Volume 10, Issue 8, 15 April 1967
Index of content:
10(1967); http://dx.doi.org/10.1063/1.1754917View Description Hide Description
Photodiode detectors having narrow spectral response without use of external filters have been fabricated. Use of high resistivity semi‐insulating GaAs in the construction of such diodes makes it possible to modulate the spectral response by application of moderate values of reverse bias. A device is described whose spectral response is expanded from a half‐width of ∼ 200 Å to typical broad‐band characteristics under 30 V reverse bias.
10(1967); http://dx.doi.org/10.1063/1.1754918View Description Hide Description
Reflection electron diffractionpatterns show strong variations in orientations of the outer layer of an NaCl filmdeposited on fused silica, due to the presence during evaporation of a dc field parallel to the surface.
Orientation effects have been observed by x‐ray diffractometry in a limited range of evaporation rates which are attributed to electrolysis of adsorbed water.
10(1967); http://dx.doi.org/10.1063/1.1754920View Description Hide Description
The ordinary fluorescence of Er3+ in Y2O3 and LaF3 crystals is observed when the crystals are excited with 6328‐Å, He‐Ne laser radiation. From the linear power dependence of the 6800‐Å fluorescence and the quadratic power dependence of the 5640‐ and 3900‐Å fluorescence on the 6328‐Å excitation, a single‐photon excitation for the 6800‐Å fluorescence and a double‐photon stepwise excitation for the 5640‐ and 3900‐Å fluorescence were proposed. The calculated photon flux of the 5640‐Å fluorescence based on the two‐photon stepwise excitation agrees with the estimated observed value.
10(1967); http://dx.doi.org/10.1063/1.1754921View Description Hide Description
A high‐speed energy correlation technique has been used to measure the time development of the width of the ultrashort pulses generated by a mode‐locked Nd+3glass laser. The laser was simultaneously Q‐switched and mode‐locked with a saturable absorber and produced a train of approximately 100 ultrashort pulses. It was found that the initial pulses in the train were of the shortest duration and that the pulse width increased from several picoseconds to about 15 picoseconds over the length of the train. The measurement technique and possible mechanisms for this behavior are discussed.
10(1967); http://dx.doi.org/10.1063/1.1754922View Description Hide Description
A theoretical expression is given for the amplitudes of the combination‐tones which result from the interaction of orthogonal laser oscillations. Combination‐tone generation is found to be highly dependent upon the degree of degeneracy of the atomic energy levels involved and upon the polarization states of the primary oscillations. The theoretical predictions are compared with the results of an experimental study of combination‐tone phenomena in He‐Ne lasers.
10(1967); http://dx.doi.org/10.1063/1.1754923View Description Hide Description
10(1967); http://dx.doi.org/10.1063/1.1754924View Description Hide Description
We report that the critical thickness for the appearance of stripe domains in evaporated permalloyfilms depends sensitively on vacuum pressure during evaporation and also that the perpendicular anisotropy constant can be obtained from the critical thickness rather precisely. It was found that the perpendicular anisotropy increases with increasing pressures and at high pressures the contribution of the magnetostrictioneffect to the anisotropy can be neglected.
10(1967); http://dx.doi.org/10.1063/1.1754925View Description Hide Description
The time dependence of the laser output pulse at 337 μ in an acetone and nitrogen gas mixture has been studied using a fast indium antimonide detector. Current pulses from a line‐type modulator were varied in length from 2 to 20 μsec with amplitudes from 50 to 180 A. The start of the laser output pulse occurred after the current pulse in the discharge was over, from 6 to 8 μsec after the end of the current pulse. These results indicate that, for the currents used, population inversion and the achievement of conditions allowing laser action, take from 6 to 8 μsec after the discharge ends to become established.
10(1967); http://dx.doi.org/10.1063/1.1754926View Description Hide Description
Laser action has been observed on vibrational‐rotational transitions between low lying vibrational levels of HX and DX (X = F, Cl, Br) formed by chemical reactions in an electrically pulsed discharge. HF wavelengths, lying between 2.7 and 3.3 μ, and DF wavelengths, lying between 3.6 and 4.2 μ, are listed and identified.