摘要:

The study of the interplay of coherent and Raman effects on femtosecond soliton collapse and pulse train generation in erbium‐doped fiber amplifiers is examined.

ISSN:0003-6951    

DOI:10.1063/1.106206

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The first observation of subnanosecond spectral hole burning is reported in tetraphenylporphine/p‐benzoquinone embedded in poly(methylmethacrylate) at liquid‐helium temperature. The hole formation mechanism is photoinduced one‐photon donor‐acceptor electron transfer, and is consistent with the mechanism predicted by the reaction exothermicity accompanying the reaction. Spectral holes burnt in the present system disappeared almost completely when the temperature was increased to 20 K.

ISSN:0003-6951    

DOI:10.1063/1.106207

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

In this letter, we describe second harmonic conversion in cubic silicon carbide (&bgr;‐SiC) at a wavelength of 1.06 &mgr;m. Epitaxial layers of &bgr;‐SiC formed by vapor phase growth on silicon are indeed birefringent, and thus phase matchable. Phase matched films of &bgr;‐SiC have respectable conversion efficiencies even in the presence of adsorption at 532 nm. Our measured value of the effective second order nonlinear susceptibility for &bgr;‐SiC is &khgr;(2)eff=1.05±0.3×10−9esu.

ISSN:0003-6951    

DOI:10.1063/1.106208

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The pneumatic infrared detector [M. J. E. Golay, Rev. Sci. Instrum.18, 347 (1947)] uses thermal expansion of a gas to detect infrared radiation. We have designed a detector based on this principle, but which is constructed entirely from micromachined silicon, and uses an electron tunneling displacement transducer to detect the expansion of the gas. The design, fabrication, and characterization of the first prototype sensor are described. Its sensitivity is competitive with the best available uncooled infrared detectors.

ISSN:0003-6951    

DOI:10.1063/1.106209

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We demonstrate a monolithically integrated waveguide polarization diversity photodector on InP with total length below 210 &mgr;m. High quantum efficiency (87% TE) and extinction ratios of 10.6 dB (TE) and 16 dB (TM) are achieved at 1.5 &mgr;m wavelength with simple fabrication processes. The device employs extremely short (21 and 31 &mgr;m) waveguide photodiodes that are suitable for high bandwidth operation.

ISSN:0003-6951    

DOI:10.1063/1.106210

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

It is found that the TiO2ultrafine particles (UFP) coated with a layer of stearic acid radicals had a significant red shift of their absorption band edge and clear photoluminescence at room temperature (RT), which are in contrast with that of bulk TiO2and naked TiO2UFP. It was concluded that these results are related to the self‐trapped exciton absorption due to the interfacial dipole layer of stearic acid radicals on the TiO2UFP surface.

ISSN:0003-6951    

DOI:10.1063/1.106211

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have produced AlxGa1−xAs‐AlAs quantum wellp‐i‐ndiode electroabsorption modulators withxas high as 0.56. Even though the material is indirect in momentum space, strong excitonic absorption exists at the direct band gap which can be modulated with an applied field. Forx=0.33, 0.43 and 0.56, we measure relative transmission changes (&Dgr;T/T0, in a surface‐normal configuration) of 62%, 51%, and 23%, respectively, at wavelengths of 677, 622, and 575 nm for 15 V bias with the intrinsic layer being 0.6 &mgr;m thick.

ISSN:0003-6951    

DOI:10.1063/1.106212

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We present results on the operation of a high sensitivity semi‐insulating multiple quantum well device for optical image processing. This device operates in the visible spectrum using II‐VI CdZnTe/ZnTe multiple quantum well structures. Incident light creates charge carriers that screen an applied ac electric field modulating the absorption and refractive index of the structure through the quantum confined Stark effect. In this way, an incident intensity pattern is recorded as an absorption and refractive index variation. The semi‐insulating nature of the material eliminates the need for pixelation. In a wave‐mixing experiment, a peak diffraction efficiency of 0.25% was observed from 2.25 &mgr;m active layer of the device. Two‐beam‐coupling gain coefficients of ∼500 cm−1at wavelengths longer than the exciton absorption peak should be possible.

ISSN:0003-6951    

DOI:10.1063/1.106417

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We present a model for the dynamic response of quantum well lasers which shows that the carrier transport across the separate confinement heterostructure region and the barriers can be critical in determining the modulation bandwidth. We also show that, depending on the particular quantum well laser structure, a large part of the experimentally measured reduction in modulation bandwidth is due to transport factors.

ISSN:0003-6951    

DOI:10.1063/1.106213

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Intense photostimulated luminescence (PSL) is observed, for the first time, in x‐irradiated NaCl:Cu single crystals. The intensity of PSL with a peak at 353 nm is linearly increased with increasing x‐ray absorbed dose over the wide range. This suggests that NaCl:Cu is useful as a material for two‐dimensional x‐ray imaging sensors in computed radiography utilizing PSL phenomenon. All the results obtained are consistent with the proposed emission mechanism of 353 nm PSL peak, based on the recombination of electrons released from theFcenters with Cu2+ions.

ISSN:0003-6951    

DOI:10.1063/1.106214

出版商:AIP    

年代:1991

数据来源: AIP