摘要:

Fabrication and characteristics of broader spectral width 1.3 &mgr;m and 1.5 &mgr;m InGaAsP superluminescent diodes having a novel stacked active layer (STAC‐SLDs) structure are reported. The emission spectral width is successfully broadened as much as twice that of conventional SLDs, yielding spectral widths of 80 and 140 nm for the 1.3 &mgr;m and the 1.5 &mgr;m SLD, respectively.

ISSN:0003-6951    

DOI:10.1063/1.102571

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Singe‐mode optical waveguides have been fabricated with a saturated bromine water etchant using single‐heterostructure GaAs/AlGaAs epitaxial material, with propagation losses as low as 0.6 dB/cm for 1.66 &mgr;m deeply etched ribs (&Dgr;neff&bartil;2.4) and losses below 0.2 dB/cm for 0.23 &mgr;m shallowly etched ribs (&Dgr;neff=0.0067), measured at &lgr;=1.5 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.102572

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

All‐optical modulation is observed at room temperature in a GaAs/AlGaAs multiple quantum well nonlinear directional coupler using femtosecond pulses. The origin of the ultrafast (<500 fs) recovery of the device is attributed to the optical Stark effect.

ISSN:0003-6951    

DOI:10.1063/1.102573

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Efficient CO2laser drilling of copper sheet has been obtained following pretreatment with excimer laser radiation at intensities of (1–2)×106W cm−2. The present studies show a significant reduction in the laser pulse energy, pulse duration, and gas assist parameters required to drill copper sheets with thicknesses of up to 1 mm. Optimization of laser drilling under these conditions involves a material removal regime that differs from that obtained at high laser intensity when drilling untreated surfaces.

ISSN:0003-6951    

DOI:10.1063/1.102574

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We describe a new type of transmission mode spatial light modulator (SLM) using a photoconductive Bi12SiO20crystal and a polymer‐dispersed liquid crystal (PDLC) composed of microdroplets of nematic liquid crystal of nonspherical shape randomly dispersed in polymer matrix. The SLM using light scattering in the PDLC has several advantages, such as no polarizer, high transmission of readout light, video rate operation, and ease of fabrication. The device, which consists of a 20 &mgr;m PDLC and a 0.5 mm Bi12SiO20crystal, has a limiting resolution of 30 lp/mm and a high uniformity of the readout image.

ISSN:0003-6951    

DOI:10.1063/1.102575

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

An experimental method for determining the transparency current density of semiconductor quantum well lasers is demonstrated in a strained‐layer InGaAs/GaAs single quantum well laser system. The experimental results are then used as a practical guide to the study of ultralow threshold lasers. A threshold current as low as 0.75 mA is observed.

ISSN:0003-6951    

DOI:10.1063/1.102598

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The properties of laser‐driven tantalum photocathodes as an electron emitter for the creation of ultrashort electron bunches and x‐ray pulses are discussed. Despite the smaller quantum efficiency of metals, their inertness, damage threshold, and lifetime compare favorably with semiconductor photocathodes. Using the fourth harmonic of a Nd:YAG laser, currents of over 3 nC per pulse have been achieved which produced x‐ray pulses with a brightness of 6.2×106Cu K&agr; x‐ray photons cm−2 sr−1and a duration of 70 ps, as determined by an x‐ray streak camera.

ISSN:0003-6951    

DOI:10.1063/1.102599

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Nondegenerate four‐wave mixing experiments have been conducted in Al0.2Ga0.8As ridge waveguides, using picosecond laser pulses. Maker fringes due to phase‐matching requirements were clearly observed, and phase‐matched nondegenerate mixing was achieved by utilizing the waveguide geometrical birefringence. Conversion efficiency up to 5×10−3for a coherent interaction length of 3 mm was obtained. The observed third‐order nonlinear susceptibility &khgr;(3)(&ohgr;3=&ohgr;1+&ohgr;1−&ohgr;2) does not display any strong resonances and exhibits a relaxation time shorter than 10 ps. From these measurements it is inferred that ‖&khgr;(3)1111‖≥8×10−11esu, and ‖&khgr;(3)1111/&khgr;(3)2112‖=2.4±0.3 for &ohgr;1and &ohgr;2≊1480 meV/ℏ.

ISSN:0003-6951    

DOI:10.1063/1.102600

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have generated electromagnetic beams from a variety of semiconductors. When a bare semiconductor wafer was illuminated by femtosecond optical pulses, electromagnetic waves radiate from the surface and form collinear diffraction‐limited electromagnetic beams in the inward and outward directions. The amplitude and phase of the radiated field depend on carrier mobility, the strength and polarity of the static internal field at the semiconductor surface.

ISSN:0003-6951    

DOI:10.1063/1.102601

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report successful fabrication of GaAs/Al0.26Ga0.74As double‐heterostructure laser diodes grown on patterned Si substrates by molecular beam epitaxy. The patterned substrates consist of exposed Si stripes with widths ranging from 9 to 70 &mgr;m and surrounded by 900 A˚ of SiN films on both sides. Oxide‐defined contact stripe lasers with stripe widths ranging from 3 to 50 &mgr;m (corresponding to each of the SiN‐defined stripe windows) were fabricated. Reduction of laser threshold current densities compared to similar lasers grown on nonpatterned Si substrates is observed, and is attributed to current confinement effect by the high‐resistivity polycrystalline GaAs/AlGaAs films surrounding the active devices. From the measurements on the longitudinal mode spectrum and far‐field patterns, lateral index guiding is also observed for the 10‐&mgr;m‐wide selective‐area grown laser.

ISSN:0003-6951    

DOI:10.1063/1.102602

出版商:AIP    

年代:1990

数据来源: AIP