Pulse duration

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

Accelerating Protons to Therapeutic Energies with Ultra-Intense Ultra-Clean and Ultra-Short Laser Pulses

Abstract: Proton acceleration by high-intensity laser pulses from ultra-thin foils for hadron therapy is discussed. With the improvement of the laser intensity contrast ratio to 10-11 achieved on Hercules laser at the University of Michigan, it became possible to attain laser-solid interactions at intensities up to 1022 W/cm2 that allows an efficient regime of laser-driven ion acceleration from submicron foils. Particle-In-Cell (PIC) computer simulations of proton acceleration in the Directed Coulomb explosion regime from ultra-thin double-layer (heavy ions / light ions) foils of different thicknesses were performed under the anticipated experimental conditions for Hercules laser with pulse energies from 3 to 15 J, pulse duration of 30 fs at full width half maximum (FWHM), focused to a spot size of 0.8 microns (FWHM). In this regime heavy ions expand predominantly in the direction of laser pulse propagation enhancing the longitudinal charge separation electric field that accelerates light ions. The dependence of the maximum proton energy on the foil thickness has been found and the laser pulse characteristics have been matched with the thickness of the target to ensure the most efficient acceleration. Moreover the proton spectrum demonstrates a peaked structure at high energies, which is required for radiation therapy. 2D PIC simulations show that a 150-500 TW laser pulse is able to accelerate protons up to 100-220 MeV energies.

Modulation circuit device, modulation method and radio communication device

Abstract: The amplitude modulator comprises: an angle modulator for angle-modulating a phase signal to be inputted; a waveform shaping means in which, (1) when the magnitude of an amplitude signal to be inputted becomes smaller than a first prescribed value, a waveform of the amplitude signal is shaped so that the magnitude of the amplitude signal of the portion which becomes small becomes the first prescribed value; and/or (2) the waveform shaping means in which, when the magnitude of the amplitude signal to be inputted becomes larger than the second prescribed value which is larger than the first prescribed value, the waveform of the amplitude signal is shaped so that the magnitude of the amplitude signal of the portion which becomes larger becomes the second prescribed value; and an amplitude modulator for amplitude modulating the signal of the output of the angle modulator by the signal of the output of the waveform shaping means.

14-fs pulse generation in Kerr-lens mode-locked prismless Cr:LiSGaF and Cr:LiSAF lasers: observation of pulse self-frequency shift

Abstract: Kerr-lens mode-locked Kr-laser-pumped Cr:LiSGaF and Cr:LiSAF lasers containing only two newly developed low-loss chirped mirrors instead of conventional dielectric resonator mirrors and generating pulses of widths as small as 14-fs with as much as 100 mW of average output power are reported We report what is to our knowledge the first experimental observation of a pulse self-frequency shift in crystalline active media that are characteristic of such short pulses at megawatt intracavity peak powers We also believe this phenomenon to be one of the significant limiting factors for pulse duration in femtosecond Cr:LiSAF-type lasers

Attosecond‐precision ultrafast photonics

Abstract: We review our recent progress toward attosecond-precision ultrafast photonics based on ultra-low timing jitter optical pulse trains from mode-locked lasers. In femtosecond mode-locked lasers, the concentration of a large number of photons in an extremely short pulse duration enables the scaling of timing jitter into the attosecond regime. To characterize such jitter levels, we developed new attosecond-resolution measurement techniques and show that standard fiber lasers can achieve sub-fs high-frequency jitter. By leveraging the ultra-low jitter of free-running mode-locked lasers, we pursued high-precision optical-optical and optical-microwave synchronization techniques. Optical signals spanning 1.5 octaves were synthesized by attosecond-precision timing and phase synchronization of two independent mode-locked lasers. High-stability microwave signals were also synthesized from mode-locked lasers with drift-free sub-10-fs precision. We further demonstrated the attosecond-precision distribution of optical pulse trains to remote locations via timing-stabilized fiber links. Finally, the application of optical pulse trains for high-resolution sampling and analog-to-digital conversion is discussed.

A multigigawatt X-Band relativistic backward wave oscillator with a modulating resonant reflector

Abstract: Effective generation regime with a high output pulse power has been experimentally realized in a relativistic backward wave oscillator (RBWO) with a resonant reflector and a slow-wave system having a diameter 1.6 times the radiation wavelength. At a guiding magnetic field of 4.5 T, the maximum peak power amounted to 4.3 GW at a frequency of 9.4 GHz, an efficiency of 31%, and a microwave pulse duration of 22 ns.