Topic
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: Two main limitations for the scaling of optical-to-THz conversion efficiencies are identified: the large spectral broadening of the optical pump spectrum in combination with large angular dispersion of the tilted pulse front and free-carrier absorption of THz radiation due to multi-photon absorption of the 800 nm radiation.
Abstract: We experimentally investigate the limits of 800-nm-to-terahertz (THz) energy conversion in lithium niobate at room temperature driven by amplified Ti:sapphire laser pulses with tilted pulse front. The influence of the pump central wavelength, pulse duration, and fluence on THz generation is studied. We achieved a high peak efficiency of 0.12% using transform limited 150 fs pulses and observed saturation of the optical-to-THz conversion efficiency at a fluence of 15 mJ/cm(2) for this pulse duration. We experimentally identify two main limitations for the scaling of optical-to-THz conversion efficiencies: (i) the large spectral broadening of the optical pump spectrum in combination with large angular dispersion of the tilted pulse front and (ii) free-carrier absorption of THz radiation due to multi-photon absorption of the 800 nm radiation.
76 citations
TL;DR: The results suggest that Cavitation was involved in the paralysis at a pulse repetition frequency (PRF) of 50 kHz, but that cavitation took place in the coupling medium and probably not within the specimen during exposures at a PRF of 5 kHz, and show an inverse relation between spatial peak pulse average intensity, or peak rarefactional pressure and sound on-time.
Abstract: Exposure conditions were determined for hind limb paralysis and lung hemorrhage of neonatal mice due to pulsed exposure (10 microsecond pulse duration) to 1 MHz focused ultrasound. Spatial peak pulse average intensity and peak rarefactional pressure levels for paralysis in 50% of specimens sonicated were determined for pulse repetition frequencies of 1, 5 and 50 kHz at 10 degrees C and 2.4 s exposure duration. The results suggest that cavitation was involved in the paralysis at a pulse repetition frequency (PRF) of 50 kHz, but that cavitation took place in the coupling medium and probably not within the specimen during exposures at a PRF of 5 kHz. The results show an inverse relation between spatial peak pulse average intensity, or peak rarefactional pressure and sound on-time. Exposure conditions for lung hemorrhage were determined for a pulse duration of 10 microseconds at 10 degrees C and exposure durations of 2.4 and 180 s. The results show that the threshold exposure conditions for lung hemorrhage are much less than the conditions for cavitational or other effects reported for tissues that do not contain well defined gas bodies. In addition, the results show an inverse relation between exposure level and either exposure duration or sound on-time, suggesting that time is an important parameter associated with bubble effects.
76 citations
TL;DR: In this article, a very similar fluorescence structure is obtained from the radiation of an ideally mode-locked laser and of a free-running laser with the same oscillating bandwith.
76 citations
TL;DR: In this article, the formation of laser-induced periodic surface structures (LIPSS) upon irradiation of silicon wafer surfaces by linearly polarized Ti:sapphire femtosecond laser pulses was studied experimentally and theoretically.
76 citations
Patent•
06 Feb 2004TL;DR: In this paper, a circuit and method for programming phase-change memory devices, such as chalcogenide memory (PRAM), is described, where a set pulse duration time is controlled by monitoring the state of the memory element during programming such as by comparing the voltage of a bit line with a reference voltage or comparing the cell resistance with a set state cell resistance.
Abstract: A circuit and method for programming phase-change memory devices, such as chalcogenide memory (PRAM), are described. The invention is directed to an approach to programming PRAM elements from a reset state to a set state or from a set state to the set state. The invention provides a novel and nonobvious PRAM device and method in which a set pulse duration time is controlled by monitoring the state of the memory element during programming such as by comparing the voltage of a bit line with a reference voltage or comparing the cell resistance with a set state cell resistance. The duration of the set pulse is controlled in response to the detected state of the memory element. The result of the approach of the invention is the significant reduction in PRAM programming errors, such as those caused by a constant-duration set pulse, as well as reduction in programming time duration and power consumption.
76 citations