摘要:

Organic electroluminescent devices with a double‐heterostructure indium‐tin‐oxide substrate/hole transport layer/emitter layer/electron transport layer/MgAg have been fabricated by vacuum vapor deposition. The organic carrier transport and emitter layers were composed of amorphous films. In the double‐heterostructure devices, the luminance continued to lie in high level, even when the emitter thickness was 50 A˚. The confinement of charge carriers and molecular excitons within a narrow emitter layer was achieved.

ISSN:0003-6951    

DOI:10.1063/1.103638

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Coupling coefficients as high as 300 cm−1have been achieved and investigated in the performance of distributed feedback lasers. High coupling has several important advantages like lower feedback sensitivity, and lower influence on facet reflectivity, thus easy handling for coatings without any penalty in terms of mode hopping. We obtain a side‐mode suppression ratio as high as 51.2 dB. 8 Gb/s ‘‘nonreturn to zero’’ modulation is demonstrated.

ISSN:0003-6951    

DOI:10.1063/1.103639

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have demonstrated intracavity second‐harmonic generation of green 532 nm light in a quasi‐cw 1064 nm Nd:YAG laser using organic nonlinear optical crystals of 4‐(N,N‐dimethylamino)‐3‐acetamidonitrobenzene (DAN) immersed in index matching fluid contained in an antireflection‐coated cuvette. This technique permits crystals to be used directly from solution growth without polishing or antireflection coating them. Up to 0.56 mW peak power of 532 nm light was generated from 2.3 W of intracavity 1064 nm peak power in 100 &mgr;s pulses. We also report preliminary results on true cw intracavity harmonic generation with antireflection‐coated DAN crystals.

ISSN:0003-6951    

DOI:10.1063/1.103640

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A dynamic reconfiguration of optical interconnections for enhanced flexibility in photonic switching systems is realized using a two‐dimensional vertical to surface transmission electrophotonic (VSTEP) device array. A matrix operational scheme for the VSTEP array is proposed and demonstrated. Through this operation, functions for light emission and for electrically programmable spatial light modulation are obtained in a single chip of the VSTEP array and a high‐speed electronic addressing of 1 ns per one line for the matrix is also confirmed.

ISSN:0003-6951    

DOI:10.1063/1.103641

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Measurements of the optic index of refraction, along thecaxis, are presented for three representative single crystals in the (PbxBa1−x) Nb2O6ferroelectric system. In particular, we show that as the temperature is lowered, crystals at the morphotropic phase boundary (x=0.63±0.03) first develop a polarization along thecaxis and then, at lower temperature, the polarization rotates to theabplane.

ISSN:0003-6951    

DOI:10.1063/1.104246

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We present an analytical technique for determining polarization‐dependent optical transition matrix elements in quantum wires which rigorously incorporates the effects of band coupling. Using this technique, we examine the polarization anisotropy of the two lowest energy optical transitions in a GaAs quantum wire. Contrary to assumptions employed in previous studies, we show that the valence states involved in these transitions are a strong admixture of light and heavy hole character. The lowest energy transition is found to be four times stronger for electric fields oriented parallel to the wire than for the perpendicular orientation. In contrast, the next highest transition does not interact with optical waves polarized along the wire axis. We discuss sources of error which arise in simpler one‐band models of this phenomenon in addition to the neglect of band coupling and show that the coupled band model presented here is essential for predicting these effects.

ISSN:0003-6951    

DOI:10.1063/1.103642

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the operation of strained‐layer InxGa1−xAs/GaAs 50‐ and 100‐period multiple quantum well optical modulators at wavelengths ranging from 1.02 to 1.07 &mgr;m. Structures were grown on GaAs substrates, as well as on strain relief InxGa1−xAs buffer layers. Devices show favorable electrical characteristics and absorption contrasts up to 57% at the exciton peak. Optical modulation of a Nd:YAG laser is demonstrated, via operation of self‐electro‐optic effect devices at 1.064 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.103643

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The cross calibration of two optical detection techniques is described for the monitoring of laser‐generated Lamb waves. Measurements of Lamb waves using an optical beam deflection technique are compared with those using a Michelson interferometer technique. Analysis shows that phase changes in acoustic waveforms relate to the physical characteristics of the two detection schemes. Results are self‐consistent, and show that the beam deflection technique is capable of providing quantitative waveform analysis.

ISSN:0003-6951    

DOI:10.1063/1.104103

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The amorphous to polycrystal transition during Kr ion beam irradiation of chemical vapor deposited silicon layers has been studied in the temperature range 320–480 °C. At each irradiation temperature the average grain diameter increases linearly with the Kr dose, while the grain density remains constant within the experimental accuracy. The growth rate follows a complex behavior which can be described by dynamic defect generation and annihilation. The absolute value of the grain growth rate is equal to that of the ion‐assisted epitaxial layer by layer crystallization in the silicon (111) orientation. This result can be related to the crystal grain structure and morphology.

ISSN:0003-6951    

DOI:10.1063/1.103644

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Thin films of zirconia have been deposited using a reactive electron beam evaporation technique onto unheated alumina and fused silica substrates. The films were post annealed in the range 300–850 °C. The influence of post‐deposition conditions on the optical properties like refractive index and absorption and nonoptical properties like structure have been studied. The structural transitions were determined using infrared (IR) absorption and x‐ray diffraction. Preliminary results of studies on the correlation between x‐ray diffraction and IR absorption data for structural characterization are reported. It has been shown that the refractive index values change considerably with each structural transition, although the optical absorption does not seem to be very adversely affected by post‐deposition annealing. Post‐deposition annealing resulted in the formation of the cubic phase at 500 °C which transformed to the tetragonal phase at 700 °C and finally monoclinic phase at 800 °C. The above‐mentioned phases were only the major phases and post‐deposition annealing did not result in single‐phase material.

ISSN:0003-6951    

DOI:10.1063/1.103645

出版商:AIP    

年代:1990

数据来源: AIP