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Because ultrafast lasers have pulse durations shorter than most characteristic relaxation times of condensed phases, it has become more important than ever to characterize their temporal, spatial, and spectral content in detail. Of increasing importance are the broad spectral bandwidth, the enhanced probability of multiphoton electronic excitations, and the possibility of creating extremely high spatio-temporal densities of electronic (or, in the case of picosecond infrared free-electron lasers, vibrational) excitation. Narrow-band tunable laser sources continue to have an important place here, because they permit state-selective excitations. Because ultrafast lasers can be used both to control the direction of laser-induced materials modification and to follow the temporal and spatial evolution of those modifications, the kinds of techniques described here are likely to be much more frequently used in the future. The most advanced techniques for doing this include: Temporal characterization based on autocorrelation and pump-probe techniques, coupled to microscopy;The spatial evolution of the laser-modified material using X-ray and electron diffraction methods; andMonitoring the temporal and spatial evolution of material removed by the laser using nonlinear time-resolved spectroscopy, such as CARS. [ABSTRACT FROM AUTHOR]

advent of broadly tunable free-electron lasers with a combination of high irradiance, low-to-moderate pulse energy, high pulse repetition frequency and high average power has opened new opportunities in materials analysis, modification and processing. This paper describes several such areas, including laser surgery, infrared laser-assisted mass spectrometry, and resonant infrared pulsed laser deposition of polymer thin films. [ABSTRACT FROM AUTHOR]

The optics of the surface plasmon resonance in the linear regime have been extensively studied and applied for almost a century. The explosive growth of interest in plasmonics, however, is focusing attention on novel plasmonic structures and nonlinear optical applications. [ABSTRACT FROM AUTHOR]