Particle behaviour of femtosecond optical pulses (original) (raw)
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IEEE Journal of Quantum Electronics, 1983
Recent advances in generation, amplification, compression, and frequency broadening of femtosecond optical pulses are reviewed. We describe use of colliding pulse mode locking to generate pulses of 65 fs duration and pulse compression to reduce those pulse durations to 30 fs. Amplification of femtosecond pulses to gigawatt powers and frequency broadening to obtain white light continuum pulses while retaining femtosecond pulse durations are also examined.
A new light source generates ultrashort infrared pulses at wavelengths around 12µm with previously unattained peak intensity and stability. First experiments in vibrational spectroscopy on water demonstrate the high potential of the system for applications. [52]
Physical Review A, 2011
Propagation of ultrashort optical pulses in a dense resonant medium is considered in the semiclassical limit. In our analysis, we place emphasis on several main points. First, we study transformations of spectra in the process of pulse propagation and interactions with another pulse. The second point involves the transient processes (including pulse compression) connected with selfinduced transparency soliton formation inside the medium. Finally, the third aspect is the study of collisions of co-and counter-propagating pulses in the medium. In the last case, the investigation of symmetric and asymmetric collisions shows the possibility of effectively controlling the parameters of transmitted radiation.
Ultrarelativistic regime in the propagation of an ultrastrong, femtosecond laser pulse in plasmas
The interaction of a multi-Petawatt, pancake-shaped laser pulse with an unmagnetized plasma is studied analytically and numerically in the regime of fully relativistic electron jitter velocities and in the context of the laser wakefield acceleration scheme. The study is applied to the specifications available at present time, or planned for the near future, of the Ti:Sa Frascati Laser for Acceleration and Multidisciplinary Experiments (FLAME) in Frascati. A set of novel nonlinear equations is derived using a three-timescale description, with an intermediate timescale associated with the nonlinear phase of the electromagnetic wave and with the spatial bending of its wave front. They describe on an equal footing both the strong and moderate laser intensity regimes, pertinent to the core and the edges of the pulse. These have fundamentally different dispersive properties since, in the core, the electrons are almost completely expelled by a very strong ponderomotive force and the electromagnetic wave packet is imbedded in a vacuum channel and has (almost) linear properties, while at the pulse edges the laser amplitude is smaller and the wave is dispersive. The new nonlinear terms in the wave equation, introduced by the nonlinear phase, describe a smooth transition to a nondispersive electromagnetic wave at very large intensities, and the simultaneous saturation of the previously known nonlocal cubic nonlinearity, without the violation of the imposed scaling laws. The temporal evolution of the laser pulse is studied by the numerical solution of the model equations in a two-dimensional geometry, with the spot diameter presently used in the selfinjection test experiment (SITE) with FLAME. The most stable initial pulse length is found to be around 1 µm, which is several times shorter than presently available. A rapid stretching of the laser pulse in the direction of propagation is observed, followed by the development of a vacuum channel and a very large electrostatic wake potential, as well as the bending of the laser wave front.
Femtosecond Laser Pulses: Generation, Measurement and Propagation
2021
In this contribution some basic properties of femtosecond laser pulse are summarized. In sections 2.1-2.5 the generation of femtosecond laser pulses via mode locking is described in simple physical terms. In section 2.6 we deal with measurement of ultrashort laser pulses. The characterization of ultrashort pulses with respect to amplitude and phase is therefore based on optical correlation techniques that make of the short pulse itself. In section 3 we start with the linear properties of ultrashort light pulses. However, due to the large bandwidth, the linear dispersion is responsible for dramatic effects. To describe and manage such dispersion effects a mathematical description of an ultrashort laser pulse is given first before we continue with methods how to change the temporal shape via the frequency domain. The chapter ends with a paragraph of the wavelet representation of an ultrashort laser pulse.
Free-space propagation of femto-second light pulses
Optics Communications, 1997
The propagation in free-space of femto-second Gaussian light beams is considered, Various different conditions are studied, In some circumstances the spectral composition of the beam change upon propagation. The spectral output of a pulsed laser is also analysed. This Gaussian pulse beam propagates without change in spectral properties.