摘要:

A novel laser structure in which a terraced substrate laser and a channeled substrate laser are connected is fabricated. The active layer of the composite cavity is twisted in the junction area between the two laser cavities. Internal reflection and polarization change occur in the twisted region. A built‐in refractive index variation is formed by the terraced substrate and the channeled substrate structures. Remarkable characteristics of the laser are a low threshold current of 40 mA, a stable fundamental transverse‐mode and single longitudinal‐mode oscillation, and a wavelength locking over a temperature range of more than 6 °C.

ISSN:0003-6951    

DOI:10.1063/1.94376

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Circular hollow nickel waveguides with an inner germanium layer are fabricated by using a method based on rf sputtering, plating, and etching techniques. Transmission losses less than 0.5 dB are achieved including launching losses for straight waveguides with 1.5 mm&fgr;×1 m at 10.6‐&mgr;m wavelength. Bending losses of the waveguides are also examined.

ISSN:0003-6951    

DOI:10.1063/1.94377

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Transverse second‐order mode oscillations in asymmetrically pumped twin‐stripe lasers are described. Both far‐field patterns and near‐field patterns have two peaks, and a stronger peak appears on the weakly pumped side. The dependence of light intensity in one peak of the far‐field pattern on the current into one stripe shows threshold characteristics. On application of rectangular pulse to one stripe, switching from one peak to the other occurs within 5 ns.

ISSN:0003-6951    

DOI:10.1063/1.94378

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Optically stable, proton‐isolated, gain‐guided (AlGa)As double heterostructure injection lasers are described. A narrow stripe width (3.5 &mgr;m) and a very shallow implantation are employed (1.3 &mgr;m from the active layer); this results in a cosh−2‐like optical mode of ∼9.0‐&mgr;m full width at half‐maximum. The far‐field profiles possess strong sidelobes at high optical output power. The optical material loss coefficient and the antiguiding parameter are derived from the measured far‐field profiles, using the theory of gain guiding. Key parameters in the description of the optical mode distribution are calculated for several values of output power.

ISSN:0003-6951    

DOI:10.1063/1.94379

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Persistent IR spectral holes in KI@B:ReO−4and in RbI@B:ReO−4crystals have been both modulated and erased with 10‐MHz ultrasound. This mechanical modulation of the hole depth leads to a new phase‐insensitive optical detector for ultrasonic waves in solids.

ISSN:0003-6951    

DOI:10.1063/1.94380

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Free‐falling spheres, released by a simple mechanism, are used as laser targets. Hot‐electron energy transport upon one‐sided irradiation with 300‐ps iodine laser pulses (6×1015W cm−2) is studied by various methods, including x‐ray pinhole photography and time‐resolved shadowgraphy. Spatial energy deposition is consistent with hot‐electron spreading in the presence of self‐generated magnetic fields, as suggested by recent experiments and simulations. The insensitivity of the results to the presence of a supporting stalk is attributed to inductive decoupling of the target. Free‐falling targets open the possibility of highly symmetric implosion experiments.

ISSN:0003-6951    

DOI:10.1063/1.94381

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Spatially resolved FeK&agr; spectra in the wavelength range of 1.7–2.0 A˚ (FeII‐XXVI) and 1.91–1.95 A˚ (FeII‐XIX) are first observed in a single shot with low‐resolution Johansson and high‐resolution Johann type crystal spectrometers, respectively. The spectra show the evident proof that the vacuum spark plasma has two different structures. One is a thermalized point plasma (≲10 &mgr;m) with high temperature (Te∼2 keV) and high density (ne∼1021cm−3). The spectrum contains x‐ray lines from FeXXIII‐XXVI. The other is an extended plasma (∼3 mm) associated with nonthermal electrons, where the region of intense emission ofK&agr; lines from FeIII‐XX shifts toward the cathode with the increase of the ionic charge.

ISSN:0003-6951    

DOI:10.1063/1.94382

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

It is demonstrated theoretically and confirmed experimentally that the intrinsic spatial resolution of a thermal wave microscope in the extreme near field limit is independent of thermal wavelength and is determined by the depth of the thermal scatterer beneath the surface of the specimen.

ISSN:0003-6951    

DOI:10.1063/1.94383

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The kinetics of the supersaturation of self‐interstitials during the thermal oxidation of silicon is reexamined by considering a finite diffusivity of these interstitials. The rate of interstitial generation is assumed to be proportional to the rate of oxidation, and the rate of surface annihilation is assumed to be a first order reaction. The result from an analytical solution shows that within a reasonable oxidation time span, a suitable power‐law kinetics is obtained, with an exponent that falls within the range of most of the reported experimental values.

ISSN:0003-6951    

DOI:10.1063/1.94384

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The transient Kapitza resistance between copper and helium II caused by a step input in power has been studied near 2 K. The resistance is affected by formation of a helium I layer whose thickness, of the order 10−4–10−5cm, is evaluated as a function of the heat flux density.

ISSN:0003-6951    

DOI:10.1063/1.94385

出版商:AIP    

年代:1983

数据来源: AIP