摘要:

A new form of read out for high density read-only memory is presented whereby a data density of400 bits/&mgr;m2,corresponding to256 Gbits/in.2,can be accessed at data rates in the tens of MHz range. The technique is based on detecting the modulation in light scattering from a sharp scattering object due to the dipole-dipole coupling between the probe and surface being scanned using a sensitive homodyne interferometer. Theoretical considerations indicate that data densities in the100 Tbits/in.2range could be accessed at data rates of 100 MHz using this technology. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119458

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A new configuration holographic memory with a one-beam geometry in a photorefractive crystal has been proposed, and recording of ten angle-multiplexed holograms in aFe:LiNbO3crystal has been experimentally demonstrated. A maximum page number of 1728 pages in theLiNbO3crystal was theoretically estimated by the angular multiplexing method at an incident beam diameter of 5.10 mm and the laser wavelength of 514.5 nm. In this new configuration, one incident beam can simultaneously play two roles as an object beam and a reference beam, therefore, an optical setup becomes simpler than conventional setups, which leads to compact and robust holographic recording system. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119465

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A definitive demonstration of the use of a photorefractive crystal to project a three-dimensional image in space is reported on. The image is bright and different perspective views of the object appear as the viewing direction is changed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119474

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report a novel time resolved double pump–probe experimental technique that may be used to characterize the excited-state parameters of organic dyes. We show that by monitoring the time evolution of the transmittance of a dye after excitation with two pump pulses, the excited singlet and triplet absorption cross sections, the lifetime of the excited singlet state, and the triplet quantum yield may all be measured. This technique has been demonstrated for silicon 2,3-naphthalocyanine bis(trihexylsiloxide).

ISSN:0003-6951    

DOI:10.1063/1.119443

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

By using chemical beam epitaxy at growth temperatures as low as 460–480 °C, we have overcome strain relaxation problems that prevented so far the successful use of InAsP quantum wells in 1.55 &mgr;m lasers. Five quantum well InAsP/InGaAsP horizontal cavity lasers showed 88&percent; internal efficiency,1.6 cm−1losses per well, and33 A/cm2transparency current density per well, which equal or even surpass the best published characteristics for 1.55 &mgr;m wavelength lasers based on any material system. Moreover, up to 17 quantum wells were integrated in a strain-balanced laser, which showed equally good characteristics. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119453

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We demonstrate noncontact measurements of the Hall mobility of doped semiconductor wafers with roughly 250 &mgr;m spatial resolution, using polarization rotation of focused beams of terahertz (THz) radiation in the presence of a static magnetic field. Quantitative and independent images of both carrier density and mobility of a doped semiconductor wafer have been obtained. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119456

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The time dependence of the kink power in weakly index guided high power stripe lasers in the AlGaAs system are investigated. A periodic dependence of the kink power on the length of the laser is observed in continuous and pulsed modes, but the pulsed mode kink curve is shifted with respect to the continuous one. This is observed to be proportional to1/&tgr;,where &tgr; is the pulse width. The kink is due to phase locking of the modes of the waveguide resulting from a shift of the effective indexes, which is driven by self-heating due to free-carrier absorption of the laser mode. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119457

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report on quantum dot (QD) lasers made of stacked InAs dots grown by metalorganic chemical vapor deposition. Successful growth of defect-free binary InAs/GaAs QDs with high lateral density(dl⩾4×1010 cm−2)was achieved in a narrow growth parameter window. The room-temperature photoluminescence (PL) intensity is enhanced up to a factor of 3 and the PL peak width is reduced by more than 30&percent; when a thin layer ofIn0.3Ga0.7Asis deposited onto the InAs QDs. A QD laser with a single sheet of such InAs/InGaAs/GaAs QDs exhibits threshold current densities as low as 12.7 and181 A/cm2at 100 and 300 K, respectively. Lasers with threefold stacked QDs show ground-state lasing and allow for cw operation at room temperature. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120556

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We proposed and demonstrated a novel design for long wavelength (1.3 &mgr;m) vertical-cavity surface-emitting lasers (VCSELs). In this design, oxygen-implanted current-confinement regions were formed in a GaAs/AlGaAs Bragg reflector which is the bottom mirror wafer bonded to an AlGaInAs/InP cavity consisting of nine strain-compensated quantum wells. Room- temperature continuous-wave (cw) operation of 1.3 &mgr;m-VCSELs with a record low cw threshold current density of1.57 kA/cm2and a record low cw threshold current of 1 mA have been realized. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119459

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The dynamics of a tuning fork shear-force feedback system, used in a near-field scanning optical microscope, have been investigated. Experiments, measuring amplitude and phase of the tuning fork oscillation as a function of driving frequency and tip-sample distance, reveal that the resonance frequency of the tuning fork changes upon approaching the sample. Either amplitude or phase of the tuning fork can be used as distance control parameter in the feedback system. Using amplitude a second-order behavior is observed while with phase only a first-order behavior is observed, and confirmed by numerical calculations. This first-order behavior results in an improved stability of our feedback system. A sample consisting of DNA strands on mica was imaged which showed a height of the DNA of 1.4 nm. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119482

出版商:AIP    

年代:1997

数据来源: AIP