摘要:

The power‐handling capability of crystals utilized for second harmonic generation (SHG) and other nonlinear frequency conversions has until recently been limited to a few watts of average output power, chiefly because of two conditions, namely, thermal instability and thermal gradients. Now, techniques have been invented that correct these conditions with a resulting order of magnitude increase in the average output power produced by SHG. This paper presents the theory for two techniques that solve the problem of thermal instability, namely, electro‐optical tuning (EOT) and piezo‐optical tuning (POT). Beam shaping, which prevents thermal gradients, will be treated in a separate paper. In this paper, the general physical theory is discussed both for EOT and POT. The equation for the phase‐match condition is given. Interactive effects of temperature change &Dgr;T, the applied electric field (E), and the stress field &sgr; on a fixed‐position crystal are treated. The general equations for EOT and POT are developed. Examples of the effect on SHG in cesium dideuterium arsenate (CD*A) are given. Using these techniques, with beam shaping to be described in a separate paper, 35 W of average output power at 0.53 &mgr; has already been demonstrated.

ISSN:0021-8979    

DOI:10.1063/1.324347

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A simple procedure is presented for computing optical transmission and Faraday‐rotation optical density (OD) planar layered structures when all internal reflections are taken into account. The procedure makes use of the Mueller matrix technique and assumes that interference effects, Faraday ellipticity, and boundary magneto‐optical effects, e.g., Kerr effect, are not important. The general formulas are applied to the case of the three‐layer structure from which two examples of some practical interest are derived, i.e., a single absorbing layer on a nonabsorbing substrate and two identical absorbing layers on either side of a nonabsorbing substrate. The solutions are substantially simplified when Faraday‐rotation angles are small.

ISSN:0021-8979    

DOI:10.1063/1.324348

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Qualitative results of an x‐ray photoelectron and optical investigation of three thin‐film transition‐metal oxides, namely, WO3, MoO3, and V2O5are reported. Data were obtained on films that werenotcoloredandcoloredby an electrochromic process. The particular electrochromic coloration process used is electrolytic in nature and employs a sandwich‐structure electrochromic cell and electrolyte pool. The optical spectra show increased absorption in the visible (red) and near‐infrared spectral regions upon coloration. The photoelectron spectra forcoloredfilms exhibit a small band near the Fermi level and asymmetric band shapes for metal core‐level bands which are absent in films that arenotcolored. The new band and the asymmetric band shapes are attributed to the presence of a reduced‐state species caused by the presence of trapped electrons and metal bronze formation. Results from coloration with different electrolyte pools, i.e., H+, Li+, Na+, K+, Cs+, and Mg2+electrolytes, are reported.

ISSN:0021-8979    

DOI:10.1063/1.324349

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Glow‐discharge optical spectroscopy has been used as a real time monitor of the transient sputtering characteristics of alloy samples containing various amounts of second‐phase precipitates. All alloys investigated reached a steady‐state sputtering condition in which the chemical composition of the sputtered target material was equal to that of the bulk target. The transient sputtering time required to reach steady state was directly related to the time required to attain a steady‐state rate of target surface cone formation and annihilation. Scanning Auger and electron microprobe analyses were used to show that cone formation in these alloys was due to masking of the matrix by slow sputtering second‐phase precipitates and surface agglomerates. At steady state, the cone number density was found to be a function of bulk‐alloy precipitate density, Ar sputtering pressure, and the sample sputtering rate. Increasing the Ar pressure resulted in increased scattering of sputtered atoms back to the target surface, while changes in overall target sputtering rate affected the surface migration and, hence, surface distribution of low‐yield species. The average cone base diameter for Inconel 718, Incoloy 800, and Monel K‐500 alloys was approximately 8 &mgr;m. The average depths removed during transient dc sputtering at an Ar pressure of 40 mTorr (5.3 Pa) and 2 kV were 1.5 &mgr;m for Inconel 718, 1.3 &mgr;m for Incoloy 800, and 0.1 &mgr;m for Monel K‐500. For comparison, high‐purity GaAs single‐crystal samples sputtered under the same conditions reached steady‐state sputtering after the removal of less than 100 A˚. In all cases, films deposited on glass substrates at ambient temperature during steady‐state sputtering had the same chemical composition as the bulk target. Inconel 718 and Incoloy 800 films also exhibited second‐phase precipitates similar to those in the bulk targets.

ISSN:0021-8979    

DOI:10.1063/1.324350

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We report lattice constants, pseudobinary phase diagrams, crystal growth, and optical properties of the chalcopyrite CdGe(As1−xPx)2and AgGa(Se1−xSx)2solid solutions. The type‐II phase‐matching angle for frequency doubling of 10.6‐&mgr;m radiation has been measured for CdGe(As1−xPx)2crystals withx=0, 0.13, and 0.19. On the basis of the results, it is estimated that 90° phase matching would be obtained forx∼0.3.

ISSN:0021-8979    

DOI:10.1063/1.324352

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The acoustic‐emission rate is shown to be a direct measure of wear rate in a brittle solid and is used to study the strong dependence of drilling rates on the fluid environment. It is proposed that aggregation of ions in the drilling fluid produces charged or noncharged species which determine the surface zeta potential. The Rebinder‐Westwood environmental effects on mechanical properties correlate well with the zeta potential and it is shown that the effects also correlate well with the state of charge of ions and ion aggregates in the fluid environment.

ISSN:0021-8979    

DOI:10.1063/1.324353

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Computer simulation of grating solar cells is used to compare the performance of this type of device with more conventional cell geometries. Criteria for the grating design and their dependence upon substrate properties are discussed. The nature of the back contact to the cell is shown to play an important role in determining the cell efficiency. In order for the grating cell to be competitive in efficiency with the normal cell geometry, the back contact must have minority‐carrier blocking properties. The efficiency of cells with ideal Ohmic back contacts is limited by geometrical effects. Recent experimental results are analyzed in terms of the results of the theoretical investigation.

ISSN:0021-8979    

DOI:10.1063/1.324354

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The generation mechanism for intermodulation products in thin ferromagnetic resonators is examined. A sketch of classical theory provides a physical picture of this mechanism. Using this theory as a base, the effect of spin‐wave scattering on intermodulation is then predicted by treating the resonant mode and spin waves as magnons; spin‐wave scattering is found theoretically to increase the intermodulation products. A comparison of the full theory with experimental results on bandpass filters made with thin YIG resonators shows good agreement.

ISSN:0021-8979    

DOI:10.1063/1.324355

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Photoemission to 1.65 &mgr; from a field‐assisted heterojunction cathode has been achieved for the first time. The all‐LPE‐grown cathode consists of ap‐type InGaAs photon‐absorbing electron‐generating layer, lattice matched to ap‐type InGaAsP transferred‐electron photoelectron‐emitting layer. Reflection‐mode quantum yield of ∼0.1&percent; at 1.55 &mgr; has been measured at 125 K.

ISSN:0021-8979    

DOI:10.1063/1.324356

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

GaxIn1−xAs light‐emitting diodes which utilize Ge as ap‐type impurity were fabricated from LPE crystals. Use of a GaAs (111) A surface as a substrate and reduction of dislocation density by a continuous grading technique yield LED’s of 0.48&percent; external quantum efficiency at 1.02‐&mgr;m wavelength. The electroluminescent response time of these diodes is the same order as that of GaAs LED’s which utilize Zn as ap‐type impurity.

ISSN:0021-8979    

DOI:10.1063/1.324357

出版商:AIP    

年代:1978

数据来源: AIP