scispace - formally typeset
Search or ask a question
Topic

Pulse duration

About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, a combined theoretical and experimental investigation of the generation of few-cycle terahertz (THz) pulses via the nonlinear effect of optical rectification and of their coherent detection via electro-optic sampling is presented.
Abstract: We present a combined theoretical and experimental investigation of the generation of few-cycle terahertz (THz) pulses via the nonlinear effect of optical rectification and of their coherent detection via electro-optic sampling. The effects of dispersive velocity matching, absorption of the optical and the THz waves, crystal thickness, pulse diameter, pump pulse duration, and two-photon absorption are discussed. The theoretical calculations are compared with the measured spectra of THz pulses that have been generated and detected in crystals of the highly nonlinear organic salt 4-N,N-dimethylamino-4′-N′-methyl stilbazolium tosylate (DAST). The results are found to be in agreement with the theory. By the selection of the optical pump wavelength between 700 and 1600 nm, we achieved several maxima of the overall generation and detection efficiency in the spectral range between 0.4 and 6.7 THz, with an optimum at 2 THz generated with 1500 nm laser pulses.

378 citations

Journal ArticleDOI
TL;DR: In this article, the authors present the results of an extensive experimental program to determine pulse power failure levels of semiconductor junctions, and a semi-empirical formula, based on experimental data and on a simple thermal failure model is given.
Abstract: Theoretical predictions of circuit failure in an Electromagnetic Pulse (EMP) environment require a knowledge of failure levels for each component of the circuit due to surge voltages or currents. For most circuits, the semiconductor devices are the weakest elements with respect to such failure. This paper presents the results of an extensive experimental program to determine pulse power failure levels of semiconductor junctions. Approximately 80 different types of silicon diodes and transistors were studied with variations in junction areas from 10-4to 10-1 cm2 and with widely varying junction geometries. Power levels of up to two kilowatts, with time durations of 0.1 to 20 microseconds, were applied to semiconductor junctions in both forward and reverse polarity modes. A semi-empirical formula, based on experimental data and on a simple thermal failure model is given. From the formula one can make order-of-magnitude estimates of the failure level as a function of pulse length for many silicon diodes or transistors whose junction area is known.

376 citations

Journal ArticleDOI
TL;DR: In vitro studies showed that the minimum zone of thermal damage varied significantly with tissue type, and the effect of denaturation temperature and pulse duration on the width of the damage zone is explained by a simple model.
Abstract: Tissue removal by infrared lasers is accompanied by thermal damage to nonablated tissue. The extent of thermal damage can be controlled by a choice of laser wavelength, irradiance, and exposure duration. The effect of exposure duration has been studied in vivo by using CO2 lasers with pulse widths that vary from 2 μsec to 50 msec. Pulse widths of 50 msec, typical of a shuttered, continuous-wave CO2 laser, produce damage regions 750 μm wide in normal guinea pig skin; the use of a 2-μseclong pulse reduced this damage zone to as little as 50 μm. Using 2-μseclong pulses, in vitro studies showed that the minimum zone of thermal damage varied significantly with tissue type. The thermal denaturation of these tissues has been studied and correlated with damage. The effect of denaturation temperature and pulse duration on the width of the damage zone is explained by a simple model.

371 citations

Journal ArticleDOI
TL;DR: In this article, it was found that GeTe-Sb2Te3 pseud-binary amorphous alloy films showed remarkably fast switching properties to laser irradiation, which is applicable to high data rate direct overwritable disk media.
Abstract: It was found that GeTe-Sb2Te3 pseud-binary amorphous alloy films showed remarkably fast switching properties to laser irradiation. By the static laser irradiation test, the film whose composition corresponded to stoichiometric compound of GeSb2Te4 were crystallized within 50ns of pulse duration at power of 8mW, whilst they could be amorphized with the same pulse duration at power of 20mW. Direct overwriting cycle test was performed on the revolving disk system for 105 times using single laser beam. CNR of more than 50dB and erasability of -22dB were obtained for linear velocity of 22m/s and overwriting frequencies of 5 and 7 MHz. The laser powers were 22 mW for recording and 10 mW for erasing. These materials will be applicable to high data rate direct overwritable disk media.

353 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the acoustic transients emitted after breakdown and cavitation bubble collapse upon focusing a Q-switch laser pulse into a liquid with special emphasis on their modifications induced by a solid boundary.
Abstract: The acoustic transients emitted after breakdown and cavitation bubble collapse upon focusing a Q‐switch laser pulse into a liquid are investigated with special emphasis on their modifications induced by a solid boundary. For measuring the form p(t)/pmax of the pressure pulses an optical technique with a resolution of 10 ns has been developed. When p(t)/pmax is known, the pressure amplitude can be determined even when a transducer with a rise time much longer than the pulse duration is used. The duration of the transients (20–30 ns) and their pressure are nearly the same after breakdown and spherical bubble collapse. During spherical collapse, a maximum pressure of about 60 kbar is developed inside a bubble with Rmax=3.5 mm, and on average 73% of the bubble energy loss is transformed into acoustic energy. The sound emission near a solid boundary strongly depends on the normalized distance γ between the bubble and the boundary. The highest pressures at the boundary are achieved for γ→0; for γ=0.2 and Rmax =3.5 mm it has been found that p=2.5 kbar. These results are discussed with respect to the mechanisms of cavitation erosion important for hydraulic cavitation, laser lithotripsy, and ocular surgery.

353 citations


Network Information
Related Topics (5)
Laser
353.1K papers, 4.3M citations
93% related
Optical fiber
167K papers, 1.8M citations
85% related
Electric field
87.1K papers, 1.4M citations
84% related
Plasma
89.6K papers, 1.3M citations
84% related
Amplifier
163.9K papers, 1.3M citations
83% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023175
2022408
2021543
2020619
2019668
2018665