摘要:

Unlike conventional semiconductor lasers, single quantum well lasers with high reflectively coatings have dramatically reduced threshold currents as a result of the smaller volume of the (active) quantum well region. A cw threshold current of 0.95 mA was obtained for a buried graded‐index separate‐confinement heterostructure single quantum well laser with facet reflectivities of ∼70%, a cavity length of 250 &mgr;m, and an active region stripe width of 1 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.97742

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The quantum confined Stark effect has been studied in InGaAsP/InP rib waveguide structures grown by gas source molecular beam epitaxy. Using 100‐A˚‐wide wells of InGaAs, a room‐temperature exciton shift of about 250 A˚ has been observed for a bias voltage of 6 V. At a wavelength of 1.64 &mgr;m a modulation depth of 35% has been achieved at a frequency of 500 MHz. We show that efficient modulation at shorter wavelength cannot be obtained in structures with thinner ternary wells. Instead, we propose and demonstrate InGaAsP modulators operating at a wavelength as short as 1.3 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.97743

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Photoacoustic spectroscopy was used to measure the pulse duration dependence of the XeCl laser ablation of polyimide, polyethylene terephthalate, and post‐mortem human aorta. It was observed that the ablation threshold exhibited only a weak dependence on pulse duration. Photoablation etch depth measurements of polyimide as a function of XeCl laser fluence indicated that over a practical etch depth range of 0.1 to 1 &mgr;m per laser pulse the etch depth was independent of the pulse duration.

ISSN:0003-6951    

DOI:10.1063/1.97744

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The carrier recombination dynamics of CdSxSe1−x‐doped color glasses under strong pumping conditions were studied with 20 ps dye laser pulses and a white light continuum. The initial blue shift of the absorption spectrum was followed by a fast coherent transient and a slower decay. The results yield an electron‐hole recombination time of ∼400 ps. An interesting wavelength dependence of the decay curves was also noted.

ISSN:0003-6951    

DOI:10.1063/1.97745

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Observation of soft x rays from a tungsten plasma produced by intense subpicosecond laser pulses is reported. X radiation of several keV photon energy was observed with just a few millijoules of laser energy. Using two consecutive pulses for the generation of the plasma the x‐ray emission is maximal for a delay of about 30 to 50 ps between the laser pulses.

ISSN:0003-6951    

DOI:10.1063/1.97696

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Room‐temperature cw operation of a GaAs/AlGaAs surface‐emitting grating‐coupled distributed feedback laser is reported. By using a transverse junction stripe scheme which provides a window structure for the surface‐emitted light, cw surface emission having a very narrow beam divergence angle of 0.13° and an output power of more than 3 mW was observed.

ISSN:0003-6951    

DOI:10.1063/1.97697

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The cw electro‐optic probing technique is for the first time proposed to detect the three‐dimensional internal field distribution in linear electro‐optic material like GaAs. By changing the incident angles and positions of the probing beam, sufficient information of the electric field distribution is included in the phase retardation of the probing beam. If certain conditions on the probing beam are satisfied, a very simple linear relation between phase retardation and each field component can be found and the whole problem becomes not only mathematically solvable but experimentally feasible. Finally, a three‐dimensional computer simulation is undertaken to illustrate the relation between field distribution and detected electro‐optic signal.

ISSN:0003-6951    

DOI:10.1063/1.97698

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report a new nearly degenerate two‐wave mixing interaction in photorefractive Bi12SiO20crystals in which the signal beam is time modulated at high frequency. The beam coupling phenomena and the time integration properties of the crystal allow us to achieve a differential gain &ggr;diffon the transmitted signal beam. The dependence of &ggr;diffversus the duty cycle of the modulated signal is analyzed. Amplification and regeneration of periodic, or random sequences of information bits are experimentally demonstrated.

ISSN:0003-6951    

DOI:10.1063/1.97699

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A plasma sustained by electromagnetic surface waves (SW’s) has been used to study the deposition rateRof hydrocarbon and fluorocarbon plasma polymer films as a function of the applied field frequencyfin the range 12–400 MHz. The SW technique allows one to vary onlyfwhile keeping constant all other parameters known to influenceR, for example, power densityPin the plasma. A plot ofR/Pat a total pressure of 200 mTorr (27 Pa) displays two plateaus, that atf<30 MHz being about five times lower than that atf>100 MHz. This is attributed to the fact that electron energy distribution functions differ fundamentally at radio and microwave frequencies, for the gas pressure range considered.

ISSN:0003-6951    

DOI:10.1063/1.97700

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Through seeded lateral overgrowth,c‐axis oriented PbTiO3films are formed on patterned Pt electrode films that are on a SrTiO3single crystal. The impedance characteristics are then measured for this sample as if it were a composite bulk wave resonator. A series of resonance and antiresonance characteristics is observed. Using a conventional circuit model, the electrical impedance is analyzed to evaluate the electromechanical coupling constantktof the PbTiO3films. It is found thatktis as large as 0.8.

ISSN:0003-6951    

DOI:10.1063/1.97701

出版商:AIP    

年代:1987

数据来源: AIP