摘要:

We have studied the interaction between two optically pumped vertical‐cavity surface‐emitting lasers (VCSELs) on a wafer as a function of their separationd. The VCSELs are strongly coupled for d⩽13 &mgr;m, leading to the appearance of higher‐order lateral modes. Ford⩾13 &mgr;m the VCSELs are weakly coupled, leading to phase locking of the individual emitters. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117971

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Obtained experimental results demonstrate that x rays can be focused to a point by using one flat InSb crystal with elliptically shaped modulated structures based on the Bragg and Fresnel diffraction principles. Ti K&agr; radiation and InSb (111) reflections are used to focus a 20‐&mgr;m source size to a point of 9 &mgr;m, which is in good agreement with predictions from the wave‐optics approach. The quality of the modulated structure fabrication is judged by the shape of the focal spot, which indicates no visible aberration effects. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117972

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We measure the diffraction of a cw probe laser beam from an absorption index grating set up in a thin film semiconductor by illumination with a moving optical interference fringe pattern. Taking advantage of the heterodyne detection principle whereby the weak diffracted laser beam is brought to interfere with the probe beam we are able to work with diffraction efficiencies as low as 10−14. When applied to amorphous hydrogenated silicon the diffraction efficiency depends in a characteristic way on an applied external electric field. We identify two physical mechanisms for the diffraction, namely a periodic temperature profile related to the absorption of the laser grating and the quadratic electro‐optical effect. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117973

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have fabricated thermally stable organic electroluminescent (EL) devices using a hole transporting material, a tetramer of triphenylamine, and a typical emitting material, tris (8‐quinolinolato) aluminum (Alq). The organic EL devices show uniform light emission in a continuous operation up to 140 °C without breakdown. A lowering of turn‐on voltage for light emission and an increase of luminous efficiency with increasing temperature are found; the significantly low turn‐on voltage of 2.1 V and the high luminous efficiency of 1.25 lm/W are obtained at 130 °C. Excellent durability of continuous operation is also achieved at the high temperature. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117974

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report the use of a poly(phenyl quinoxaline) (PPQ) as an electron transporting conjugated polymer for electroluminescence (EL) applications. Single‐layer PPQ devices with ITO anode and aluminium cathode show unipolar electron transport with current densities up to 60 mA/cm2but no emission. Two‐layer structures combining PPQ as electron transport material with the hole transporting poly(2,5‐dialkoxy‐p‐phenylene vinylene) (PDAOPV) show strong emission from the PDAOPV with brightnesses up to 250 cd/m2. These two‐layer structures have a maximum EL quantum efficiency of 0.35% which is ten‐fold enhanced compared with the corresponding single‐layer PDAOPV devices. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117975

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Recently using KrF high power laser (248 nm; 350 fs; 5.0×1016W/cm2) in the Rutherford Appleton Laboratory an experimental search for recombination extreme ultraviolet (XUV) laser action in Li‐like nitrogen ions was performed. To understand the experimental results of line emission at 24.7 nm in the 3d5/2–2p3/2transition of the Li‐like nitrogen ion a simulation was undertaken using a one‐dimensional Lagrangian hydrodynamic code. From the simulation results, we confirmed that there was nonlinear dependence of spectral line emission on the gas density which was well matched to the experimental results. Only a six times increase of the 24.7 nm emission intensity was obtained when the plasma length was increased 1000 times from 1 &mgr;m as an optically thin case to 1 mm. Also, the spatial profile of the electron density and temperature was obtained and the electron temperature was about 40–50 eV which was too high for the optical field ionization x‐ray lasing. We could not find evidence of x‐ray laser gain. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117976

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Exciton‐polariton mode splitting of quantum wells (QWs) in a microcavity is experimentally and theoretically investigated under a high magnetic field up to 14.5 T. The magnetic field dependence of the splitting interval has been measured for the precisely tuned photon and exciton mode. It is found that the splitting interval increases with an increase of the magnetic field, which shows enhancement of magnetoexciton‐photon interaction. Theoretical analysis using a transfer matrix method and a variational method demonstrates that these properties are mainly caused by the increase of exciton oscillator strength due to the magnetic field. The effect of the number of QWs on the mode splitting is also discussed. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117977

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The feasibility of using copper nitride and tin nitride thin films as write‐once optical recording media was explored. The Cu3N and SnNxfilms were obtained by the reactive sputtering method. They were thermally decomposed into Cu and Sn films at 470 and 550 °C, respectively. The Cu film obtained by the thermal decomposition showed a large difference in reflectance which is applicable to the optical recording media. The Sn film obtained by the thermal decomposition included SnO, and consequently it showed a small difference in reflectance from that of SnNxfilm. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117978

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A strongly enhanced luminescence efficiency of zincborate glasses and glass fibers doped with trivalent europium or terbium is reported. The enhancement is attributed to a high content of direct gap ZnO nanocrystallites which operate as sensitizer for the rare‐earth ions. The glasses have a low softening point and are designed to be compatible with the silicon technology. Applications as scintillating devices integrated on silicon are suggested. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117979

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Silica‐titania sol‐gel planar waveguides were deposited on silica glass disks by spin coating. Fluorescence lifetimes as high as 375 &mgr;s were measured in neodymium‐doped sol‐gel planar waveguides and 1.78 ms for an erbium‐doped film. Quenching was found to occur for the former at concentrations above 1 at. % of neodymium. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117980

出版商:AIP    

年代:1996

数据来源: AIP