摘要:

Data are presented on vertical-cavity surface-emitting lasers that use high contrast distributed Bragg reflectors on both sides of the cavity. The upper reflector consists of a six pair ZnSe/MgF quarter-wave stack, while the lower reflector consists of an eleven pairAlxOy/GaAsstack fabricated using selective oxidation. Strain due to the lower reflector is reduced by usingAlxOylayers of less than a quarter-wave thickness. Device sizes ranging from 1 to 7 &mgr;m diameters are characterized, with a minimum threshold current of 53 &mgr;A. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118689

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report a broadband coherent terahertz detection system using GaP as a free-space electro-optic field sensor with a demonstrated 3 dB bandwidth of 3.6 THz, useful bandwidth of 7 THz, and a pulse width of 185 fs. These figures represent new records in the coherent detection of free-space THz radiation. Sensor response as a function of crystal thickness and copropagation velocity mismatch dispersion in the THz regime is studied. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118691

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Improved dynamic properties of strained single quantum well (QW) lasers were obtained by the incorporation of ann-type &dgr; doping at close proximity to the strained QW active layer. The resultant modulation bandwidth was almost doubled, from 3.5 GHz to more than 6.2 GHz. The increased modulation bandwidth is attributed to an improved carrier injection resulting from the enhancement of the carrier transit time into the QW, as well as a decrease in the significance of the adverse contribution of carrier transport effects. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118692

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Porous silicon was doped by Er ions using electroplating and was converted to silicon-rich silicon oxide (SRSO) by partial thermal oxidation at 900 °C. The room-temperature photoluminescence (PL) at ∼1.5 &mgr;m is intense and narrow (⩽15 meV) and decreases by less than 50&percent; from 12 to 300 K. The PL spectrum reveals no luminescence bands related to Si-bandedge recombination, point defects, or dislocations and shows that theEr3+centers are the most efficient radiative recombination centers. A light-emitting diode (LED) with an active layer made of Er-doped SRSO (SRSO:Er) was manufactured and room temperature electroluminescence at ∼1.5 &mgr;m was demonstrated. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118693

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Quasiphase-matched second harmonic generation (SHG) has been realized in periodically domain-inverted strontium barium niobate(Sr0.6Ba0.4Nb2O6,so-called SBN) crystal plate induced by an external electric field. Both the coercive field and Curie temperature have been determined throughin situobservation of the second harmonic signals. The measured SHG conversion efficiency is about 10&percent; at a fundamental wavelength of 977.8 nm. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118694

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The observation of infrared emission between superlattice conduction minibands is reported. Electrons resonantly injected into the first excited state miniband by an applied electric field make a radiative transition to the ground state miniband. The spectra are dominated by direct high oscillator strength transitions at the mini-Brillouin zone edge and the peak wavelength can be tailored over a broad infrared range by designing the superlattice minigap. At high bias, the spectra extend to wavelengths corresponding to transitions from high lying states near the mini-Brillouin zone center. Experiments in AlInAs/GaInAs superlattices have demonstrated peak luminescence wavelengths of &lgr;=5 and 7 &mgr;m. At high currents, the spectra broaden to shorter wavelengths (down to 3 &mgr;m) as electrons are tunnel injected high into the second miniband. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118695

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We investigate the correlation between the electrical and optical characteristics of selectively oxidized vertical-cavity surface-emitting lasers (VCSELs). Electrical derivative analysis is used on VCSELs to study the electrical performance and its correlation with the polarization-resolved optical powers and spectra. Characteristic features are shown in theIdV/dIcurves near major transition points of VCSEL operation. From theIdV/dIcurve we are able to precisely identify important operating currents such as the lasing threshold, the higher-order mode lasing current, and the cut-off current. Five operation regions are defined in the polarization-resolvedL−Icurves based on these currents and their temperature dependences are also studied. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118690

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Second-harmonic generation from &lgr;=1.06 &mgr;m fundamental light has been measured in both evaporated and spin-coated films of trinitro-substituted subphthalocyanines. Ordering of these noncentrosymmetric molecules with the dipole moment perpendicular to the film face has been achieved either by the deposition process (evaporated samples) or by corona poling (spin-coated samples). The second-order susceptibilities&khgr;31(2)=2.36×10−9esu (for vacuum evaporated samples) and&khgr;31(2)=9.62×10−10–1.14×10−9esu (for poled spin-coated samples) have been determined by comparison with anX-cutLiNbO3crystal used as reference. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118696

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We present a combined wavelength-polarization selector made of holographic polarization beamsplitting cubes in series. Each unit cube comprises a pair of prisms and a transmission-type phase volume hologram. The assembled selector, when examined with an intensity modulated beam of known polarization state, demonstrated our designated target. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118697

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We compare the recombination dynamics of GaN single crystals to that of epitaxial cubic GaN layers on GaAs(001) using picosecond photoluminescence (PL) spectroscopy. At low temperatures, the band-edge PL decay time of the layer is much shorter than that of the crystals, evidencing the importance of nonradiative processes in the case of the layer. However, at room temperature both the emission spectra and their decay times of layer and crystals are almost identical. At 300 K the decay times are short (10 ps) for low excitation density and increase to values of 100 ps at moderate excitation density reflecting the saturation of nonradiative recombination channels. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118698

出版商:AIP    

年代:1997

数据来源: AIP