摘要:

A meaningful power threshold for focused laser damage in polymethyl methacrylate (PMMA) is established. It is also shown that the type (but not the extent) of damage is identical for theQ‐switched and non‐Q‐switched laser pulses for the range of power levels used. Finally, it is explained why the observed focused laser damage in PMMA is so much more extensive in the non‐Q‐switched case than in theQ‐switched case, even though the latter type of laser pulse has an inherently higher peak power.

ISSN:0003-6951    

DOI:10.1063/1.1655263

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Extensive data are collected and presented to test the coupled‐carrier equations and attending density‐switching criterion proposed to describe nonthermal threshold switching in amorphous semiconductors. The equations and switching criterion predict in magnitude and functional form a wide range of phenomena found in the off‐state, during the switching‐on, in the on‐state, and during the switching‐off of amorphous chalcogenide films. The critical temperature noted in a variety of experiments is identified as the elevated temperature at which the switching criterion is fulfilled thermally in the presence of a small field.

ISSN:0003-6951    

DOI:10.1063/1.1655264

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A uv‐photopreionized TEA CO2&sngbnd;N2discharge is incorporated in an actively mode‐locked CO2laser system capable of producing individual pulses of peak power of > 200 MW with durations ∼ 1 nsec. Spectral examination of the laser output indicates that oscillation occurs simultaneously on several rotational lines of the 10.4‐&mgr; band.

ISSN:0003-6951    

DOI:10.1063/1.1655266

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We have measured the ground‐state population distribution of OH in a flame by detecting the resonance fluorescence excited by a high‐power tunable uv laser beam. This technique provides spatial, temporal, and spectral resolutions which are not possible with absorption measurements involving conventional light sources. It should prove particularly valuable in studying the dynamics of combustion.

ISSN:0003-6951    

DOI:10.1063/1.1655267

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

InxGa1−xAs Schottky‐barrier diodes for detection in the 0.9–1.06‐&mgr;m wavelength range have been incorporated in high‐purity GaAs planar waveguides using a selective epitaxial growth process. A quantum efficiency of 60% at 1.06 &mgr;m has been obtained for these detectors, and current gain has been observed.

ISSN:0003-6951    

DOI:10.1063/1.1655268

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The sensitivity of LiTaO3crystals to hologram formation has been observed to vary with impurity concentration. For a writing wavelength of 488.0 nm and power density of 1.1 W/cm2the sensitivity varied from a value comparable to the most sensitive doped LiNbO3for an impure crystal to a value more than 5 orders of magnitude smaller for a purer crystal. Fatigue effects were observed upon write‐erase cycling. These effects were dependent upon writing and erasure polarization and power density and could be minimized by proper choice of optical parameters.

ISSN:0003-6951    

DOI:10.1063/1.1655269

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We use the wave equation and WKB approximate solutions to study the general properties of modes in a waveguide whose index of refraction decreases monotonically with distance below its surface, due to variation of either ionic or electronic contributions. The modes are found to have oscillations that increase in amplitude and in spacing with increasing depth. For modes with smaller propagation constants the oscillatory regions, as well as the decaying regions, are found to penetrate more deeply.

ISSN:0003-6951    

DOI:10.1063/1.1655270

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A technique has been developed for determination of the sign of charge carrier transported across an insulating film on a semiconductor substrate, utilizing the charge‐carrier separation properties of a shallowp‐njunction diffused into the semiconductor. For thermally grown SiO2, unmetallized and contacted by a corona discharge in dry air, electrons are found to carry the current for both polarities of surface potential. Also demonstrated is electron‐hole pair production in the Si by electrons entering from the oxide.

ISSN:0003-6951    

DOI:10.1063/1.1655271

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The Koster‐Slater one‐band one‐site model has been employed to investigate the modulus of the wave function of an electron bound to a N isoelectronic trap in GaAs1−xPx:N as a function of crystal compositionx. The no‐phonon recombination transition involving the trapped electron is enhanced as the crystal composition is changed to bring the &Ggr; conduction band minimum,E&Ggr;, near the N‐trap level,EN. Absorption data taken onx= 1.0 andx= 0.53 GaAs1−xPx:N are consistent with the calculated increase in the probability density in the &Ggr; region asE&Ggr;decreases relative toEX. The change in the internal quantum efficiency as a function of crystal composition has been calculated assuming that the nonradiative component of recombination is independent ofx. By weighting the internal recombination‐radiation quantum efficiency by the photopic response of the eye, we have determined that the optimum range of crystal compositions in which to fabricate GaAs1−xPx:N LED's is 0.6 ≤x≤ 0.8. This result is in good agreement with current GaAs1−xPx:N LED fabrication processes.

ISSN:0003-6951    

DOI:10.1063/1.1655272

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The introduction of hydrogen into single crystals of barium sodium niobate, which occurs during the usual poling procedure, causes refractive‐index changes that permit the propagation of optical guided waves. Propagation of TM modes can be achieved even when the boundary between the hydrogenated and unhydrogenated region of the crystal is remote from the crystal faces. For thin hydrogenated layers, both TE and TM modes can be propagated. Phase‐matched frequency doubling of the cw output of a Nd&sngbnd;YAG laser was demonstrated in such a layer.

ISSN:0003-6951    

DOI:10.1063/1.1655273

出版商:AIP    

年代:1974

数据来源: AIP