摘要:

The vertical energy flux density for the electromagnetic fields near the surface of a silver strip on a glass substrate is computed for an incident plane wave to aid in the measurement of the width of the strip. The dimensions of the strip cross section, e.g., 300 nm by 100 nm, are a fraction of the wavelength of the incident light , 632.8 nm. The flux 1 nm above the surface shows sharp spikes at the edges of the strip. The features of the fields near the surface could be used for accurate determination of the width of the strip by measurements up to about 30 nm above the strip. The effects of other variables are also shown in the figures.

ISSN:0003-6951    

DOI:10.1063/1.98295

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Pulsed photothermal radiometry (PPTR) has been used to analyze depth profile of layered materials, including biological tissue. An analytic theory for the time dependence of the PPTR signal has been developed and compared with experimental results on inert materials and living human skin.

ISSN:0003-6951    

DOI:10.1063/1.98985

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Reduced KNbO3crystals are shown to have the fastest photorefractive response times for applications in the visible wavelength region. Grating build‐up times at cw illumination in the microsecond region are reported which allow the use of such crystals for real‐time applications. The reduction treatment and a new method for the investigation of the photorefractive homogeneity during reduction are presented.

ISSN:0003-6951    

DOI:10.1063/1.98296

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Distributed feedback lasers emitting in a stable dynamic single mode at 1.5 &mgr;m wavelength in a temperature range of more than 50 °C have been developed using the so‐called flat‐surface buried heterostructure. Threshold currents as low as 14 mA in cw (8 mA in pulse) operating and output powers as high as 20 mW/facet were obtained. By detuning the Bragg wavelength to the shorter wavelength side of the gain peak, and by reducing the confinement factor, a wavelength chirp as a function of modulation current as low as 0.003 nm/mA has been obtained. This value corresponds to a total chirp of 0.1–0.2 nm under normal modulation conditions.

ISSN:0003-6951    

DOI:10.1063/1.98977

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Pulsed photothermal radiometry relies on the flash heating of a surface and the detection of the time dependence of the surface cooling by infrared radiometry. We show that this is useful as a nondestructive and noncontact technique to quantify the thermal conductivity of a subsurface epoxy bond underneath an opaque surface. The degree of curing of the epoxy can also be monitored.

ISSN:0003-6951    

DOI:10.1063/1.98955

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Super‐resolution imaging at optical wavelengths has been achieved with collection mode near‐field scanning optical microscopy. Reproducible images of 0.25‐&mgr;m aluminum lines separated by 0.25 &mgr;m have been generated with a peak edge sharpness of 0.07 &mgr;m. Images taken with differing probe sizes and at various heights demonstrate that the smallest resolvable features are roughly determined by the greater of the aperture size and the aperture to sample separation.

ISSN:0003-6951    

DOI:10.1063/1.98956

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Deflection of a diode laser beam using an injection‐type deflector monolithically integrated with a very long waveguide is demonstrated. The deflector and the waveguide constitute a laser cavity. The waveguide filters out higher order modes, and only the fundamental‐mode light is incident on the deflector. Because the incident light is of a fixed single mode, the deflection of the output beam is very smooth. The deflection mechanism is primarily due to interference between constituent modes for short deflectors, and phase‐front tilting of each mode for long deflectors.

ISSN:0003-6951    

DOI:10.1063/1.98957

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Single quantum well, graded refractive index separate confinement heterostucture (SQW GRINSCH) lasers with well thicknesses in the range of 65–480 A˚ have been grown by molecular beam epitaxy (MBE) on (100) and off of (100) by 4° toward (111)Asubstrates. The threshold current density appears to be independent of the well thickness in the range of 65–165 A˚ due to the compensating effects of volume of inversion and optical confinement. Under optimum growth conditions, the tilted substrates led to lower threshold current densities, the lowest value being 93 A/cm2for a 520‐&mgr;m‐long cavity laser with a 125‐A˚‐thick well. To our knowledge, this is by far the best ever reported threshold current density obtained in a semiconductor injection laser. Deviations from optimum growth conditions drastically increased the threshold current density on (100) substrates whereas the degradation for those on the tilted substrates was much less pronounced.

ISSN:0003-6951    

DOI:10.1063/1.98958

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Utilizing three electrodes and three independent voltages in Ti:LiNbO3directional coupler optical switches, we have achieved significant improvements in switching extinction over the standard uniform &Dgr;&bgr; configuration. The reductions in optical crosstalk vary from 3 to 24 dB for both switching states of several fabricated devices. We have observed a bar state extinction of −47.8 dB, which is the largest extinction ratio reported to date. We find that switching measurements are limited by the largest contrast ratio which can be obtained in the optical waveguides.

ISSN:0003-6951    

DOI:10.1063/1.98959

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Second‐order susceptibility of AlxGa1−xAs/GaAs asymmetric coupled quantum well is calculated. The magnitudes of second‐harmonic and linear electro‐optic coefficients are found to be comparable to that of LiNbO3. Further progress can lead to engineering of novel synthetic nonlinear materials.

ISSN:0003-6951    

DOI:10.1063/1.98960

出版商:AIP    

年代:1987

数据来源: AIP