摘要:

First‐order soliton pulses of 77–250 fs duration have been generated in the wavelength region from 1.37 to 1.49 &mgr;m. These solitons are formed by transmitting dye laser pulses at 1.34 &mgr;m of 1 ps duration and peak intensity of ≊0.66 GW/cm2through optical single mode fibers. Soliton narrowing and soliton self‐frequency shift are the dominant shaping mechanisms.

ISSN:0003-6951    

DOI:10.1063/1.97959

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A 248‐nm laser pulse of 35 ns duration was split spatially into two beams: a strong beam used to completely ablate in a single pulse 1000‐ and 5000‐A˚‐thick polyimide films on fused silica substrates, and a weak, time‐delayed probe beam directed almost perpendicularly onto the sample through the ablated fragments in order to measure their transmission versus time. When ablating the 1000‐A˚‐thick film at 1.1 J/cm2, a weak attenuation of the probe beam with a maximum value of 10–12% was observed during the laser pulse. Ablation of the 5000‐A˚‐thick film at 4.2 J/cm2showed a strong attenuation of 83% which lasted for 90 ns from the beginning of the ablating laser pulse and then dropped to 50% at 130 ns. These results indicate increased attenuation of the laser beam as the laser fluence increases, thus explaining the reduced ablation efficiency at high fluences.

ISSN:0003-6951    

DOI:10.1063/1.97960

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Room‐temperature continuous‐wave (cw) operation of a GaInP/AlGaInP multiquantum well (MQW) laser was achieved for the first time. The threshold current was 70 mA at 22 °C for a device with an 8‐&mgr;m‐wide and a 250‐&mgr;m‐long planar stripe. The emission wavelength was 668 nm. The characteristic temperatureT0was 138 K under cw operation. The wafer with the MQW structure composed of 100‐A˚‐thick GaInP wells and 40‐A˚‐thick AlGaInP barrier layers was grown by atmospheric pressure metalorganic chemical vapor deposition.

ISSN:0003-6951    

DOI:10.1063/1.97961

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We show that large changes are introduced into the operational characteristics of nonlinear directional couplers by both loss and saturation of the nonlinearity, especially the latter. Specific numerical examples are given.

ISSN:0003-6951    

DOI:10.1063/1.97962

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The polarization dependence of the gain/current relation and threshold current of quasi‐index‐guided laser diodes is analyzed for the case of &lgr;=1.3 &mgr;m InGaAsP‐InP ridge‐waveguide lasers. Thereby it is shown that three different regimes for the stripe width and the lateral effective index discontinuity can be distinguished where one modal polarization (TE or TM) predominates. The significance of this finding on laser design and polarization control is discussed, and a comparison is performed on experimental results.

ISSN:0003-6951    

DOI:10.1063/1.97963

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report on the excimer laser‐induced photoablation of some organosilane polymers utilizing quartz microbalance techniques to monitor the nature of the ablation phenomenon. A fluence threshold for the ablation process is identified beyond which the material removal rate depends nonlinearly on the adsorbed laser fluence. Below this threshold, photo‐oxidation of the polymer is observed as evidenced by mass uptake of the film. Our results suggest that photoablation of the polysilanes studied is a result of a combination of thermal and photochemical processes.

ISSN:0003-6951    

DOI:10.1063/1.97964

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

An optical technique is described which converts multilobed far‐field patterns from in‐phase laser arrays into a single‐lobed pattern. The technique redistributes the output light from the laser array to produce a uniformly illuminated aperture. This filled aperture produces negligible side lobes, and efficiently channels the array power into the main lobe. Experiments performed on a ten‐elementY‐guide laser array show an increase in main lobe power from 51 to 90% of the total array power.

ISSN:0003-6951    

DOI:10.1063/1.98258

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The extension of a previous model using an asymmetrical double‐probe theory is set out to describe rf discharges in the opposite limit of mainly capacitive electrode sheaths. It reasonably agrees with available experimental results for an excitation frequency equal to or greater than 13.56 MHz.

ISSN:0003-6951    

DOI:10.1063/1.97965

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

&agr;‐tungsten films that adhere well to silicon dioxide were deposited using a dc abnormal‐glow discharge through WF6, H2, and Ar. Film resistivities on the order of 30 &mgr;&OHgr; cm and deposition rates as high as 200 A˚/min were obtained without heating the substrate externally. X‐ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy measurements indicate that electron scattering at the grain boundaries has limited the conductivity of the plasma‐deposited films. Tungsten films having resistivities within a factor of two times that of bulk tungsten were produced with a two‐step process utilizing plasma and conventional chemical vapor deposition.

ISSN:0003-6951    

DOI:10.1063/1.97966

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A NaF plasma from a capillary discharge has been imploded with a 1.2‐MA driving current to produce an intense source of sodiumK‐shell x rays. A peak power of 25 GW in a 20‐ns pulse was measured for the sodium He‐&agr; line which can be used as the pump radiation for a Na/Ne XUV laser scheme.

ISSN:0003-6951    

DOI:10.1063/1.97967

出版商:AIP    

年代:1987

数据来源: AIP