摘要:

We review the work done to date in the field of nonlinear integrated optics. Emphasis is placed on (intrinsic) second‐ and third‐order phenomena occurring in planar geometry structures and several applications are discussed. All of the nonlinear interactions are discussed in a single notation.

ISSN:0021-8979    

DOI:10.1063/1.336205

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The rf acceleration of moderate current (≲1 A) electron beams to 500 keV in a TE111cylindrical cavity resonator is described. Experimental results are compared with theory. rf to beam energy conversion efficiencies in excess of 50% have been observed. The resultant axis‐encircling beam with a large ratio of perpendicular velocity to longitudinal velocity is ideal as a driver for a high‐harmonic gyrotron.

ISSN:0021-8979    

DOI:10.1063/1.336262

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Application of electrohydrodynamic instability theory to a planar liquid‐lithium surface suggests that liquid lithium may provide a large‐area ion source for intense ion‐beam diodes. Such a source could uniformly produce ions on a nanosecond time scale if the applied electric field exceeds 10 MV/cm. Wavelengths and growth times of the most rapidly growing instability have been calculated to first order as a function of applied electric field. Results have been interpreted in the context of an ion source for a light ion‐beam driver for inertial confinement fusion.

ISSN:0021-8979    

DOI:10.1063/1.336263

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We analyze the nonlinear coupled differential equations for the nonlinear coherent coupler by extending the Stokes parameters formalism. The existence of bifurcation and instability phenomena is proved.

ISSN:0021-8979    

DOI:10.1063/1.336264

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Two different quantum well heterostructure wafers are used to fabricate buried‐heterostructure AlxGa1−xAs‐GaAs quantum well lasers using Si‐induced layer disordering (via Si diffusion). In contrast to the first wafer (QWH1), the second quantum well wafer (QWH2) utilizes Zn instead of Mg as thep‐type dopant in the top AlxGa1−xAs confining layer and yields, because of concentration mismatch in acceptor and donor doping in the confining layers (nZn>nSe), inferior laser diodes owing to Zn diffusion from thep‐type to then‐type confining layer during high temperature processing (850 °C Si diffusion). The first quantum well heterostructure, however, employs a lower concentration Mg doping for itsp‐type confining layer (nMg<nSe) and yields high performance devices when used with the Si‐induced layer‐disordering process. For QWH1 thep‐njunction and injection is not displaced (as for QWH2) from the QW active region during Si‐induced layer disordering (850 °C annealing). A fabrication process is presented in which quantum well laser diodes are built with active regions as narrow in width as 0.6 &mgr;m, cw room‐temperature laser threshold currents as low as 3 mA, and pulsed current thresholds as low as 1.5 mA.

ISSN:0021-8979    

DOI:10.1063/1.336265

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

WhenY‐cut LiNbO3substrates are proton exchanged in pure benzoic acid to fabricate optical waveguides, they suffer surface damage, and a consequent degradation in optical properties. This effect is mainly produced by a remarkably large strain in the exchanged layer in a direction normal to the surface. This strain leads to a large number of cracks and to the peeling off of the exchanged layer itself. This paper presents a probable explanation of the mechanism involved.

ISSN:0021-8979    

DOI:10.1063/1.336266

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The scattering of ultrasonic waves by oblate spheroidal voids of very high aspect ratios (a:b=1:20) is analyzed using theT‐matrix method. By using an iterative Gram–Schmidt orthogonalization procedure, and by enforcing the unitarity and the symmetry properties of theTmatrix at each iteration, numerical results are presented for normalized frequencieskpbup to 15.0. Aspect ratios up to 1:20 and such high frequencies were previously not amenable to computations using the conventionalT‐matrix procedure. Scattering by smooth as well as rough voids having periodically corrugated surfaces is studied. All computations were carried out on a DEC VAX 11/730 minicomputer.

ISSN:0021-8979    

DOI:10.1063/1.336267

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Results of experimental measurements and theoretical calculations on ultrasonic leaky Lamb‐wave propagation in fiber‐reinforced, unidirectional composite laminates are presented. With the Lamb wave vector oriented parallel to the fiber direction, dispersion curves of phase velocity versus frequency and plate thickness have been constructed from measurements of ultrasonic reflection from fluid‐loaded composite plates. The experimental results are supported by a theoretical model of Lamb‐wave propagation in the composite plate. The model begins with an approximate calculation of the effective, homogeneous, transversely isotropic elastic behavior of a unidirectional composite laminate in the long‐wavelength limit, using a two‐step procedure based on alternating layered media. This intermediate continuum result is then incorporated into a calculation of the ultrasonic reflection coefficient of a fluid‐loaded anisotropic plate, which is assumed to approximate the fibrous composite laminate. Good quantitative agreement with the model is found if the fiber volume fraction is taken to be an adjustable parameter. However, not all portions of the dispersion curves predicted by the model can be observed in the data. It is conjectured that relative differences in mode coupling account for this discrepancy.

ISSN:0021-8979    

DOI:10.1063/1.336268

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We investigate a heat flow instability arising due to transverse perturbation of an initially uniform flow. Its growth rate is shown to be determined by the magnitude of the heat flux. The presence of ion acoustic turbulence driven by the flux itself leads to stabilization of the instability due to a decrease of the transverse heat flow.

ISSN:0021-8979    

DOI:10.1063/1.336269

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Radiation‐induced defects in Zr‐based fluoride glasses have been characterized using optical absorption and electron spin resonance (ESR) techniques. The optical absorption bands due to interstitial fluorine atoms, the F−2, FCl−, Cl−2centers, and Zr3+centers have been identified by correlating optical absorption and ESR measurements. Polarized bleaching experiments indicate that the hole‐type centers, and the Zr3+centers have anisotropic defect configurations. X‐ray excitation at 14 K generates a broad, asymmetric emission band at 337 nm (3.68 eV), which is assigned to a localized‐excited state similar to that for self‐trapped excitons in halide crystals. The intensity of the x‐ray induced emission provides further evidence that radiolysis defect production occurs in this material. The optical tail of the radiation‐induced Zr3+absorption affects infrared transmission. Evidence is presented that the CCl4reactive‐atmosphere process introduces a significant amount of Cl−(∼5%) in the glass.

ISSN:0021-8979    

DOI:10.1063/1.336270

出版商:AIP    

年代:1985

数据来源: AIP