摘要:

An experimental technique based on frequency-resolved four-wave mixing is proposed for the investigation of phonon-assisted capture of electrons and holes in electrically pumped semiconductor quantum wells. We show how this technique can be used to directly measure the intrinsic capture lifetime, with no need for involved numerical fits. We also present experimental results from an application of the technique to a multiquantum-well semiconductor optical amplifier. The possible impact of phase matching on the results is discussed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120453

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The atomic layer deposition technique has been applied to the growth ofAl2O3thin films on the substrates of Si(100), 100-nm-thickSiO2covered Si(100)[SiO2/Si(100)],and 90-nm-thick TiN coveredSiO2/Si(100).The growth rate ofAl2O3films was 0.19 nm/cycle and identical for all substrates employed under the surface controlled process. However, the optical properties ofAl2O3films were significantly affected by different substrates. The average interband-oscillator energy and refractive index parameter were determined to be 3.330 eV and2.992×10−14 eV m2forAl2O3film grown on Si(100), while those for the film grown onSiO2/Si(100)were 4.492 eV and2.074×10−14 eV m2,respectively. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120454

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A 2.9 &mgr;m diode laser withInAs/GaSb/Ga0.75In0.25Sb/GaSbsuperlattice active region displays a maximum operating temperature of 260 K. At 200 K, the threshold current density is1.1 kA/cm2and the quantum efficiency is>15&percent;.The peak output power per facet exceeds 800 mW at 100 K and 200 mW at 200 K for a 0.05&percent; duty cycle. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120455

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Visible electroluminescence (EL) is observed at room temperature by current injection intoEu:CaF2layers containing 7.5 and 8.0 at. &percent; Eu grown by molecular beam epitaxy on lightly doped (100)p-type silicon. The EL spectra are broad with peaks near 700 and 600 nm, respectively. Room temperature photoluminescence spectra for the same samples exhibited peaks near 420 nm, with higher doped samples showing a more pronounced long wavelength tail. Although both metal and indium–tin–oxide (ITO) contacts were successfully used for current injection, the best EL intensity stability was achieved with contacts made of a 100 Å thick Al layer covered by a 2500 Å thick ITO layer. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120456

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Efficient recording of polarization gratings in dye-doped liquid crystals is reported. By exploiting the effect of light-induced anchoring of the molecular director, it has been possible to write stable holographic gratings with a diffraction efficiency of 8&percent; at a resolution of 1000 lines/mm. The required surface energy density of0.3 J/cm2sets these materials among the most sensitive for optical storage. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120457

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have generated pulses with 11 fs duration, tunable between 500 and 700 nm, using a noncollinear &bgr;-barium borate optical parametric amplifier pumped by the second harmonic of a Ti:sapphire laser. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120458

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A unipolar semiconductor laser emitting in the mid-infrared spectral region is demonstrated. The laser scheme relies on a simple three-level system in GaAs/AlGaAs asymmetric coupled quantum wells. Population inversion between excited states is achieved by optical pumping of electrons from the ground state with aCO2laser. Long-wavelength(≈15.5 &mgr;m)laser emission is demonstrated. The laser is operated in the pulsed regime up to a temperature of 110 K and with an output peak power≈0.4 Wat 77 K. Unipolar quantum well semiconductor lasers based on this principle are capable of covering the long wavelength mid-infrared spectral region above 12 &mgr;m. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120459

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We demonstrate difference frequency generation of 4 &mgr;m radiation from 1 to 1.32 &mgr;m pumps in GaAs-based waveguides. Phase matching is obtained by using form birefringence in selectively oxidized AlGaAs/AlAs multilayers. A tunability over50 cm−1around 4 &mgr;m is demonstrated by changing the waveguide temperature and one pump wavelength. A much larger tunability may be achieved by using two tunable sources. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120460

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Observations in high bandwidth graded-index plastic optical fibers (GI POFs) are reported of strong mode coupling and its characteristic square root-like fiber length dependence of the optical pulse broadening. We have further found that the measured refractive index profile is not parabolic, but consists of two markedly different regions. Analysis of the index profile reveals that strong mode coupling increases the GI POF bandwidth from its profile-determined value of 0.43 GHz to its measured value of 3.0 GHz for 100 m. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120461

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In order to apply scanning near-field optical microscopy to life science, it is essential to have an accurate distance feedback that also works on soft biological samples in liquids. In this letter, we report measurements of neuron cells in aqueous solution using an advanced piezoelectrical shear-force detection setup. Simultaneously obtained topographical and fluorescence images are presented, demonstrating a resolution below 100 nm in the optical image. The influence of the water level on the shear-force signal and the interaction between near-field probe and soft organic samples are discussed. Stable feedback in fluids is obtained with tip–sample interaction forces below 100 pN. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120462

出版商:AIP    

年代:1997

数据来源: AIP