摘要:

Above a distinct threshold laser flux of 70‐MW/cm2peak (for a pulse consisting of a 150‐ns spike and a 1.8‐&mgr;s tail), the calorimetrically measured effective absorptance of unpolished 3003 alloy aluminum increases abruptly to roughly 14%. While too high to be ascribed to ordinary metal infrared absorptance at any reasonable temperature, this value is typical of total‐energy thermal coupling in air with air plasma ignition. We propose that this absorptance is in fact due to the ignition of a plasma in metal vapor produced by thermally isolated metal defects, rather than to a metal‐dielectric transition.

ISSN:0003-6951    

DOI:10.1063/1.91161

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A low‐temperature‐adapted photoacoustic cell using an electret microphone and a MOSFET preamplifier is described. This cell can operate between 5 and 300 K in a gas‐flow cryostat. By way of illustration, it is used here to perform a new kind of photoacoustic measurement, i.e., to study the specific‐heat anomaly of various insulators in the neighborhood of magnetic phase transitions.

ISSN:0003-6951    

DOI:10.1063/1.91162

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We have examined the performance of a 2‐liter KrF oscillator pumped by a high‐intensity electron beam. For input pump rates of 7 MW/cm3, up to 80 J of laser energy is extracted from the cavity in 50 ns with an efficiency (laser energy divided by deposited electron‐beam energy) of 11%. Values of the small‐signal‐gain length productg0L, the absorption length product &agr;L, and the saturation intensityIswere determined to be 6–16, 0.3–0.6, and 1–10 MW/cm2, respectively.

ISSN:0003-6951    

DOI:10.1063/1.91163

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Stripe‐geometry contacts have been produced by focusing aQ‐switched Nd : YAG laser with a cylindric lens on metallized (AlxGa1−xAs) DH lasers. The contact formation has been performed directly on thep‐type AlGaAs cladding layer without a protecting gas ambient. The laser diodes fabricated from this material exhibited low threshold currents and have been operated cw at room temperature. The nearfield and spectral properties are comparable to diodes fabricated by conventional techniques.

ISSN:0003-6951    

DOI:10.1063/1.91164

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Fabrication and lasing characteristics of InGaAsP/InP distributed‐feedback injection lasers are described. An InGaAsP active layer, ap‐InP clad layer, and ann‐InGaAsP cap layer are successively grown on an InP substrate with a 0.32‐&mgr;m periodic corrugation. The diodes emit at a wavelength of 1.1 &mgr;m up to 170 K under pulsed operation. Single longitudinal mode oscillation and a small temperature dependence of the lasing wavelength of 0.054 nm/K are obtained in these diodes.

ISSN:0003-6951    

DOI:10.1063/1.91165

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The liquid‐crystal alignment properties of gratings with a 1–10‐&mgr;m period are described. Experiments are presented to compare the roles of interfacial interactions and surface topography in determining alignment. It is shown that grooves are neither necessary nor always sufficient to produce alignment. Interfacial forces can give rise to strongly pinned alignment, governed by various biases applied during the first appearance of long‐range order at the interface.

ISSN:0003-6951    

DOI:10.1063/1.91166

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We have used pulsed‐laser radiation to grow homoepitaxialp‐njunctions in silicon. Doped amorphous silicon was deposited on (100) and (111) silicon substrates and annealed with aQ‐switched ruby laser. By this technique, perfect epitaxial layers with good electrical characteristics and controlled dopant profiles can be achieved. The technique can potentially be competitive with or replace ion implantation for many semiconductor‐device applications.

ISSN:0003-6951    

DOI:10.1063/1.91167

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Thin GaAs ribbons from Ga‐AsCl3‐H2epitaxy are flexible. The rapid growth occurs along a ⟨112¯⟩ vector. The thin edges are {110}‐type planes while the flat surfaces appear to be {111}A. A ribbon of dimensions 2×0.1×0.002 cm3can be bent to 1 cm diameter without breakage.

ISSN:0003-6951    

DOI:10.1063/1.91168

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Optical bistability has been observed in a semiconductor for the first time. The bistable etalon consists of a GaAlAs‐GaAs‐GaAlAs molecular‐beam‐epitaxially‐grown sandwich with 90% reflectivity coatings. The bistability is primarily dispersive with the nonlinear refractive index arising from light‐induced changes in exciton absorption. Using light of frequency just below the exciton peak, we observed bistability from 5 to 120 °K with 40‐ns turn‐off and subnanosecond turn‐on times with 1 mW/&mgr;m2holding intensity.

ISSN:0003-6951    

DOI:10.1063/1.91157

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We present a theoretical calculation and experimental data on the effective third‐order susceptibilities &khgr;(3)for degenerate four‐wave mixing near the band gap of semiconductors. The closeness of the calculated and experimental values for the effective &khgr;(3)in silicon at 1.06 &mgr;m indicates the utility of our simple calculation. The large values of &khgr;(3)indicate the possibility of high‐efficiency degenerate four‐wave mixing in semiconductors, especially at longer wavelengths.

ISSN:0003-6951    

DOI:10.1063/1.91158

出版商:AIP    

年代:1979

数据来源: AIP