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1 Feb 1972

Volume 20, Issue 3, pp. 101-145


X‐Ray—Induced Variation of Time Constant of Yb+3 Sensitizer

H. N. Hersh and G. Ban

Appl. Phys. Lett. 20, 101 (1972); http://dx.doi.org/10.1063/1.1654064 (2 pages) | Cited 1 time

Online Publication Date: 22 October 2003

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We describe a unique method for continuously and independently varying the rate‐controlling time constant of excited Yb+3 ions in rare‐earth up‐converting phosphors. We show, in the system BaYb2F8: Er, that at all values of the time constant, the power radiated is directly proportional to the square of the observed radiative lifetime, in accordance with the 2‐transfer model of Auzel. The decrease in this time constant arises from the introduction of radiation‐produced defects which selectively affect the Yb+3 rather than the activator ions. The phenomenon can be used to study energy transfer from Yb+3 to any activator.

Laser Diagnostics of a Potassium Plasma Using Selective Excitation Spectroscopy

R. M. Measures and A. B. Rodrigo

Appl. Phys. Lett. 20, 102 (1972); http://dx.doi.org/10.1063/1.1654065 (3 pages) | Cited 3 times

Online Publication Date: 22 October 2003

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A thermally tuned Q‐switched ruby laser has been used to selectively excite the 6939‐A transition in a potassium plasma. A burst of intensified spontaneous emission at both 6911 and 6939 A has been observed. This enhanced emission contains information on the local properties of the plasma as demonstrated by the observed dependence of the signal duration upon the free‐electron density.

Acceptor State of Gold in Silicon—Resolution of an Anomaly

Louis C. Parrillo and Walter C. Johnson

Appl. Phys. Lett. 20, 104 (1972); http://dx.doi.org/10.1063/1.1654066 (3 pages) | Cited 21 times

Online Publication Date: 22 October 2003

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We propose that a severe anomaly among the parameters of the gold acceptor state in silicon can be resolved by taking into account the temperature dependence of all the parameters. The temperature variation of most consequence is that of the trap energy level with respect to the band edges. We show that if the trap maintains a constant relative position in the gap, the resulting corrections to the activation energies place the trap nearly 0.1 eV higher in the gap at 300°K than was supposed, and all of the available data are brought into agreement.

Enhanced Annealing Effects in Boron‐Implanted Layers in Silicon by Postimplantation of Silicon Ions

L. ‐O. Bauer

Appl. Phys. Lett. 20, 107 (1972); http://dx.doi.org/10.1063/1.1654067 (3 pages) | Cited 5 times

Online Publication Date: 22 October 2003

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Various effects of postimplantation of silicon ions on boron‐implanted layers are reported. The amount of enhanced annealing depends critically on the target temperature during implantation and on the dose of silicon ions used. At 100 keV, a 5×1015∕cm2 silicon dose is necessary to create an amorphous layer extending up to the surface at room temperature. Close to 100% of the boron ions located in this layer become electrically active after annealing at 600°C. For boron doses approximately greater than 3×1015∕cm2, shallow silicon implantations produce stronger enhanced annealing than expected. For boron doses less than 2×1014∕cm2, little or no enhanced annealing is observed.

Neutron Damage in GaP Light‐Emitting Diodes

C. E. Barnes

Appl. Phys. Lett. 20, 110 (1972); http://dx.doi.org/10.1063/1.1654068 (3 pages) | Cited 7 times

Online Publication Date: 22 October 2003

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The effects of neutron damage on the red and green light output at 300 °K of GaP lightemitting diodes have been examined. The results indicate that the diodes are not sensitive to neutron irradiation in those voltage regions where the radiative current is due to spacecharge recombination in the depletion layer. As a consequence of this, it is shown that the response of the diodes to neutron irradiation can be used to elucidate the radiative currentflow mechanisms in these devices.

Effect of the Nonuniform dc Field on Carrier Waves in Negative‐Differential‐Mobility Semiconductors

M. Bini and G. R. Bisio

Appl. Phys. Lett. 20, 112 (1972); http://dx.doi.org/10.1063/1.1654069 (3 pages)

Online Publication Date: 22 October 2003

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The growth of a carrier wave propagating through a negative‐differential‐mobility semiconducting sample is discussed under nonuniform dc bias conditions. A simple analytical expression for the over‐all numerical gain is given in terms of current density and of the input and output carrier‐wave velocities only. Applications to n‐type GaAs are discussed.

Scanning X‐Ray Emission Microscopy

H. J. Leamy and S. D. Ferris

Appl. Phys. Lett. 20, 115 (1972); http://dx.doi.org/10.1063/1.1654070 (2 pages)

Online Publication Date: 22 October 2003

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This letter describes the production of continuous tone micrographs from the x radiation emitted by a specimen subjected to electron bombardment in a scanning electron microscope. The x rays are collected and energy analyzed with an energy‐dispersive spectrometer so that topographically rough specimens may be examined. The images reveal variations in specimen topography and composition.

Mode‐Selection Technique for Continuously Pumped Repetitively Q‐Switched Lasers

E. O. Ammann and J. M. Yarborough

Appl. Phys. Lett. 20, 117 (1972); http://dx.doi.org/10.1063/1.1654071 (4 pages) | Cited 4 times

Online Publication Date: 22 October 2003

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A mode‐selection technique is described which applies specifically to continuously pumped repetitively Q‐switched lasers. The technique is based on opening the Q switch just as the laser gain exceeds the Q‐switch hold‐off loss. This results in a reduction of the number of both longitudinal and transverse modes present in the Q‐switched output. Of particular interest is the simplicity and convenience of this scheme, since it does not require the introduction of any components inside the laser cavity. Experimental data are presented on a continuously pumped repetitively Q‐switched Nd: YAlO3 laser.

Improved Infrared‐Response Technique for Determining Impurity and Defect Levels in Semiconductors

A. H. Sher and W. J. Keery

Appl. Phys. Lett. 20, 120 (1972); http://dx.doi.org/10.1063/1.1654072 (3 pages)

Online Publication Date: 22 October 2003

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The response of reverse‐biased germanium diodes to monochromatic infrared radiation has been studied. Specimens included those fabricated from crystals doped with either copper or gold, or subjected to heat treatment. Preliminary results are reported that show the technique to be useful for identifying such impurities or defects in both lithium‐compensated and high‐purity germanium specimens.

Selected‐Zone Dark‐Field Electron Microscopy

Klaus Heinemann and Helmut Poppa

Appl. Phys. Lett. 20, 122 (1972); http://dx.doi.org/10.1063/1.1654073 (4 pages) | Cited 28 times

Online Publication Date: 22 October 2003

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Selection of image‐forming electrons that have passed through a small annular zone of the objective lens drastically reduces the resolution‐limiting influence of chromatic aberration. Special objective‐lens aperture diaphragms are needed for this new method of obtaining high‐quality images. The manufacture of the diaphragms is described. High‐resolution and high‐contrast images of crystallographic specimens in the light of selected Bragg‐diffracted beams without preference to azimuthal orientations were obtained. In particular, {111}‐lattice planes of gold were observed as well as interference fringes (``pseudo'' lattice images) between two nonsymmetrical Au {111} diffracted beams, displaying spacings and azimuthal directions characteristic of regular {200}‐ and {220}‐lattice fringes, although the {200} and {220} diffracted beams were omitted by the specific annular aperture used. Such ``pseudo'' lattice images allow deposit orientation determinations in the same way as ``ordinary'' lattice images.

Passive Mode Locking of Flashlamp‐Pumped Dye Lasers Tunable between 580 and 700 nm

E. G. Arthurs, D. J. Bradley, and A. G. Roddie

Appl. Phys. Lett. 20, 125 (1972); http://dx.doi.org/10.1063/1.1654074 (3 pages) | Cited 38 times

Online Publication Date: 22 October 2003

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Employing polymethine dyes as saturable absorbers and intracavity Fabry‐Perot interferometers, a flashlamp‐pumped cresyl‐violet dye laser has been mode locked to produce picosecond pulses (3–5 psec) frequency tunable from 644 to 704 nm. The frequency tuning ranges of mode‐locked rhodamine 6G and rhodamine B dye lasers have also been extended to cover 584 to 645 nm.

Nonlinear Materials for Acoustic‐Surface‐Wave Convolver

T. C. Lim, E. A. Kraut, and R. B. Thompson

Appl. Phys. Lett. 20, 127 (1972); http://dx.doi.org/10.1063/1.1654075 (3 pages) | Cited 19 times

Online Publication Date: 22 October 2003

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Acoustic‐surface‐wave convolution by nonlinear mixing has been observed in cubic, hexagonal, and trigonal crystals. The magnitudes of the phenomenological nonlinear surface‐wave coupling constants are tabulated and compared with the linear electromechanical coupling factor 2(ΔV∕V). It has been found that the basal plane of PZT‐8 has a larger nonlinear coupling constant than that of the commonly used Y‐cut Z‐propagating LiNbO3.

Kinetic Cooling of a Gas by Absorption of CO2 Laser Radiation

Frederick G. Gebhardt and David C. Smith

Appl. Phys. Lett. 20, 129 (1972); http://dx.doi.org/10.1063/1.1654076 (4 pages) | Cited 39 times

Online Publication Date: 22 October 2003

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The effect of kinetic cooling due to the absorption of 10.6‐μ CO2 laser radiation in the atmosphere has recently been predicted. In this letter, experimental evidence for this effect is presented. Transient‐density increases due to the kinetic cooling have been observed in CO2☒N2 mixtures following the propagation of an ∼ 1‐μsec 0.5‐J CO2 laser pulse through the gas. The experiments were performed with varying concentrations of CO2 and the observed cooling and subsequent heating effects are explained using the usual three‐level approximation for vibrational‐energy transfer in CO2☒N2, together with known relaxation rates.

Extension of Absolute Frequency Measurements to the cw He☒Ne Laser at 88 THz (3.39 μ)

K. M. Evenson, G. W. Day, J. S. Wells, and L. O. Mullen

Appl. Phys. Lett. 20, 133 (1972); http://dx.doi.org/10.1063/1.1654077 (2 pages) | Cited 32 times

Online Publication Date: 22 October 2003

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The highest absolute frequency measurement yet reported is described. The frequency of the 3.39‐μ line from a He☒Ne laser oscillating at the methane absorption frequency was found to be 88.376245 (55) THz. The frequency was measured by beating the 88‐THz radiation with the R(30) line from a cw CO2 laser and a 48‐GHz klystron in a tungsten‐on‐nickel point‐contact diode. The speed of light calculated from this frequency and previous wave‐length measurements is in agreement with the accepted value and of comparable accuracy.

Nonlinear Optical Properties of Ferroelectric Lead Titanate

S. Singh, J. P. Remeika, and J. R. Potopowicz

Appl. Phys. Lett. 20, 135 (1972); http://dx.doi.org/10.1063/1.1654078 (3 pages) | Cited 35 times

Online Publication Date: 22 October 2003

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Optical transmission, refractive‐index, and nonlinear optical properties of single domain PbTiO3 have been measured between room temperature and the Curie temperature Tc. The second‐harmonic coefficient d31 is found to be the highest for any room‐temperature ferroelectric. Since the birefringence is small (approximately 0.008), phase‐matched SHG is not possible, but nondegenerate three‐frequency mixing should be possible. The Miller δ coefficients are analyzed in terms of Jerphagnon's formulation and poor agreement is observed.

Electric‐Discharge Gas‐Dynamic Laser

Tehmau Kan, Joseph A. Stregack, and William S. Watt

Appl. Phys. Lett. 20, 137 (1972); http://dx.doi.org/10.1063/1.1654079 (3 pages) | Cited 6 times

Online Publication Date: 22 October 2003

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See Also: Erratum

Show Abstract
Laser action on the CO vibrational‐rotational bands between 4.8 and 5.3 μ is produced by electrical excitation of CO : N2 : O2 : He mixtures followed by expansion in a supersonic nozzle. Conversion of electrical energy into laser output occurs with ∼ 2% efficiency and small‐signal gains in excess of 0.8% cm−1 have been observed.

Photodimer Distributed Feedback Laser

R. L. Fork, K. R. German, and E. A. Chandross

Appl. Phys. Lett. 20, 139 (1972); http://dx.doi.org/10.1063/1.1654080 (3 pages) | Cited 8 times

Online Publication Date: 22 October 2003

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A tunable (0.567–0.605 μ) solid‐state dye laser with a small active volume (10 μ×80 μ×1 cm), which uses a nondestructively read‐reversible optical‐memory material to control the intensity and wavelength of the laser emission, is described. The optical‐memory material, photodimers of acridizinium ethylhexanesulfonate, provides distributed feedback in the form of an adjustable‐period phase grating which can be optically written (0.364 μ) or erased (0.313 μ). Reproducibility of laser switching, time and spectral structure, and operation at low temperatures where photodegradation of the dye is significantly reduced are discussed.

Efficient Variable Threshold Acousto‐optic Q Switching of Flash‐Pumped Nd:YAG

W. C. Scott and M. de Wit

Appl. Phys. Lett. 20, 141 (1972); http://dx.doi.org/10.1063/1.1654081 (3 pages)

Online Publication Date: 22 October 2003

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A flash‐pumped Nd:YAG laser has been effectively Q switched with an acousto‐optic beam deflector in a resonator arranged such that the deflected laser beam goes into feedback while the undeflected beam is the output. This allows the laser threshold, and consequently the output pulse energy, to be electronically controlled via the rf power applied to the deflector permitting the extraction within a single pump flash of a sequence of Q‐switched pulses with individually predetermined energies and spacings. Further, because the low Q state of the resonator involves almost 100% round‐trip loss and no power to the deflector, high standoff capability and low‐rf‐power requirements are realized.

Light‐Guiding Structures of Photoresist Films

H. W. Weber, R. Ulrich, E. A. Chandross, and W. J. Tomlinson

Appl. Phys. Lett. 20, 143 (1972); http://dx.doi.org/10.1063/1.1654082 (3 pages) | Cited 9 times

Online Publication Date: 22 October 2003

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We have made light‐guiding thin films with losses of ∼ 2.2 dB∕cm at 0.633 μm from Kodak KPR photoresist which has been processed to remove a photosensitizer which absorbs in the visible. Curved and straight optical strip guides as narrow as 5 μm have been written in these films and have shown light guiding with losses of 3 to 8 dB∕cm at 0.633 μm.
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