摘要:

We show that it is possible to produce time- and path-length-dependent oscillations in the two-photon detection probability of an entangled photon pair when none exists in the detection probability for single photons.

ISSN:0950-0340    

DOI:10.1080/09500349608232865

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A novel method for improving measurement abilities of a particle image velocimetry by using wavelet-matched filtering is proposed. Based on an edge enhancement and multiscaling properties of a wavelet transform, an optical production of a sharp autocorrelation peak from a doubly exposed particle image is demonstrated.

ISSN:0950-0340    

DOI:10.1080/09500349608232866

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Far zone spectral shifts, including free space propagation of light from a planar secondary, partially coherent source represented by the exit face of a few-mode fibre waveguide, are investigated in the paraxial regime by using frequency-dependent linearly polarized (LP) modes guided by the fibre waveguide. The origin of the far zone blue or red spectral shift of individual frequency-dependent LP modes, as well as of their superposition at the particular observation point, is clarified. In particular, the dependence of the wavelength shifts of spectra on the position of the observation point in the far zone plane and the primary source linewidth is studied for the two-mode, weakly guiding, step-index fibre waveguide.

ISSN:0950-0340    

DOI:10.1080/09500349608232867

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In photoelastic investigations, one uses the property of stress induced birefringence for stress analysis. Normal polariscopes are used for such studies. However, the accuracy of the methods is low. For better accuracy, interferometric and holographic methods are generally used. Holography, along with a shearing technique, is also used to obtain partial derivatives of displacement with respect to spatial co-ordinates. In these methods, the resultant fringe pattern is obtained from the mutually shifted holograms and the generation of such patterns requires four exposures altogether.

ISSN:0950-0340    

DOI:10.1080/09500349608232868

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A joint transform correlator, performing pure phase correlation by a phase spatial light modulator in the input to the second stage optical setup, is proposed. It can deliver excellent correlation performance in the presence of non-overlapping noise or additive noise. The proposed method extracts the interference fringe phase information from the joint power spectrum by simple subtraction and division operations; the extracted phase is then encoded onto a phase spatial light modulator to obtain the correlation results. To extract the fringe phasors, the proposed scheme uses an 50/50 beamsplitter and an λ/4 plate in the optical setup, and two CCDs to capture the joint power spectrum and the phase shifted joint power spectrum respectively. This system is found to be equivalent to correlation between only the Fourier phases of the reference and input images; however, there are practical difficulties in implementing this type of pure phase correlation using the VanderLugt architecture. Computer simulations show that the proposed joint transform correlator out-performs binary joint transform correlation, using the binarization methods of multilevel threshold function and adaptive windowing threshold, when the targets are embedded in either non-overlapping noise or scenes with additive noise; performance is maintained even when the target has a very low light contrast ratio in a severely noise corrupted input scene.

ISSN:0950-0340    

DOI:10.1080/09500349608232869

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We present an analytical technique for investigating the behaviour of a coherently driven atom damped by a squeezed vacuum with finite squeezing bandwidth. A master equation and analytic expressions for the fluorescent spectrum are derived for the simple case of a two-level atom exactly resonant with the frequencies of both the squeezed field and the driving field. Suitable choices of driving strength, phase and squeezing source lead to either sub-natural lincwidths of the Rabi sidebands or a sub-natural linewidth of the central spectral peak or indeed sub-natural linewidths of all three spectral peaks when squeezing bandwidths are taken into account. We also establish the remarkable result that in the strong driving regime, the width of the central peak of the fluorescent spectrum depends solely on the squeezing found at the Rabi sideband frequencies.

ISSN:0950-0340    

DOI:10.1080/09500349608232870

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The effective medium theory of one-dimensional and two-dimensional periodic structures are investigated. A method based on a Fourier decomposition of the wave propagating along the direction perpendicular to the periodic structures allows one to determine the zeroth-, first- and second-order effective indices. For one-dimensional problems, we derive closed-form expressions of the effective indices for both TE and TM polarization. Our result can be applied to arbitrary periodic structure with symmetric or non-symmetric lamellar or continuously varying index profiles. The theoretical predictions are carefully validated using rigorous coupled-wave analysis. For the two-dimensional case, only symmetric structures are discussed and the computation of the zeroth-, first-, and second-order effective indices requires the inversion of an infinite matrix which can be truncated and simply solved numerically. The EMT prediction is qualitatively validated using rigorous computation for small period-to-wavelength ratios. It is shown that for large period-to-wavelength ratios near the cutoff value, no analogy between 2-D periodic structures and homogeneous media holds for highly modulated lamellar gratings.

ISSN:0950-0340    

DOI:10.1080/09500349608232871

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

By manipulating the discrete optical levels inside an optical resonator, we obtain a classical realization of a twisted Landau-Zener model. We experimentally demonstrate the geometric amplitude factor in the transition amplitude that arises for this model. We consider in particular the region of parameter space addressed in the original study of the geometric amplitude factor by M. V. Berry [7].

ISSN:0950-0340    

DOI:10.1080/09500349608232872

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Josephson junctions are quantum mechanical devices with sinusoidal nonlinearity and their use as amplifiers of non-classical microwaves in cavities at low temperatures, is discussed. Self-pumped amplifiers as well as externally pumped three- and four-photon amplifiers are considered, and a quantum theory that describes their operation is developed. It is shown that the sinusoidal nonlinearity can be expanded into a series of terms, the first few of which are familiar from quantum optical amplifiers that use nonlinear optical materials, while the others are higher order corrections.

ISSN:0950-0340    

DOI:10.1080/09500349608232873

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A macroscopic theory for scanning optical near field microscopy is presented. The theory, based upon the Rayleigh method, solves rigorously the electromagnetic field near a multilayer system with arbitrary one-dimension structure on its interfaces. The method is suitable for boths- andp-polarized incident light. It may also apply in cases where the resonances in the system, such as the plasmon in a metallic sample, become important.

ISSN:0950-0340    

DOI:10.1080/09500349608232874

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor