摘要:

Contactless electroreflectance, at both 300 and 20 K, has been used to investigate a vertically coupled quantum dot (QD)-based InAs/GaAs laser structure. Signals have been observed from all the relevant portions of the sample including the QDs and wetting layer. The energies of the QD transitions provide evidence for both lateral as well as vertical coupling. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119160

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Extended defects from 5-, 2-, and 1-keVSi+ion implantation are investigated by transmission electron microscopy using implantation doses of 1 and3×1014 cm−2and annealing temperatures from 750 to 900 °C. Despite the proximity of the surface, {311}-type defects are observed even for 1 keV. Samples with a peak concentration of excess interstitials exceeding ∼1&percent; of the atomic density also contain some {311} defects which are corrugated across their width. These so-called zig-zag {311} defects are more stable than the ordinary {311} defects, having a dissolution rate at 750 °C which is ten times smaller. Due to their enhanced stability, the zig-zag {311} defects grow to lengths that are many times longer than their distance from the surface. It is proposed that zig-zag {311} defects form during the early stages of annealing by coalescence the high volume density of {311} defects confined within a very narrow implanted layer. These findings indicate that defect formation and dissolution will continue to control the interstitial supersaturation from ion implantation down to very low energies. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119161

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Electro-optic modulation up to 113 GHz has been demonstrated using traveling wave polymer modulators. The modulation signal was directly detected at 1.3 &mgr;m using a laser heterodyne system with an external-cavity tunable semiconductor laser. The device optical response variation, as a function of frequency over the wholeWband, was within 3 dB. A well-matched coplanar probe was used to launchWband millimeter wave driving power into the microstrip line electrode on the device. Based upon these measurements, high speed electrodes with integrated millimeter wave transitions had been fabricated and tested. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119162

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Cobalt dopedBaTiO3thin films have been fabricated using two-target pulsed laser ablation within situlaser annealing. KrF laser ablated simultaneously bothBaTiO3andCo3O4sintered targets and the cobalt concentration could simply be controlled at the concentration range of 0.08&percent;–5&percent; by adjusting laser fluences, off-axis deposition angles, and laser-irradiated area for Co ablation. AllCo:BaTiO3films were epitaxially grown on MgO(100) substrate. Optical absorption coefficients were measured at visible region of the spectrum with increasing Co dopant concentrations. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119163

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A high-repetition-rate, femtosecond optical parametric oscillator based on bulk periodically poled lithium niobate is described. This optical parametric oscillator is continuously tunable from 1.12 to 1.50 &mgr;m in the signal branch, and signal pulses as short as 60 fs have been observed. The corresponding turning range for the idler branch is from 1.68 to 2.72 &mgr;m. Modifications which should result in a femtosecond optical parametric oscillator with a pumping threshold of less than 50 mW are discussed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119164

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A Vernier-type unidirectionalEr3+-doped fiber compound ring is constructed. Simultaneous lasing oscillations at multiple wavelengths are obtained by adopting a number of fiber gratings as the wavelength selective elements. The output exhibits reduced linewidths and nearly identical powers at the emission wavelengths, and the spectrum is free from parasitic oscillations. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119165

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Modal dispersion phase-matched second harmonic generation is demonstrated in new poled polymer waveguide geometries with a nonlinear optical core consisting of two side-chain polymers with different glass transition temperatures. After poling above and between the respective glass transitions, the sign of the nonlinear optical coefficient is reversed in the two polymers, thereby improving the overlap integral. Conversion efficiencies up to7&percent;/W cm2were achieved in the first experiments. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119166

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Polarization switching in gain-guided, vertical-cavity, surface-emitting lasers was studied as a function of the active region temperature. We show that polarization switching occurs even when the active region temperature is kept constant during fast pulse low duty cycle operation. This temperature independent polarization switching phenomenon is explained in terms of a recently developed model. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119167

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A combination of thin-film deposition and physical masking steps were used to generate libraries of the rare earth activated refractory metal oxides,Gd(La,Sr)AlOx.Systematic variation of composition and processing conditions afforded tricolor phosphors with the following nominal compositions,(Gd0.46Sr0.31)Al1.23OxF1.38:Eu0.062+(green),La0.5Al1.5Ox:Eu0.042+(blue), andGd0.77Al1.23Ox:Eu0.063+(red), which had quantum efficiencies of ⩾94&percent;, ≃60&percent;, and ⩾93&percent;, respectively at&lgr;maxex.The high quenching temperatures (250–350 °C), good chromaticities and refractory nature of these phosphors are desirable features for display applications. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119168

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

It is shown that thin layers of palladium coated magnesium lanthanide alloys reversibly go through an optical transition by variation of the hydrogen concentration, just as has recently been shown for pure lanthanides. With these layers optical switches can be constructed that exhibit three different optical states: a color-neutral transparent state at high hydrogen concentration, a nontransparent dark absorbing state at intermediate hydrogen pressures, and a highly reflective metallic state at low hydrogen pressures. The ratio in transmission between the transparent state and the reflecting state is more than 1000. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119169

出版商:AIP    

年代:1997

数据来源: AIP