摘要:

Maskless plating has been achieved through a new technique that utilizes a cw or pulsed laser, focused onto an electrode in an electroplating bath. In the region of optical absorption on the cathode, plating enhancement rates on the order of 103occur for optical power densities on the order of 104W/cm2. Laser scanning produces a plating pattern along the scanning path. A qualitative theory based on convective mass transport is used to explain the results.

ISSN:0003-6951    

DOI:10.1063/1.91242

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The growth of In1−xGaxAsyP1−ydouble heterostructure (DH) laser material by liquid phase epitaxy (LPE) under near‐equilibrium growth conditions which produce small growth rates is described. Broad‐area threshold current densities for this material are as low as 670 A/cm2for 0.1‐&mgr;m active layers which is the lowest value yet reported for this material system. This value is comparable with the best reported value for LPE Ga1−xAlxAs with a similar refractive index step. For comparison, material grown at higher growth rates using the commonly employed two‐phase and supercooling techniques are found to give consistently higher threshold current densities than those grown under near‐equilibrium conditions in the same LPE system. The spontaneous luminescence observed in window lasers grown by the near‐equilibrium method appears uniform with no evidence of dark absorbing regions which could cause self‐pulsations in the laser output during initial operation.

ISSN:0003-6951    

DOI:10.1063/1.91243

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

By exploring the simple periodic heat‐flux principle of the photoacoustic cell we propose and demonstrate experimentally the usefulness of the photoacoustic cell for studying the ferromagnetic resonance. An interesting feature of this technique is that it offers special advantages over conventional spectroscopic methods used in ferromagnetic resonance because of the simplicity of measurements. An application is made for the case of an iron thin foil.

ISSN:0003-6951    

DOI:10.1063/1.91244

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We report the observation of optical stability for a plane parallel semiconductor crystal which forms a Fabry‐Perot interferometer using only the natural reflectivity of its surfaces. Nonlinear transmission is observed for cw laser intensities above ∼ 100 W/cm2for radiation at 1895 cm−1near the energy gap of InSb at 5 K. The effect is interpreted in terms of a very large intensity‐dependent refractive index giving a 5&lgr;/2 optical thickness change for an intensity of ∼2 kW/cm2. Clear bistability is seen in fifth‐order interference, the first such observation above first order in an intrinsic, one‐element system, in addition to regions exhibiting signal amplification. The same crystal also shows strong modulation of the transmission of one laser beam induced by a second, with real signal gain, thus demonstrating an ’’optical transistor.’’

ISSN:0003-6951    

DOI:10.1063/1.91245

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Coherent amplification of images illuminated by the 632.8‐nm radiation of He‐Ne has been successfully demonstrated using a two‐stage injection‐locked pulsed dye amplifier technique. A gain of three times has been measured using Cresyl Violet 620 and Rhodamine B in ethanol, while maintaining signal bandwidth, relative phase, and direction, over a one‐quarter &mgr;s pulse duration. A space bandwidth product of 500 000 was obtained by incorporation of the image amplifier into an optical image processing system.

ISSN:0003-6951    

DOI:10.1063/1.91246

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Pulse compression has been observed for the spontaneously generated backward Raman wave in Pb vapor pumped by the XeCl laser. A compression factor in excess of 6.7 was observed with a photon efficiency of 42%.

ISSN:0003-6951    

DOI:10.1063/1.91247

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An efficient ac Kerr switch for the transfer of temporal pulse shapes between the visible and infrared spectral regions has been constructed using liquid O2. Employing group velocity matching techniques, this switch, which is applicable throughout the infrared, has ultimate switching speeds of 0.1–0.3 ps.

ISSN:0003-6951    

DOI:10.1063/1.91248

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The treatment of an array of small metal particles as a continuous effective medium is shown to be possible for visible and near infrared frequencies at much larger particle sizes and separations than often supposed. Specific upper limits are evaluated for chromium. Results are based on the strongly correlated model. For this, the usual topology, variation, and attenuation of the field strength over average unit cell dimensions are permissible, provided such variations are characteristic of the effective medium as a whole. As wavelength decreases, the leading contribution to diffuse scattering off such composite films should come from terms proportional to &lgr;−8not the Rayleigh term.

ISSN:0003-6951    

DOI:10.1063/1.91249

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Both ac and dc orange (580 nm) electroluminescence (EL) are reported for thin films of ZnF2 : Mn sandwiched between SiO semi‐insulating films. All layers are formed by vacuum evaporation and no postdeposition annealing is required. Unique power input and efficiency‐vs‐frequency characteristics are observed, in part due to the 0.1‐s lifetime of excited Mn in ZnF2; hysteresis in the brightness‐voltage characteristic occurs. The brightness and power efficiency are found to be, respectively, 10 f L and 0.5% under suitable operating conditions.

ISSN:0003-6951    

DOI:10.1063/1.91240

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Low‐current‐threshold room‐temperature injection GaAs‐AlxGa1−xAs multi‐quantum‐well (MQW) lasers have been prepared by molecular beam epitaxy. Under pulsed current injection, lasing emission attributed to then=1 electron‐to‐light‐hole (1e‐lh) confined‐particle transition was observed at threshold. Above threshold, lasing emission involving then=1 electron‐to‐heavy‐hole transition (1e−hh) became dominant. Single longitudinal mode operation has also been observed for these broad‐area MQW lasers. For heat‐sink temperatures between 8 and 100 °C, the lasing current thresholdIthfor the 1e−hhtransition has an exponential variation with temperature of the formIth∝ exp(T/T0), whereT0=230 °K.

ISSN:0003-6951    

DOI:10.1063/1.91241

出版商:AIP    

年代:1979

数据来源: AIP