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15 Dec 1971

Volume 19, Issue 12, pp. 503-541


Stark‐Effect Modulation of a CO2 Laser by NH2 D

A. R. Johnston and R. D. S. Melville

Appl. Phys. Lett. 19, 503 (1971); http://dx.doi.org/10.1063/1.1653790 (4 pages) | Cited 12 times

Online Publication Date: 22 October 2003

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The molecular Stark effect in NH2D was used to modulate the 10. 6‐μ P(20) line of a CO2 laser yielding a modulation depth of 40% from a 200‐V cm−1 rms signal applied to a 19. 7‐cm gas cell external to the laser. NH2D was prepared by mixing ND3 and NH3. The absorption coefficient of the M=4 Stark‐split line was measured as a function of mixing ratio and pressure. The observed pressure‐broadening coefficient was 32. 5 MHz∕Torr.

Atmospheric‐Pressure Pulsed CO2 Laser Utilizing Preionization by High‐Energy Electrons

R. K. Garnsworthy, L. E. S. Mathias, and C. H. H. Carmichael

Appl. Phys. Lett. 19, 506 (1971); http://dx.doi.org/10.1063/1.1653791 (3 pages) | Cited 23 times

Online Publication Date: 22 October 2003

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An atmospheric‐pressure pulsed CO2 laser is described in which the gas is preionized by the injection of high‐energy electrons into the laser volume. These electrons are derived from a high‐voltage (120‐kV) glow discharge surrounding the laser. The preionization achieved has allowed 300 J to be delivered to 1. 7 liter of gas in a single discharge without the development of arcs, irrespective of whether the gas contained helium. The highest output energy (20 J) was obtained with a mixture of CO2, N2, and He in the proportions 3 : 3 : 4 by volume.

High‐Density Resonantly Sustained Plasma in a Variable‐Length Cylindrical Cavity

R. M. Fredericks and J. Asmussen

Appl. Phys. Lett. 19, 508 (1971); http://dx.doi.org/10.1063/1.1653792 (3 pages) | Cited 5 times

Online Publication Date: 22 October 2003

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It is demonstrated that linear bounded plasma theory can be used to understand and predict the high‐power behavior of a resonantly sustained plasma inside a variable‐length cylindrical cavity. Plasma densities of over 11 critical densities (> 1012 cm−3) can easily be produced by varying the cavity length.

Excitation Mechanism of the Water‐Vapor Laser

J. P. Pichamuthu, J. C. Hassler, and P. D. Coleman

Appl. Phys. Lett. 19, 510 (1971); http://dx.doi.org/10.1063/1.1653793 (3 pages) | Cited 7 times

Online Publication Date: 22 October 2003

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Experiments are described which indicate that the water‐vapor laser is pumped by selective excitation of the upper lasing level through direct electron impact. A simple model based upon this idea is shown to explain the general behavior of the laser, and to give an estimate for the collision number for the relaxation of the 020 mode of H2O of the order of 20.

Interfacial Barrier Effects in III‐V Photoemitters

R. L. Bell, L. W. James, G. A. Antypas, J. Edgecumbe, and R. L. Moon

Appl. Phys. Lett. 19, 513 (1971); http://dx.doi.org/10.1063/1.1653794 (3 pages) | Cited 11 times

Online Publication Date: 22 October 2003

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Published data show strong evidence for the existence of an interfacial barrier on GaInAs photocathodes contrary to the claims made. Thermally assisted emission of photoelectrons over an interfacial barrier of height 1. 1 eV is shown here to explain the data. Energy distribution curves from a barrier‐limited InAsP sample show that thermally assisted emission dominates over tunneling emission. The barrier height is shown to increase when Rb is substituted for Cs in the activation layer.

Self‐Pumped Josephson Parametric Amplification

H. Kanter and A. H. Silver

Appl. Phys. Lett. 19, 515 (1971); http://dx.doi.org/10.1063/1.1653795 (3 pages) | Cited 14 times

Online Publication Date: 22 October 2003

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Parametric gain has been demonstrated at 30 MHz using the nonlinear inductance of Josephson point‐contact devices. SQUID‐type configurations were used to achieve degenerate‐mode negative‐resistance amplification with self‐pumping achieved via the internal Josephson oscillations. Gain as large as 11 dB was measured. The small‐signal analysis predicts parametric amplification and delineates the importance of the critical current, circuit loss, and circuit coupling efficiency.

Characteristics of a Mode‐Locked TEA CO2 Laser

R. L. Abrams and O. R. Wood

Appl. Phys. Lett. 19, 518 (1971); http://dx.doi.org/10.1063/1.1653796 (3 pages) | Cited 14 times

Online Publication Date: 22 October 2003

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The pulse width of a mode‐locked TEA CO2 laser has been accurately measured for the first time. The dependence of the pulse width on cavity modulation frequency and cavity loss has been determined. The results are evaluated in light of existing theory.

Implanted‐Barrier Two‐Phase Charge‐Coupled Device

R. H. Krambeck, R. H. Walden, and K. A. Pickar

Appl. Phys. Lett. 19, 520 (1971); http://dx.doi.org/10.1063/1.1653797 (3 pages)

Online Publication Date: 22 October 2003

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A new kind of charge‐coupled device (CCD) utilizing an ion‐implanted barrier and only two nonoverlapping electrodes per bit is described. The use of implanted charge substantially simplifies device structure. The two‐electrode‐per‐bit configuration permits operation with only one clock. In addition, the device performs better than any previously reported CCD with a loss per transfer of less than 0. 1% up to 6. 5 MHz and 2% at 17 MHz.

Rayleigh‐Wave Propagation on Bi12 GeO20

E. Bridoux, J. M. Rouvaen, C. Coussot, and E. Dieulesaint

Appl. Phys. Lett. 19, 523 (1971); http://dx.doi.org/10.1063/1.1653798 (2 pages) | Cited 1 time

Online Publication Date: 22 October 2003

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Theoretical values of mechanical displacement, potential, and velocity of surface waves propagating in the [001] direction on [110]‐cut Bi12GeO20 are reported. The results of an experimental investigation performed at 50 MHz using interdigital transducers and optical probing are presented. The velocity measured is in excellent agreement with the theoretical value and the attenuation is very low, 0. 1 dB∕μsec being an estimated upper limit. Second‐harmonic generation which was measured by optical probing had an intensity proportional to the square of both the interaction length and the fundamental acoustic power, indicating nonlinear effects in the propagating medium at an acoustic input power of 28 dBm.

Diffusivity and Solubility of Si in the Al Metallization of Integrated Circuits

J. O. McCaldin and H. Sankur

Appl. Phys. Lett. 19, 524 (1971); http://dx.doi.org/10.1063/1.1653799 (4 pages) | Cited 79 times

Online Publication Date: 22 October 2003

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Si was diffused along the evaporated Al layer of an integrated‐circuit structure at temperatures between 360 and 560 °C, and the resulting concentration profile analyzed by electron microprobe. The Si solubility was found to agree with literature values for Si in wrought Al. The Si diffusivity was found to be substantially enhanced, however, probably due to a high density of imperfections in the evaporated Al film. Our measured diffusivities indicate an activation energy EA ≃ 0. 8 eV, about 40% less than the value for Si in wrought Al.

Efficient Parametric Mixing in CdSe

R. L. Herbst and R. L. Byer

Appl. Phys. Lett. 19, 527 (1971); http://dx.doi.org/10.1063/1.1653800 (4 pages) | Cited 23 times

Online Publication Date: 22 October 2003

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We have obtained the first phase‐matched nonlinear interaction in CdSe and have observed a 35% conversion efficiency for mixing 10.6 μ with a pump at 1.833 μ to generate a signal at 2.2 μ. The mixing process phase matches at 77° to the optic axis and confirms the predicted phase‐matching angle. The measured nonlinear coefficient value of 2.5 × 10−22 mks agrees with previous results. The mixing experiment shows than an angle‐tuned or pump‐tuned infrared parametric oscillator is possible using CdSe as the nonlinear element.

Direct Microscopic Simulation of Gunn‐Domain Phenomena

P. A. Lebwohl and P. J. Price

Appl. Phys. Lett. 19, 530 (1971); http://dx.doi.org/10.1063/1.1653801 (3 pages) | Cited 22 times

Online Publication Date: 22 October 2003

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An elaboration of the Monte Carlo computation of hot‐electron states, such as to represent a time‐dependent ensemble, is applied to the study of the instabilities associated with negative differential conductance. A two‐band semiconductor model, approximately equivalent to GaAs, is used; and the instantaneous space‐charge field parallel to the applied field is included in the particle dynamics. Spontaneous Gunn domains, successively traveling from cathode to anode at the expected speed, are obtained. This method should be suitable for investigating the instability phenomena on space and time scales shorter than are appropriate for the macroscopic theories.

Cinnabar (α HgS), a Promising Acousto‐optical Material

J. Sapriel

Appl. Phys. Lett. 19, 533 (1971); http://dx.doi.org/10.1063/1.1653802 (3 pages) | Cited 10 times

Online Publication Date: 22 October 2003

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Several acousto‐optical characteristics of cinnabar have been measured at 6328 and at 10 600 Å. All observed figures of merit are far higher than those of the most efficient photoelastic materials and the acoustic losses are quite low. For instance, at 6328 Å, the figures of merit M1, M2, and M3 are, respectively, 211, 632, and 513 times greater than the corresponding values in fused silica. The associated acoustic attenuation is only 7.1 dB∕cm at 500 MHz. To demonstrate the potential of cinnabar, an XY deflector has been calculated from measured acoustic and photoelastic constants. 100% of an incident laser beam (6328 Å) could be deflected in 62 500 different positions with an access time of 1 μsec, the acoustic power needed being only 210 mW for each stage!

Premixed cw Electric‐Discharge CO Chemical Lasers

C. J. Ultee

Appl. Phys. Lett. 19, 535 (1971); http://dx.doi.org/10.1063/1.1653803 (3 pages)

Online Publication Date: 22 October 2003

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cw lasing has been observed by discharging premixed CS2☒O2. The spectral distribution of the output suggests a chemical‐pumping mechanism. Additional observations on CS2 + O2 flames indicate the possibility of a flame laser.

Xenon‐Helium Laser at High Pressure and High Repetition Rate

Russell Targ and Michael W. Sasnett

Appl. Phys. Lett. 19, 537 (1971); http://dx.doi.org/10.1063/1.1653804 (3 pages) | Cited 5 times

Online Publication Date: 22 October 2003

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We report pulsed laser action in neutral xenon in the infrared at a repetition rate of 1.4 kHz, using a transversely excited helium‐xenon discharge. This high prf was made possible by the use of transverse gas flow to remove the residual ions from the discharge region. We have been able to obtain 5.2 W of average power from the 80‐cm‐long closed‐cycle device in which the flow velocity was 30 m∕sec. The electrical efficiency observed in this work was 0.12% which is very close to the estimated maximum obtainable. The output spectrum included components at 2.027, 3.508, and 3.652 μ.

Temperature Dependence of Structure on the I‐V Curves of Superconducting Point Contacts

Marcello Puma and Bascom S. Deaver

Appl. Phys. Lett. 19, 539 (1971); http://dx.doi.org/10.1063/1.1653805 (3 pages) | Cited 6 times

Online Publication Date: 22 October 2003

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In addition to the structure at V=2Δ∕ne (2Δ is the energy gap, n is an integer), we observe prominent structure on the I‐V curves of superconducting point contacts at V≫2Δ∕e. We have studied the temperature dependence of all the structure and find some features vary like Δ(T) and others vary linearly with T4. These variations are interpreted in terms of a simple equivalent circuit model of the point contact and indicate that all of the features for clean point contacts are related to the Josephson Effect.
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