was increased by one order of magnitude (from 0.038 to 0.331nm/ppm), and the limit of detection improved three-fold as well. The RIfS method was compared to a gravimetric technique (quartz crystal microbalance, QCM), and at the same time the adsorbed vapour amount (ns) that gives rise of Δλ was investigated: linear Δλ vs. ns curves were determined in the 0–60ppm concentration range.

Novel Design of Sagnac Interferometry Assisted with Surface Plasmon Resonance Based Sensor Technique

In this work, we demonstrate a novel design to investigate interfacial reaction of optical activity materials, utilizing a Sagnac interferometer assisted with surface plasmon resonance based sensor technique. Upon application to interrogate optical activity, the type-2 optical configuration of close loop in this work can entirely encircle the interaction zone of surface plasmon resonance reacting with optical activity medium, while the type-1 optical configuration of close loop does partially. The greater the geometrical phase owing to the encircled interaction zone between optical activity medium and polarized light, the larger the phase shift of interference pattern modulated by the concentration of optical activity medium. The slope of phase shift in interference phase pattern of p-wave vs. concentration of dextrose solution determined with this method is greatly improved, 3000 times better than that with Lee's method, 18,600 times with Lin's method, and 222,000 times with Chou's method. Besides, the pinch point of phase shift vs. concentration indicates the ending of interference pattern phase shift as the concentration of each tested optical activity medium keeps climbing up, and can reflect the strong dependence of molecular shape during interfacial adsorption.

Passive striation based geo‐acoustic inversion using ships of opportunity.

The coherent interaction of acoustic multipaths leads to an interference pattern in range. As range changes, the locations of the peaks (and troughs) of this interference pattern shift (as the group velocities of the modes change) in a sometimes predictable fashion. The intensity pattern of a moving source, plotted as a function of range and frequency, is commonly referred to as striation patterns. These patterns are commonly observed in the passing of a loud surface vessel in the spectrogram of a single hydrophone. In this paper, a geoacoustic method is presented based upon the quantitative measure of striation slope (wave guide invariant parameter) and the striation spacing in frequency (reciprocal time spread). Both of these parameters are generally sensitive to the geo‐acoustic parameters of the sediment. In 2003 this technique was applied to a passing surface ship [K. Heaney, IEEE JOE 29(1), 43–50 (2003)] and to a range‐dependent benchmark case [K. Heaney, IEEE JOE 29(1), 88–99 (2003)]. The approach in these papers compared the measured acoustic observables with those from a table predicted by the forward computation using the broadband PE. Current implementation of the algorithm uses a Gaussian beam code to efficiently compute the acoustic observables.

Quantum effects of electric fields and potentials on electron motion: an introduction to theoretical and practical aspects

In the so-called electric Aharonov–Bohm effect, a quantum interference pattern shift is produced when electrons move in an electric field free region but, at the same time, in the presence of a time-dependent electric potential. Analogous fringe shifts are observed in interference experiments where electrons, travelling through an electrostatic field, suffer a classical lag effect produced by electric forces. Since these experiments are reported mainly in specialized journals, it could be rather difficult and time consuming for a student to attain a comprehensive overview of the subject. Therefore, particular attention has been addressed to reviewing the theory, to describing a couple of experiments and to the interpretation of the results. We believe that students can be suitably introduced to exploring the ‘paradoxical’ aspects of the interaction of electrons with electric potentials and fields.

Analysis of the Kinetics of Diffraction Efficiency during the Holographic Grating Recording in Azobenzene Functionalized Polymers

The laser-assisted holographic grating recording process in films of azobenzene functionalized polymers is usually studied by observation of the efficiency of light scattering on a developing in time diffraction grating. Various possible mechanisms contributing to grating formation as well as the bulk or surface origin (bulk refractive index and/or relief grating) of light scattering make the analysis of kinetics of grating recording, from the light scattering data only, difficult and ambiguous. To fully explain experimentally observed various and complex (frequently nonexponential) kinetics of the first-order light diffraction intensity, we considered a simple single-exponential growth of the two phase gratings in the same polymer film. In modeling we assumed that the bulk refractive index grating Deltan(t) and the surface relief grating Deltad(t) differ considerably in their growth rates and we allowed for a nonstationary phase shift Deltaphi(t) between them which was experimentally observed during the recording process. The origin of the nonstationary phase shift is a result of a slow shift of interference pattern due to delicate symmetry breaking in illumination conditions (e.g., difference in beam intensities and deviation of exact symmetrical beam incidence angles on the sample). Changing only such parameters as stationary amplitudes of refractive index and relief gratings for a span of phase shifts (0-pi) between them, we obtained a series of kinetic responses which we discuss and interpret. The various examples of temporal evolution of diffraction efficiency for the same grating formation kinetics, modeled in our work, supply evidence that great care must be taken to properly interpret the experimental results.

Propagation of Electromagnetic Waves in Media Undergoing Complex Motions

Results of a theoretical and experimental investigation into new effects in moving-media optics are presented. An exact analytical solution is obtained for the trajectory of the wave vector of a monochromatic electromagnetic plane wave in a medium undergoing a complex motion. It is shown that the spatial dragging of the electromagnetic wave by the moving medium can be described correctly in the general case only if relativistic terms of order β2 are taken into account. Also, in this investigation a spatial effect of the light drag was observed at a wavelength of λ =0· 63299 μm by means of an optical disk with a refractive index n=1· 4766, a radius of R0 =0· 06 m rotating at a frequency of ω =25 Hz. A relative shift of the interference pattern, monitored by the time of the interference band motion across the aperture of a photodetector for the disk rotating in the opposite directions, amounted to \(\Delta_\Sigma^{\rm exp} =0\cdot 0076\pm 0\cdot 0030\) of the interference bandwidth. The results of theoretical calculations of the expected interference pattern shift on the basis of the total solution of the dispersion equation in the experiment are in agreement with the experimental results. Analysis of the results obtained suggests that the detected effects determine a wide class of observed phenomena, even when the velocities of moving media are non-relativistic.

The effect of light entrainment observed in an optical disk interferometer

The propagation of an electromagnetic radiation in a rotating medium is determined by superposition of the primary wave and the secondary waves appearing as a result of the interaction of the electromagnetic radiation with atoms of the moving medium. By solving a dispersion equation, it is possible to determine the radiation wavevector in any local region of the trajectory with an allowance for a spatial distribution of the medium velocity [1]. The solution was repeatedly verified in experiment, but the complexity of such investigations allowed only certain particular cases to be studied such as the longitudinal Fizeau effect [2, 3] and the normal velocity break [4, 5], in which the light beam is affected by either normal or tangential components of the medium velocity. Propagating in a rotating medium, the electromagnetic wave is simultaneously affected by both normal and tangential components of the motion. Therefore, experimental observation of the spatial effect of the light wave entrainment is verification of the total solution of the dispersion equation. Below we present the results of a series of experiments on the measurement of a shift of the light interference pattern in the scheme of a double-beam twopass disk interferometer (Fig. 1). In this scheme, the light beam from laser 1 incident on a beam divider 3 was split into two beams. These beams entered the optical disk 3 to be reflected from flat mirror surfaces. The exit beams reflected from angle prism 4 changed paths, passed through the optical disk in the reverse direction, and entered the divider again. Mixed on the divider mirror, the beams passed through an objective lens 5 to display the interference pattern on a screen 8. The light intensity was measured by photodetector 6 (a photodiode of the FD256 type operating in the generator mode). The light source was an LGN-302 laser operating at λ = 0.63299 µ m and producing the beam with a power of P 0 ≈ 0.84 W for both horizontal and vertical polarization components. The rotating medium was a disk with a diameter of 120 mm and a thickness of 30 mm made of an LK5 grade glass ( n = 1.4766 for λ = 0.63299 µ m). In order to increase the optical pathlength by multiple reflections, the disk edge surfaces were mirror coated so as to provide for the reflection coefficient R = 0.9. Reversal of the disk rotation direction resulted in inversion of the sign of the phase shift between interfering light beams and, accordingly, of the direction of the shift of the interference pattern. Since the optical

Refractive index profiling of a GRIN optical fiber using a modulated speckled sheet of light

A method for calculating the refractive index of GRIN optical fiber from its transverse interference pattern is presented.In this method the transverse interference fringe pattern through an optical fiber using a sheet of light is applied to get the refractive index profile of it. The optical fiber is not immersed in a matching liquid as used in different techniques [Barakat N, El-Hennawi HA, El-Zaiat SY, Hassan R. Pure Appl Opt 1996;5:27]. In this method a sheet of He–Ne laser light is allowed to illuminate the fiber. The light sheet is divided into two parts, the first is refracted through the fiber while the second is used as a reference beam. Interference pattern will be obtained between these two rays displaying the refractive index variation along the fiber radius. The fringe shift of such interference pattern has been measured and used to calculate the deflection angle of light refracted by the fiber and the cladding. An equation is derived to calculate the refractive index profile difference ratio δn at different positions across the fiber cross section in terms of the corresponding deflection angle and is verified experimentally. The optical path difference between these two rays (refracted and reference beam divided by the fiber) has been derived and the fringe shift obtained has been used to calculate the refractive index profile of the fiber. Introducing a ground glass screen on the passage of the two light beams (refracted and reference beam divided by the fiber), two superimposed identical speckle patterns are formed leading to the formation of a third speckle pattern modulated by a grid structure displaying the optical thickness of the fiber.

Interferometric measurement of the physical constants of laser dye solvents

The absolute value of refractive index and its variation with temperature of benzene and chloroform at He-Ne laser wavelength 6328 Å are measured. The measurements are carried out using laser interferometric technique. This technique is based on the shift of interference pattern when rotating the sample in one arm of a newly developed Mach–Zehnder interferometer. The refractive index shows a linear relationship with temperature in the range of interest. The thermal refractive index coefficients of benzene and chloroform are all negative. Applying Maxwell’s theory and Lorentz–Lorenz function, the obtained results are used for calculating the optical permittivity (or dielectric susceptibility) as a function of temperature and many other important related physical constants.

Expectation values in the Aharonov-Bohm effect

It has been well established that, as predicted by Aharonov and Böhm, electron interference patterns can be shifted by the introduction of electromagnetic potentials, even if the electrons never enter the region in which the fields are nonzero. In this paper we prove that, even though the interference pattern shifts, none of the moments of the electron’s positionr, nor of its kinetic momentumπ, are affected. On the other hand, we prove that the expectation value of the operator sina·π (witha a certain fixed vector), which was first introduced by Aharonov, Pendleton and Peterson,does shift.

Classical Electromagnetic Deflections and Lag Effects Associated with Quantum Interference Pattern Shifts: Considerations Related to the Aharonov-Bohm Effect

Classical electromagnetic lag effects can give rise to quantum interference pattern shifts such as that observed experimentally in the Aharonov-Bohm effect involving electrons passing a solenoid. This paper presents an extensive comparison between interference pattern shifts based upon classical electromagnetic fields, and based upon classical electromagnetic potentials as suggested by Aharonov and Bohm. Stress is placed upon the difference between two types of interference pattern shifts: those involving deflection of the entire interference pattern and those involving a deflection of only the double-slit pattern while leaving the single-slit envelope undisplaced. The first type of shift is produced by a classical deflecting force. The second type of shift can be produced by classical electromagnetic lag effects, and is also the type of shift associated with the Aharonov-Bohm effect. The two types are confused in the literature. A new experiment is proposed which shows the relationship between a classical lag effect, due to electrostatic fields on electrons passing along different paths, and the associated quantum interference pattern shifts. The experiment is analyzed in detail using the WKB approximation in the Schr\odinger equation and also semiclassical ideas. The classical limit for the situation illustrates the Bohr correspondence principle, showing the relative lag between the electron wave packets becoming a measurable classical lag with a disappearance of the interference pattern as the lag becomes large compared to the wave-packet dimensions. For small shifts, the phase change predicted for the new experiment is identical with the scalar potential effect proposed by Aharonov and Bohm for a slightly different, time-varying experimental arrangement. The theoretical and experimental differences for large phase shifts are noted. The possibility is raised that a new classical electromagnetic lag effect may occur for electrons passing a small solenoid. Using a particular model for energy conservation, the predicted lag effect can be calculated and is associated with a quantum interference pattern shift of the same magnitude as predicted by Aharonov and Bohm based upon the electromagnetic vector potential. Thus the possibility exists that the experiments of Chambers and of M\ollenstedt and Bayh may not confirm the ideas of Aharonov and Bohm on the vector potential in quantum theory. Several experiments are suggested which allow confirmation that the Aharonov-Bohm effect indeed involves local effects of the classical electromagnetic potential, rather than local electromagnetic fields leading to a new classical lag effect and hence to the observed quantum interference pattern shift.

Misinterpretation of the Aharonov-Bohm Effect

It is pointed out that accounts in the literature sometimes misinterpret the Aharonov-Bohm effect, involving the shift in interference pattern for electrons passing a long solenoid. The quantum description and experimental verification of the effect are reviewed, and it is emphasized that both theory and experiment indicate that there is no deflection of the average momentum of the electrons passing the solenoid. There is no average force on the electrons due to the solenoid. It is remarked that the Aharonov-Bohm effect involves the shift of double-slit interference fringes which is independent of the quantum unit of action ħ and yet allows a natural classical limit.