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By particle-in-cell simulation and analysis, we propose a plasma approach to generate a relativistic chirped pulse based on a laser-foil interaction. When two counterpropagating circularly polarized pulses interact with an overdense foil, the driving pulse (with a larger laser field amplitude) will accelerate the whole foil to form a double-layer structure, and the scattered pulse (with a smaller laser field amplitude) is reflected by this flying layer. Because of the Doppler effect and the varying velocity of the layer, the reflected pulse is up-shifted for frequency and chirped; thus, it could be compressed to a nearly single-cycled relativistic laser pulse with a short wavelength. Simulations show that a nearly single-cycled subfemtosecond relativistic pulse can be generated with a wavelength of 0.2 μm after dispersion compensation.

We have experimentally demonstrated an ultra-dispersive optical prism made from a coherently driven Rb atomic vapor. The prism possesses spectral angular dispersion that is 6 orders of magnitude higher than that of a prism made of optical glass; such angular dispersion allows one to spatially resolve light beams with different frequencies separated by a few kilohertz. The prism operates near the resonant frequency of atomic vapor and its dispersion is optically controlled by a coherent driving field.

We show that molecular orientation can be controlled by sequential three-photon Raman excitations with time-delayed dual-color ultrashort laser pulses. The field-free molecular orientation created by a dual-color ultrashort laser pulse can be significantly enhanced or completely suppressed when another in-phase or antiphase dual-color ultrashort laser pulse is applied at its full revival time. By applying the second dual-color ultrashort laser pulse at the half-revival time, the odd and even rotational wave packets for the impulsive molecular orientation can be promoted and depressed by changing its carrier-envelope phase.

Inertia of optical nonlinearity is shown to distort the temporal profile of the intensity-dependent phase shift of an ultrashort laser pulse relative to the phase induced by the instantaneous optical nonlinearity. We demonstrate that a weakly inertial optical nonlinearity, whose response time is smaller than the pulse width, tends to redshift the light field and generates a cubic-phase correction to the quadratic phase, thus complicating the chirp of the spectrally broadened field. For very short light pulses with pulse widths shorter than the response times of optical nonlinearity, the redshift and cubic-phase terms often dominate the nonlinear phase shift, giving rise to phase profiles significantly different from those induced by instantaneous optical nonlinearity.

We present a systematic study of the transmitted field of an ultrashort pulse through Young’s double slit. We show how the spatial-temporal distribution of the field in the near and intermediate zone is affected by the input polarization state of the pulse. The analysis has been separated to study the dispersion, the diffraction and the interference effects individually. A combination of these effects provide the key to understand the temporal dependence of the field observed at various distinctive locations. A thorough understanding of the near- and intermediate-field distribution of a single- or double-slit for an ultrashort pulse can be exploited in many near-field applications, and tailored by tuning the width, thickness, and separation of the slits.

We theoretically investigate carrier-envelope phase dependence of few-cycle ultrashort laser pulse propagation in a polar molecule medium. Our results show that a soliton pulse can be generated during the two-photon resonant propagation of few-cycle pulse in the polar molecule medium. Moreover, the main features of the soliton pulse, such as pulse duration and intensity, depend crucially on the carrier-envelope phase of the incident pulse, which could be utilized to determine the carrier-envelope phase of a few-cycle ultrashort laser pulse from a mode-locked oscillator.

The propagation of an arbitrary polarized few-cycle ultrashort laser pulse in a degenerate three-level medium is investigated by using an iterative predictor-corrector finite-difference time-domain method. It is found that the polarization evolution of the ultrashort laser pulse is dependent not only on the initial atomic coherence of the medium but also on the polarization condition of the incident laser pulse. When the initial effective area is equal to 2 pi, complete linear-to-circular and circular-to-linear polarization conversion of few-cycle ultrashort laser pulses can be achieved due to the quantum interference effects between the two different transition paths.

We investigate the possibility of optical pulse compression of high energy ultrashort laser pulses in an argon-filled planar waveguide, based on two level coupled mode theory and the full 3D nonlinear Schrödinger equation. We derive general expressions for controlling the spatial beam profile and the extent of the spectral broadening. The analysis and simulations suggest that the proposed method should be appropriate for optical pulse compression of ultrashort laser pulses with energies as high as 600 mJ.

Tunable and stable ultrashort laser pulses in the visible spectrum are generated with high efficiency by four-wave mixing process during the filamentation of near-infrared and infrared laser pulses in gases. It is shown that these tunable ultrashort pulses have a very low energy fluctuation and an excellent mode quality due to the processes of intensity clamping and self-filtering in the filament.

Self-similar propagation of ultrashort, parabolic pulses in a laser resonator is observed theoretically and experimentally. This constitutes a new type of pulse-shaping in modelocked lasers: in contrast to the well-known static (soliton-like) and breathing (dispersion-managed soliton) pulse evolutions, asymptotic solutions to the nonlinear wave equation that governs pulse propagation in most of the laser cavity are observed. Stable self-similar pulses exist with energies much greater than can be tolerated in soliton-like pulse shaping, and this will have implications for practical lasers., Comment: 4 pages, 5 figures, submitted to Phys. Rev. Lett