摘要:

We show that the electromagnetic fields diffracted from the indexmatched gratings in conical mountings can be obtained from the fields diffracted from the same grating in classical mountings.

ISSN:0950-0340    

DOI:10.1080/09500349808231662

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A new scheme for high-efficiency phase conjugation of broadband laser radiation in photorefractive crystals is proposed. The scheme utilizes a dispersive ‘2–f’ system for decoupling of the photo-induced index gratings written by the different frequency components. Self-pumped phase conjugated reflectivity of 25% have been achieved over bandwidths of tens of nanometres in an undoped BaTiO3crystal using broad-spectrum Ti: sapphire laser pulses.

ISSN:0950-0340    

DOI:10.1080/09500349808231663

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The propagation of solitons in dissipative, elliptically birefringent single-mode fibres is considered analytically by a variational technique, in terms of a theoretical model of two coupled nonlinear Schrödinger equations with all the oscillating terms, arising from nonlinear polarization. For nearly equal amplitudes of the interacting solitons of different polarizations, the frequency of relative oscillations of soliton positions has been determined.

ISSN:0950-0340    

DOI:10.1080/09500349808231664

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The propagation properties of the pulsed zeroth-order Bessel beams are discussed. It is shown that, as a result of the non-diffracting property of the Bessel function beams on propagation, the corresponding pulsed Bessel beams may propagate with some special characteristics, and as an example the time Gaussian-shaped pulsed zeroth-order Bessel beams are considered. We find that, for this type of beam, the spectral intensity and pulse energy will always remain unchanged when the beams propagate through the free space, while the temporal shape of the pulse will change with the propagation distance.

ISSN:0950-0340    

DOI:10.1080/09500349808231665

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We study the interaction of a small number of resonant two-level atoms in a cavity coupled to a quasi-continuum of cavity modes. During the interaction we induce externally a phase step to one of the atoms. As a result an enhancement in the photon emission to the field is observed. The phase step is obtained by a pulse which causes the atom to be off-resonance for a short time interval. The effect is strongest in cases where the number of atoms is small. The enhancement is not restricted to a small parameter range but should be observable in many systems even though the φ phase shift gives the best enhancement.

ISSN:0950-0340    

DOI:10.1080/09500349808231666

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In the present paper we show that when a linearly polarized wave is incident on an uniaxial crystal–isotropic medium interface, the refracted ray is elliptically polarized when the incidence angle is greater than the limiting one of inhibited reflection. We also calculate the eccentricity of the ellipse of polarization and the angle between its major axis with the incidence plane.

ISSN:0950-0340    

DOI:10.1080/09500349808231667

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The effect of a resonator's optical path fluctuation (ROPF) on a fibre-optic ring resonator is described. It makes the transmission characteristics degrade and the effective fineness decrease. It is similar to the effect of light-source temporal coherence, but different from that of the continuous resonator's optical path alteration.

ISSN:0950-0340    

DOI:10.1080/09500349808231668

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The realization and theoretical limits of the spectral resolution in double Fourier interferometric imaging (DFII) with a phase telescope array are presented. The realization and the effects of optical path difference (OPD) modulations are discussed. Two basic requirements for OPD modulations must be met in the design and operation of a double Fourier interferometer: symmetric OPD modulations about zero OPD and identical OPD modulations at all the available spatial frequencies. The Gibbs phenomenon due to OPD modulations affects the source's spectral brightness distribution, but, for a point source, not the complex visibility. Theoretically, without loss in spatial image fidelity, it is not possible to perform DFII with a telescope array when the aperture synthesis is done only by the Earth's rotation. In practice, DFII can be realized under approximation. In this case, relations between the spectral resolution, the interferometer's parameters and the observed star's parameters are derived. For a two-aperture interferometer with an east-west baseline of 100 m and telescope diameter of 8 m, the spectral resolution is limited to several thousands or less for a star having a magnitude of five, six or fainter, a field of view equal to or larger than the Airy disc of the diffraction pattern of the single telescope aperture and a signal-to-noise ratio of three in the interferogram.

ISSN:0950-0340    

DOI:10.1080/09500349808231669

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The assessment of optical focusing systems with obscured rectangular pupil masks suffering from spherical aberration is performed by use of a novel technique for the computation of the irradiance distribution along the optical axis. It is shown that all the values of this function for a variable spherical aberration can be obtained from a single bidimensional phase-space representation: a Wigner distribution function associated with the pupil function of the system. Several numerical examples illustrating the behaviour of such aberrated systems are presented and some interesting features of the results are discussed.

ISSN:0950-0340    

DOI:10.1080/09500349808231670

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Quantum formalism of Fraunhofer diffraction is obtained. The state of the diffraction optical field is connected with the state of the incident optical field by a diffraction factor. Based on this formalism, correlations of the diffraction modes are calculated with different kinds of incident optical fields. Influence of correlations of the incident modes on the diffraction pattern is analysed and an explanation of ‘ghost’ diffraction is proposed.

ISSN:0950-0340    

DOI:10.1080/09500349808231671

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor