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1 May 1971

Volume 18, Issue 9, pp. 365-408


INFLUENCE OF DISCHARGE PROPERTIES ON CO2 LASER GAIN

W. J. Wiegand, M. C. Fowler, and J. A. Benda

Appl. Phys. Lett. 18, 365 (1971); http://dx.doi.org/10.1063/1.1653699 (3 pages) | Cited 8 times

Online Publication Date: 22 October 2003

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The radial variation of small‐signal gain α0 at 10.6 μm was measured in a cylindrical, electrically excited CO2 laser amplifier. The radial‐gain profile changed markedly with increasing current. This was interpreted in terms of the dependence of gain on electron density and gas temperature. A modified Schottky analysis of the positive column was used to characterize the discharge properties. Values of electron density and gas temperature thus obtained were combined with the reported dependence of α0 on these parameters permitting calculation of the radial variation of α0. Comparison of calculated and measured values of α0 yielded good quantitative agreement, indicating that the analytical model accurately represents the features of the important physical phenomena which influence small‐signal gain. These results emphasize the necessity of maintaining a low gas temperature to achieve maximum laser performance.

CANCELLATION OF SLIT‐WIDTH AND DOPPLER BROADENING EFFECTS IN THE SPECTROSCOPY OF FAST ION BEAMS

John O. Stoner and John A. Leavitt

Appl. Phys. Lett. 18, 368 (1971); http://dx.doi.org/10.1063/1.1653700 (2 pages) | Cited 17 times

Online Publication Date: 22 October 2003

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We use the Doppler shift of light emitted by fast ion beams to cancel the broadening introduced by opening the spectrometer entrance slit. Hence, wide slits are used to increase collected flux with minimal increase in recorded linewidth.

TRANSVERSE SPATIAL DIFFUSION OF PHASE‐DISPERSED PULSES

Dae M. Kim, Pradeep L. Shah, and T. A. Rabson

Appl. Phys. Lett. 18, 369 (1971); http://dx.doi.org/10.1063/1.1653701 (2 pages) | Cited 1 time

Online Publication Date: 22 October 2003

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The transverse spatial diffusion of phase‐dispersed pulses is shown to have significant effects on the theoretical limit of the dechirped pulse duration, output‐beam cross section, and its TPF display. The possibility of recovering temporal and spectral contents of pulses from its two‐dimensional TPF is discussed.

LONG‐WAVELENGTH PHOTOEMISSION FROM Ga1 − xInxAs ALLOYS

D. G. Fisher, R. E. Enstrom, and B. F. Williams

Appl. Phys. Lett. 18, 371 (1971); http://dx.doi.org/10.1063/1.1653703 (3 pages) | Cited 15 times

Online Publication Date: 22 October 2003

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We have activated epitaxial layers of vapor‐deposited Ga1−xInxAs alloys in the bandgap range 0.96–1.18 eV with Cs and O2. The Cs☒O was determined to be ∼1 monolayer thick. For each sample the photothreshold energy was approximately equal to the bandgap energy. A long‐wavelength limit of approximately 1.3 μm was determined for valence‐band emission. There was no evidence of an internal barrier which might have decreased this limit. Spectral yield data were analyzed to give a surface escape probability versus bandgap plot.

ON THE DIRECTION OF ELECTROMIGRATION IN THIN SILVER, GOLD, AND COPPER FILMS

R. E. Hummel and R. M. Breitling

Appl. Phys. Lett. 18, 373 (1971); http://dx.doi.org/10.1063/1.1653704 (3 pages) | Cited 21 times

Online Publication Date: 22 October 2003

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Migration of ions in thin silver, copper, and gold films under the influence of a direct current has been found to be directed towards the cathode, contrary to observations in bulk metals. This was concluded from resistance and radioactive tracer measurements as well as scanning electron micrographs. The results can be explained by using the concept that electromigration in thin films is confined to grain boundaries, and the electron concentration in the grain boundary is different from that in the bulk.

FREQUENCY SHIFT AND SUPPRESSION OF ION‐WAVE INSTABILITY BY HIGH‐FREQUENCY ELECTRIC FIELD

S. Aihara and S. Takamura

Appl. Phys. Lett. 18, 375 (1971); http://dx.doi.org/10.1063/1.1653705 (3 pages) | Cited 3 times

Online Publication Date: 22 October 2003

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The frequency of an ion wave decreases in an rf electric field. At the same time strong suppression of the ion‐wave instability occurs. The frequency shift is explained by the additional pressure which is produced by the spatial modulation of the rf field by the ion wave.

SIMULTANEOUS INTRACAVITY FREQUENCY DOUBLING AND MODE LOCKING IN A Nd: YAG LASER

C. B. Hitz and L. M. Osterink

Appl. Phys. Lett. 18, 378 (1971); http://dx.doi.org/10.1063/1.1653706 (3 pages) | Cited 8 times

Online Publication Date: 22 October 2003

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An efficient internally frequency‐doubled mode‐locked Nd:YAG laser has been operated. An interaction between the intracavity harmonic generation and mode locking, which results in a lengthening of the mode‐locked pulse and a corresponding decrease in fundamental circulating power, has been observed with this laser. The laser makes use of an intracavity harmonic mirror to produce 1.5 W of 0.53‐μ power in the output beam. A significant decrease in laser noise is observed when the laser is mode locked.

EXCITATION OF Hg+ 1942 Å IN THE HIGH‐CURRENT—LOW‐PRESSURE DISCHARGE

Peter D. Johnson

Appl. Phys. Lett. 18, 381 (1971); http://dx.doi.org/10.1063/1.1653707 (2 pages) | Cited 4 times

Online Publication Date: 22 October 2003

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The intensity of the 1942‐Å Hg+ ion resonance line in Hg‐inert‐gas discharges has been measured as a function of current density and Hg pressure in the range from 1 to about 15 A∕cm2 and pressure from 10−3 to 0.5 Torr. In the Hg☒Ar discharge the intensity of this line varies as the 1.75 power of the current density, while in Hg☒Kr, the exponent is 2.0. There is evidence for volume recombination which is inhibited when Ar is replaced by Kr.

HIGH‐INTENSITY TUNABLE InSb SPIN‐FLIP RAMAN LASER

R. L. Aggarwal, B. Lax, C. E. Chase, C. R. Pidgeon, D. Limbert, and F. Brown

Appl. Phys. Lett. 18, 383 (1971); http://dx.doi.org/10.1063/1.1653708 (3 pages) | Cited 25 times

Online Publication Date: 22 October 2003

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Stimulated spin‐flip Raman scattering with output peak power as high as ∼ 1 kW has been obtained from n‐type InSb (ne ≃ 2 × 1016 cm−3) pumped with 10.6‐μ radiation from a pulsed high‐pressure CO2 laser. The output is tunable from 11.2 to 12.8 μ with magnetic fields from 25 to 100 kG. The threshold intensity for stimulated scattering has been measured to be as low as 4 × 104 W∕cm2, which is more than one order of magnitude lower than those reported earlier. The high intensity (∼ 1 kW) in the Stokes line excites a second stimulated Stokes line tunable from 12.0 to 14.6 μ with output power of several watts. In addition, a stimulated anti‐Stokes line, tunable from 10.0 to 9.0 μ, with output power of ∼ 30 W has been observed.

ABSORPTION IN CO2 AT 10.6 μ WITH ROTATIONAL LINE OVERLAP

W. H. Christiansen, G. J. Mullaney, and A. Hertzberg

Appl. Phys. Lett. 18, 385 (1971); http://dx.doi.org/10.1063/1.1653709 (3 pages) | Cited 13 times

Online Publication Date: 22 October 2003

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The results of a calculation and measurement of the absorption of 10.6‐μ laser radiation by CO2 at high pressures are described. It is shown that the effect of rotational line overlap becomes significant at pressures slightly greater than 1 atm. At 8 atm, for example, the calculated absorption coefficient is twice that without including line overlap. Measurements, however, indicate a larger effect than is predicted.

EXPERIMENTAL DETERMINATION OF THE CROSS SECTION FOR MULTIPHOTON IONIZATION OF NEON NEAR A RESONANCE

G. Baravian, R. Benattar, J. Bretagne, G. Callede, J. L. Godart, and G. Sultan

Appl. Phys. Lett. 18, 387 (1971); http://dx.doi.org/10.1063/1.1653710 (3 pages) | Cited 10 times

Online Publication Date: 22 October 2003

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We measure the number of charges produced when a laser beam is focused in neon. Taking into account the configuration of the emitted modes we obtain experimental values for the cross section for multiphoton ionization. By varying the energy of the emitted photons, we can compare our results with a single‐mode theory.

EFFECT OF BIAS AND CATHODE BOUNDARY CONDITIONS ON GaAs SPACE‐CHARGE AMPLIFIERS

W. J. Williamson

Appl. Phys. Lett. 18, 389 (1971); http://dx.doi.org/10.1063/1.1653711 (2 pages) | Cited 1 time

Online Publication Date: 22 October 2003

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A simple one‐dimensional model is used to calculate the performance of GaAs traveling‐wave space‐charge amplifiers. It is shown that an inbuilt field at the cathode boundary can have a controlling effect on the device performance. The model gives good agreement with experimental results and indicates optimum preparation and operating conditions.

BaTiO3 FILMS PREPARED BY RF SPUTTERING ONTO InSb OR GaAs

Shosan Iida and Shoei Kataoka

Appl. Phys. Lett. 18, 391 (1971); http://dx.doi.org/10.1063/1.1653712 (2 pages) | Cited 2 times

Online Publication Date: 22 October 2003

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BaTiO3 films were prepared onto InSb or GaAs semiconductor by RF sputtering with a tetrode apparatus at about 300°C. Analysis by x‐ray diffraction patterns shows that the films are of tetragonal structure of BaTiO3. Electrical properties of these films were measured and the Curie point was observed at 120–140°C.

CONVOLUTION AND TIME INVERSION USING PARAMETRIC INTERACTIONS OF ACOUSTIC SURFACE WAVES

M. Luukkala and G. S. Kino

Appl. Phys. Lett. 18, 393 (1971); http://dx.doi.org/10.1063/1.1653713 (2 pages) | Cited 42 times

Online Publication Date: 22 October 2003

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We report on the observation of acoustic convolution, time inversion, and electronically variable delay in real time using 105‐ and 220‐MHz surface acoustic waves in YZ‐cut LiNbO3 delay rods. The time inversion is a special case of correlation, where a short ``pip'' pulse will create a reflection in time for the injected input signal pulse. The conversion losses in the processing were 64–74 dB.

TUNABLE DISTRIBUTED‐FEEDBACK DYE LASER

C. V. Shank, J. E. Bjorkholm, and H. Kogelnik

Appl. Phys. Lett. 18, 395 (1971); http://dx.doi.org/10.1063/1.1653714 (2 pages) | Cited 115 times

Online Publication Date: 22 October 2003

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Efficient broadly tunable dye‐laser action with a narrow line output has been demonstrated with a mirrorless laser system using distributed feedback. The feedback was obtained from a spatial modulation of both gain and index of refraction, induced by pumping a liquid organic dye solution with fringes formed by the interference of two coherent light beams. The device was tunable over 640 Å either by varying the angle between interfering pump beams or the refractive index of the dye solvent. Linewidths less than 0.01 Å were measured and a peak power of 36 kW was observed.

EFFECTS OF THERMALLY DIFFUSED IMPURITIES ON PROPAGATION OF ELASTIC SURFACE WAVES ON THE FERROELECTRIC CERAMICS

K. Toda, K. Takahashi, and K. Okazaki

Appl. Phys. Lett. 18, 396 (1971); http://dx.doi.org/10.1063/1.1653715 (3 pages) | Cited 2 times

Online Publication Date: 22 October 2003

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It is shown that impurities introduced by thermal diffusion can improve propagation properties of surface waves excited on unpolarized ceramic plates using an interdigital arrangement of electrodes. In BaTiO3 ceramics, CO2O3 reduces the attenuation constant of surface waves to one‐half the values obtained with specimens with no added impurities. In the most favorable case, the output voltage due to the surface waves increased by a factor of 3.

EXPERIMENTS ON LIGHT WAVES IN A THIN TAPERED FILM AND A NEW LIGHT‐WAVE COUPLER

P. K. Tien and R. J. Martin

Appl. Phys. Lett. 18, 398 (1971); http://dx.doi.org/10.1063/1.1653716 (4 pages) | Cited 30 times

Online Publication Date: 22 October 2003

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We discuss experiments in an asymmetric optical waveguide which is simply a dielectric film deposited on a substrate. The film has a tapered edge. Near this edge and depending on the angle of incidence, a guided light wave in the film may be totally reflected or it can enter into the substrate as radiation modes. In the latter case, the tapered film edge is used here to couple light energy into or out of the film.

METAL‐DEPENDENT INTERFACE STATES IN THIN MOS STRUCTURES

Samares Kar and Walter E. Dahlke

Appl. Phys. Lett. 18, 401 (1971); http://dx.doi.org/10.1063/1.1653717 (3 pages) | Cited 11 times

Online Publication Date: 22 October 2003

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Admittance measurements of MOS structures with oxide layers 20 to 40 Å thick have been made to determine interface‐state distributions for various metal contacts. These distributions for Au, Cr, Cu, and Mg, exhibiting comparatively sharp characteristic peaks, increase rapidly with decreasing oxide thickness and sample annealing, thus indicating a strong influence of metal diffusion through the oxide on interface‐state formation.

SEMICONDUCTOR LASERS OPERATING CONTINUOUSLY IN THE ``VISIBLE'' AT ROOM TEMPERATURE

B. I. Miller, J. E. Ripper, J. C. Dyment, E. Pinkas, and M. B. Panish

Appl. Phys. Lett. 18, 403 (1971); http://dx.doi.org/10.1063/1.1653718 (3 pages) | Cited 16 times

Online Publication Date: 22 October 2003

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Continuous operation of AlxGa1−xAs☒Aly Ga1−yAs☒AlzGa1−zAs double heterostructure injection lasers at room temperature has been achieved with diodes whose lasing energy was as high as 1.61 eV (7730 Å). This energy was achieved with y = 0.20, and at this energy the far-field radiation pattern was visible. In the pulsed mode, low thresholds have been achieved up to 7450 Å (1.66 eV) using both broad-contact and stripe-geometry lasers. The lasing threshold remains relatively unchanged in the range y = 0 to 0.21.

SIMULTANEOUS MODE LOCKING AND PULSE COUPLING OF THE CO2 LASER

R. G. Eguchi, W. H. Steier, M. M. Mann, and W. B. Lacina

Appl. Phys. Lett. 18, 406 (1971); http://dx.doi.org/10.1063/1.1653719 (3 pages) | Cited 2 times

Online Publication Date: 22 October 2003

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Simultaneous mode locking and pulse coupling of a CO2 laser has been achieved using a single internal GaAs element with electrodes on both the (001) and (110) faces. Coupling of pulses from the laser did not affect the stability of the mode‐locked pulse train. Possible application of the technique to pulse‐code modulation of the CO2 laser is discussed.
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ERRATUM: STIMULATED EMISSION IN A PERIODIC STRUCTURE

H. Kogelnik and C. V. Shank

Appl. Phys. Lett. 18, 408 (1971); http://dx.doi.org/10.1063/1.1653720 (1 page)

Online Publication Date: 22 October 2003

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