摘要:

We consider the evolution of the electrons’ phase‐space distribution as they move through the interaction region in a free‐electron laser.

ISSN:0021-8979    

DOI:10.1063/1.325977

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Infrared absorption by acetylene and diesel smoke particles was measured using a differential optoacoustic cell driven by a 3.4‐W CO2laser. Real‐time particle mass concentration measurements are demonstrated. In addition we found the average particle extinction cross sections per unit mass of acetylene and diesel smoke were 0.94±0.1 m2/g and 0.83±0.2 m2/g, respectively, at the 10.6‐&mgr;m wavelength.

ISSN:0021-8979    

DOI:10.1063/1.325978

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An undoped Ge photocapacitive detector is reported which has peak normalized detectivitiesD*&lgr;at wavelengh 1.4 &mgr;m and chopping frequencies 13–103Hz of 9×1012, 1×1012, 4×109cm Hz1/2/W, operating respectively at temperatures 77, 195, and 295 °K. The observed temperature, spectral, and frequency response of the signal and noise are explained in terms of the measured space charge and interface state properties of the device.

ISSN:0021-8979    

DOI:10.1063/1.325979

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Proton‐induced x‐ray emission (PIXE) was used to measure the sputtering yields of thin films bombarded by 1.0 keV Ar+at normal incidence. The films consisted of vacuum‐evaporated iron, chromium, and an Fe‐Cr alloy. An integral approximation to the theoretical x‐ray yield equation was developed that resulted in the determination of the thicknesses of the thin films. In general, this appoximation can be used to measure film thicknesses up to several hundred nanometers. The sputtering yields were determined by measuring the slope of the straight‐line fit to the experimental data which was obtained as film thickness versus accumulated sputtering charge. The chromium sputtering yield, measured by PIXE for a chromium film evaporated onto an electropolished iron substrate, agreed within 5% of that obtained using an energy‐dispersive x‐ray analyzer attached to an SEM. The sputtering yields measured for iron and chromium films with initial thicknesses between 5×1017and 9×1017atoms/cm2deposited onto a nickel substrate wereS(Fe) =1.23 atoms/ion andS(Cr) =0.93 atoms/ion. The agreement with previously published data forS(Fe) is good; no published data onS(Cr) are known. Using recently derived values for the nuclear stopping power, the measured iron and chromium sputtering yields agree well with Sigmund’s theory. The total sputtering yield obtained for an Fe‐35Cr alloy was 1.17 atoms/ion, and the elemental sputtering yields for the alloy were in the ratio of their concentrations. The advantages of using the PIXE technique over other techniques currently being used, particularly for compounds, are discussed.

ISSN:0021-8979    

DOI:10.1063/1.325980

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The use of rotational Raman scattering for nondestructive analysis of laser fusion microsphere targets is reported. Typical hollow‐glass‐microsphere sample characteristics are 100 &mgr;m in diameter, 1.0 &mgr;m in glass wall thickness, and 0.5 nl in volume, containing a mixture of hydrogen, deuterium, and tritium gases at pressures of 10–70 atm (total gas sample weights of 5 ng). Relative species mole fraction measurements for all hydrogen isotope species are determined from spectral peak height analysis of rotational Raman spectra. Accuracies of ±0.01 (mole fraction) are obtained from spectra requiring 20 min scan time. Individual species detectability limits are less than 100 picogram. Absolute partial pressure measurements (accurate to ±20%) are obtained using calibration spheres of known diameter and pressure.

ISSN:0021-8979    

DOI:10.1063/1.325981

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Ion implantation is an attractive method for writing optical circuits for use in integrated optics. In LiNbO3it is shown that there are large changes produced in both refractive indicesn0andneby the energy deposited in nuclear collisions between the implanted ions and the lattice. The process is insensitive to ion species and at 300 K a universal curve exists for the decrease ofn0as a function of deposited energy by nuclear collisions. Saturation changes of −6% occur at 300 °K, and larger values are noted for 77 K implants. The saturation condition is reached after the deposition of ∼1022keV cm−3from the ion beams. Because the indices are reduced, ion beams have been used to write low index boundaries to define waveguiding regions. By using energetic light ions (e.g., 2‐MeV He+) negligible change is produced in the surface layer where the energy loss is primarily electronic and thus the low index region is formed deep within the solid. The computed and measured mode characteristics are in good agreement. The guides show complex annealing characteristics but absorption losses are negligible after annealing at 200 °C. Guiding action exists after heat treatments up to some 400 °C. The surface layers retain crystallinity and electro‐optic properties; as a demonstration of this we report results from three‐dimensional modulators formed by helium‐ion implantation.

ISSN:0021-8979    

DOI:10.1063/1.325982

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Phase‐matched second‐harmonic generation has been achieved in twinned as‐grown ribbon ’’whiskers’’ of GaP about 50 &mgr;m wide and of submicrometer thicknesses. These naturally occurring slab waveguides were pumped with a Nd : YAG laser at a wavelength of 1.064 &mgr;m, and the second‐harmonic output was observed as greenlight at 0.532 &mgr;m wavelength. Experiments concerning the second‐harmonic generation are described, and the results are related to those expected from the crystallography of, and the modal dispersion in, the slab‐waveguide ribbons.

ISSN:0021-8979    

DOI:10.1063/1.325964

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Photoluminescence degradation observed in room‐temperature‐lifetested GaAs/GaAlAs DH stripe lasers has been correlated with the strain field induced in the devices by the stripe‐defining oxide. A degradation mechanism based on strain‐ and nonradiative‐recombination‐enhanced point‐defect migration is proposed.

ISSN:0021-8979    

DOI:10.1063/1.325965

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A new phase detector, which uses an acousto‐optic modulation and optical heterodyne technique, has been developed. The minimum detectable phase difference is 4 °, with a temporal response of 10 &mgr;sec and a spatial resolution of 0.14 mm. This phase detector was used to measure fluctuations in the wave front of a cw HF chemical laser beam caused by mechanical vibration, medium turbulence, and gain variation. Potential applications are laser beam quality measurement, beam steering measurement, and sensing for an active resonator.

ISSN:0021-8979    

DOI:10.1063/1.325966

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Plasmas produced with focused 10.6‐&mgr;m radiation from a high‐pressure pulsed CO2laser have been used to initiate a number of neutral‐gas recombination lasers. The results have implications for the future development of high‐efficiency lasers in the near infrared.

ISSN:0021-8979    

DOI:10.1063/1.325967

出版商:AIP    

年代:1979

数据来源: AIP