摘要:

Synchronous noncollinear upconversion detection is reported for the first time with a Nd:YAG laser in AgGaS2.Q‐switched pump laser pulses with a repetition rate up to 50 Hz were synchronized with intracavity chopped continuous wave CO2laser pulses. Results were obtained both by tuning the CO2laser and by varying the angle between the laser beams.

ISSN:0003-6951    

DOI:10.1063/1.101410

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report for the first time the generation of optimized space‐invariant fan‐out elements, so‐called Dammann gratings [H. Dammann and K. Go¨rtler, Opt. Commun.3, 312 (1971)] in plasma silicon nitride. Diffraction efficiencies as high as 65% have been achieved. Using simulated annealing and the greedy algorithm, grating structures with fan‐out as large as 201×201 can readily be calculated. Low absorption and high optical quality together with its ease of structuring make silicon nitride an ideal medium for the construction of phase‐only optical elements.

ISSN:0003-6951    

DOI:10.1063/1.101331

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The CdSxSe1−xmicrocrystallites contained in colored filter glasses have been considered to be spherical. This letter demonstrates that in fact they are hexagonal columns, implying a wurtzite structure. Microcrystallite grain growth is observed in real time using an electron beam annealing method. Each grain is confirmed by energy dispersive spectrometry to be CdSxSe1−x. The grain size difference produces different optical transmission spectra due to quantum size effects. On the optical transmission spectrum of a sample with grains of 30 A˚, a new absorption band appears. This band can be explained by size quantization of the valence band.

ISSN:0003-6951    

DOI:10.1063/1.101332

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We have developed a radiation to coherent light converter with a monolithically integrated semiconductor chip that consists of a chromium‐doped GaAs photoconductor detector and a GaAlAs laser diode. When irradiated, the electric pulse generated by the photoconductor detector modulates the laser diode, which has been biased above the lasing threshold, thus converting a radiation pulse to an electric pulse and then to a light pulse. The laser pulse is then transmitted to a fast recorder through a high bandwidth optical fiber. In the absence of a single‐step x‐ray pumped laser, our converter appears to be the first integrated device that can efficiently convert x‐ray flux into coherent light. This device has been tested successfully with the 50 ps electron beams of 17 MeV linear accelerator and with 50 ns x‐ray pulses from aZ‐pinch plasma source.

ISSN:0003-6951    

DOI:10.1063/1.101333

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We demonstrate how an adequate choice of growth conditions and GaAs/AlGaAs superlattice series leads to a desired refractive index profile and to confinement of light at the cusp of a planarized structure over a previously photolithographically etched groove. Waveguiding at 1.52 &mgr;m wavelength with measured propagation losses of 1.5 dB/cm was obtained in these structures. The effect of growth parameters is discussed and potential applications of this concept to other structures suitable for guided‐wave devices are proposed.

ISSN:0003-6951    

DOI:10.1063/1.101334

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The problem of photoacoustic pulse generation is treated using generalized thermoelastic equations, specifically incorporating the hyperbolic heat conduction equation to avoid an infinite thermal propagation velocity. The assumption of equality of longitudinal and thermal velocities leads to a simplification of the solution in certain limiting cases, enabling insights into the character of the solution, without appreciably affecting the numerical results. The effect(s) of approximations made by previous authors may also be assessed. Numerical Hankel–Laplace transform inversion is shown to be practical for the general case, allowing such calculations to be duplicated by others.

ISSN:0003-6951    

DOI:10.1063/1.101335

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Neutral CH3radicals in a capacitively coupled rf discharge in methane have been detected with a quadrupole mass spectrometer utilizing a threshold ionization technique. The absolute density of CH3radicals was measured at pressures from 0.5 to 20 mTorr, together with the ionic composition of the methane plasma. The principal ionic species were CH+5and C2H+5, except in the low‐pressure region, suggesting the importance of ion‐molecule reactions in the plasma. The lifetime of CH3radicals in the afterglow of pulsed rf discharges was measured and explained in terms of the recombination reaction CH3+CH3→C2H6.

ISSN:0003-6951    

DOI:10.1063/1.101336

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Surface modification during oxygen plasma etching of polysilylmethylstyrene resists has been monitored using x‐ray photoelectron spectroscopy. Plasma exposure converted the silicon present in the polymers to an oxidized surface region which prevented further chemical etching. Conversion was more rapid and more complete when etching under conditions where higher energy ion bombardment occurred. Polysilylmethylstyrene reached a steady‐state oxide thickness between 3.4 and 5.8 nm, depending on etching conditions. A copolymer of this material with chloromethylstyrene showed a comparable thickness when etched at high ion energies, but did not reach a steady state when etched at conditions where the average ion energy was below 110 eV.

ISSN:0003-6951    

DOI:10.1063/1.101337

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The effect of 20 MeV Cl4+ions incident on Au‐SiO2and Ag‐SiO2interfaces was investigated using high‐resolution transmission electron microscopy. Cross‐sectional micrographs expose beam‐induced gold interfacial transport and migration into the SiO2. No such migration was observed for silver films. The relevance of this phenomenon to the adhesion improvement found at corresponding irradiation doses is discussed.

ISSN:0003-6951    

DOI:10.1063/1.101383

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Is silicon dioxide a viscous liquid or an elastic solid at silicon processing temperatures? Simple calculations using either assumption lead to gross discrepancies with experimental observations. This letter shows that a plastic flow model resolves these discrepancies. Flow develops much sooner than predicted by a linear viscoelastic model. Large deformations (<5%) are accommodated almost entirely by plastic flow. Small deformations are accommodated either elastically or by plastic flow depending on temperature.

ISSN:0003-6951    

DOI:10.1063/1.101384

出版商:AIP    

年代:1989

数据来源: AIP