摘要:

We have investigated formation of Ge-related defects in aGeO2–SiO2glass fiber preformed by poling with ArF laser excitation. Electric field dependence of the induced-defect concentrations was measured by means of the optical absorption. Several color centers such as the germanium electron-trapped centers and the GeE′center were induced. Concentrations of the induced germanium electron-trapped centers and GeE′center increase with increasing the electric field. Conversion efficiency from the germanium electron-trapped centers to the GeE′center was found to be independent of the electric field. The present result strongly suggests that the poling with ArF laser excitation is effective in the presentGeO2–SiO2glass for the formation of germanium electron-trapped centers. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119749

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have studied laser-induced-fluorescence (LIF) spectra of SiO+produced by laser ablation of a Si wafer in oxygen ambient gas. Emission from neutral and ionic species of Si atoms and SiO molecules is also studied in the laser-induced plasma plume. The optimum oxygen pressure for the formation of molecular ions is found to be ∼120 mTorr. The rotational temperature of SiO+ions shows rapid thermalization toward room temperature within 20 &mgr;s. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119750

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

There is a great deal of interest in developing &pgr;-conjugated polymeric semiconductor based diode lasers which can yield lasing under electrical excitation. Towards this goal, tunable cavity lasing was achieved in a poly(para-phenylene vinylene) derivative alternating block copolymer, BMPPV, dispersed in an active solid matrix of poly(9-vinylcarbazole), with which this block co-polymer also exhibits strong electroluminescence. The laser operated in the blue region of the spectrum over the range 480 to 510 nm, with an optical efficiency approaching 10&percent;. Linewidth narrowing and a narrowing of the temporal profile are reported. Operating lifetime of the solid-state laser was in excess of 5000 pulses at the same pumping position on the sample. Lasing properties of the same block copolymer in the solution phase were also investigated and the results compared with the solid state laser performance. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119751

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We compute the optical gain of various quantum wells for use in 850 nm lasers. In particular, we investigate compressively strained wells of AlGaInAs, InGaAs, or InGaAsP without any assumptions of the material quality. Reductions of up to 43&percent; in the radiative current and 24&percent; in the sheet carrier density can be expected, compared with GaAs/AlGaAs wells. For the case of vertical-cavity surface-emitting lasers and distributed feedback lasers, compressive strain is particularly attractive in reducing the temperature sensitivity and fabrication tolerances for low threshold and efficient operation. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119708

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Ca, Ag, and Ge atoms quench the photoluminescence (PL) of an organic thin film, tris-(8-hydroxyquinoline) aluminum(Alq3), a model organic material for organic light emitting diodes. The observed PL quenching behavior was similar for all three elements, independent of their metallic nature. Due to strong interactions at theCa/Alq3interface, the quenching was much less effective at submonolayer coverages. We have also observed that proper oxidation of Ca at theCa/Alq3interface can significantly recover the quenched luminescence ofAlq3. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119709

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Guided-mode resonance optical filters are made from thin-film structures which consist of azopolymer films deposited on top of slab waveguides. Surface relief gratings can be optically induced on the azopolymer films. The transmission and reflection spectra as a function of the angle of incidence of the probe beam exhibit very sharp resonance features which correspond to coupling into the waveguide modes. Coupling into the overlying azopolymer film is also observed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119710

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Contradirectional two-wave mixing (CTWM) in Rh-dopedBaTiO3crystal is investigated. The experimental results show that the energy transfer of CTWM has some distinctive characteristics different from forward two-wave mixing. Theoretical analysis of CTWM is presented in good agreement with the experimental observations. Both the experimental and theoretical studies show that the energy transfer direction of CTWM depends not only on the orientation of the crystalcaxis and the sign of the light-induced carriers, but also on the electro-optic coefficients. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119711

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A surface-normal reflective optical modulator for 1.3 &mgr;m wavelength was investigated using the Wannier–Stark effect of an InP/InGaAsP superlattice. Electroabsorption properties of two devices with different miniband widths were compared. A larger extinction ratio was obtained from the modulator with the larger miniband width. The extinction ratio of 3.3 dB was achieved at 28 V. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119712

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Arrays of single-mode optical waveguides, couplers, and interferometers were fabricated from a UV curable prepolymer using microtransfer molding. The coupling between the waveguides was reproducible and consistent across the array and was controlled after fabrication by additional UV exposure. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119713

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We investigate two schemes for wavelength conversion based on the cascading of two successive second order processes in a quasi-phase-matched lithium niobate channel waveguide. Efficient conversion over the full erbium amplifier bandwidth is possible with a single multi-hundred milliwatt pump laser operating around 1.55 &mgr;m. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119714

出版商:AIP    

年代:1997

数据来源: AIP