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Pulse duration
About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.
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TL;DR: The generation of high energy subpicosecond pulses with a pulse energy of up to 25.9 microJ at a pulse duration of 928 fs directly from a thin-disk laser oscillator with active multipass cell is demonstrated.
Abstract: The pulse shaping dynamics of a diode-pumped laser oscillator with active multipass cell was studied experimentally and numerically. We demonstrate the generation of high energy subpicosecond pulses with a pulse energy of up to 25.9µJ at a pulse duration of 928fs directly from a thin-disk laser oscillator. These results are achieved by employing a selfimaging active multipass geometry operated in ambient atmosphere. Stable single pulse operation has been obtained with an average output power in excess of 76W and at a repetition rate of 2.93MHz. Self starting passive mode locking was accomplished using a semiconductor saturable absorber mirror. The experimental results are compared with numerical simulations, showing good agreement including the appearance of Kelly sidebands. Furthermore, a modified soliton-area theorem for approximating the pulse duration is presented.
131 citations
TL;DR: Raman amplification of subpicosecond laser pulses up to 95 times is demonstrated at corresponding frequencies in a gas-jet plasma and theoretical simulations show a qualitative agreement with the measurements.
Abstract: Raman amplification of subpicosecond laser pulses up to 95 times is demonstrated at corresponding frequencies in a gas-jet plasma. The larger amplification is accompanied by a broader bandwidth and shorter pulse duration. Theoretical simulations show a qualitative agreement with the measurements, and the effects of the plasma conditions and laser intensities are discussed.
131 citations
TL;DR: In this paper, the constant fraction of pulse height trigger has been shown to provide the optimum time resolution with a scintillator-photomultiplier system, and a circuit suitable for general use is presented.
131 citations
TL;DR: The pulses used were based on the frequency offset correction inversion technique, as well as time dilation of functions, but the RF amplitude, frequency sweep, and gradient functions were all generated using a genetic algorithm with an evaluation function that took into account both the desired inversion profile and the transmit field inhomogeneity.
Abstract: The radiofrequency (RF) transmit field is severely inhomogeneous at ultrahigh field due to both RF penetration and RF coil design issues. This particularly impairs image quality for sequences that use inversion pulses such as magnetization prepared rapid acquisition gradient echo and limits the use of quantitative arterial spin labeling sequences such as flow-attenuated inversion recovery. Here we have used a search algorithm to produce inversion pulses tailored to take into account the heterogeneity of the RF transmit field at 7 T. This created a slice selective inversion pulse that worked well (good slice profile and uniform inversion) over the range of RF amplitudes typically obtained in the head at 7 T while still maintaining an experimentally achievable pulse length and pulse amplitude in the brain at 7 T. The pulses used were based on the frequency offset correction inversion technique, as well as time dilation of functions, but the RF amplitude, frequency sweep, and gradient functions were all generated using a genetic algorithm with an evaluation function that took into account both the desired inversion profile and the transmit field inhomogeneity.
131 citations
TL;DR: In this article, mode-locking dynamics in a small section of an edge-emitting quantum cascade laser (QCL) were modeled and simulated based on the Maxwell-Bloch equations in an open two-level system.
Abstract: We report the unequivocal demonstration of mid-infrared mode-locked pulses from a semiconductor laser. The train of short pulses was generated by actively modulating the current and hence the optical gain in a small section of an edge-emitting quantum cascade laser (QCL). Pulses with pulse duration at full-width-at-half-maximum of about 3 ps and energy of 0.5 pJ were characterized using a second-order interferometric autocorrelation technique based on a nonlinear quantum well infrared photodetector. The mode-locking dynamics in the QCLs was modelled and simulated based on Maxwell-Bloch equations in an open two-level system. We anticipate our results to be a significant step toward a compact, electrically-pumped source generating ultrashort light pulses in the mid-infrared and terahertz spectral ranges.
130 citations