摘要:

Recent work on imaging coherently illuminated objects through a time-varying random screen has demonstrated the possibility of recovering the Fourier modulus of the object spectrum. We suggest an approach which, although limited to restricted conditions, enables both the modulus and the phase of the object to be recovered from the time-averaged image spectrum.

ISSN:0950-0340    

DOI:10.1080/09500349314551651

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The phenomenon of surface plasmon resonance is commonly observed by recording variations in the reflectivity of radiation incident upon a metallic film whilst scanning the angle of incidence. A new experimental configuration has been devised in which light passes through such a system twice. Normally, for a resonance minimum, as recorded in conventional arrangements, a double-passage experiment would result in a broadening of the resonance. In the present situation by suitable choice of input and output polarizations a resonance maximum is recorded. Then a double-pass experiment has the effect of sharpening the resonance maximum which may thereby provide increased sensitivity in the field of the optical sensing.

ISSN:0950-0340    

DOI:10.1080/09500349314551661

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We use a recent stochastical diffusion model of quantum evolution to represent the evolution of a three-level quantum system undergoing quantum jumps. This is possible because the continuous change in the quantum state in this diffusion model is so rapid that it appears to be instantaneous in comparison with the time between transitions. Experimental data from a study of the intermittent fluorescence of a single trapped24Mg+ion and equivalent theoretical data are shown to be strikingly similar. Statistical comparisons of the data are also made.

ISSN:0950-0340    

DOI:10.1080/09500349314551671

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We show how two atoms may become entangled through their interaction with a cavity field and through this entanglement violate at certain interaction times the relevant Bell's inequality derived from a locally realistic model of the atomic correlations.

ISSN:0950-0340    

DOI:10.1080/09500349314551681

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A pulsed neodymium-doped yttrium aluminium garnet laser mode locked by a novel nonlinear Michelson interferometer, where one branch contains a frequency-doubling potassium titanyl orthophosphate crystal, is reported for the first time. Under the optimal experimental condition, shorter than 10 ps average pulse width at 1·06 μm and up to 95% reproducibility of mode locking can be obtained, and the stability of output energy is about 7·5%. Finally, the reason why its mode-locking output characteristics have been significantly improved is also analysed in this paper.

ISSN:0950-0340    

DOI:10.1080/09500349314551691

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The geometric phase arising from rotation of the plane of polarization of an electromagnetic wave is similar to that acquired by a spin-1/2 particle in a magnetic field. We describe an interferometric arrangement using an optically active medium that can be used to observe this change.

ISSN:0950-0340    

DOI:10.1080/09500349314551701

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In white light interferometry, the visibility of the fringes is directly related to the optical path difference between the two interfering beams. With a very short coherence length light source, the zero-order interference fringe may be detected by a simple maximum intensity location while the reference mirror is shifted by a piezoelectric transducer. We use this possibility for high-resolution profilometry. We discuss the maximum sampling distance, which guarantees a correct detection, as a function of the self coherence function of the light source. A practical configuration based on Mirau interferometric microscope objective was built. The experimental results show the nanometric resolution of this technique and its ability to profile surfaces with sharp slopes and deep holes. The application field of either heterodyne or confocal profilometers may be extended by associating them with the proposed method.

ISSN:0950-0340    

DOI:10.1080/09500349314551711

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The nonlinear optical susceptibility is calculated for a system of two closely located bound excitons by treating the test field as a perturbation in pump-probe experiments. The effect of photon trapping on the spectral hole burning is found to be dramatic in the transient regime for both on-resonance and off-resonance pumping.

ISSN:0950-0340    

DOI:10.1080/09500349314551721

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This paper describes a novel polarimetric technique for mapping the spatiotemporal birefringent parameters characterizing an anti-ferroelectric liquid crystal cell. A linearly polarized beam of light transmitted by the liquid crystal cell turns into an elliptically polarized beam. Some birefringent irregularities existing over the cell make state of polarization of the elliptically polarized beam of light be spatiotemporal. This beam works as a signal beam to interfere with a reference beam consisting of two orthogonal linearly polarized components. The resultant interference pattern is taken by a charge-coupled device video camera and recorded in a computer. The computer gives the information required for determining the spatiotemporal birefringent parameters that characterize the liquid crystal cell. The major advantage is that the two-dimensional distribution of the birefringent axes as well as the two principal refractive indices can be determined simultaneously, and no use of any optical components for polarization alignment makes it possible to follow a rapid change in birefringent parameters within the maximum frame rate of the video camera. A change in time-dependent birefringent parameter is measured at every 0·1 ms for the demonstration experiment.

ISSN:0950-0340    

DOI:10.1080/09500349314551731

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The radiative decay of surface plasmon polaritons has been investigated in an attempt to characterize the surface roughness of Ag films prepared under different conditions. The polaritons were excited by the method of attenuated total reflection of light. The films were deposited on the face of a 60° BK-7 glass prism at a rate that was deliberately fixed in two different ranges (centred on 0·1 and 10 nms−1) and in some cases a CaF2underlayer was used to roughen the film surfaces. The intensity of the scattered light emitted from the opposite face of the films was measured as a function of direction for each using the same sensitivity scale and was correlated with the preparation of the film. It was found that on nominally smooth substrates fast-deposited thinner films give out more light and are deduced to have greater short wavelength (300–600 nm) roughness amplitude. There is also evidence for long wavelenth (7μm) periodic roughness due to the prism substrate itself. On CaF2roughened surfaces the light output from the films is further increased and the peak intensity is backward directed with respect to the exciting laser beam direction. Here roughness on a lateral scale of 350 nm is responsible. Also, elastic scattering of surface plasmon polaritons at grain boundaries reduces the light output from fast deposited, small grain, films on CaF2roughened surfaces. Overall, a consistent picture of roughness induced radiative polariton decay emerges for all cases studied.

ISSN:0950-0340    

DOI:10.1080/09500349314551741

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor