摘要:

cw pumped laser emission on six different wavelengths is obtained for the first time in a LiYF4:15% Er3+crystal at room temperature under diode laser excitation for 2.66, 2.716, 2.81 &mgr;m emissions and under argon ion laser excitation for 2.77, 2.81, 2.84, 2.85 &mgr;m emissions. Threshold of 5 mW absorbed power at 0.795 &mgr;m (diode) is obtained for the 2.81 &mgr;m wavelength. Time and power evolution of the laser emissions are presented. The type of up‐conversion taking place during 2.81 &mgr;m laser emission is shown to be of the addition of photons by energy transfer (APTE) type involving a two‐photon summation which depopulates the4I11/2rather than the4I13/2state as up to now believed.

ISSN:0003-6951    

DOI:10.1063/1.100885

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Nonlinear photorefractive wave mixing in waveguides provides unusual intermode coupling effects which are independent of the overall light intensities. We present and demonstrate processes in which high‐order modes of a guided beam are converted into the low modes (funnel‐like) and vice versa (antifunnel‐like). We also show capabilities of launching and amplifying a guided beam by pumping the waveguide laterally. Another use of polarization state conversion is discussed.

ISSN:0003-6951    

DOI:10.1063/1.100886

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Diffraction‐coupled arrays of InGaAsP/InP buried‐heterostructure lasers are reported. These arrays, fabricated by ion beam assisted etching and mass transport, have a novel scalloped mirror at the end of the coupling section that greatly increases the coupling between stripes and reduces the feedback into the same stripe. Far‐field patterns show sharply defined lobes that are as narrow as 3°. An output section with cylindrical mirrors has been incorporated into the arrays to increase the power in the central far‐field lobe. Threshold currents as low as 150 mA have been obtained for eight‐stripe arrays.

ISSN:0003-6951    

DOI:10.1063/1.100864

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A neodymium phosphate glass regenerative amplifier is used for both pulse energy amplification and spectral broadening. After compression by a grating pair, 0.55 ps pulses of 11 &mgr;J energy are generated at a 370 Hz repetition rate.

ISSN:0003-6951    

DOI:10.1063/1.100865

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

During titanium silicide (TiSi2) formation by rapid thermal annealing (RTA), the redistribution of implanted arsenic was investigated by means of Auger electron spectroscopy (AES) and secondary‐ion mass spectroscopy (SIMS). By using 30 nm amorphous silicon (a‐Si) film deposited sequentially on 50 nm titanium film without breaking the vacuum, the As dopant redistribution is suppressed due to the reduction of consumption of silicon substrate (Si‐sub) during TiSi2formation. The AES shows that the silicon, which is required for TiSi2formation, is supplied from thea‐Si film more rapidly than from the Si‐sub. Also, the conversion of deposited Ti film into TiSi2is complete because thea‐Si film on Ti film prevents the infiltration of oxygen impurity into the Ti film during the exposure to air before annealing.

ISSN:0003-6951    

DOI:10.1063/1.101468

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Chiral dopants are reported which enable one to compensate for the temperature dependence of the optical characteristics of twisted nematic liquid‐crystal displays. Temperature compensation is achieved by the addition of a small amount of only one chiral compound to the liquid‐crystal mixture. This procedure is more precise and less laborious than a previously reported method, which utilizes two or more chiral dopants.

ISSN:0003-6951    

DOI:10.1063/1.101360

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The adsorption of trimethylgallium (TMG) on GaAs (110) surface at room temperature was studied with ultraviolet photoemission spectroscopy by use of synchrotron radiation. The adsorption was found to saturate for TMG exposure as low as 3 langmuirs (L) resulting in a coverage of less than 0.1 monolayer. It is concluded that TMG molecules are adsorbed on the GaAs surface without decomposition.

ISSN:0003-6951    

DOI:10.1063/1.100866

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The influence of Yb added to the melt, on the near‐band‐gap emission of Ga1−xAlxAs grown by liquid phase epitaxy, is reported. No characteristic Yb3+emission is found, but a pronounced narrowing of the bound‐exciton spectrum is observed for Yb concentrations in the Ga melt below 100 ppm. A similar effect is seen in conduction band to acceptor transitions, for which the smallest linewidth observed is limited by fluctuations in composition and agrees well with the currently accepted 66:34 band‐offset partition between the conduction and valence bands of GaAs/Ga1−xAlxAs heterojunctions in the direct band‐gap range.

ISSN:0003-6951    

DOI:10.1063/1.100867

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Recent experiments have shown that ion pairing has a major influence on the diffusion and precipitation of oppositely charged impurities in silicon. Published data are used to obtain ion pairing coefficients &OHgr; forn‐type impurities with B and In. A single value, &OHgr;=0.17/ni, suffices to describe the cases P‐B, As‐B, and Sb‐B. For P‐In and Sb‐In, &OHgr; is roughly an order of magnitude smaller. These observations are consistent with the picture that paired ions occupy adjacent substitutional sites, with a small perturbation in their Coulomb binding arising from elastic effects.

ISSN:0003-6951    

DOI:10.1063/1.100868

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A series of experimental investigations on the solid phase recrystallization of molecular beam deposited gallium arsenide films on silicon dioxide/tantalum/nickel substrates has been performed. The activation energy for recrystallization is unexpectedly small (0.55 eV) in the temperature range 450–600 °C. When a thin amorphous germanium layer was grown before gallium arsenide deposition, an enhanced grain growth of gallium arsenide occurs together with anomalous germanium diffusion into the gallium arsenide layer in a semieutectic phase reaction. An enhancement of grain growth has also been observed by the utilization of a graphoepitaxy substrate having inverted pyramidal relief.

ISSN:0003-6951    

DOI:10.1063/1.100869

出版商:AIP    

年代:1989

数据来源: AIP