摘要:

General conditions for four‐wave mixing processes are investigated for the three‐dimensional geometry. Unlike the standard two‐frequency coherent Raman scattering, the use of three laser beams allows great flexibility in the phase‐matching condition. Theoretically calculated plots are presented for dispersive and nondispersive media and are compared with experimental results in carbon disulphide and hydrogen gas, respectively.

ISSN:0003-6951    

DOI:10.1063/1.90194

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A laser plasma isolator was developed to attenuate a retropulse in a high‐power CO2laser system. An attenuation ratio of 1/20 of a main laser beam (∼1‐J 3‐nsec pulse‐width FWHM) was obtained by blowing off a carbon plasma induced by a plasma production laser beam (∼0.5‐J 3‐nsec pulse‐width FWHM) onto the waist of the main laser beam.

ISSN:0003-6951    

DOI:10.1063/1.90195

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Constricted double‐heterojunction (CDH) lasers have been prepared in a double‐dovetail channel structure, which consistently provides cw fundamental‐mode operation. Oscillation in both single lateral and single longitudinal modes (spectral halfwidth <0.09 A˚) is obtained at drive currents 50–100% above threshold and to cw power levels as high as 12 mW. ’’Kinkless’’ power‐current curves at 20 and 70°C have been obtained from all lasers prepared to date to power levels close to that at which degradation occurs (∼30 mW cw at 20 °C for a 3–4‐&mgr;m‐wide lasing region). Threshold currents of 55–75 mA and external differential quantum efficiencies (one facet) of 15–17% are obtained from 120–150‐&mgr;m‐long diodes with a reflector on one facet. Threshold current ratios as low as 1.26 have been measured between 20 and 70 °C.

ISSN:0003-6951    

DOI:10.1063/1.90196

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Experimental evidence shows that toroidal or helical‐circular metallic waveguides, operating on the whispering‐gallery principle, can be bent significantly without affecting either their ray‐guiding or modal properties. These remarkable properties, reported here for the first time for any type of surface guide, result from the fact that the allowed deformations are geodesic and conserve the curvature of the rays. Scanning in one or two dimensions with a diffraction‐limited beam has been achieved.

ISSN:0003-6951    

DOI:10.1063/1.90197

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Measurements of the heating of metal targets in air by laser pulses with plasma ignition have shown substantial enhancement of thermal coupling compared to simple infrared absorption. This heat is in some cases spread over an area much larger than the laser spot. We present direct measurements of the spatial distribution of aluminum target heating with a high‐energy (11 kJ, 40 &mgr;s) CO2laser pulse. This observed distribution is compared to that calculated for a model of thermal coupling via thermal emission from a vertically propagating disk‐shaped plasma. This model yields a better fit to the data than is obtained for a model of coupling via thermal conduction from a hydrodynamically expanding plasma due to Robin.

ISSN:0003-6951    

DOI:10.1063/1.90198

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Enhanced laser action of KrF* is observed for a diluent mixture of Ar and Ne. If the Ar diluent is replaced by neon, the maximum output is practically unchanged. For an optimized mixture of Ne and Ar the output is increased by more than 50%. The system, with an active length of 50 cm and a diameter of 4 cm, is transversely excited by an e‐beam with a pulse duration of 30 nsec, current density of 100 A/cm2, and energy of 750 kV. The maximum output energy is 2.1 J.

ISSN:0003-6951    

DOI:10.1063/1.90199

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We have observed light‐sensitive oxygen‐induced low‐energy electron losses at amorphous silicon surfaces at 7.6, 10.1, and 12.9 eV. The crucial feature of our interpretation is the requirement that surface states in the band gap, isolated from the valence and conduction bands, must be involved in the loss transitions. An energy‐level scheme, based on the above requirement and on the valence‐ and conduction‐band structure determined by others, can readily account for the observed loss transitions and their light sensitivity.

ISSN:0003-6951    

DOI:10.1063/1.90200

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

From the fact that good silicon JFET’s do not have any flicker noise, it is concluded that flicker noise in semiconductors and semiconductor devices cannot be a true bulk effect. Since JFET’s have no semiconductor‐oxide interface to speak of, whereas all other semiconductor devices do, this points to the semiconductor‐oxide interface as the source of 1/fnoise. This leads to the following model. The carriers are trapped and detrapped by oxide traps, and this gives rise to two distinct noise effects: density fluctuation noise that can be described by the McWhorter model and mobility fluctuation noise that could possibly be described by the Kleinpenning model. The two models might therefore ultimately be unified into a single model, and it would depend on the device under study whether one or the other noise effect would predominate.

ISSN:0003-6951    

DOI:10.1063/1.90201

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Thin films of antimony‐doped tin dioxide are deposited by dc sputtering from sintered targets containing 10, 20, and 30% Sb2O3by weight of SnO2. The concentrations of Sb, Sn, and O in the films and in the target surfaces are determined by using Auger electron spectroscopy. It is observed that the Sb content in the films depends nonlinearly upon the Sb2O3contents of the targets, and that the films become increasingly resistive with Sb2O3content beyond 10% in the target. In the films the Sb content is less than the Sn content, although the reverse is true in the case of the targets.

ISSN:0003-6951    

DOI:10.1063/1.90202

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The ability of a cw‐pumped Nd : YAG laser to anneal process‐induced slip damage in silicon is demonstrated via x‐ray topography as well as Sirtl etching. Severely dislocated regions of a silicon wafer were scanned by the laser at various power levels. X‐ray topographs of the regions indicate that 55–110 J/cm2can anneal even severely damaged material. Further, the depth of the anneal is estimated to be between 10 and 25 &mgr;.

ISSN:0003-6951    

DOI:10.1063/1.90203

出版商:AIP    

年代:1978

数据来源: AIP