摘要:

Strong similarities Between the spatio-temporal dynamics of singly resonant optical parametric oscillators operating by out of Phase-matching, and those of parametrically excited surface waves studied in hydrodynamics, are Pointed Out.

ISSN:0950-0340    

DOI:10.1080/09500349608232787

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Optical waveguides have been fabricated in Cr3+:Gd3Ga5O12by the method of He4+ion implantation at energies of around 2·8 MeV. Preliminary results indicate losses of the order of 3 dB cm−1with little or no effect on the absorption, emission or radiative lifetimes of the implanted material.

ISSN:0950-0340    

DOI:10.1080/09500349608232788

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A phenomenological explanation is made of different types of resonances in the reflectivity curves of a prism coupler in the region of surface plasmon excitation. The approach is based on the poles and zeros of the scattering operator and demonstrates that the existence of peaks instead of dips is natural and is determined by the positions of the pole and the zero in the complex plane.

ISSN:0950-0340    

DOI:10.1080/09500349608232789

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We present a detailed experimental investigation of the influence of the refractive index and thickness of a waveguiding planar layer placed between two fibres in a polished type single-mode optical fibre coupler. Experiments were performed for different distances between the fibres. The investigation not only revealed some new possibilities for the practical use of such coupler, but provided a reliable quantitative database for future theoretical modelling of this complex waveguiding structure.

ISSN:0950-0340    

DOI:10.1080/09500349608232790

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The relationship between the beam energy at the output of an optical system, the Wigner distribution function at the input and the complex optical system matrix has been derived for an arbitrary light distribution.

ISSN:0950-0340    

DOI:10.1080/09500349608232791

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

It is shown that a rotationally symmetric surface, which is the border between two optical media, can focus a parallel light beam to a point only when the profile of the surface is an ellipse or a hyperbola with eccentricity equal to the ratio of refractive indices of both media. In fact, as is well known, the conic sections do not describe the corneal profile well, so a new analytical approximation for the corneal contour is given. This simple approximation in the case of a rotationally symmetric surface is based on the hyperbolic cosine function with two parameters, the radius of curvature at the apex of the cornea and a parameter describing the stability of the central curvature. The hyperbolic cosine function can also be used to approximate a 3-D non-rotational surface in the case of a cornea with axial astigmatism. The 3-D contour map of deviation of the hyperbolic cosine approximation from a reference sphere is compared with an interferogram of a corneain vivo, recorded in a Twyman-Green interferometer.

ISSN:0950-0340    

DOI:10.1080/09500349608232792

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The inhomogeneity of thin films of ZrO2and TiO2was reduced by ion beam bombardment with mixed argon and oxygen as a working gas during deposition. The inhomogeneities of the films were calculated from transmission monitoring curves. The optimum ion beam voltage and ion beam current density are 900 V and 12 μA cm−2for TiO2film.

ISSN:0950-0340    

DOI:10.1080/09500349608232793

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper we describe a superposition model for Bessel-Gauss beams, in which higher orders are included. An analogous model leads to a different class of beams, namely the modified Bessel-Gauss beams. Then a generalized set of beams, containing the previous beams as particular cases, is introduced. The behaviour of these beams upon propagation is investigated, both analytically and numerically.

ISSN:0950-0340    

DOI:10.1080/09500349608232794

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper considers the evanescent vectorial field occurring when light is focused by a high-aperture lens through a planar interface between media of mismatched refractive index. Using a rigorous vectorial electromagnetic treatment developed previously for a similar problem by Török et al. in 1995, the time-averaged electric energy density distributions in the vicinity of the interface are numerically evaluated for a number of refractive indices. Axial distributions are shown for sine and Herschel conditions and the two-dimensional time-averaged electric energy density distributions are shown in the 0° and 90° meridional planes.

ISSN:0950-0340    

DOI:10.1080/09500349608232795

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The temporal frequency response is derived for phase modulation in two-wave mixing for photorefractive crystals with long charge photocarrier lifetimes. Theoretical analysis shows that when the photorefractive response time is comparable with the photocarrier lifetime, the effects of the latter on the frequency transfer function must be considered. The present analysis is applied for Bi12SiO20-type photoreafractive crystals.

ISSN:0950-0340    

DOI:10.1080/09500349608232796

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor