摘要:

The principal behaviour of the far-from-core fields of bound modes on non-circular weakly guiding optical waveguides with infinite uniform cladding is investigated. The field function can be split into a purely radial factor, decaying nearly exponentially with the distance from the core similarly to the fundamental-mode field on circular fibres, and a purely azimuthal factor, which retains its shape at all large distances. However, the relative non-circularity of the field vanishes at infinity. Coupling coefficients for parallel waveguides are calculated from two-dimensional Gaussian approximations for the fields and the refractive-index distributions.

ISSN:0950-0340    

DOI:10.1080/713823355

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Two formulae are derived which make it possible to determine the normalized source spectrum and the degree of spectral coherence of any planar, secondary, quasi-homogeneous source of a certain class, from the knowledge of the far-zone spectrum of the radiated field. The results are illustrated by computed curves. The new inversion formulas are also used to derive a generalized version of a scaling law (1986,Phys. Rev. Lett.,56, 1370) for the invariance of the normalized spectrum of light on propagation in free space.

ISSN:0950-0340    

DOI:10.1080/713823348

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper the problem of exact summation over vibrational states of intermediate electronic level excited by resonance Raman scattering in a molecular system with an arbitrary number of vibrational modes is solved with the help of the coherent state representation. For matrix elements of the resonance Raman (RR) amplitude the expressions in the form of an integral and multiple series as well as recurrence relations are obtained. The interpretation of RR spectra of linear-chain mixed-valence platinum complexes is given as an illustration.

ISSN:0950-0340    

DOI:10.1080/713823352

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A correction to the two-dimensional (2D) BPM analysis of integrated optics lenses based on the effective refractive index (ERI) method is proposed. The modification takes into account the modal conversion effects in depth, by introducing a proper fictitious element in the 2D-BPM analysis. Comparisons with the three-dimensional (3D) BPM results show the validity of this method, which overcomes the CPU time limitations of a 3D-BPM.

ISSN:0950-0340    

DOI:10.1080/713823351

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new design of Mach-Zehnder interferometer (MZI), efficiently suitable for stable single mode operation and laser cavity frequency tuning, is developed. This development eliminates the using of any additional etalons. The design is compact, broadband, low loss, easily adjustable in the laser cavity, and has a free spectral range (FSR) of 42·5 GHz. This design permits different uses in the field of laser spectroscopy and laser applications.

ISSN:0950-0340    

DOI:10.1080/713823357

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The influence of the atomic coherence on the collapses and revivals of the atomic inversion is some generalized Jaynes-Cummings models is examined. It is shown that the collapse and revival times are independent of the initial state of the atom, while the amplitude of the revivals is sensitive to this coherence and the phase of the field. Under certain conditions, the amplitude of the revivals can be decreased and the revivals can become the doublet structure.

ISSN:0950-0340    

DOI:10.1080/713823345

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Real-time holographic recording has recently been demonstrated (1990,Jpn J. appl. Phys., 29 L1840) using the optical heterodyne scanning technique proposed by Poon (1985,Jp. Opt. Soc. Am.A, 2 521). In this paper we discuss the reconstruction of holograms generated by the heterodyne scanning technique. The primary concentration is on real-time reconstruction using an electron beam addressed spatial light modulator (EBSLM). For comparison, coherent reconstruction methods are also presented. Additional topics to be addressed are the spatial frequency limitations of the EBSLM and the derivation of the incoherent point spread function (PSF) of the holographic imaging system. Based upon the derived PSF, the reconstructed real image of a simple slit object is formulated and compared with experimental observations. Descriptions of the scanning holographic recording technique and the operation of the EBSLM are also presented.

ISSN:0950-0340    

DOI:10.1080/713823350

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The extra photon echo decay due to ion-ion, velocity-changing collisions is computed. The strong velocity dependence of the collision frequency is shown to decrease the decay constant by 30%.

ISSN:0950-0340    

DOI:10.1080/713823353

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We consider a two-level atom in a strong laser field, described by the Jaynes-Cummings Hamiltonian in the rotating-wave approximation, yielding the well known dressed states. Diagonalization of the total Hamiltonian is attained by introducing dressed-atomic and photon operators. The quantum theory of measurement of finite duration is used to explore the nature of the physical observables corresponding to the dressed operators. A measuring apparatus is contrived in order to observe the bare-atomic population and the bare-photon number in a dressed state of the system. It is shown that, if the duration ‰ of the measurement is longer than the Rabi period of the system, the apparatus leads to observation of the dressed-atomic population and of the dressed-photon number rather than of the corresponding bare quantities for which it was designed. Conceptual and practical consequences of this result are discussed.

ISSN:0950-0340    

DOI:10.1080/713823347

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper has studied the noise suppression qualities of median and mean filters, and has modelled the blurring effect of the mean filter. It has demonstrated that, when the signal-to-noise ratio is sufficiently low, the overall loss of accuracy introduced by the blurring effect of the mean filter can be more than cancelled out by the improved noise suppression properties it sometimes exhibits. However, this cannot occur for long-tailed noise distributions characterised by median relative noisiness index values of less than unity, for which the median filter is superior both in its noise suppression properties and also in its natural absence from signal distortion effects.

ISSN:0950-0340    

DOI:10.1080/713823346

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor