摘要:

Submicrometer optical gratings are produced in a GaAs surface by a laser‐enhanced, wet‐etching process which permits the fabrication of different grating profiles. The etch process was investigated byinsituoptical measurements of the diffracted beams and electron microscopy.

ISSN:0003-6951    

DOI:10.1063/1.94250

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Some of the perovskite oxides such as La0.7Sr0.3CoO3sintered at 1150 °C can have the function, when used as cathode materials in sealed‐off CO2lasers, to improve both output power and operating life. While the output power of the order of 50 W/m has become obtainable in sealed‐off tubes, the longest life observed was 4400 h. It has been shown that this improvement comes from the simultaneous presence of the following properties in some perovskites, of oxygen emissivity, catalytic activity, metallic conductivity, and low sputtering rate.

ISSN:0003-6951    

DOI:10.1063/1.94251

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

An intrinsic absorptive optical bistability is observed in the transmission of high intensity, nanosecond laser pulses through thin CdS platelets at liquid helium temperature. The bistability is due to a renormalization of the band gap which is caused by the formation of an electron hole plasma and occurs in a broad spectral range below the excitonic resonances. The switching times are in the subnanosecond range. The dependence on photon energy is investigated and discussed.

ISSN:0003-6951    

DOI:10.1063/1.94252

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A combined high‐speed analog to digital converter, and optical transmitter, based on the frequency tuning capability of cleaved‐coupled‐cavity semiconductor lasers is proposed and demonstrated. The device, which acts as a level discriminator with optical outputs can either continuously sample the analog input or be strobed at rates up to ∼ 1 Gsamples/s. A four‐level conversion of a 100‐MHz sinusoidal input is shown.

ISSN:0003-6951    

DOI:10.1063/1.94253

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A near‐infrared reflectivity exceeding 60% at 2.5‐&mgr;m wavelength has been observed for a polycrystalline, rf sputter‐deposited electrochromic (EC) WO3film in a deeply colored state. This reflectivity is considerably higher than that previously reported for a thermally evaporated EC‐WO3film that was crystallized by a post‐deposition thermal anneal. The shapes of the x‐ray spectra of the two films are also different. The results of ellipsometry measurements of the optical constants provide convincing evidence for the validity of a free‐electron Drude model to explain the reflectivity modulation observed in polycrystalline EC‐WO3.

ISSN:0003-6951    

DOI:10.1063/1.94254

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A nine‐unit phase‐locked array of index‐guided channel‐substrate‐planar large‐optical‐cavity AlGaAs diode lasers is fabricated by one‐step liquid phase epitaxial growth over a 5‐&mgr;m period sawtooth grating etched into a GaAs substrate. Two‐lobed, 180° phase shift operation is achieved to 75‐mW cw power and to 400‐mW peak pulsed power. Strong coherent optical coupling between the array units provides single‐longitudinal‐mode array operation to 80‐mW cw output power. The cw and pulsed threshold currents are in the 250–400‐mA range. Single‐lobe, 0° phase shift operation, with the single beam peaked at 0°, is achieved to 200‐mW peak power.

ISSN:0003-6951    

DOI:10.1063/1.94239

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

This letter describes the first observations of x‐ray generated ultrasonic signals in materials. The x rays used were the pulsed x‐ray beams of continuous energy spectrum taken from a high‐energy synchrotron source. The ultrasonic signals were detected with conventional piezoelectric transducers attached to stainless steel specimens.

ISSN:0003-6951    

DOI:10.1063/1.94240

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The first spectroscopic measurements ofR′ aggregate color centers contained in polycrystalline LiF hosts are reported. The inhomogeneous and homogeneous widths of the 830‐nm zero phonon line are measured by conventional grating spectroscopy and by photochemical hole burning spectroscopy using a current tuned GaAlAs diode laser with 3‐mW output power. An extensive photochemical hole burning comparison between single and polycrystalline samples is presented.

ISSN:0003-6951    

DOI:10.1063/1.94241

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

During recrystallization of encapsulated silicon films on SiO2, by the graphite strip heater technique, the silicon sometimes breaks apart and agglomerates into small beads or stripes. By secondary ion mass spectroscopy analysis, it was found that a high concentration of nitrogen at the interface between the silicon and the top SiO2capping layer is needed to prevent this from occurring. Incorporation of hydrogen into the crystallization ambient was found to cause the beading to occur. The initial stages of the bead formation were investigated by scanning electron cross‐section microscopy.

ISSN:0003-6951    

DOI:10.1063/1.94242

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A metalorganic chemical vapor deposition process for preparingc‐axis‐oriented ZnO films in a simple system of the type commercially available for SiO2deposition is described. The resulting layers are highly uniform in thickness and adhere to a variety of substrates. Film properties and structure are described briefly.

ISSN:0003-6951    

DOI:10.1063/1.94243

出版商:AIP    

年代:1983

数据来源: AIP