Ultrashort pulses were produced at 248 nm by using a transverse-discharge KrF* excimer laser as a high-energy amplifier system. Input pulses for the amplifier system were obtained by upconverting the output of a modelocked visible dye laser to the ultraviolet by using nonlinear crystals. Pulses of up to 20 mJ; in energy with 10-30-psec duration were obtained at 10 pulses/sec. The output pulse w...

We have demonstrated efficient conversion of ultrashort-pulse laser energy to x rays with energies above 1 keV, using laser-produced plasmas generated on a variety of microstructured surfaces. Lithographically produced grating targets generated 0.1 mJ of kilo-electron-volt x rays, and porous gold and aluminum targets emitted 1 mJ. This represents an improvement of a factor of 100 over flat targ...

We present an analysis and demonstration of few-cycle ultrashort laser pulse characterization using second-harmonic dispersion scans and numerical phase retrieval algorithms. The sensitivity and robustness of this technique with respect to noise, measurement bandwidth and complexity of the measured pulses is discussed through numerical examples and experimental results. Using this technique, we...

Using femtosecond laser machining, we have fabricated photonic bandgap materials that influence propagation of phonon-polaritons in ferroelectric crystals. Broadband polaritons were generated with impulsive stimulated Raman scattering (ISRS) using an ultrashort laser pulse, and the spatial and temporal evolution of the polaritons were imaged as they propagated through the fabricated structures ...

We present what is to our knowledge the most complete 1-D numerical analysis of the evolution and the propagation dynamics of an ultrashort laser pulse in a Ti:Sapphire laser oscillator. This study confirms the dispersion managed model of mode-locking, and emphasizes the role of the Kerr nonlinearity in generating mode-locked spectra with a smooth and well− behaved spectral phase. A very good a...

Results of laser-induced breakdown experiments in fused silica (SiOJ employing 150 fs-7 ns, 780 mn laser pulses are reported. The avalanche ionization mechanism is found to dominate over the entire pulse-width range. Fluence breakdown threshold does not follow the scaling of F,6, when pulses are shorter than 10 ps. The impact ionization coefficient of SiO, is measured up to -3 X 10’ V/cm. The r...

We report measurements demonstrating the concept of the free-electron laser (FEL) superradiant cascade. Radiation (λ(rad) = 200 nm) at the second harmonic of a short, intense seed laser pulse (λ(seed) = 400 nm) was generated by the cascaded FEL scheme at the transition between the modulator and radiator undulator sections. The superradiance of the ultrashort pulse is confirmed by detailed measu...