摘要:

It is demonstrated for the first time that by injection‐current control, the lasing wavelength was able to be switched from the lowest (n=1) quantized state transition to the second (n=2) transition for a single quantum well laser diode. The separation in energy was as wide as >50 meV. This novel function of a laser was realized as a result of appropriately increased threshold gain. This diode, moreover, acted as a multiple wavelength‐emitting laser.

ISSN:0003-6951    

DOI:10.1063/1.97248

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Buried heterostructure phased array lasers have been fabricated with ‘‘Y’’ coupling regions to produce in‐phase locking. The far‐field pattern corresponding to the in‐phase emission of ten waveguides is stable under wide variations of operating conditions. Power outputs of up to 200 mW cw and 400 mW pulsed are obtained from a ten‐element (50 &mgr;m aperture) array. By monitoring the far‐field pattern under impulse excitation, the phase locking is shown to evolve in less than 300 ps.

ISSN:0003-6951    

DOI:10.1063/1.97249

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A plasma erosion opening switch, coupled to a small capacitor bank, conducts 120 kA for 400 ns before opening in 40 ns. Voltages above 170 kV are produced through the use of an electron beam diode. These voltages exceed the initial capacitor bank voltage by a factor of 4. Current and magnetic field measurements indicate that the same current conduction and opening processes observed in earlier erosion switch experiments are involved here at tenfold greater conduction times, verifying the current controlled nature of plasma erosion switch operation.

ISSN:0003-6951    

DOI:10.1063/1.97250

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We present an innovative approach to the study of electrical damage in insulators, involving laser excited fluorescence probes. Specimens first subjected to surface flashover in vacuum were stained with highly fluorescent dyes, chosen to have varied chemical properties, and examined under laser excitation. Surface flashover tracks, locations of corona discharge, and other features were readily revealed, even when no damage was visible to the naked eye. Our results indicate that chemical changes, charge distributions, and structural features arising from electrical, mechanical, and thermal stresses can be probed.

ISSN:0003-6951    

DOI:10.1063/1.97251

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A well defined spectrum of peaks ind2I/dV2vsVhas been obtained with a tunneling microscope immersed in liquid helium. The positions of the peaks correspond closely to the energies of the phonons of the graphite sample and the tungsten tip. We propose that electrons coupling to the bulk phonons near the tip to sample gap cause the observed increases in the tunneling conductance. Spectroscopic imaging at a phonon energy shows spatial variations of the vibrational spectra on an atomic scale.

ISSN:0003-6951    

DOI:10.1063/1.97252

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

This letter discusses the synthesis of CoNxfilms using rf diode reactive sputtering. It describes the properties of crystal structures in CoNxthin films and in particular, the post‐annealing effects on the crystal structures of CoNx. The CoNxfilms have the crystal structures of &egr;‐Co(hcp), &agr;‐Co(fcc), &agr;’‐Co(fcc) as a superstructure of &agr;‐Co, &ggr;‐Co3N(hcp), and &dgr;‐Co2N(orthorhombic). The crystal structures have topotaxial relationships with each other, and exist in a wider composition range than in bulk.

ISSN:0003-6951    

DOI:10.1063/1.97253

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A detector to sense the position of a beam of light with a resolution of less than 100 A˚ has been fabricated with a Ti/Si amorphous superlattice onp‐type Si. There are two regions of photovoltaic sensitivity, a low sensitivity region having a response of 1.6 mV/mm and a high sensitivity region having 1.5 mV/&mgr;m. This novel detector can sense the light spot position over large lateral dimensions, while the high central sensitivity region would permit servo driving to a null position with a high degree of precision. These characteristics also suggest the use of this device in a variety of other photonic transducers.

ISSN:0003-6951    

DOI:10.1063/1.97254

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

New magneto‐optical methods combining integrated dc superconducting quantum interference device and fiber optic technology have allowed energy‐ and polarization‐dependent magnetization measurements to be made on a 10‐&mgr;m‐diam sample of Cd1−xMnxTe. Direct optically induced magnetization data probe the energetics of magnetic polaron formation and reveal the ultimate spin orientation with respect to the incident photon angular momentum.

ISSN:0003-6951    

DOI:10.1063/1.97255

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We have investigated the low‐temperature properties of a GaAsn‐i‐ndiode where the intrinsic region consists of a linearly graded gap of AlGaAs, and is surrounded by lightly doped GaAs regions. The current‐voltage (I‐V) characteristics are strongly asymmetric and are dominated by the graded cap. UnstableI‐Vcharacteristics are obtained in forward bias. Random switching is seen between resistance levels. This is ascribed to single electron events at traps near the abrupt heterojunction of the graded gap—the first such observation in a large area device.

ISSN:0003-6951    

DOI:10.1063/1.97256

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Metal‐semiconductor field‐effect transistors (MESFET’s) having quarter‐micron gate lengths were fabricated in GaAs films grown directly on ⟨100⟩ silicon tilted towards ⟨110⟩ by 4°. Following the growth of 2 &mgr;m undoped GaAs buffer layer a 3 &mgr;m GaAs doped with Si to a level of 3×1017cm−3was grown all by molecular beam epitaxy. Devices showed good dc characteristics with extrinsic transconductances as high as 360 mS/mm. Extrapolation of the short‐circuit current gain calculated from scattering parameters measured up to 20 GHz indicated a current gain cut‐off frequency of 55 GHz, which is comparable to the best MESFET on GaAs substrates. The noise figure measured at 18 GHz was 2.8 dB, which is about 1.4 dB higher than that on GaAs substrates.

ISSN:0003-6951    

DOI:10.1063/1.97257

出版商:AIP    

年代:1986

数据来源: AIP