摘要:

It is demonstrated that in optical waveguides formed by ion implantation in LiNbO3, the lower modes for the extraordinary index exist in a buried region of enhanced index, and so may be unable to couple with a surface prism. This is because a shallow region of slightly reduced index near to the surface necessitates the tunnelling of power to these ‘‘missing modes.’’ The number of such modes can be inferred from a comparison of data for two different wavelengths, and confirmation of this together with an estimation of their positions may be obtained by surface stripping. By taking them into account it has been possible to model the profile index by using a stepped base to the optical well.

ISSN:0003-6951    

DOI:10.1063/1.101397

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

In‐line spectral filters are designed and realized using the tapering technique to provide additional isolation to the demultiplexing fused fiber couplers. The typical performances obtained are less than 1 dB loss with more than 15 dB isolation in a 40 nm range around the desired wavelengths.

ISSN:0003-6951    

DOI:10.1063/1.100737

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report results of degenerate four‐wave mixing measurements of nonresonant nonlinearities in a variety of high‐index lead and bismuth containing oxide glasses and the chalcogenide As2S3. The third‐order nonlinear susceptibilities of the oxide glasses are found to scale with the heavy metal content. A lead‐bismuth‐gallate glass was identified with a nonresonant &khgr;3equal to 42±7×10−14esu, which is approximately three times larger than that of any glass previously reported.

ISSN:0003-6951    

DOI:10.1063/1.100697

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Phased‐locked operation of a three‐element linear grating‐surface‐emitting laser diode array in the InGaAsP/InP material system is demonstrated. Far‐field patterns and spectra indicate coherence across the length of the array and dynamic wavelength stability due to grating feedback.

ISSN:0003-6951    

DOI:10.1063/1.100698

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We present the design, construction, and test results of a novel microwiggler structure with a periodicity of 2.4 mm for free‐electron laser applications. The experimentally demonstrated tunability of field amplitude provides versatile means for field tapering, optical klystron configurations, improving field uniformity, and electron beam matching at the wiggler entrance.

ISSN:0003-6951    

DOI:10.1063/1.100699

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Studies of a cyclotron autoresonance maser are presented. The measurements are carried out at a frequency of 35 GHz using a mildly relativistic electron beam (1.5 MeV, 260 A) generated by a field emission electron gun followed by an emittance selector that removes the outer, hot electrons. Perpendicular energy is imparted to the electrons by means of a bifilar helical wiggler. Measurements give a small signal gain of 90 dB/m and a saturated power output of 10 MW. The corresponding electronic efficiency is 3%. Computer simulations are also presented.

ISSN:0003-6951    

DOI:10.1063/1.100700

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Using a small electron beam device, we have observed time‐dependent competition among the 1.73, 2.03, 2.63, and 2.65 &mgr;m lines of the xenon laser in a high‐pressure argon buffer. The small‐signal gain and saturation intensity for each of these lines have also been measured. The maximum specific energy output of the laser was 1.7 J/l  and the efficiency was 2.3%.

ISSN:0003-6951    

DOI:10.1063/1.100701

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A new method for the measurement of the density‐radius product (&rgr;R) of laser‐imploded plasmas is presented. Deuterium‐tritium‐hydrogen fuel mixture is used and the spectrum of protons elastically scattered by 14.1 MeV neutrons is measured with nuclear emulsion. The reliability of this method was certified by comparing the inferred &rgr;Rvalue with that from the secondary reaction method in equivalent experimental conditions.

ISSN:0003-6951    

DOI:10.1063/1.100702

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A silicon‐on‐silicon dioxide structure (silicon‐on‐insulator) produced by combined ‘‘van der Waals’’ bonding and laser fusing has been studied by cross‐sectional transmission electron microscopy. Areas in the silicon corresponding to the regions which are locally melted by the laser beam were found to contain a high density of dislocations after fusing. The radius and depth of these defect areas, as observed in the microscope, are compared with a simple analytical model of the laser‐induced melting process.

ISSN:0003-6951    

DOI:10.1063/1.101398

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We present evidence of Si diffusion in 100 A˚ layers of CoSi2grown by room‐temperature codeposition and annealing on Si(111) substrates. By monitoring the intensity of the Co MVVand Si LVVAuger peaks, we find a Si‐rich surface layer after annealing, in agreement with the results of others. We find that this layer can be removed by chemical etching and re‐formed by subsequent annealing. By measuring the intensity of the plasmon energy loss peak associated with the Co L23VVAuger peak, we conclude that the Si must exist on top of the CoSi2and we obtain the effective Si overlayer thickness as a function of annealing temperature by calibrating the plasmon loss data against known overlayer thicknesses on unannealed samples. We find similar results on samples grown both with and without the addition of a 10 A˚ Si cap to prevent pinhole formation in the CoSi2and we have indications that the same type of diffusion occurs also beneath the native oxide layer on samples that have not had the surface Si removed by chemical etching. In all of the samples studied, Si diffusion was observed to be non‐negligible at temperatures on the order of 400 °C, which is well below the point where pinhole formation is first observed. This result suggests that the diffusion does not depend on the presence of observable pinholes as previously thought.

ISSN:0003-6951    

DOI:10.1063/1.101399

出版商:AIP    

年代:1989

数据来源: AIP