摘要:

The spectrum of the output from an external‐cavity laser containing five discrete diode lasers operating as a coherent ensemble has been shown to correspond to a single mode of the cavity with very narrow linewidth. For cw operation, the linewidth is within the 7.5‐MHz measurement resolution. Pulsed outputs from a low‐level cw baseline are reported for which the single‐mode pulse output is also within the 7.5‐MHz measurement resolution. The measured linewidth of the single‐mode pulse output with no cw output is 9 MHz.

ISSN:0003-6951    

DOI:10.1063/1.98243

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The heat dissipation in upside down mounted ridge‐waveguide lasers equipped with a double‐channel structure is analyzed by a simplified device model. Assuming an isothermal active region, the thermal resistance is obtained by means of conformal mapping. A comparison to published experimental results shows good agreement.

ISSN:0003-6951    

DOI:10.1063/1.98128

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report the first observations of lasing action in electron beam pumped ZnSe grown by molecular beam epitaxy on (100) GaAs substrates. In spite of the small thicknesses (approximately 2 &mgr;m) of the films used, lasing thresholds as low as 3.9 A/cm2have been measured at an accelerating voltage of 20 kV when the (nominal) sample temperature was 15 K. Threshold currents increased for sample temperatures greater than 100 K, and for accelerating voltages both less than and greater than 20 kV.

ISSN:0003-6951    

DOI:10.1063/1.98130

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report the use of Ce‐doped SrxBa1−xNb2O6,x=0.60 and 0.75, as the holographic four‐wave mixing medium in the construction of a self‐starting passive phase conjugate mirror using internal reflection. Without correcting for Fresnel reflections, a steady‐state phase conjugate reflectivity of 25% was measured with Sr0.75Ba0.25Nb2O6:Ce. The distortion correcting property of such a mirror was demonstrated using an imaging experiment.

ISSN:0003-6951    

DOI:10.1063/1.98122

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

At high concentrations of an infrared absorbing gas, the optical absorption length for the incident radiation can become small compared with the thermal diffusion length in the gas. A description of the optoacoustic effect consequently must include thermal conduction of heat to the cell window since sound generation takes place in a thin layer of gas adjacent to the entrance window. A piston model is given here for the optoacoustic effect generated in a highly absorbing gas; in addition, experiments are reported that show new phase and amplitude dependences of the acoustic signal on gas concentrations, and modulation frequency.

ISSN:0003-6951    

DOI:10.1063/1.98123

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Grain growth of ⟨100⟩ textured Ge films on amorphous SiO2substrates during 900 °C isothermal annealing was observed by transmission electron microscopy. An rf sputtering technique was used to deposit the films. By using initially ⟨100⟩ textured film, grain growth (∼1.5 &mgr;m diameter) occurs and is enhanced (∼2 &mgr;m diameter) by square‐wave‐shape grooves fabricated on a SiO2surface, although initial films are relatively thick (0.6 &mgr;m). On the other hand, this grooving edge also has an effect of interrupting the grain growth. These grain growths can be explained by the minimization of the energy required for grain rotation (rotational energy) during grain coalescence.

ISSN:0003-6951    

DOI:10.1063/1.98124

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We have studied the process of buried oxide formation as a function of implantation and annealing conditions. Concentrating on substoichiometric implants (<1×1018O/cm2), we varied the implantation energies from 100 keV to 1 MeV. Some apparent precipitation of SiO2similar to that observed in Czochralski‐grown silicon occurs on implantation. This means that formation of the buried oxide layer and perfection of the overlying crystalline Si layer depend more strongly on the substrate temperature during the implant than on the annealing temperature.

ISSN:0003-6951    

DOI:10.1063/1.98264

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The increase in surface conductivity upon illumination of semi‐insulating GaAs was used to enable surface‐topography measurements with a scanning tunneling microscope (STM). Images were recorded in ultrahigh vacuum and in air using a HeNe laser and a halogen lamp for the generation of a photoconductive top layer. From the current‐voltage characteristics of the tip‐sample contact the maximum feedback‐controlled tunnel current at a given voltage can be deduced. A calculation of the increase in carrier density and conductance upon illumination is given, which confirms the possibility of using STM on highly resistive photoconductive materials. Further implications and applications are discussed.

ISSN:0003-6951    

DOI:10.1063/1.98125

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We have performed finite element analyses of beveled diamond anvils. Our analyses show that double beveling can improve the performance of the diamond anvil cell and maintain the stability of the sample, which is often sacrificed when large angle single bevel diamonds are used.

ISSN:0003-6951    

DOI:10.1063/1.98115

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

It has been previously observed that the impact surface of [100] shock‐loaded lithium fluoride is a strong source of dislocations. These dislocations, on one side of the impact surface, are nearly all of the same sign and move in the same direction when the driving (impact) stress is maintained. This produces an excess of like‐signed dislocations between the impact surface and the advancing planar shock front. It is shown that inclusion of dislocation transport effects in the equation for dislocation regeneration is required when surface sources are present. A derivation of the general expression of dislocation transport is presented along with some specific results for [100] loaded lithium fluoride. These results have important consequences regarding proper analysis of elastic precursor decay and rate‐dependent plastic deformation in shock‐loaded solids.

ISSN:0003-6951    

DOI:10.1063/1.98116

出版商:AIP    

年代:1987

数据来源: AIP