摘要:

Optical delay times and pulse widths of five Ar:Xe laser lines have been measured as a function of the total gas pressure. Both the delay time and the pulse width appeared to be almost linearly dependent on the inverse gas pressure. For a total gas pressure of 14 bars the delay times were around 100 ns, at a total gas pressure of 1 bar the laser output typically appeared after 1–3 &mgr;s.

ISSN:0003-6951    

DOI:10.1063/1.101005

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Wideband scanning of a light beam through the use of magnetostatic waves has been accomplished for the first time. Specifically, a guided‐light beam at a wavelength of 1.317 &mgr;m in an yttrium iron garnet‐gadolinium gallium garnet waveguide was Bragg diffracted by magnetostatic forward volume waves (MSFVWs) operating at a frequency range of 2–7 GHz. Wideband scanning of the light beam was accomplished simply by changing the frequency of the MSFVW continuously from center frequencies of 2.5 and 6.0 GHz while keeping the dc magnetic field fixed or by continuously tuning the dc magnetic field while keeping the frequency of the MSFVW fixed at the center frequencies. A large number of resolvable scan spot positions were obtained in both cases. The resulting wideband magneto‐optic Bragg cell or light beam scanner was also used to perform spectral analysis of wideband rf signals at a center frequency of 3.2 GHz. Potential advantages of the magneto‐optic Bragg cell and scanner over the existing acousto‐optic counterparts also identified.

ISSN:0003-6951    

DOI:10.1063/1.101006

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

It is shown that noise from light‐scattering fluctuations inherent in an optical Kerr medium sets a lower limit on the incident probe power required to achieve meaningful phase conjugation by four‐wave mixing. For visible wavelengths and room temperatures, we determine that about 10 &mgr;W of probe power is needed to obtain a signal‐to‐noise ratio of unity in the conjugate wave for reflectivities that are less than or near the first oscillation condition.

ISSN:0003-6951    

DOI:10.1063/1.101007

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

It is shown theoretically that optical bistability is possible in a self‐electro‐optic effect device (SEED) with single asymmetric quantum wells because of the blue shift of the optical absorption edge with applied field possible in such structures (in contrast to the normal red shift in symmetric wells). The concept is a simplification of the scheme of J. Khurgin [Appl. Phys. Lett.53, 779 (1988)] (which uses unequal, opposed pairs of asymmetric wells) and shares the potential advantages of lower loss in the transmitting state and less stringent requirements on the exciton absorption peaks.

ISSN:0003-6951    

DOI:10.1063/1.101008

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The spatial mode characteristics of gain‐guided broad‐area quantum well lasers grown by organometallic chemical vapor deposition were investigated experimentally. GaAs/AlGaAs quantum well lasers grown on 6°‐off (100) oriented substrates exhibit excellent material uniformity, which allows study of their modal behavior. Gain‐guided broad‐area lasers fabricated on such uniform material demonstrate nearly ideal gain‐guiding modal behavior. These lasers tend to lase in the fundamental mode near threshold and emit single‐lobed far‐field patterns. In these well‐behaved broad‐area lasers, we have identified the mechanism for degradation in the spatial coherence at high pumping levels as the onset of higher order lateral modes.

ISSN:0003-6951    

DOI:10.1063/1.101009

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

To generate ultrashort pulse train at a high repetition rate, Zn was doped to the active region of distributed‐feedback lasers. Increase in the differential gain and reduction of the carrier lifetime have been confirmed. The 3 dB bandwidth was increased to 16 GHz. The 14 ps single longitudinal mode optical pulse train at a repetition rate of 14 GHz was generated by gain‐switched operation.

ISSN:0003-6951    

DOI:10.1063/1.101010

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The effect on H−production by adding barium to a hydrogen discharge, in a small magnetically filtered multicusp ion source, has been investigated. It is found that the addition of barium can increase the H−output by a factor of 30. A strong dependence of H−output on the temperature of the ion source wall has also been observed.

ISSN:0003-6951    

DOI:10.1063/1.101011

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Novel methods of GaAs surface passivation are investigated. Passivation is acheived by simple chemical treatments using aqueous solutions of Na2S, KOH, RuCl3, and K2Se. GaAspnhomojunction solar cells are used to evaluate the effectiveness of these passivation techniques. A significant reduction in minority‐carrier surface recombination velocity is demonstrated. In the best case, the surface recombination velocity decreased from 5×106cm/s (untreated surface) to 103cm/s. In addition, we observe improvements in solar cell photogenerated current, short wavelength spectral response, open‐circuit voltage, and junction ‘‘dark’’ current.

ISSN:0003-6951    

DOI:10.1063/1.101012

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Amorphic diamond films characterized by a high percentage ofsp3bonds have been prepared in an UHV environment with a laser plasma source of carbon ions. Peak power densities in excess of 1011W/cm2were found necessary to produce films at growth rates of 0.5 &mgr;m/h over areas of 20 cm2having optical quality sufficient to show bright interference colors.

ISSN:0003-6951    

DOI:10.1063/1.101013

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The influence of growth temperature on the interfacial abruptness of strained Ge layers, a few monolayers thick, embedded in Si has been studied using Raman spectroscopy to identify the presence of GeGe and GeSi bonds and medium energy ion scattering to characterize the spatial extent of the layers. Atomically sharp interfaces are observed for growth temperatures just above the crystalline to amorphous transition range, with pseudomorphic growth found for growth temperatures >∼250 °C. Asymmetric mixing of Ge into the Si capping layer occurs during growth at higher temperatures. Significantly less intermixing occurs on annealing after growth, pointing to the role of dynamical processes occurring at the growth front.

ISSN:0003-6951    

DOI:10.1063/1.101014

出版商:AIP    

年代:1989

数据来源: AIP