摘要:

Three methods of obtaining the Mie scattering function are considered and compared. Legendre polynomials and Clebsh-Gordon coefficients are employed and an exact expression for the expansion of the Mie kernel in spherical harmonics is given.

ISSN:0950-0340    

DOI:10.1080/09500348914550781

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This paper describes self-deflection effects arising from the propagation of symmetric and asymmetric three-dimensional scalar optical beams through thin nonlinear layers. The model of nonlinearity used includes both saturation and absorption. In several cases, significant differences are observed between the present three-dimensional results and previous two-dimensional results based on the Kerr model of nonlinearity. Also, the existence of a large axial component of the self-deflected beam for a three-dimensional geometry against the absence of this component for a two-dimensional geometry is discussed.

ISSN:0950-0340    

DOI:10.1080/09500348914550791

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The population model of cavity photons previously introduced is analysed by identifying the non-Markov evolution in terms of phases whose durations are themselves independent and exponentially distributed random variables. The resulting radiation is shown to have thermal characteristics for an appropriate choice of the population parameters. The detection process is explicitly introduced and its characteristics are obtained. The model is shown to be viable enough to produce intensity spectra of different shapes corresponding to the resulting radiation.

ISSN:0950-0340    

DOI:10.1080/09500348914550801

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A theoretical analysis of an optical processing system for time-space shaping of short light pulses is presented. The optical scheme considered consists of two gratings with a 4-f Fourier-processing system placed between them. Using an expansion of the field over a set of temporal and spatial modes, we find an expression for the output field as a function of the input field and of the system parameters. Our approach allows the solving of the inverse problem: a determination of the filter function, which will give a preliminary designed output pulse shape. The formalism developed could be applied in the description of other similar systems.

ISSN:0950-0340    

DOI:10.1080/09500348914550811

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The effect of non-uniform transmission filters on the axial and extra-axial responses of aberrated optical systems is studied. The axial Strehl ratio (SR) is increased by varying the filter transmission function and the extra-axial SR by shifting the filter position along the axis of the optical system. It is shown that a filter which optimizes the axial SR can also improve the extra-axial SR. There are some positions of the filter for which the total results are improved. These positions are explained from the lack of radial symmetry of the wave aberration. The filters which improve the SR are also studied in terms of energy transmission.

ISSN:0950-0340    

DOI:10.1080/09500348914550821

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A theoretical model for non-uniform volume gratings is described in which the refractive index modulation and grating vector are allowed to vary with depth. The predictions of the model are compared with the measured angular response of reflection gratings recorded in dichromated gelatin and the variations of the grating parameters with depth are deduced. Gratings produced by different processing techniques are analysed and the effects of processing on grating non-uniformities are discussed.

ISSN:0950-0340    

DOI:10.1080/09500348914550831

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A methodology for designing pairs of layers to reduce the peak electric-field intensity in the critical layers of multilayer polarizers and oblique incidence reflectors is presented. It is shown that, for S-polarized radiation, the peak field intensity in the first high-index layer of a polarizer having (H/2 L H/2) as the basic stack, can be reduced by about a factor of seven by adding a single pair of layers on the side of incidence. Further, about a factor of four reduction in peak field intensity for S-polarized radiation occurs in the first high-index layer of a (HL)7H polarizer and oblique-incidence reflectors with the addition of three pairs of layers having different thicknesses. This methodology can also be applied for designing pairs of layers for reducing peak electric-field intensity for P-polarized radiation.

ISSN:0950-0340    

DOI:10.1080/09500348914550841

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The fringes of a double-layer interferometer containing a birefringent plate, cut from a biaxial crystal, are split into two separate components belonging to the ordinary and extraordinary waves whose refractive indices have a difference determining the component separation. The dependence of the intensity ratio of the resolved components upon the angle of ray propagation in the crystal is used to identify the axes of a biaxial crystal like muscovite mica. A fringe count with a rotated sample accurately determines its optical thickness from which the absolute values of the refractive indices are deduced. The sensitivity of the double-layer interferometer to dispersion effects is so high that a birefringence dispersion is measurable and either the anisotropy of the atomic number density or the splitting of the characteristic spectral line is detectable.

ISSN:0950-0340    

DOI:10.1080/09500348914550851

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A guided-wave multimode multi/demultiplexer which comprises interference filters and gradient-index waveguides was investigated both theoretically and experimentally. Effective design considerations concerning filter configuration and waveguide geometry led to a high-performance multi/demultiplexer in a glass substrate. Original filter configurations suitable for operation in a waveguide were devised through theoretical analysis. The transmission band-widths for two channels with 100 nm separation were as wide as 66 nm. Waveguide parameters were optimized to obtain low transmission loss (propagation loss plus slot loss) and also to realize efficient coupling to input/output fibres. The insertion losses were around 1 dB for demultiplexing and less than 2 db for multiplexing.

ISSN:0950-0340    

DOI:10.1080/09500348914550861

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0950-0340    

DOI:10.1080/09500348914550891

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor