摘要:

A novel technique in time resolved luminescence spectroscopy called population mixing using a subpicosecond cw mode‐locked dye laser has been developed and applied top‐type GaAs at low temperatures. Using this technique the relaxation lifetime for electron recombination was measured to be 39±7 ps forp‐type GaAs with Zn at 6×1018cm−3hole concentration. This is comparable to the relaxation time measured by a streak camera.

ISSN:0003-6951    

DOI:10.1063/1.92617

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We present the results of a detailed experimental study of the self‐focusing of a low intensity cw laser in its passage through a nematic liquid‐crystal film. The results are in quantitative agreement with our theory of optically induced birefringence as a function of geometry, thickness, and intensity. We have also quantitatively measured the relative contribution from thermal lensing effect.

ISSN:0003-6951    

DOI:10.1063/1.92618

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A new class of organic quinoid systems possessing intrinsically large, nonlinear second‐order optical susceptibilities has been developed based on theoretical calculations and dc‐induced second‐harmonic generation measurements of the molecular second‐order optical susceptibilities &bgr;. For one example, 2‐(4‐dicyanomethylenecyclohexa‐2, 5‐dienylidine)‐imidazolidine (DCNQI), &bgr;x= −240±60×10−30cm5/esu. The unusually large magnitude and sign originate from certain charge‐correlated features in the quinoid ground and excited states.

ISSN:0003-6951    

DOI:10.1063/1.92619

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We have butt coupled 13‐mW cw and 27‐mW (5‐&mgr;s‐long pulses, 5% duty cycle) optical power into a single mode Ti‐LiNbO3optical waveguide by using single‐mode diode lasers at &lgr; = 0.84 &mgr;m. Coupling efficiencies greater than 68% were observed. These are the highest diode‐laser powers coupled by any means into the technologically important class of LiNbO3optical waveguides. Our observations support the theory of butt coupling between injection lasers and waveguides at hitherto unavailable power levels and efficiencies. The light coupled into the waveguide has a substantially reduced incoherent power level when compared to that emitted by the laser.

ISSN:0003-6951    

DOI:10.1063/1.92620

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An apparatus for an accurate, repeated measurement of the acoustic resonance frequencies of a photoacoustic cell is described. The shift of the resonance frequency of the first radial mode, caused by mixing of CH4and N2in the resonator, is monitored by repeated recording of the acoustic resonance curves. The time needed to reach the equilibrium concentrations varies between minutes and several days depending on the mixing procedure employed and the composition of the gas mixture. It is shown that condensation of the gases for a short time accelerates the mixing process considerably.

ISSN:0003-6951    

DOI:10.1063/1.92621

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Laser induced irreversible changes in the absorption of alkali halides has been observed by using repetitively pulsed laser calorimetry. These changes occur at intensities below that required for laser induced breakdown and necessitate a change in the definition of laser damage threshold. A simple model is proposed to explain these observations based on the accumulation of microscopic failures as a result of each pulse.

ISSN:0003-6951    

DOI:10.1063/1.92622

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An epitaxial tellurium dioxide layer has been observed on an oxidized {110} surface of a cadmium telluride single crystal. The structure of the oxide layer has been determined using high‐resolution transmission electron microscopy (TEM) and identified as that of the mineral tellurite (TeO2). The interface is abrupt and coherent throughout the observed region. Crystallographic relationships at the interface suggest a model for oxidation.

ISSN:0003-6951    

DOI:10.1063/1.92623

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Heteroepitaxial films on CdTe have been grown by molecular beam epitaxy (MBE) on InSb (001) orientation substrates at growth temperatures ≲220 °C. The structural perfection of these films has been explored by double crystal x‐ray diffraction techniques, which reveal that films of ∼1 &mgr;m thick grown at 150 and 220 °C are free of low‐angle grain boundaries and are exactly lattice matched to the InSb substrate. The lattice parameter mismatch is accommodated by misfit elastic strain.

ISSN:0003-6951    

DOI:10.1063/1.92616

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An Ar‐ion laser has been used to activate surface pyrolytic deposition of polycrystalline Si in a several micrometer reaction zone. Controlled doping with boron during deposition allows one‐step direct writing of highly conducting Si lines with linewidths as small as 1 &mgr;m. An unexpectedly fast deposition rate is associated with changes in the reaction kinetics as the dimensions of the reaction volume are reduced to microscopic lengths.

ISSN:0003-6951    

DOI:10.1063/1.92624

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Room‐temperature electron diffusion lengths (Ln) were determined for lattice matched,p‐type InGaAsP and InGaAs layers grown by liquid phase epitaxy on Sn‐doped (100)‐InP substrates by measuring the variation of the short‐circuit photocurrent as a focused laser beam was scanned along a beveled (&Vthgr;∼1 °)p‐njunction. The hole concentrations, determined by capacitance‐voltage (C‐V) measurements, indicated an almost linear relationship between the hole concentrations in both the quaternary and ternary layers and the amount of Zn in the melt for the growth temperatures and substrate orientation used in this work. The electron diffusion lengths were longest at the lowest hole concentrations and decreased monotonically as the concentration increased. At the lowest doping levels,Lnwas 3.5 &mgr;m atp= 3×1015cm−3for the quaternary and 2.5 &mgr;m atp= 1.4×1016cm−3for the ternary. At the highest hole concentration (p= 5×1018cm−3)Lnwas 0.13 and 0.83 &mgr;m for InGaAsP and InGaAs, respectively.

ISSN:0003-6951    

DOI:10.1063/1.92625

出版商:AIP    

年代:1981

数据来源: AIP