摘要:

Coherent operation of a monolithic linear array of InGaAsP buried‐heterostructure lasers operating at &lgr;=1.3 &mgr;m has been acheived by means of a spatial filter in an external cavity. An array of mass‐transported InP microlenses was used to collimate the beams of the individual laser elements and couple the laser array output to the external cavity. The coherent array output exhibited a narrow (3.2 mrad), three‐lobe far‐field pattern with ∼65% of the energy concentrated in the central peak.

ISSN:0003-6951    

DOI:10.1063/1.102087

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We describe an all solid‐state (holosteric) laser source which produces subpicosecond pulses at 1.4 &mgr;m. The system consists of a diode laser pumped Nd:YAG laser which is frequency modulated (FM) mode locked andQswitched at 1.32 &mgr;m. In continuous wave operation the laser produces pulses of 19 ps while simultaneousQswitching and mode locking result in 30 ps pulses being contained in aQ‐switched envelope of energy 2.1 &mgr;J. The output of the laser, when passed through a 1 km single‐mode optical fiber, produces a spectrally broad Raman signal with its peak at 1.4 &mgr;m and the overall conversion efficiency at 12%. The pulse duration at 1.4 &mgr;m has been measured to be 280 fs. We believe this is the first time that subpicosecond light pulses have been generated by an all solid‐state laser system.

ISSN:0003-6951    

DOI:10.1063/1.102088

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Data are presented on the efficiency, reliability, and temperature dependence of wavelength and threshold for strained‐layer InxGa1−xAs‐GaAs (x∼0.25, &lgr;>1.06 &mgr;m) separate confinement heterostructure lasers for several thicknesses near the critical thickness. Devices with well thicknesses of 100 A˚ exhibit excellent time‐zero characteristics and reliability, while those with 143 A˚ wells have higher initial thresholds and degrade rapidly.

ISSN:0003-6951    

DOI:10.1063/1.102089

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Sapphire single‐crystal fibers with diameters of 110 &mgr;m and lengths of over 2 m have been grown by the laser‐heated pedestal growth method. The fibers are free of imperfections such as voids and bubbles. The minimum loss of 0.5 dB/m was measured in the near infrared at 1064 nm. Absorption loss at 2936 nm was 0.88 dB/m with a damage threshold higher than 1.2 kJ/cm2for 110‐&mgr;s‐long pulses making tissue ablation feasible with fibers several meters in length.

ISSN:0003-6951    

DOI:10.1063/1.102348

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We demonstrate high‐speed performance of InGaAs barrier‐enhanced metal‐semiconductor‐metal (M‐S‐M) Schottky barrier photodetectors monolithically integrated with double‐heterostructure InP/InGaAsP/InP waveguides. Pulse response widths of 77 ps are recorded, with an associated 3 dB power bandwidth of 1.7 GHz. Photodetectors acting as both ‘‘taps’’ of the waveguided signal and as ‘‘terminal’’ devices were fabricated. These detectors have application in receivers which are integrated with semiconductor waveguides for on‐chip optical signal processing.

ISSN:0003-6951    

DOI:10.1063/1.102073

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The observation of fluorescence from ionic rare‐gas alkali molecules excited by an electron beam is reported. Gas mixtures of argon and xenon with hot vapors of either rubidium or cesium were excited to obtain emission from (XeRb)+at 164 nm and (XeCs)+at 160 nm. The spectral features observed in (XeRb)+are assigned to three upper electronic states.

ISSN:0003-6951    

DOI:10.1063/1.102349

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Insitumass spectral measurements of gas composition at the substrate surface were made during filament‐assisted diamond growth. The input gases were various mixtures of CH4, O2, and H2chosen in order to discern the effects of oxygen addition on diamond formation and growth. The gas phase chemistry was modeled as a one‐dimensional flow reactor, and the measured and calculated species mole fractions were in good agreement. The model was then used to estimate mole fractions of several atomic and radical species which could not be measured. We find that addition of O2has only a small effect on the radical mole fractions. However, O2can reduce the effective initial hydrocarbon mole fraction, which is important because higher quality diamond is grown at a lower initial hydrocarbon mole fraction. Most important, perhaps is that O2addition leads to the formation of sufficient gas phase OH to remove nondiamond (pyrolytic) carbon from the film. Thus, O2addition allows diamond films to be grown under composition and temperature conditions which otherwise would produce largely nondiamond carbon.

ISSN:0003-6951    

DOI:10.1063/1.102350

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

An electrodeposition technique for making multilayered thin films, based on controlled deposition from two different solutions, is described. Ni/NiPxand NiPx/NiPymultilayered thin films with repeat lengths as low as 20 A˚ have been prepared. They show up to three low‐angle x‐ray peaks corresponding to the electron density modulation.

ISSN:0003-6951    

DOI:10.1063/1.102351

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report on the observation of the rapid drift mobility of metallic silver under an applied electric field on the surface of a pyrolitically deposited tin oxide film. Silver dag contacts were applied to the surface of the film which was maintained in air at a temperature of 330 °C under a potential difference of a few volts. Under these conditions metallic silver was seen to migrate across the film forming both fractal and dense packed structures.

ISSN:0003-6951    

DOI:10.1063/1.102074

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

In this letter we report on the use of selective metalorganic vapor phase epitaxy growth as an original tool to alleviate the problem of random formation of microcracks in thick GaAs‐on‐Si heteroepitaxial layers. Through the use of a special mask design including the definition of sharp wedges in the SiO2mask material, the thermally induced stress in the GaAs‐on‐Si layers preferentially relaxes at precisely located sites on the substrate. The influence of mask configuration, wedge shape, wedge orientation, and layer thickness on microcrack formation has been investigated. Results obtained show that small‐area SiO2wedges are useful for the definition of microcrack location, and thus eventually for optoelectronic device processing.

ISSN:0003-6951    

DOI:10.1063/1.102056

出版商:AIP    

年代:1989

数据来源: AIP