摘要:

Total and partial reflection are demonstrated at the bends of V‐shaped lasers. By varying the angle of incidence to the facet at the bend, the reflectivity at this facet can be changed. Two totally and one partially reflecting V‐shaped lasers are combined in a unibodied structure to realize a triangular‐shaped ring laser (trilaser). Trilasers are made of three sections which meet at three facets. Two of the facets provide total internal reflection while the third allows partial transmission from which light output is obtained. TheQof the resultant planar cavity is modified by geometry, without the need for facet coating. V‐shaped lasers and trilasers are formed by using the chemically assisted ion beam etching technique in an AlGaAs/GaAs‐based single quantum well graded‐index separate confinement heterostructure material.

ISSN:0003-6951    

DOI:10.1063/1.105317

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Experimental investigations of the focusing behavior of rods having acoustically graded‐index profile across the rod diameter are presented for the first time. The ray acoustics approach is used for the theoretical interpretation. Acoustic velocity profiles have been measured using a 225 MHz line focus beam scanning acoustic microscope. The focusing behavior is visualized with a Schlieren system.

ISSN:0003-6951    

DOI:10.1063/1.105318

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A ZnSe/ZnSSe blue semiconductor laser was demonstrated to show very low threshold by direct photopumping of the ZnSe active layer. The lowest threshold at the excitation wavelength of 445 nm was 10 kW/cm2at 300 K which is equivalent to the current density of 3.6 kA/cm2. This is the lowest threshold ever reported in II‐VI photopumped lasers and is approaching the theoretically calculated threshold. The characteristic temperature of the threshold, which characterizes the temperature dependence of the threshold in the exponential form, was 124 K up to the measured 400 K and was comparable to III‐V double‐heterostructure lasers. The differential quantum efficiency remained the similar level up to 400 K and its decrease observed at 400 K was within 23% of the efficiency at 300 K.

ISSN:0003-6951    

DOI:10.1063/1.105319

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Experimental investigation into the cumulative nature of two‐wave mixing in photorefractive BaTiO3crystal has been carried out. Signal beam amplification via two‐beam coupling has been studied with continuous wave exposure and periodic pulse exposure. A comparison of the two shows the presence of a noncumulative component in the signal beam gain. Dependence of this component on crystalc‐axis orientation has been measured.  <l >

ISSN:0003-6951    

DOI:10.1063/1.105320

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Buried heterostructure lasers fabricated using a three‐step gas source molecular beam epitaxy (GSMBE) process are presented for the first time. We propose a new structure design compatible with nonselective regrowth for the blocking layers, therefore avoiding the use of a dielectric mask. The structure is terminated by a second overgrowth after a material lift‐off. Preliminary results show cw operation with threshold currents of 60 mA for 800‐&mgr;m‐long devices and maximum output power up to 27 mW per facet.

ISSN:0003-6951    

DOI:10.1063/1.105321

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Contamination due to particles generated and suspended in silane rf plasmas is investigated. Powder is rendered visible by illumination of the reactor volume. This simple diagnostic for global, spatio‐temporal powder dynamics is used to study particle formation, trapping, and powder reduction by power modulation.

ISSN:0003-6951    

DOI:10.1063/1.105322

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The composition of ultrathin oxides grown on both [100] and [111]Si substrates in pure N2O in a conventional furnace has been studied using Auger electron spectroscopy (AES) analysis, chemical etching, and electrical measurements. Results show a peak nitrogen concentration at the Si‐SiO2interface which decreases from the Si‐SiO2interface to the oxide surface. This nitrogen distribution is responsible for superior electrical properties of metal‐oxide‐semiconductor (MOS) devices with these films as gate dielectrics.

ISSN:0003-6951    

DOI:10.1063/1.105323

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Clusters of metallic silver have been formed by electrodeposition within the surface of an oxide glass which was subjected to an alkali silver ion exchange process. The clusters have a fractal structure with a Hausdorff dimensionDaround 1.86 over a length scale 10–140 &mgr;m. Electron micrograph of the sample indicates the possibility of a crossover to a nonfractal regime at length scales of the order of a few hundred nanometers. The fractal growth within the glass results in the formation of a glass metal nanocomposite with a particle diameter around 12 nm.

ISSN:0003-6951    

DOI:10.1063/1.105324

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The compressive deformation behavior of Nd2Fe14B single crystals at temperatures between 900 and 1100 °C has been investigated. Considerable ductility occurs only at temperatures above 1000 °C, suggesting that the plasticity of the Nd2Fe14B phase has very little effect on the formation of texture during die‐upsetting of microcrystalline Nd‐Fe‐B hard magnetic alloys.

ISSN:0003-6951    

DOI:10.1063/1.105325

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have prepared continuous amorphous antimony thin films by low‐energy cluster beam deposition. Contrary to the antimony films prepared by molecular beam deposition, this new technique allows preparation of continuous amorphous films which are stable at room temperature. This study has been carried out by combining electrical measurements and transmission electron microscopy observations.

ISSN:0003-6951    

DOI:10.1063/1.105326

出版商:AIP    

年代:1991

数据来源: AIP