O. Svelto

Er:Yb-doped waveguide laser fabricated by femtosecond laser pulses

Laser action is demonstrated in a 20-mm-long waveguide fabricated on an Er:Yb-doped phosphate glass by femtosecond laser pulses. An output power of 1.7 mW with approximately 300 mW of pump power coupled into the waveguide is obtained at 1533.5 nm. Waveguides are manufactured with the 520-nm radiation from a frequency-doubled, diode-pumped, cavity-dumped Yb:glass laser operating at a 166-KHz repetition rate, with a 300-fs pulse duration.

Solid-state laser unstable resonators with tapered reflectivity mirrors: the super-Gaussian approach

A general procedure for treating solid-state laser unstable resonators with tapered reflectivity mirrors within the framework of geometrical optics is presented. A suitable choice of the analytical form of the reflectivity profile, which can simulate many experimental devices, makes possible the derivation of simple design equations for the resonator parameters. Experiments performed with a pulsed Nd:YAG laser containing a variable-reflectivity output coupler, implemented with vacuum evaporation techniques, are discussed. >

Passive mode locking by carbon nanotubes in a femtosecond laser written waveguide laser

The authors report on the first demonstration of mode locking in an active waveguide laser manufactured by femtosecond laser writing. The active waveguide is fabricated in an Er–Yb-doped phosphate glass, and the mode locker is a fiber-pigtailed saturable absorber device based on single-wall carbon nanotubes specially designed to efficiently operate at 1.5μm. Transform-limited 1.6ps pulses were observed in a ring laser cavity configuration.

Intensity noise reduction in a single-frequency ytterbium-codoped erbium laser

We report on intensity noise suppression in a diode-pumped, single-frequency erbium bulk-glass laser codoped with ytterbium. Using an optoelectronic feedback circuit, we acheived a 30-dB reduction of the relaxation oscillation peak, at 160-kHz frequency, to a relative intensity noise of 2114 dByHz. A useful output power of 15 mW at 1533-nm wavelength was obtained.

40GHz pulse train generation at 1.5µm by using a chirped fiber grating as frequency multiplier

Pulse-train multiplication based on the temporal Talbot effect in a linearly chirped fiber Bragg grating has been experimentally demonstrated. A 40-GHz repetition-rate, nearly transform-limited 10-ps duration optical pulse train at 1.533 mum has been obtained from a 2.5-GHz mode-locked Er- Yb:glass laser by use of a 100-cm-long linearly chirped apodized fiber grating.

Ultrafast processes in spectroscopy

Ultrashort Pulse Lasers. All Solid-State Tunable Ultrafast Laser Oscillators and Amplifiers for Real-World Applications Including Medical Imaging N.P. Barry, et al. Ultrafast Spectroscopy of Atoms and Molecules. Vibrational Coherence in Photoisomerization Reaction of Cis-stilbene in Solution D.K. Palit, et al. Ultrafast Non-Linear Optical Phenomena. Ultrafast Temporal Dynamics in an Optical Microscopic Cavity P. Mataloni, et al. Ultrafast Spectroscopy of Semiconductors. Optical Cross-talk between Quantum Wells D. Weber, et al. Generation and Applications of Intense Ultrashort Pulse. High-Brightness Excimer Lasers S. Szatmari, et al. Frequency Conversion. Femtosecond Pulse Compression by Sum-Frequency Generation in BBO A. Varanavicius, et al. Ultrafast Non-Linear Optics in Organics. Femtosecond Dynamics in Conjugated Polymers T. Kobayashi. Applications of Ultrafast Lasers in Medicine and Ultrafast Processes in Biophysics. Imaging Through Diffusing Media with Time Resolved Transmittance R. Cubeddu, et al. Ultrafast Spectroscopy of Metals, Insulators and Confined Systems. New Ultrafast Measurement Techniques. Superconductors and the Terahertz Spectroscopy. Ultrafast Optoelectronics. 139 Additional Articles. Index.

Radially variable reflectivity output coupler of novel design for unstable resonators

An output coupler with radially variable reflectivity, based on a Fabry-Perot interferometer made of two suitable spherical mirrors, is proposed. Application to a pulsed Nd:YAG laser with an unstable resonator has produced diffraction-limited output beams with energy up to 300 mJ.

Propagation, manipulation, and control of picosecond optical pulses at 1.5 µm in fiber Bragg gratings

We review the main techniques and the most recent experimental achievements obtained by our group on manipulation and control of picosecond optical pulse trains at 1.5-µm based on fiber Bragg grating (FBG) devices of interest in ultrafast optoelectronics. In particular, all-optical techniques for repetition-rate multiplication of picosecond mode-locked pulse trains that use linearly chirped FBGs and pulse-shaping techniques based on Fourier spectral filtering in a novel class of dispersive FBGs are presented. Theoretical and experimental results on the control of the light speed in FBG structures, including superluminal transmission and reflection of picosecond pulses, are also discussed.

Analysis of quarter-wave dielectric-mirror dispersion in femtosecond dye-laser cavities.

Analysis of dispersion produced by a lambda/4 multilayer dielectric mirror as a function of its construction parameters is presented. The amount of dispersion can be estimated from a careful inspection of the measured reflectivity curve. In some cases, which seem to be of practical relevance, the value of dispersion is such as to prevent pulses shorter than ~50 fsec from being produced in the mode-locked laser cavity.

FLUORESCENCE OF COMPLEXES OF QUINACRINE MUSTARD WITH DNA. I. INFLUENCE OF THE DNA BASE COMPOSITION ON THE DECAY TIME IN BACTERIA

The fluorescence of several bacterial DNAs stained with quinacrine mustard have been investigated using a laser microfluorometer with a spatial resolution of ‐ 0.3 μm and a temporal resolution of ˜0.3 ns connected to a digital signal averager.