摘要:

A surface emitting laser diode (SELD) with a bent double heterostructure is fabricated on a grooved substrate. This SELD has a facet angle of 20 ° and lased at a threshold current of 120 mA. The external quantum efficiency is 33%. The far‐field pattern has sharp peaks at 10 ° and 18 ° and wider emission bands between 25 ° and 45 °. Radiation loss by the bent waveguide is also estimated by the equivalent current source model.

ISSN:0003-6951    

DOI:10.1063/1.98073

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Novel planar optoelectronic devices with two‐dimensional exciton absorption controlled by free‐carrier‐induced bleaching are proposed. Exciton‐resonant light propagates along a single mode rib waveguide containing a single quantum well (SQW), the only absorbing medium in the waveguide. Three such devices operating as optical modulators are (1) a gate‐controlled field‐effect transistor optical modulator (FETOM), (2) an optically readable memory element, and (3) an optically switched charge storage device. The FETOM, in which free‐carrier density in the SQW is controlled by gate voltage, offers high speed (37.5 ps), small size (125 &mgr;m), and low power (86 nW/MHz).

ISSN:0003-6951    

DOI:10.1063/1.98074

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A train of pulses is generated by coupling the cw output of a single frequency He‐Ne laser into a passive ring ‘‘cavity’’ which contains an acousto‐optic frequency shifter. Each cavity pass shifts the frequency of the wave by 80 MHz. This results in an intensity pattern which is an Airy function in time. For a single frequency input, the output pulse width is 2 ns with a repetition rate of 80 MHz. Data are also presented on the output of this device for multimode cw input.

ISSN:0003-6951    

DOI:10.1063/1.98075

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Ridge waveguide lasers emitting near 1 &mgr;m have been made on a GaAs substrate using a single GaInAs strained‐layer quantum well in a GaAs/AlGaAs graded‐index separate confinement heterostructure. The epitaxial layers were grown by low‐pressure metalorganic chemical vapor deposition, and the ridge waveguide was fabricated by chemically assisted ion beam etching. The lasers have threshold currents near 17 mA with fundamental lateral mode operation to five times this value. These are the first reported strained‐layer current‐injection lasers to run cw at room temperature; they operate, without bonding, to greater than 24 mW/facet (100 mA dc), and have 18 mW/facet (80 mA dc) lifetimes in excess of 144 h.

ISSN:0003-6951    

DOI:10.1063/1.98076

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report on the use of picosecond duration laser pulses to generate picosecond acoustic pulses in metal films on the order of 200 nm thick. The acoustic pulses are detected by means of transient piezoreflectance measurements. We demonstrate the use of a thin metal overlayer to enhance the piezoreflectance signal.

ISSN:0003-6951    

DOI:10.1063/1.98077

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

X‐ray conversion efficiency in a 0.53‐&mgr;m laser‐produced copper plasma is studied in the 1.5–5.0 keV range as a function of laser pulse duration (&tgr;L) with a laser intensity of 1×1014W/cm2. The efficiency increases as &tgr;1.3Lat pulse lengths of less than 400 ps. For a 200‐ps pulse duration, an enhancement of the conversion efficiency is observed with the use of a prepulse. The efficiency is found to be proportional to the scale length of a preformed plasma. Enhancement of a factor 3 is observed for the shots with a prepulse.

ISSN:0003-6951    

DOI:10.1063/1.98078

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A new scheme has been developed to measure laser‐induced temperature distributions on solid surfaces, based on a first‐order phase transition of an optically and thermally thin surface film where the transformed zone periphery marks the phase change isotherm of the film material. In order to test the technique, experimental measurements were made on a system for which analytical theoretical calculations and input parameters were available: steady‐state 9.27‐&mgr;m CO2laser heating of semi‐infinite SiC samples. The melting of polycrystalline films of NaCl (m.p. of 801 °C) and the eutectic mixture of NaCl‐KCl (m.p. of 660 °C) spray deposited on the SiC surface served as the indicator. For a particular set of irradiation conditions, theoretical calculations were compared with experiment as a function of incident power.

ISSN:0003-6951    

DOI:10.1063/1.98079

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Mechanical stresses are known to cause hillock formation and creep voids in aluminum based interconnect on integrated circuits. While the effects of differential thermal expansion between an aluminum film and a silicon substrate are well known, the effects on an encapsulated narrow aluminum line are not. We report here an analysis of the stresses generated in such a line upon cooling from 400 °C after passivation deposition. At 25 °C the principal stresses in the aluminum are all tensile with magnitudes several times the yield strength. The aluminum need not fail, but a high driving force for creep remains. High stresses also are generated in the passivation which could lead to cracking.

ISSN:0003-6951    

DOI:10.1063/1.98263

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Diamond thin films have been formed by dc plasma chemical vapor deposition with a high growth rate (∼20 &mgr;m/h). The diamond has been grown from methane (CH4) and hydrogen (H2) mixed gases on Si and &agr;‐Al2O3substrates at a pressure of 200 Torr without surface scratching by diamond orc‐BN powder. The obtained films have good crystallinity in the sense of electron and x‐ray diffraction. Vicker’s hardness of the film is the same as that of natural diamond (∼10 000 kg/mm2). The influence of the dc discharge in a low vacuum (∼200 Torr) on diamond synthesis will be discussed briefly.

ISSN:0003-6951    

DOI:10.1063/1.98080

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The steady‐state current‐voltage characteristics resulting from charge injection from a metal into an organic charge transporting polymer are found to deviate significantly from the space‐charge‐limited values when a Langmuir–Blodgett film of cadmium stearate is interposed between the metal and the organic polymer. A phenomenological model of charge injection is proposed to account for the observed features, and to quantify the injection level of a non‐Ohmic contact.

ISSN:0003-6951    

DOI:10.1063/1.98081

出版商:AIP    

年代:1987

数据来源: AIP