摘要:

Graded‐index separate‐confinement heterostructure InGaAs/AlGaAs single quantum well diode lasers emitting at 1.02 &mgr;m have been fabricated from structures grown by organometallic vapor phase epitaxy. Under pulsed operation, threshold current densities as low as 65 A/cm2, the lowest reported for InGaAs/AsGaAs lasers, have been obtained for a cavity lengthLof 1500 &mgr;m. Differential quantum efficiencies as high as 90% have been obtained forL=300 &mgr;m. Output powers as high as 1.6 W per facet and power conversion efficiencies as high as 47% have been obtained for continuous operation of uncoated lasers withL=1000 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.103678

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Monolithic bistable e´talons with a GaAs/Al0.3Ga0.7As multiple quantum well active layer and AlAs/Al0.1Ga0.9As Bragg reflectors have been fabricated by metalorganic vapor phase epitaxy. The design of the whole structure is such that a good cavity finesse and a high contrast in the reflective mode are simultaneously obtained. This results in a bistability power threshold of <3 mW at 838 nm and a contrast ratio as high as 30:1. The nonlinear refractive index is shown to saturate at higher power, which evidences the need of a good cavity finesse for such bistable devices.

ISSN:0003-6951    

DOI:10.1063/1.103679

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the first room‐temperature observation of Wannier–Stark localization under waveguide configuration in a short‐period InGaAs‐InAlAs superlattice. Using the ‘‘oblique’’ transition connecting a hole localized in a well with an electron localized in the adjacent well we have achieved a modulator having a 20 dB extinction ratio and a 3 dB attenuation with a drive voltage as low as 0.8 V. Our device is a 560‐&mgr;m‐long waveguide operating at 1.55 &mgr;m under TE polarization mode.

ISSN:0003-6951    

DOI:10.1063/1.103680

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The scattering of stimulated emission within InGaAsP semiconductor diode lasers has been measured and correlated with the measured spectral output of the lasers. It is found that the spectral output of the diode lasers is strongly dependent on internal scattering. It is also found that the amount of scattering is characteristic of the laser structure. A theoretical model has been developed which demonstrates the effect of scattering on the spectral output, and which explains the differences observed in the spectral output of different structures in terms of the internal scattering.

ISSN:0003-6951    

DOI:10.1063/1.103681

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We describe the wavelength dependence of small‐signal picosecond pulse energy gain and cw power gain, as well as saturation energy and saturation output power spectra, in 1.5 &mgr;m multiple quantum well optical amplifiers of different lengths and under various drive conditions. The present devices have gain spectra with bandwidths (3 dB) that can exceed 1000 A˚. Saturation output energies and powers increase with wavelength and are as large as 5 pJ and ∼40 mW, respectively.

ISSN:0003-6951    

DOI:10.1063/1.103682

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We discuss the first investigation of Bi1−xSbxas an infrared nonlinear optical material. Nondegenerate four‐wave mixing experiments at CO2laser wavelengths yield a large nonlinearity (&khgr;(3)≊3×10−4esu) which does not saturate at power densities up to 0.5 MW/cm2. Both the ambient and substrate interfaces of the film are highly reflective and the e´talon they form is found to have a large effect on the transmission and reflectivity spectra of the as‐grown films. This suggests the possibility that constructive interference of the film’s internal optical fields could be used to considerably enhance the nonlinear signal.

ISSN:0003-6951    

DOI:10.1063/1.103683

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Current pulse shapes have been measured in negative and positive corona discharges mostly in dry air. Negative corona Trichel pulses and pulses corresponding to the primary streamer/cathode contact in a positive point‐plane gap were found to exhibit remarkable similarities, indicating a positive‐streamer‐like mechanism for the Trichel pulse development. High‐frequency instabilities of the high‐pressure filamentary glow discharge, which can be responsible for the arcing from freshly polished cathodes, were observed and attributed to local positive‐streamer‐like breakdowns of the cathode sheath.

ISSN:0003-6951    

DOI:10.1063/1.103684

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We present in this letter Si 2pcore level photoemission measurements on the Er/Si (111) interface formed at room temperature. These spectroscopic data are compared with those measured on amorphous silicide films for various Er concentrations grown by coevaporation of Er and Si species at room temperature under ultrahigh vacuum conditions. This study reveals a strong interaction between Er and the Si (111) substrate even at very low coverage. A mixed interface is observed with silicide formation up to 6 monolayers of deposited metal which corresponds to the onset of erbium metal overgrowth. The Er concentration in the interfacial silicide is found to increase as a function of the deposited Er thickness. A model for the interface is proposed and discussed.

ISSN:0003-6951    

DOI:10.1063/1.103685

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The sign of photoinduced free carriers of LiNbO3:Mg and LiNbO3:Mg:Fe(0.05 wt. %) with various MgO contents has been determined by the holographic technique. The photorefraction of these crystals has also been studied. The enhanced resistance to photorefraction of LiNbO3:Mg(≳5 mol % MgO) results from the occurrence of photoinduced hole free carriers, whose concentration is nearly equal to the electron concentration.

ISSN:0003-6951    

DOI:10.1063/1.103686

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Two types of twins with different atomic structure may exist in GaAs: rotation type and reflection type. A selective chemical etching technique was employed to clarify which of these two twin types occurs in practical GaAs crystals. Twins in an As‐rich horizontal Bridgman (HB) GaAs, a Ga‐rich HB GaAs, and a liquid‐encapsulated Czochralski GaAs were studied, and the results showed that all of the studied twins were rotation type. This suggests that the bonding configuration at the twin plane is a more important factor than stoichiometry of the crystal, in determining the type of twins in GaAs.

ISSN:0003-6951    

DOI:10.1063/1.103687

出版商:AIP    

年代:1990

数据来源: AIP