摘要:

High output power (700 mW) in a nearly diffraction‐limited (0.7°) single‐lobed nonsteering output beam is obtained from a gain‐guided diode laser array in a novel, easily fabricated external cavity configuration. The laser output beam is collimated in both lateral and vertical directions. Differential quantum efficiency as high as 70% has been measured along with excellent linearity of the optical power versus current characteristic. The power and efficiency are the highest reported for a coupled‐stripe laser array emitting a narrow single‐lobed beam.

ISSN:0003-6951    

DOI:10.1063/1.97801

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A new liquid‐crystal display (LCD) is presented with a much better gray‐scale capability than twisted nematic LCD’s and a comparably good contrast. In the not‐energized state the coloration of the display is weak, enabling full color applications. Due to its improved gray‐scale capability which results from the shallow slope of the electro‐optical characteristics, the display is particularly suited for active matrix applications.

ISSN:0003-6951    

DOI:10.1063/1.97802

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

It is shown that a semiconductor laser driven by short electrical current pulses represents a high‐speed gate for external optical signals. Based on this finding a novel sampling technique for the detection of light pulses is demonstrated. Conventional semiconductor lasers can be used as sampling gates in a cross correlation arrangement. The time resolution is observed to be better than 10 ps under appropriate injection conditions of the sampling laser. Computer simulations of the sampling system are carried out in the framework of the rate equation model. The theoretical predictions on the time response and the dynamics of the sampling system agree with the experimental observations.

ISSN:0003-6951    

DOI:10.1063/1.97803

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

An acoustic wave device utilizing plate modes having components of displacement parallel to a crystal surface has been demonstrated to be an effective sensor of liquid shear viscosity (&eegr;) over a wide viscosity range. When a liquid is present on the sensor surface, the propagation loss of the acoustic wave depends upon &eegr; in a calculable fashion. Because the device functions at 159 MHz, liquid relaxation effects occur with high viscosity liquids, causing the propagation loss to saturate. Viscosity is sampled in the 50‐nm‐thick liquid layer which couples to the acoustic wave, so that only a single drop of liquid is required for measurement.

ISSN:0003-6951    

DOI:10.1063/1.97804

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The design of a novel electron gun suitable for intense beam cyclotron resonance devices is introduced here. An annular Pierce‐type gun is used in conjunction with an unbalanced nonadiabatic field reversal and an adiabatic compression region to produce an axis‐encircling beam. This beam is ideally suited for interaction with electromagnetic waves that have strong on‐axis electric fields (e.g., the TE011mode). Low velocity spreads are achieved by utilizing the beam self‐fields in the compression region and by focusing in the Pierce gun.

ISSN:0003-6951    

DOI:10.1063/1.97805

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We have developed a new technique useful in imaging microstructures such as small particles, multilayers, and superlattices on a substrate. By producing images at various angles with respect to the substrate we have been able to obtain new information on interfacial structure not yet available with other techniques.

ISSN:0003-6951    

DOI:10.1063/1.97806

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A (001)CdTe epitaxial layer on a (001)GaAs substrate was studied by x‐ray diffraction between 10 and 360 K. The CdTe growth took place at 380 °C in a vertical gas flow metalorganic chemical vapor deposition reactor. Lattice parameters and integrated intensities of both the substrate and the epitaxial layer using the (00l) and (hhh) Bragg reflections reveal three important features. Firstly, the GaAs substrate does not exhibit severe strain after deposition and it is as perfect as a bulk GaAs. Secondly, the CdTe unit cell distorts tetragonally witha⊥>a∥below 300 K. The decay of the (00l) reflection intensities as a function of the temperature yields a Debye temperature of 142 K, the same value as for bulk CdTe. Thirdly, a temperature‐dependent isotropic static displacement of the Cd and the Te atoms is introduced to account for the anomalous behavior of the (hhh) intensities.

ISSN:0003-6951    

DOI:10.1063/1.97807

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Ion mixing of elemental 4d‐5dmetallic bilayers at 77 K by 600 keV Xe++ions has been studied to test the validity of the phenomenological model of ion mixing that predicts a dependence on the chemical heats of mixing, &Dgr;Hmix, and on the cohesive energies, &Dgr;Hcoh, of the bilayer elements. A series of samples was chosen to minimize the variation in kinematical properties between samples while maximizing the variation in heats of mixing. The experimental results agree well with the model’s predictions, and the experimentally determined constantsK1=0.034 A˚ andK2=27 agree with those of previous work.

ISSN:0003-6951    

DOI:10.1063/1.98253

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The effect of laser pulse width and amplitude on the kinetics of laser‐induced phase transformations of thin films of Te alloys has been mapped. This map, called a phase transformation kinetics diagram, shows distinct regions of crystallization and amorphization and allows important material parameters to be determined. The observed regions were correlated with results from temperature modeling. The minimum crystallization time was measured to be 50 ns for pure Te and increases to 550 ns for Te80Sn20and 80 &mgr;s for Te90Ge10. A boundary, determined by the critical quench rate, separates the region of melt followed by amorphous quench, from melt followed by crystallization. Three methods of reversible cycling are demonstrated.

ISSN:0003-6951    

DOI:10.1063/1.97808

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A surface deformation technique measures the energy deposited in sapphire surfaces irradiated by focused excimer laser light. The absorbed energy creates ≲3 electron‐hole pairs/oxygen atom, consistent with a photochemical etching mechanism.

ISSN:0003-6951    

DOI:10.1063/1.97809

出版商:AIP    

年代:1987

数据来源: AIP