摘要:

Refractive indices of fluoride glass fibers were measured for the first time and a remarkable decrease in the refractive index during fiber fabrication processes has been observed. This decrease is most likely due to the change in the glass structure during fiber drawing and due to the stress induced during preform fabrication processes.

ISSN:0003-6951    

DOI:10.1063/1.102831

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A method for enhancing guided‐wave second‐harmonic generation (SHG) phase matched by a Cerenkov radiation scheme by means of tailoring the transverse (ydirection) nonlinear susceptibility profile in the waveguide channel is proposed. Specifically, linear and domain‐inverted (poled) channels embedded in a nonlinear substrate are considered, and the SHG efficiency for each structure is compared with that for the conventional nonlinear channel without domain inversion. Through electromagnetic field analysis, a significant enhancement of SHG is demonstrated, particularly with the domain inverted channel.

ISSN:0003-6951    

DOI:10.1063/1.102832

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A polarization‐independent acoustically tunable optical filter is described, with 1.3 nm bandwidth and 145 nm tuning range demonstrated about a center wavelength of 1525 nm. Filtered and unfiltered beams exit from different ports of this 2×2 integrated‐optic structure fabricated on a LiNbO3substrate. The filter conversion efficiency was 97% for unpolarized light, limited by imperfect splitting of the directional‐coupler polarizing beamsplitters. Using an unpolarized, 105‐nm‐wide light‐emitting diode as the optical source, 16 dB isolation of the filtered port was achieved, both with respect to the nearest nulls and the remote background spectrum.

ISSN:0003-6951    

DOI:10.1063/1.102833

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the results of measurements of the electrically induced refractive index change caused by the free‐carrier effect in a silicon Schottky diode. We find that for the wavelength &lgr;=1.3 &mgr;m, the real part of the refractive index changes by as much as ‖&Dgr;n‖∼0.01 for current densities less than 1 A/cm2. This refractive index change produced changes in the input‐coupling efficiency as large as 75% in our sample geometry.

ISSN:0003-6951    

DOI:10.1063/1.102834

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We show numerically that solitary waves, localized in two transverse dimensions, are emitted when a high‐power Gaussian beam is launched into a slab waveguide in which the cladding displays a saturable self‐focusing nonlinearity.

ISSN:0003-6951    

DOI:10.1063/1.102835

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the first observation of optical nonlinearities due to subband structures in the growth direction of ann‐type superlattice by four‐wave mixing in an end‐firing configuration. We observe a nearly eightfold increase in the third‐order optical susceptibility when the electric fields of the CO2laser are changed from a parallel to a perpendicular orientation to the plane of an Al0.08In0.92Sb/InSb superlattice. No change is observed in a control InSb epilayer under similar conditions.

ISSN:0003-6951    

DOI:10.1063/1.102836

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the performance of a 970 nm strained‐layer InGaAs/GaAlAs quantum well laser and its application for pumping Er‐doped optical fiber amplifiers. The laser was grown by molecular beam epitaxy and has three In0.2Ga0.8As/GaAs quantum wells. For a 5‐&mgr;m‐wide and 400‐&mgr;m‐long ridge‐waveguide laser, a cw threshold current of 20 mA and an external quantum efficiency of 0.28 mW/mA per facet were obtained. Maximum output power exceeds 32 mW/facet. With antireflection coating, even higher external quantum efficiency (0.40 mW/mA) was achieved, and more than 20 mW of power was coupled into a single mode fiber. Preliminary experiments of pumping the Er‐doped fiber amplifier gave 15 dB of gain at 1.555 &mgr;m for a pump power of 14 mW into the Er fiber.

ISSN:0003-6951    

DOI:10.1063/1.102837

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have observed lateral electronic beam steering of light emitted by monolithic, two‐dimensional, grating‐surface‐emitting, mutually injection coupled arrays of diode lasers in the AlGaAs/GaAs system. Positionally staggered Y‐branch subarrays are optically connected through pumped waveguides which provide the required phase shift. These observations taken in conjunction with previously reported work on steering such arrays in the longitudinal direction now demonstrate, for the first time, monolithic, two‐dimensional‐coherent‐diode‐laser arrays that may be electronically steered in two orthogonal directions.

ISSN:0003-6951    

DOI:10.1063/1.102838

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A novel method for wavelength‐selective demultiplexing photodetection, making use of an extremely abrupt absorption edge of the optical bistability, has been proposed. As a demonstration of the principle, experimental data are presented on the dual‐wavelength selectivity of ann‐i‐p‐i‐nphotodetector with two intrinsic detection regions composed of GaAs/AlAs multiple quantum wells.

ISSN:0003-6951    

DOI:10.1063/1.103178

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A laser pulse, when focused on a metal sample, produces characteristic elastic waveforms, which depend on whether thermoelastic or ablative/evaporative mechanisms dominate the generation process. In the thermoelastic regime, with an unconstrained surface, the predominant axial displacement is opposite to the direction of propagation (negative), but there is typically a small transient positive displacement. This precursor is not predicted by elastic point source models, but is predicted by models including thermal diffusion. A recent formulation of pulsed photoacoustic generation is used to show how the precursor arises from interaction of the thermal and elastic modes at the illuminated surface.

ISSN:0003-6951    

DOI:10.1063/1.102839

出版商:AIP    

年代:1990

数据来源: AIP