Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Cavitation in trees

Sap is transported under tension (i.e. negative pressure) in trees, according to the tension-cohesion theory. Since water is physically instable under negative pressure, a risk of cavitation is possible. Techniques have been developed during the past two decennia to study cavitation in trees. Trees appear remarkably immune to cavitation events. Cavities form only when extreme water stresses occur or when sap freezes. Nucleation is heterogeneous in trees, presumably caused by the aspiration of air bubbles through conduit walls. Threshold xylem pressures for cavitation vary greatly between species, in concordance with the great functional and ecological diversity of trees. To cite this article: H. Cochard, C. R. Physique 7 (2006).     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.     

Optical Pulse Compression Schemes That Use Nonlinear Bragg Gratings

Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains.     

Conductively cooled all-solid-state zigzag slab laser

A diode pumped, Q-switched Nd：YAG zigzag slab laser is developed using passive conduction cooling. Flat-flat and unstable resonators are adopted in this experiment. The 150-mJ multi-mode and 100-mJ single-mode laser outputs with pulse width of 10 ns are achieved, corresponding to optical efficiencies of 19% and 13%, respectively. The experimental result demonstrates that the laser has the property of compact structure, high efficiency, reliability, and high beam quality. The design of laser has a potential application in space environment.     

The nature of empirical constants in the equation relating the frequency of the stretching vibration of oh-groups to parameters of the [MO n ]-polyhedrons coordinating these groups

Institute of Physicoorganic Chemistry, Academy of Sciences of Belarus, 220603, Minsk, Ul. Surganova, 13, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 1, pp. 104–107, January–February, 1995.     

Quantitative analysis results of CE-1 X-ray fluorescence spectrometer ground base experiment

As the nearest celestial body to the earth, the moon has become a hot spot again in astronomy field recently. The element analysis is a much important subject in many lunar projects. Remote X-ray spectrometry plays an important role in the geochemical exploration of the solar bodies. Because of th equasi-vacuum atmosphere on the moon, which has no absorption of X-ray, the X-ray fluorescence analysis is an effective way to determine the elemental abundance of lunar surface. The CE-1 X-ray fluorescence spectrometer (CE-1/XFS) aims to map the major elemental compositions on the lunar surface. This paper describes a method for quantitative analysis of elemental compositions. A series of ground base experiments are done to examine the capability of XFS. The obtained results, which show a reasonable agreement with the certified values at a 30% uncertainty level for major elements, are presented.     

A new tuning procedure for the DTL RF field pattern

The DTL tank is a multi-cell cavity.In a fabricated tank,the measured average axial field E0 for each cell may obviously deviate from the designed value.It is generally thought the deviation is due to the errors in fabrication and assembly.But it is not always true.In this paper,it is shown that the deviation may already exist before fabrication in some cases.It is partly due to the imperfection of the current design procedures.A new design method is introduced to reduce the deviation in the design stage.     

Effect of oxygen on the optical properties of ZnSe in the region of 0.44–20 μm

Moscow Power Engineering Institute, 14, Krasnokazarmennaya Str., Moscow, GSP, 105835, Russia. Translated from Zhurnal Prikladnois Spektroskopii, Vol. 63, No. 4, pp. 646–651, July–August, 1996.     

Speech endpoint detection in low-SNRs environment based on perception spectrogram structure boundary parameter

The Perception Spectrogram Structure Boundary（PSSB）parameter is proposed for speech endpoint detection as a preprocess of speech or speaker recognition.At first a hearing perception speech enhancement is carried out.Then the two-dimensional enhancement is performed upon the sound spectrogram according to the difference between the determinacy distribution characteristic of speech and the random distribution characteristic of noise.Finally a decision for endpoint was made by the PSSB parameter.Experimental results show that,in a low SNR environment from-10 dB to 10 dB,the algorithm proposed in this paper may achieve higher accuracy than the extant endpoint detection algorithms.The detection accuracy of 75.2%can be reached even in the extremely low SNR at-10 dB.Therefore it is suitable for speech endpoint detection in low-SNRs environment.     

Energy transfer as a method for investigation of the structure of electrolytes

S. I. Vavilov State Optical Institute, Russia, 199034, St. Peterburg, Birzhevaya Liniya, 12. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 3, pp. 38–42, May–June, 1995.     

The effect of complexing processes on energy transfer Tl+→Gd3+ and Tl+→Tb3+ in glass

T. Shevchenko Kiev University, 252022 Kiev, Pr. Akad. Glushakova, 6, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 3, pp. 192–196, May–June, 1995.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

Optical properties of pure and doped Y3Fe5O12 single crystals

Institute of Physics of Solids and Semiconductors, Academy of Sciences of Belarus, 17, P. Brovka Str., GSP, Minsk, 220072. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 63, No. 4, pp. 667–675, July–August, 1996.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Classical mechanics in non-commutative phase space

In this paper the laws of motion of classical particles have been investigated in a non-commutative phase space.The corresponding non-commutative relations contain not only spatial non-commutativity but also momentum non-commutativity.First,new Poisson brackets have been defined in non-commutative phase space.They contain corrections due to the non-commutativity of coordinates and momenta.On the basis of this new Poisson brackets,a new modified second law of Newton has been obtained.For two cases,the free particle and the harmonic oscillator,the equations of motion are derived on basis of the modified second law of Newton and the linear transformation (Phys.Rev.D,2005,72:025010).The consistency between both methods is demonstrated.It is shown that a free particle in commutative space is not a free particle with zero-acceleration in the non-commutative phase space.but it remains a free particle with zero-acceleration in non-commutative space if only the coordinates are non-commutative.     

AEGIS-K code for linear kinetic analysis of toroidally axisymmetric plasma stability

A linear kinetic stability code for tokamak plasmas: AEGIS-K (Adaptive EiGenfunction Independent Solutions-Kinetic), is described. The AEGIS-K code is based on the newly developed gyrokinetic theory [L.J. Zheng, M.T. Kotschenreuther, J.W. Van Dam, Phys. Plasmas 14 (2007) 072505]. The success in recovering the ideal magnetohydrodynamics (MHD) from this newly developed gyrokinetic theory in the proper limit leads the AEGIS-K code to be featured by being fully kinetic in essence but hybrid in appearance. The radial adaptive shooting scheme based on the method of the independent solution decomposition in the MHD AEGIS code [L.J. Zheng, M.T. Kotschenreuther, J. Comp. Phys. 211 (2006) 748] is extended to the kinetic calculation. A numerical method is developed to solve the gyrokinetic equation of lowest order for the response to the independent solutions of the electromagnetic perturbations, with the quasineutrality condition taken into account. A transform method is implemented to allow the pre-computed Z-function (i.e., the plasma dispersion function) to be used to reduce the integration dimension in the moment calculation and to assure the numerical accuracy in determining the wave–particle resonance effects. Periodic boundary condition along the whole banana orbit is introduced to treat the trapped particles, in contrast to the usual reflection symmetry conditions at the banana tips. Due to the adaptive feature, the AEGIS-K code is able to resolve the coupling between the kinetic resonances and the shear Alfvén continuum damping. Application of the AEGIS-K code to compute the resistive wall modes in ITER is discussed.     

Stable anticipation synchronization in mutually coupled vertical-cavity surface-emitting lasers system

Two vertical-cavity surface-emitting lasers(VCSELs) are mutually coupled through a partially transparent mirror (PTM) placed in the pathway. The PTM plays the role of external mirror,which controls the feedback strength and coupling strength.We numerically simulate this system by establishing a visible SIMULINK model.The results demonstrate that the anticipation synchronization is achieved and it can tolerate some extent frequency detuning.Moreover,the system shows similar chaos-pass filtering effect on unidirectionally coupled system even both VCSELs are modulated.This system allows simultaneously bidirectional secure message transmission on public channels.     

Collective effects for long bunches in dual harmonic RF systems

The storage of long bunches for large time intervals needs flattened stationary buckets with a large bucket height.Collective effects from the space charge and resistive impedance are studied by looking at the incoherent particle motion for the matched and mismatched bunches.Increasing the RF amplitude with particle number provides r.m.s wise matching for modest intensities.The incoherent motion of large amplitude particles depends on the details of the RF system.The resulting debunching process is a combination of the too small full RF acceptance together with the mismatch,enhanced by the collective effects.Irregular single particle motion is not associated with the coherent dipole instability.For the stationary phase space distribution of the Hofmann-Pedersen approach and for the dual harmonic RF system,stability limits are presented,which are too low if using realistic input distributions.For single and dual harmonic RF system with d＝0.31,the tracking results are shown for intensities,by a factor of 3 above the threshold values.Small resistive impedances lead to coherent oscillations around the equilibrium phase value,as energy loss by resistive impedance is compensated by the energy gain of the RF system.