摘要:

Vertical cavity etalons with asymmetric superlattice claddings have been fabricated. As predicted earlier, the cavities with sawtooth superlattice claddings grown on (100) oriented substrate are birefringent with the new optical axes along (011) and (01¯1) directions. The difference in the resonant wavelengths of the cavity modes polarized along (011) and (01¯1) are measured to be about +0.3 and −0.3 A˚ for the two senses of our sawtooth superlattice structures. The change of the sign of the wavelength shift indicates that the observation is not due to an electro‐optic effect of the incorporatedp‐njunction but is due to the reduction of the III‐V crystalline symmetry by the presence of the asymmetric superlattice. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114459

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Highly efficient photoluminescence (PL) was observed from a new class of AlP/GaP quantum‐confined geometry, neighboring confinement structure (NCS). The PL intensity of AlP/GaP NCSs was even higher than that of a 300‐period AlP/GaP superlattice (SL), and the PL of the NCS exhibited much improved immunity against thermal quenching compared to SLs. The luminescence origin of the NCS was confirmed from the well width dependence of the PL peak shift. The peak shifts were compared with the calculation within the effective mass approximation using the previously reported band parameters for AlP and GaP. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114460

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The nonlinear optical response of an asymmetric &lgr;/4‐shifted distributed‐feedback GaAs/AlAs heterostructure is investigated using numerical methods, and also demonstrated experimentally. This structure exhibited both optical switching and bistability at incident wavelengths near &lgr;=884 nm. The observed bistability threshold of less than 1 kW cm−2is more than an order of magnitude smaller than that of any previously measured distributed‐feedback heterostructures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114461

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We study the dominant mechanism for the temperature sensitivity of the differential quantum efficiency and threshold current of 1.3 &mgr;m InP‐based strained‐layer multiple‐quantum‐well (MQW) lasers. We show that the temperature dependence of both properties is separated into two regions at critical temperaturec). Belowc, the temperature dependence of internal loss in the QWs plays a very important role in determining the temperature sensitivity of the differential quantum efficiency. On the other hand, abovec, its temperature sensitivity is affected more by the internal loss in the separate confinement heterostructure (SCH) region. Excellent correlation is observed between the spillover of holes into the SCH region andc. It is also shown that the Auger recombination current plays a more significant role in determining the temperature dependence of threshold current belowc. However, abovec, electrostatic band‐profile deformation, which causes a significant increase in loss and radiative recombination current in the SCH region, plays the more dominant role than the Auger recombination current. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114462

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An optical laser trap with fluorescence excitation/emission capability has been integrated in a flow cytometric geometry for the study of microparticle confinement and off‐axis fluorescence detection in laminar flow streams. Measurements of particle escape velocity, trapping efficiency, and fluorescence intensity are presented for 2 &mgr;m diameter dye‐tagged latex microspheres in laminar flow streams having velocities of up to 12 mm/s. Experimental results are compared with theoretical values for flow velocity and fluorescence intensity and found to be in excellent agreement. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114463

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We show lasing (with the threshold of &mgr;J order) due to morphology‐dependent resonances (MDRs) from solid polystyrene spheres with volume‐distributed europium (Eu) chelates. Lasing spectra depending on MDRs are reported, and a practical usefulness of the Eu chelate laser with the solid spheres is described compared with the previous one with liquid spheres.

ISSN:0003-6951    

DOI:10.1063/1.114464

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Using a Tersoff‐type empirical potential energy function, the free energy of formation for microvoids in silicon containing from 1 to 57 vacancies was calculated as a function of temperature and vacancy supersaturation. The results apply equally well to microvoid nucleation during crystal growth or, at low temperatures, as a consequence of ion implantation. The results indicate that homogeneous nucleation is an unlikely process for the crystal growth case where heterogeneous nucleation via adsorbate attachment to the microvoid surface is a very likely process. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114465

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We found the ferroelectric coercive field of LiTaO3, both in forward and reverse direction, vary with time after the domain is inverted. The coercive field drops when the domain is inverted, then gradually recovers. This phenomenon is light sensitive. The existence of a net time‐varying internal electric field after domain inversion is hypothesized. The internal field is composed of the depolarization field, which is due to the spontaneous electric dipole moments, and an opposite direction time‐varying space‐charge field which is due to the redistribution of free‐carriers transport under the influence of the depolarization field. Electro‐optical effect caused by the internal electric field has been observed by means of aninsituoptical monitoring technique for the domain inversion process. Theinsituoptical monitoring technique is based on using the LiTaO3thin‐plate crystal as a low finesse Fabry–Perot interferometer. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114466

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An intermetallic compound which grows at a rate greater than 1 &mgr;m/s has been observed in the liquid/solid reaction at 250 °C between molten eutectic SnPb solder and solid Pd. The intermetallic PdSn3does not form as a diffusion barrier between the reactants, rather it grows as lamellae into the molten solder. The growth direction is normal to the liquid/solid interface, where the molten solder between the lamellae serves as fast diffusion channels during the reaction. For comparison, molten Sn (Pb‐free) reacts with Pd at a rate slower by one order of magnitude. The intermetallics, in this case, grow as a diffusion barrier between the Sn and Pd. The role of Pb in the extremely fast eutectic soldering reaction is discussed, in view of the trend of searching for a Pb‐free solder in electronic packaging. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114467

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Epitaxial thin films of bismuth titanate Bi4Ti3O12have been grown by laser molecular beam epitaxy on SrTiO3(001) and Bi2Sr2CaCu2O8(001) single crystal at low processing temperature. X‐ray diffraction patterns exhibit thatc‐axis oriented Bi4Ti3O12thin films can be grown at a substrate temperature as low as 450 °C with good crystallinity and no presence of secondary phases. RHEED patterns evidence the flat surface of the films and the layer‐by‐layer growth mode. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114468

出版商:AIP    

年代:1995

数据来源: AIP