摘要:

Results are presented from polymer/molecular organic heterostructure light emitting diodes composed of a layer of the conjugated conducting polymer poly(p‐phenylene vinylene) (PPV), and a layer of fluorescent molecular compoundtris(8‐hydroxy) quinoline aluminum (Alq). The external quantum efficiency of these heterostructure LEDs is ∼0.1%, which is over one order of magnitude higher than that of simple PPV LEDs. The electroluminescence (EL) spectra indicate that both materials in the device emit comparable amounts of light. The dependence of the EL spectra on the layer thicknesses and its independence on bias suggest that neutral excitons are formed in the Alq, far from the PPV/Alq interface, and subsequently diffuse into the PPV layer. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114119

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Room‐temperature operation of ZnSe‐active‐layer double heterostructure laser diode has succeeded. The lasing wavelength was 471 nm. The emission energy shift with the increasing current is explained by the band filling and the band shrinkage. The threshold carrier density is calculated to be 4×1018cm−3. The mechanism of the stimulated emission of II–VI double heterostructure laser diode is concluded to be the recombination of the electron‐hole plasma. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114120

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Frequency doubling is observed in an aluminum nitride waveguide deposited by dc reactive magnetron sputtering. Phase‐matching conditions are obtained by tuning the wavelength of an optical parametric oscillator pumped by a pulsed Nd:YAG laser. The maximum second harmonic generation efficiency is obtained for the TM0(&ohgr;)‐TM2(2&ohgr;) conversion process and is estimated to be around 4×10−8W−1. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114121

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The laser emission spectra of several vertical cavity surface emitting lasers, following pulsed laser excitation, have been measured with a temporal resolution of <1 ps. With broadband excitation, emission was observed from multiple longitudinal modes when pumped well above threshold. The output‐pulse decay times of modes located near the edges of the high reflecting zone were significantly shorter than the decay times of modes located near zone center. The zone‐edge modes were not observed when narrow‐band photoexcitation was used, indicating that broadband excitation results in seeding of the laser cavity. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114091

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We give the analytical fundamental dark soliton solutions of the (2+1)‐dimensional nonlinear Schrodinger equation [(2+1)‐D NSE]. The solutions reduce to (1+1)‐D dark soliton solutions when the width of soliton in one transverse direction is much wider than that in the other direction, which is in good agreement with the experimental observation of the dark spatial solitons. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.114092

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The excess waveguiding optical loss of nonlinear optical polymers induced by poling was studied both experimentally and theoretically. The loss was found to be caused by the inhomogeneities in the orientation of the nonlinear optical moiety after poling and is strongly dependent on the uniformity of the guiding and cladding films and the magnitude of the poling field. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114093

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy carried out on bulk samples of Er2S3‐doped Ge33As12Se55glasses demonstrate that Er3+is incorporated in optically active sites in the glass and gives rise to a broad ∼1500–1600 nm4I13/2→4I15/2PL spectrum similar to those observed in Er‐doped oxide glasses. The novel PLE spectrum of the 1550 nm Er3+PL band comprises a superposition of relatively sharp peaks which are attributable to the characteristic4I15/2→4I11/2and4I15/2→4I9/2Er3+absorption transitions at 810 and 980 nm, respectively, and a broad, below‐gap PLE band characteristic of the weak defect or impurity absorption tails in chalcogenide glasses which decrease exponentially with decreasing photon energy. At high energy the exponentially rising Urbach absorption edge, which leads to competing nonradiative decay mechanisms, imposes an exponentially decreasing slope on the PLE spectrum. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114094

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Organic electroluminescent (EL) devices have been fabricated which have a MgF2layer doped withN, N’‐diphenyl‐N, N’‐bis(3‐methylphenyl)‐[1,1’‐biphenyl]‐4, 4’‐diamine (TPD) as the hole‐ transporting layer, and the emitting layer oftris‐(8‐hydroxyquinoline) aluminum (Alq). For the organic EL devices, bright green emission with 2600 cd/m2is observed at a voltage of 15 V. The luminous efficiency is about 0.3 lm/W at a current density of 100 mA/cm2. This high efficiency indicates that the diamine doped MgF2layer plays the role of hole transport and confinement of electrons in the emitting layer. It is also found that the thermal stability of the organic EL device is higher than that of the conventional organic EL device. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114095

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A method of calculating as‐deposited elemental film composition during the actual deposition process was developed using optical emission spectroscopy of the glow discharge. These results are demonstrated by analyses of a series of thin film Ag1−xSixalloys fabricated using radio frequency sputter deposition with composite Ag+Si sputter targets. Using intensity ratios of the Si (251.6 nm), Ag (328.1 nm), and Ar (419.8 nm) emission lines after equilibration of the substrate temperature, estimates of at. % Si in the films were calculated which agreed well with post‐deposition composition measurements of the films by Auger electron spectroscopy. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114096

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Using high resolution x‐ray diffraction, it is shown that hot wall epitaxy is an appropriate growth technique in order to obtain perfect monocrystalline C60thin films with a thickness up to 150 nm. The full width at half‐maximum of rocking curves of the C60(111) reflex measured on such films is about 210 arcsec. Rocking curves of thicker films exhibit a complex shape, which is interpreted as a result of a change in the growth mode of C60films exceeding a critical thickness. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114097

出版商:AIP    

年代:1995

数据来源: AIP