A femtosecond electron bunch is essential for the observation of ultrafast phenomena. In order to improve the time resolution of pulse radiolysis and ultrafast electron diffraction (UED), that involve the use of an ultrashort electron bunch and ultrashort light, a femtosecond photocathode RF gun was investigated experimentally. The bunch length due to space-charge and RF effects in the gun was ...

We demonstrate electro-optic ultrafast control of the optical quality factor of an on-chip silicon microcavity. The micrometer-sized cavity is formed by light confinement between two microring resonators acting as frequency selective mirrors. The ring resonators are integrated into p-i-n junctions enabling ultrafast injection and extraction of carriers. We show tuning of the cavity quality fact...

Coupling ultrashort optical field waveforms to ultrafast molecular vibrations in an impulsively excited Raman medium is shown to enable the generation of frequency-tunable sub-half-cycle multigigawatt light pulses. In a gas-filled hollow waveguide, this coupled-state dynamics is strongly assisted by soliton effects, which help to suppress temporal stretching of subcycle optical pulses, providin...

A quantum-dynamical analysis of exciton dissociation at polymer heterojunctions is presented, using a hierarchical electron-phonon model parametrized for three electronic states and 28 vibrational modes. Two representative interfacial configurations are considered, both of which exhibit an ultrafast exciton decay. The efficiency of the process depends critically on the presence of intermediate ...

Ultrafast all-optical switching is demonstrated in an oxygen-ion implanted silicon-oninsulator microring resonator. The spectral response of the device is rapidly modulated via femtosecond optical excitation and subsequent recombination of charge carriers at artificially introduced ultrafast recombination centers. At an implantation dose of 1 × 1012 cm−2 the carrier lifetime is reduced to 55 ps...

We have studied five patients who have exhibited an unusual alkaline phosphatase isoenzyme (ALP EC 3.1.3.1) migrating in an ultrafast position electrophoretically on cellulose acetate. This ALP isoenzyme has been identified in patients with benign and malignant liver diseases. In addition, a number of these patients exhibited a regular ALP liver isoenzyme and a fast (preliver) ALP isoenzyme in ...

We present a detailed discussion of the complimentary fields of the application of two-dimensional infrared (2D-IR) spectroscopy in comparison with two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy. Transient 2D-IR (T2D-IR) spectroscopy of nonequilibrium ensembles is probably one of the most promising strengths of 2D-IR spectroscopy, as the possibilities of 2D-NMR spectroscopy ar...

We present an analysis of the optical loop mirror in which a nonlinear optical element is asymmetrically placed in the loop. This analysis provides a general framework for the operation of a recently invented ultrafast all-optical switch known as the terahertz optical asymmetric demultiplexer. We show that a loop with small asymmetry, such as that used in the terahertz optical asymmetric demult...

Fundamental interactions induced by lattice vibrations on ultrafast time scales have become increasingly important for modern nanoscience and technology. Experimental access to the physical properties of acoustic phonons in the terahertz-frequency range and over the entire Brillouin zone is crucial for understanding electric and thermal transport in solids and their compounds. Here we report on...