摘要:

The angular spectra of bulk waves mode converted from surface wave reflections at a free‐metallized, mass‐loaded, and 90° crystal corner interface were measured ony‐zlithium niobate. The fraction of surface acoustic wave energy converted into shear bulk wave energy was dependent on the strength of the surface perturbation at the interface.

ISSN:0003-6951    

DOI:10.1063/1.90042

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Surface‐acoustic‐wave guides have been obtained by ion‐implanting narrow channels on lithium niobate substrates. Guides of different widths have been tested at 150 MHz. Two doses of helium ions at 100 keV have been used. The acoustic power distribution profiles along a guide length close to 21 mm were determined by optical probing. Air‐gap silicon convolvers have been implemented with this kind of guide. An external figure of merit equal to −49 dBm has been measured, whereas without guidance the external figure of merit is only close to −61 dBm for the same transducer pattern.

ISSN:0003-6951    

DOI:10.1063/1.90018

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Insitux‐ray topography is used for the study of misfit dislocations in growing heteroepitaxial layers. Topograms taken from Ge layers on GaAs substrates show the generation of misfit dislocations at various locations commencing at a layer thickness of about 1000 A˚. These dislocations elongate and eventually grow to a dense cross‐grid array. The specially designed epitaxial reactor and the topographic arrangement with a time resolution between 2 and 20 sec are briefly described.

ISSN:0003-6951    

DOI:10.1063/1.90043

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Two kinds of diffuse x‐ray scattering were found in a very perfect silicon single crystal. One of them forms a cigar shape, extending along the [111] direction. The other is a disk shape whose normal is also parallel to the [111] direction in reciprocal space. Both diffuse scatterings are predominant along the crystal pulling [111] direction. From simple Fourier inversion of the shapes of the diffuse scatterings, it is concluded that the platelike defects and needlelike defects are the origins of the diffuse scatterings. The platelike defects observed differ from those observed by Patel for Czochralski silicon with heat treatment.

ISSN:0003-6951    

DOI:10.1063/1.90044

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Two‐dimensional (r‐z) magnetohydrodynamic simulations of the electromagnetic implosion of metallic foil plasmas show, for certain initial configurations, a tendency to develop large‐amplitude perturbations characteristic of the hydromagnetic Rayleigh‐Taylor instability. These perturbations develop at the plasma magnetic field interface for plasma configurations where the density gradient scale length, the characteristic dimension for the instability, is short. The effects on the plasma dynamics of the implosion will be discussed for several initial foil configurations. In general, the growth rates and linear mode structure are found to be influenced by the plasma shell thickness and density gradient scale length, in agreement with theory. The most destructive modes are found to be those with wavelengths of the order of the plasma shell thickness.

ISSN:0003-6951    

DOI:10.1063/1.90045

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The use of a laser as a tool for annealing of ion‐implantation damage is described. The principal results obtained are as follows: (1) electrical measurements show that activity comparable to that of a 1000 °C 30‐min anneal can be obtained; (2) TEM measurements show that complete recrystallization of the damaged layer occurs during the laser anneal; (3) impurity profiles obtained from SIMS measurments show that the dopant atoms remain in the LSS profile during annealing. Simple diodes were fabricated to examine the feasibility of the method for device fabrication.

ISSN:0003-6951    

DOI:10.1063/1.90046

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Radiation‐induced conduction in polyethylene‐terephthalate (PET) has been measured under high electric field (1.0×106to 1.6×108V/m). In a 6‐&mgr;m‐thick PET film, saturation of the radiation‐induced current occurs at field strengths above 1.2×108V/m. This has been demonstrated by the thickness and dose rate dependence of the induced current. Radiation‐induced conductivity increases monotonically with field strength, then shows a saturation tendency. This may be explained by geminate recombination. Above 1×108V/m, slowly increasing radiation‐induced current appears. This may be caused by electron injection from the cathode, enhanced by the accumulation of the hetero space charges near it.

ISSN:0003-6951    

DOI:10.1063/1.90019

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A new chemical process has been developed that significantly affects the susceptibility of LiNbO3crystals and optical waveguiding layers to the laser‐induced effects known as optical damage. The process involves controlling the nonstoichiometry of LiNbO3by diffusion of lithium oxide. Susceptibility to optical damage in bulk crystals was reduced by increasing the nonstoichiometry (out‐diffusion) and enhanced by decreasing the nonstoichiometry (in‐diffusion). Typically, low‐loss optical waveguides formed by the process supported one or more TE modes and tolerated more than 10 kW/cm2laser transmission at 488.0 nm without inducing any measurable beam profile distortion.

ISSN:0003-6951    

DOI:10.1063/1.90020

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Fabry‐Perot nonlinear optic devices may undergo regenerative pulsations. Such effects may be used to convert cw laser power into a train of light pulses.

ISSN:0003-6951    

DOI:10.1063/1.90021

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A precise value of the third‐order nonresonant susceptibility ratio of carbon disulphide to benzene is determined from coherent anti‐Stokes Raman scattering (CARS) experiments in mixtures of the two liquids. The value is derived from the variation of the frequency separation between the Raman resonance and the interference minimum as a function of the relative concentration of the liquids. The method offers special advantages in many situations of interest.

ISSN:0003-6951    

DOI:10.1063/1.90022

出版商:AIP    

年代:1978

数据来源: AIP