摘要:

A novel self‐aligned buried‐ridge striped planar (BRSP) GaAlAs/GaAs diode laser structure is presented. The structure was grown by two‐step liquid phase epitaxy using preferential growth and melt etch. A Ga1−yAlyAs layer with a wide range of Al concentration (y>0.05) is selectively grown outside the ridge and can be an effective melt‐etching mask. As a result, the BRSP structure can incorporate virtually all effective index steps, i.e., the positive, negative, and complex index steps. The threshold current of the BRSP structure is between 70 and 100 mA. The BRSP structure may prove to be of importance in the realization of linear array lasers.

ISSN:0003-6951    

DOI:10.1063/1.102732

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The nonlinear properties of a distributed feedback grating in a waveguide characterized by a diffusive thermal nonlinearity were investigated experimentally. Reflection and transmission were measured in an InSb planar structure, and all‐optical tuning of the reflectivity was achieved either by a guided wave incident onto the distributed feedback grating near its Bragg condition, or by a second guided beam tuned far from the Bragg condition.

ISSN:0003-6951    

DOI:10.1063/1.102710

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have studied the optical absorption properties of a GaAs/AlAs short‐period superlattice at room temperature in an electric field perpendicular to the layers. Several pronounced optical transitions related to Wannier–Stark localization are observed indicating a coherence length of at least five superlattice periods. These transitions produce multiple regions of negative differential photoconductivity which are used to realize a multistable self‐electro‐optic effect device.

ISSN:0003-6951    

DOI:10.1063/1.102711

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Crystals with the K2NiF4structure are good hosts for transition metal and rare‐earth ions. Continuous‐wave room‐temperature laser action in a neodymium‐doped crystal with this structure, CaYAlO4, was observed using a GaAlAs diode laser array for end pumping of the laser rod. The free‐running laser operated at a wavelength of 1080.6 nm.

ISSN:0003-6951    

DOI:10.1063/1.102712

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A concise and fundamentally straightforward physical model that accounts for the nonlinear gain in both semiconductor amplifiers and lasers is presented. Calculations based on this model yield results that agree very well with observed transient gain recovery dynamics in semiconductor laser amplifiers. The value of the symmetric steady‐state gain suppression factor is found to be &bgr;=1.67×10−23m3in good agreement with experiment. The model accounts for a wavelength dependence of the asymmetric part of the nonlinear gain observed in direct mixing experiments observed in semiconductor lasers.

ISSN:0003-6951    

DOI:10.1063/1.102713

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We investigate self‐induced transparency soliton switching in a nonlinear two‐level resonant dual‐waveguide directional coupler. The soliton transfer properties of the coupler depend on the input pulse area; for areas larger than &pgr;, an integer number of 2&pgr; solitons is transmitted from the output ports. Tapered coupling provides digital transmission characteristics. A specific example of application to impurity bound excitons in semiconductors is discussed.

ISSN:0003-6951    

DOI:10.1063/1.102714

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Special current distributions that are widely assumed to have vanishing self‐force in fact can have sizable magnetic forces. The Lorentz self‐force is often miscomputed by ignoring part of the magnetic self‐field in the traditional model of force‐free configurations. Furthermore, magnetic stresses in general do not vanish when the Lorentz force does. These stresses are responsible for the observed deformation of Lorentz force‐free electromagnets. Although straightforward, these results revise some long‐established models in superconducting magnet design, magnetic confinement fusion, and astrophysical magnetic fields.

ISSN:0003-6951    

DOI:10.1063/1.102715

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The growth of diamond films on (001) Si substrates by bias‐controlled chemical vapor deposition is described. The film quality as judged by Raman spectroscopy and scanning electron microscopy depends strongly on the biasing conditions. Under low current reverse bias conditions, highly facetted cubo‐octahedral diamond growth exhibiting a single sharp Raman line at 1332 cm−1was obtained, while biasing in high current conditions which created a plasma resulted in multiply twinned, microcrystalline growth incorporatingsp2‐bonded carbon into the diamond film.

ISSN:0003-6951    

DOI:10.1063/1.102716

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A two‐terminal, monolithic cascade solar cell with an efficiency of 27.3% is reported. The device structure consists of a Ga0.5In0.5P homojunction grown epitaxially upon a GaAs homojunction, with a GaAs tunnel diode interconnect. The tandem combination of these two materials is lattice matched, and has a theoretical efficiency of 34%. The device was grown by metalorganic chemical vapor deposition at 700 °C, using trimethylgallium, trimethylindium, arsine, and phosphine as sources. The minority‐carrier transport properties of the Ga0.5In0.5P are shown to be relatively insensitive to variations of the growth temperature and phosphine overpressure. Other factors that affect the efficiency of the device are presented and discussed.

ISSN:0003-6951    

DOI:10.1063/1.102717

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Stimulated emission from a clearly defined quantum well transition has been observed from single quantum wells as thin as two monolayers (ML, 1 ML=2.83 A˚). These results are unexpected since previous experimental and theoretical work has indicated that if the well widthLzis smaller than the scattering path length of electrons or holes, carrier collection becomes inefficient and the quantum well cannot support stimulated emission. Laser thresholds of these separate confinement, single quantum well samples are quite low, despite the fact that these ultrathin quantum wells are undoped and do not have graded band‐gap confining layers. These unexpected results can be explained in terms of the spatial extent of the wave function rather than the well thickness.

ISSN:0003-6951    

DOI:10.1063/1.102718

出版商:AIP    

年代:1990

数据来源: AIP