We have measured the longitudinal power distribution inside a random distributed feedback Raman fiber laser. The observed distribution has a sharp maximum whose position depends on pump power. The spatial distribution profiles are different for the first and the second Stokes waves. Both analytic solution and results of direct numerical modeling are in excellent agreement with experimental obse...

We develop a coherent anti-Stokes Raman scattering (CARS) microscopy system equipped with a tunable picosecond laser for high-speed wavelength scanning. An acousto-optic tunable filter (AOTF) is integrated in the laser cavity to enable wavelength scanning by varying the radio frequency waves applied to the AOTF crystal. An end mirror attached on a piezoelectric actuator and a pair of parallel p...

We present a wavelength-swept coherent anti-Stokes Raman scattering (WS-CARS) spectroscopy system for hyperspectral imaging in thick tissue. We use a strategy where the Raman lines are excited sequentially, circumventing the need for a spectrometer. This fibre laser system, consisting of a pump laser synchronized with a rapidly tunable programmable laser (PL), can access Raman lines over a sign...

Inertial-confinement lascr fusion requires propagation of high-intensity, pulseshaped IR and UV laser beams through long air paths. Such beams are subject to losses and decreased beam quality because of stimulated rotational Raman scattering (SRRS) in the atmosphere. With short pulses, it is necessary to use transient Raman theory to include buildup and relaxation of the mcdium. Imperfect beam ...

The effect of nitrogen addition and laser fluence on the atomic structure of amorphous carbon films (a-C) synthesized by femtosecond pulsed laser deposition has been studied. The chemical bonding in the films was investigated by means of X-ray photoelectron (XPS) and Raman spectroscopies. XPS studies revealed a decrease in the sp3 bonded carbon sites and an associated increase in the N−sp2C bon...

Iron chromium oxide microspheres were generated by pulsed laser irradiation on the surface of two commercial samples of stainless steel at room temperature. An Ytterbium pulsed fiber laser was used for this purpose. Raman spectroscopy was used for the characterization of the microspheres, whose size was found to be about 0.2-1.7 μm, as revealed by SEM analysis. The laser irradiation on the surf...

Active mode-locking of Raman fiber laser is experimentally investigated for the first time. An all fiber connected and polarization maintaining loop cavity of ~500 m long is pumped by a linearly polarized 1120 nm Yb fiber laser and modulated by an acousto-optic modulator. Stable 2 ns width pulse train at 1178 nm is obtained with modulator opening time of > 50 ns. At higher power, pulses become ...

OBJECTIVE This study evaluated the molecular and morphological changes on dentin elements after Er:YAG laser irradiation. BACKGROUND DATA Spectroscopy studies reporting the effects of Er:YAG laser irradiation as an alternative to acid etching are needed to better understand the laser's effects. METHODS The occlusal one-third of the crown of six human third molars was removed. The dentin sur...

Four different schemes for the generation of femtosecond input pulses for ArF amplifiers are described. Pulse energies of 100 nJ were obtained with phase-matched frequency mixing of a Raman-shifted frequency-doubled pulse derived from a 537-nm femtosecond dye-laser pulse. Excellent spatial, spectral, and amplitude stability was obtained when a broadband, nanosecond dye laser at 690 nm was used ...