摘要:

We investigate normal and anomalous longitudinal mode hops in GaAs/AlGaAs-based distributed Bragg reflector (DBR) lasers; anomalous mode hops are defined as those which move toward shorter wavelengths with increasing temperature, which is unexpected. The two-section DBR lasers discussed in this letter, consisting of a gain section and an unpumped Bragg reflector, typically exhibit one mode hop in a 10 K temperature range. Although the longer wavelength modes are expected to start lasing when raising device temperature, occasional mode hops to a shorter wavelength are seen. We derive a model for temperature-dependent wavelength tuning, with which the overheating of the gain section is described empirically. This model allows an accurate numerical simulation of both kinds of temperature-induced longitudinal mode hops. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119494

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

AlN film with high transmissivity was deposited onto organic photoconductor (OPC) surface and the surface hardness was increased by between 31.9&percent; and 61.5&percent;, and the surface roughness was also decreased. The electrophotographic properties of the OPC coated with AlN film were also improved, thus confirming the suitability of AlN film for enhancing the operating life of OPC. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119495

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Photodarkening is reported in 4-(N,N-diethylamino)-&bgr;-nitrostyrene solutions. The photodarkening is due to the formation of new absorption bands and is thought to be a photochemical effect of the structural changes. In degenerate four-wave mixing, a resonant effect is observed around the new absorption bands but the fast response behavior does not change. After darkening, the excitation spectrum becomes complicated, which implies a multipath decay that may show the fast response in the resonant region. The solvent and concentration dependence of the darkening property is also reported. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119496

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A compact system for high-resolution spectroscopy and quantitative photon flux and brilliance measurements of pulsed soft x-ray sources is described. The calibrated system combines a novel elliptical off-axis reflection zone plate with charge-coupled device detection for simultaneous spectral and spatial measurements. Experiments on a water-window droplet-target laser-plasma source demonstrate &lgr;/&Dgr;&lgr;⩾1000 spectral resolution and absolute flux and brilliance measurements. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119497

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Temperature dependence of self-formed quantum dot lasers with a multi-stacked dot layer has been investigated in detail. Lasers oscillating at different subbands exhibit different behaviors against temperature change both in the spectral characteristics and the threshold current. A discontinuous shift of lasing wavelength from the second subband to the ground state is observed with lowering temperature, which is strongly related to emission efficiency of quantum dots and thermal excitation of carriers to higher-order subbands. High characteristic temperature over 300 K has been achieved in a laser with high-reflection coating on both facets in the temperature range 60–200 K. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120426

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Lateral superlattices in porous silicon layers have been generated. Using the photosensitivity of the etching process, periodic stripes are formed not only on the surface but also in the depth of the layer. The modulation depth depends on the illumination wavelength. The periodicity is obtained from the interference pattern of two laser beams, and can be easily modified by changing the wavelength or the incidence angles of the beams. The samples formed by this procedure were characterized by light diffraction. Two-dimensional structures can also be obtained by rotating the sample or by interference of four laser beams. This kind of in-depth lithography and the resulting low-cost fabrication of gratings out of porous silicon offer a wide range of potential applications in integrated optics and photonics. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119498

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In this letter, we present a novel structure for light amplitude modulation based on a lateralp-i-ndiode combined with a Bragg reflector which transforms the phase shift induced by the plasma dispersion effect in the intrinsic region of the diode into a voltage controlled variation of the reflectivity of the Bragg mirror. Numerical simulations show a modulation depth of 50&percent; achieved in about 12 ns with a power dissipation of 4.0 mW and an insertion loss of 1.0 dB. The device is demonstrated to be very attractive in terms of power dissipation as compared to a Mach–Zehnder interferometer occupying the same area on chip. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119499

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Electrons photoexcited into the normally unoccupied states of vacuum deposited thin films of tris (8-hydroxy quinoline) aluminum (Alq) have been studied with excite-probe harmonic laser photoemission. Both valence and transiently excited empty states are observed. A surface recombination velocity of75±30 cm/shas been determined. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119500

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Distributed-feedback (dfb) laser oscillation is reported inCe3+-dopedLiSrAlF6(LiSAF). Tunable operation of theCe3+:LiSAFdfb laser is achieved in the ultraviolet wavelength region from 289 to 293 nm. At the peak emission wavelength of 290 nm, dfb lasing linewidths are less than the 1 Å resolution limit of the 1 m spectrometer. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119501

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

During the phase of dust nucleation in plasma enhanced chemical vapor deposition systems, nanometer-sized dust particles appear in large concentrations. The dispersion characteristics of dust acoustic waves in such a plasma during the nucleation phase is analyzed. It is shown that the dispersion properties of the dust acoustic wave depend sensitively on the particle size. It is proposed to use dust acoustic waves as a novel particle size diagnostic for nanometer-sized particles. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119502

出版商:AIP    

年代:1997

数据来源: AIP