摘要:

Emission dynamics of 1.5 &mgr;m InGaAs/InGaAsP quasi‐quantum wire lasers excited by ultrashort optical pulses were investigated. Wire distributed feedback lasers with different nanometer wire widths and distances between the wires, which were realized by dry‐etching technique, were compared in detail. The dependence of dynamic behavior on wire width was observed. Detailed theoretical simulations show that, the improvement of dynamic response with decrease of wire width is attributed to a superlinear increase of differential gain with decrease of wire width, which counteracts the negative effects due to decrease of packing density of the active region and increase of electron relaxation time.

ISSN:0003-6951    

DOI:10.1063/1.118035

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

An experimental study on the propagation of a sheet electron beam of energy ∼200 keV, current ∼80–250 A, and pulse duration of ∼100–150 ns through a planar five‐period electromagnetic wiggler has been carried out as a part of the development of a pulsed, high‐power mm wave free‐electron laser. Beam focusing is observed for peak wiggler magnetic fields up to 2.5 kG, and enhancements in propagated beam current efficiencies by 40%–65% are found for different values of the initial beam current. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118036

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The third‐order susceptibilities &khgr;(3)(−3&ohgr;:&ohgr;,&ohgr;,&ohgr;) of Langmuir–Blodgett films of a series of octasubstituted metallophthalocyanines have been measured by third‐harmonic generation experiments at 1.064 and 1.904 &mgr;m. For the latter excitation wavelength a marked enhancement of the nonlinearity for the cobalt‐containing compound has been found, and &khgr;(3)values are one order of magnitude larger than for the other systems. The effect has been associated to the role of two‐photon allowed metal (possiblyd−d) transitions in the cobalt derivative. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118037

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The ultrafast non‐linear optical dynamics of C60thin films were investigated at low excitation levels. The pump‐probe response observed at low power is found to differ significantly from the ultrafast non‐exponential behavior observed at higher intensity. It is determined that the ultrafast relaxation processes measured at higher fluence levels are affected by phototransformation of C60. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118038

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The steady‐state additive mode locking of a laser incorporating phase‐mismatched frequency converter in an external cavity is analyzed. The model includes a main cavity with a slowly bleaching lasing transition and a fiber with &khgr;(2)grating, in the form of Fabry‐Pe´rot interferometer. The dependence of the parameters of the spectral‐limited pulse on the laser control parameter is investigated. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118039

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The thermodynamic and photochemical stability of Ga2O3–GaAs interfaces fabricated usinginsitumultiple‐chamber molecular beam epitaxy has been investigated. The Ga2O3films were deposited on clean, atomically ordered (100) GaAs surfaces using a molecular beam of gallium oxide. Thermally induced degradation of electronic interface properties such as interface recombination velocityS(5750±1250 cm/s) and interface state densityDit(mid‐1010cm−2 eV−1range) has not been observed after rapid thermal annealing at 800 °C. Furthermore, no interface degradation has been detected during exposure to high intensity laser light. The preservation of excellent electronic interface properties and the absence of interfacial chemical reactions are attributed to AsxOyand elemental As free Ga2O3–GaAs interfaces. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118040

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A new type of x‐ray interference mirrors using hydrogenated carbon films of various densities is described. The reflection coefficient and resolution of multilayer carbon structures obtained in the soft x‐ray range (1.54–44.7 A˚) are investigated experimentally and theoretically. As is shown, hydrogenated carbon films can be used to create mirrors with high resolution. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118041

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have studied the electroabsorptive properties of symmetrically strained (GaIn)As/Ga(PAs) superlattices consisting of 100 periods. Photocurrent measurements at 4 K reveal a pronounced pseudo‐blue shift and a Wannier–Stark splitting of the heavy‐hole exciton transition. A self‐electro‐optic effect device has been realized which makes use of the pseudo‐blue shift due to the Wannier–Stark localization and of the transparency of the GaAs substrate. The self‐electro‐optic effect devices show on–off contrast ratios of 2.1 at 77 K and of 1.3 at room temperature. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118042

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report the demonstration of a guided‐wave nonlinear process in the material rubidium titanyl arsenate (RTA). Quasi‐phase‐matched frequency doubling of 874.5 nm light was achieved in a Cs:RTA waveguide, with a normalized conversion efficiency of 225%/W cm2. We also report phase matching characteristics for bulk periodically poled RTA. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118043

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Copper–sodium ion‐exchanged glass waveguides are fabricated and characterized. Optical absorption andm‐lines spectroscopy analyses are presented. No stress‐induced birefringence is observed from refractive index profiles reconstruction, and the Cu+oxidation state is shown to mostly determine the refractive index change. Comparison between compositional in‐depth profiles and index profiles is allowed to obtain the variation in the electronic polarizability due to the Cu+–Na+exchange. The diffusion coefficient of Cu+in soda‐lime glass is also calculated. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118044

出版商:AIP    

年代:1996

数据来源: AIP