摘要:

Monolithic integration of a new type of optoelectronic device which functions not only as a lateral‐current‐injection laser but also as a junction field‐effect transistor based on a modulation‐doped heterostructure is proposed and demonstrated for the first time. The static and dynamic modulation characteristics of the integrated device were studied. The dynamicon/offratio of 9 in the light output was observed with the preliminary modulation experiment at the repetition frequency of 50 MHz.

ISSN:0003-6951    

DOI:10.1063/1.105403

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Injection of a weak cw radiation in aQ‐switched AlGaAs laser diode is shown to produce single‐mode pulses with a quasi‐linear downchirp of very large amplitude. Strong pulse compression can be achieved by using single‐mode dispersive fibers at the laser output. Time‐resolved spectroscopic measurements of the laser pulses are presented. Optical solitary pulses shorter than 2 ps are obtained after compression, which corresponds to a pulse compression factor larger than 15. Although the laser‐fiber coupling is not fully optimized, peak powers exceeding 3 W are measured at the fiber output. These performances are believed to be the best ever reported for an electrically pumpedQ‐switched AlGaAs laser diode.

ISSN:0003-6951    

DOI:10.1063/1.105404

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A grating spectrograph in InGaAsP/InP suitable for use in the wavelength region from 1.2 to 1.6 &mgr;m is presented. Experiments for devices with a channel spacing of 3.7 nm and more than 30 channels between 1.48 and 1.59 &mgr;m are described. The measured cross talk level is below −25 dB. The devices have only very low polarization sensitivity. This spectrograph is suited for monolithic integration with photodiodes, laser diodes, or optical amplifiers on a single chip.

ISSN:0003-6951    

DOI:10.1063/1.105405

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The two‐photon absorption coefficient of potassium dihydrogen phosphate at &lgr;=216 nm was measured to be &bgr;=(6.0±0.5)10−10cm/W. The presence of impurities is shown to increase nonlinear losses at very low intensities,I≊107W/cm2.

ISSN:0003-6951    

DOI:10.1063/1.105406

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Monolithic two‐dimensional surface‐emitting arrays of strained‐layer InGaAs/AlGaAs and AlInGaAs/AlGaAs diode lasers have been fabricated and operated pulsed with low‐threshold current densities and differential quantum efficiencies greater than 50%. The InGaAs/AlGaAs arrays emit at 1.03 &mgr;m, while the AlInGaAs/AlGaAs arrays emit at 0.815 &mgr;m. Thus, it should be possible to fabricate monolithic arrays with comparable performance over a wide wavelength range. The individual lasers of the arrays are horizontal folded‐cavity devices with two 45° internal reflectors and two top‐surface facets. The design is simple to implement using optical pattern‐generator masks, optical projection printing, and chlorine ion‐beam‐assisted etching in key fabrication steps.

ISSN:0003-6951    

DOI:10.1063/1.105407

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Ultrafast refractive index dynamics in AlGaAs diode laser amplifiers were studied using 440 fs optical pulses. Refractive index changes consistent with a free carrier heating model proposed to explain earlier studies of gain dynamics in diode lasers are exhibited. We also observe an apparently instantaneous refractive index change that corresponds to ann2⊥of −5×10−12cm2/W.

ISSN:0003-6951    

DOI:10.1063/1.105408

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Particulate contamination (dust) has been observed to accumulate near the sheath‐plasma boundary in both radio‐frequency (rf) and direct‐current (dc) discharges. We have developed and applied a hybrid Monte Carlo‐fluid simulation of electron, ion, and charged dust transport in rf discharges to investigate the dynamics of particulate contamination. The processes governing the transport of charged dust in the model are drift of partially shielded particles in the electric field, collisions with the fill gases, and viscous ion drag arising from Coulomb interactions of particles with ions drifting and diffusing in the plasma. We find that negatively charged dust particles accumulate near the sheath‐plasma boundary, and that transport of the particles is dominated by ion drag.

ISSN:0003-6951    

DOI:10.1063/1.105409

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Transmitted diffraction profiles of a thin Ge 620 crystal at Bragg angles around and including &pgr;/2 were obtained for different crystal temperatures using CoK&agr;1radiation. A grooved crystal monochromator operating at Bragg angles near 89.5°, providing a highly monochromatic beam in the forward direction, is described. Rocking curves widths of 30 arcmin and energy resolution &Dgr;E/E=1.66×10−5were measured. Great sensitivity with crystal temperature and incident wavelength were observed. An intensity enhancement at the normal incidence position due to multiple diffraction occurrence was detected.

ISSN:0003-6951    

DOI:10.1063/1.105378

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The surface modifications of as‐grown superconducting Bi‐Sr‐Ca‐Cu‐O (BSCCO) films prepared by radio frequency plasma flash evaporation were carried out with a scanning tunneling microscope (STM). The as‐grown films were identified as highlyc‐axis‐oriented, lowTc(80 K) phase Bi2Sr2Ca1Cu2Oxwith some residue such as (Sr,Ca)3Cu5Oxfrom x‐ray diffraction patterns. The as‐grown film deposited at about 750 °C exhibited a superconducting critical temperatureTcof 76 K and a critical current densityJcof 8.8×104A/cm2under zero magnetic field at 27 K. The nanometer‐size surface modifications between 2 and 50 nm, especially layered etching, of the prepared BSCCO films were successfully performed by using a STM in air.

ISSN:0003-6951    

DOI:10.1063/1.105379

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Laser etching of transparent conducting films of fluorine‐doped tin oxide and indium‐tin oxide has been investigated using an excimer laser at 248 nm. The etch depth per pulse as a function of laser fluence was measured and compared with the predictions of an explicit finite difference thermal model. Direct laser patterning of these films was demonstrated. The sheet resistance of a 50‐&mgr;m‐wide conducting channel formed by laser ablation was measured and compared with the value for the original film.

ISSN:0003-6951    

DOI:10.1063/1.105380

出版商:AIP    

年代:1991

数据来源: AIP