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1

Digitale Medien

A relatively simple way to produce THz bursts of optical pulses (1992)

MacFarlane, D. L. ; Narayan, V.

[S.l.] : American Institute of Physics (AIP)

Review of Scientific Instruments 63 (1992), S. 4092-4095

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ISSN: 1089-7623

Quelle: AIP Digital Archive

Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik

Notizen: We present the design, construction, and demonstration of a device to produce short, high-frequency bursts of ultrashort optical pulses. Specifically, we use a folded delay line structure called the optical rattler to produce a 600-GHz burst of 400-fs pulses.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.1143217

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2

Digitale Medien

Pump considerations for gain switched diode lasers (1990)

MacFarlane, D. L.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 68 (1990), S. 3013-3015

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: We calculate the conditions under which a gain switched diode laser is optimized with respect to the width of the injection current pump pulse. We find, for both biased and unbiased operations, that a current pulse of approximately 20 ps corresponds to a Dirac delta function, a situation which yields the shortest, most intense output pulses.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.346441

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3

Digitale Medien

Tunable repetition rate optical spectroscopy with high-power visible diode lasers (1993)

Tatum, J. A. ; MacFarlane, D. L. ; Serreze, H. B.

[S.l.] : American Institute of Physics (AIP)

Review of Scientific Instruments 64 (1993), S. 2123-2127

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ISSN: 1089-7623

Quelle: AIP Digital Archive

Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik

Notizen: The methodology and apparatus are described to perform tunable repetition rate optical spectroscopic measurements using high-power visible diode lasers. Here, a train of picosecond pulses interrogates a material, a sample, or a device under test. The response of the sample or device varies as the pulse repetition frequency changes. Using an rf modulated high-power AlGaInP 670-nm diode laser, the pulse train repetition frequency may be smoothly varied from the kHz range up to the GHz range. The power and the pulse width may be kept constant by adjusting the rf power and the dc injection current. This procedure is automated through computer control. Here we describe the details of our particular setup and present examples of the technique.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.1143947

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4

Digitale Medien

Compact, inexpensive, visible diode laser source of high repetition rate picosecond pulses (1992)

Tatum, J. A. ; Jennings, J. W. ; MacFarlane, D. L.

[S.l.] : American Institute of Physics (AIP)

Review of Scientific Instruments 63 (1992), S. 2950-2953

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ISSN: 1089-7623

Quelle: AIP Digital Archive

Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik

Notizen: We discuss the techniques and describe the circuitry to build a visible diode laser picosecond light source. The rf circuitry is easy and inexpensive to build, and the final package is quite compact. Stable, low jitter, 108-Hz trains of ∼100-ps, 670-nm optical pulses are therefore readily attainable.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.1142592

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5

Digitale Medien

Effects of bandwidth-limiting tuning elements in synchronously pumped mode-locked lasers (1990)

Zandi, Bahram ; Casperson, Lee W. ; MacFarlane, D. L.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 67 (1990), S. 2229-2234

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: A description of bandwidth-limiting tuning filters is introduced into a semiclassical model for synchronously pumped mode-locked dye lasers. The finite phase memory of the molecular wave functions is included as are the isotropic molecular distribution and the finite vibrational relaxation times. The new set of equations has been solved numerically using the best available values for the various parameters. The results have been compared with experimental data obtained using a rhodamine 6G dye laser, which is synchronously pumped using an acousto-optically mode-locked argon laser. Tuning element effects have been studied using two- and three-plate birefringent filters and a tuning wedge, and the experimental results agree with the numerical solutions.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.345536

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6

Digitale Medien

Laser beam alignment devices for ultrashort pulses (1991)

MacFarlane, D. L.

[S.l.] : American Institute of Physics (AIP)

Review of Scientific Instruments 62 (1991), S. 1899-1903

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ISSN: 1089-7623

Quelle: AIP Digital Archive

Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik

Notizen: We describe two novel devices for optical beam alignment. One allows for a variable angle, fixed position of incidence upon a target. The other allows for a variable position, fixed angle of incidence upon a target. Cascaded together, these devices allow placement of a laser beam upon a sample with arbitrary angle and arbitrary position of incidence. These devices are particularly useful for experiments and applications involving ultrashort pulses since the time of flight through either of these devices is a constant independent of the angle of incidence and position of incidence.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.1142389

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7

Digitale Medien

Beam quality of high-power broad-area visible diode lasers (1994)

Tatum, J. A. ; Staszewski, R. ; Macfarlane, D. L. ; [weitere]

Springer

Optical and quantum electronics 26 (1994), S. 911-928

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ISSN: 1572-817X

Quelle: Springer Online Journal Archives 1860-2000

Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik

Notizen: Abstract We characterize the beam quality of visible-wavelength GRIN-SCH-SQW lasers in terms of geometry and driving current. A second-moment-based, free beam measurement of M 2 yields values ranging from near unity on the plane parallel to the junction, to near 10 in the perpendicular plane. The M 2 values exhibit a dependence on the shape of the L-I characteristic. Higher-order moments are uso quantitatively describe the changes in beam shape as a function of current, and a correlation between the kurtosis and M 2 is observed.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00340558

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8

Digitale Medien

Comparing networks with differing neural-node functions using transputer-based genetic algorithms (1993)

Jones, Antonia J. ; Macfarlane, D.

Springer

Neural computing & applications 1 (1993), S. 256-267

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ISSN: 1433-3058

Schlagwort(e): Backpropagation ; Genetic algorithms ; Ellipsoidal nodes ; Quadratic nodes ; Speech recognition ; E-task

Quelle: Springer Online Journal Archives 1860-2000

Thema: Informatik , Mathematik

Notizen: Abstract Different neural net node computational functions are compared using feedforward backpropagation networks. Three node types are examined: the standard model, ellipsoidal nodes and quadratic nodes. After preliminary experiments on simple small problems, in which quadratic nodes performed very well, networks of differing nodes types are applied to the speech recognition 104 speaker E-task using a fixed architecture. Ellipsoidal nodes were found to work well, but not as well as the standard model. Quadratic nodes did not perform well on the larger task. To facilitate an architecture independent comparison a transputer-based genetic algorithm is then used to compare ellipsoidal and mixed ellipsoidal and standard networks with the standard model. These experiments confirmed the earlier conclusion that ellipsoidal networks could not compare favourably with the standard model on the 104 speaker E-task. In an evolutionary search in which layer node types were free to adjust ellipsoidal nodes had a tendency to become extinct or barely survive. If the presence of ellipsoidal nodes was enforced then the resulting networks again performed poorly when compared with the standard model.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02098744

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9

Digitale Medien

23Na NMR in urethane cross-linked polyether solid polymer electrolytes (1994)

Forsyth, M. ; Smith, M. E. ; Meakin, P. ; [weitere]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2077-2084

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ISSN: 0887-6266

Schlagwort(e): NMR ; polyether urethane polymer electrolytes ; sodium triflate ; Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: Sodium triflate/polyether urethane polymer electrolytes ranging in concentration from 0.05 molal to 1.75 molal have been investigated via 23Na static solid-state NMR. Room temperature spectra and spin lattice relaxation times were consistent with a single narrow resonance indicating the presence of only mobile ionic species. The concentration and temperature dependence of relaxation times, chemical shifts, and linewidth have been investigated. The results suggest either a single species or rapid exchange between a number of species (even at temperatures below the glass transition temperature, Tg). The linewidth decreases with increasing concentration of ions and remains temperature independent below Tg. Below Tg a maximum quadrupolar interaction constant of 2 MHz is calculated. The addition of plasticizer to the polymer electrolyte causes significant chemical shift changes that depend on the solvent donicity of the plasticizer. The linewidth and T1 relaxation times also depend on the Tg of the plasticized systems. Previous 23Na NMR literature results are reviewed and qualitative models developed to account for the variation in results. © 1994 John Wiley & Sons, Inc.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/polb.1994.090321214

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