Generation Of Tunable Ultrashort Pulses Research Articles

Numerical modeling of mid-infrared ultrashort pulse propagation in Er3+: fluoride fiber amplifiers

We present a numerical model to study the amplification and spectral conversion of ultrashort pulses at 2.8 μm in Er3+: fluoride fibers. This model includes accurate measurements of the gain and Raman properties of fluorozirconate fibers and agrees well with the experimental results. Interesting new features of such mid-infrared fiber amplifiers are discussed for various seeding conditions and fiber parameters. Among these features is the attractor property of the amplifier, which significantly increases the output stability of the tunable ultrafast system. When using the appropriate seed and fiber parameters, the model predicts the generation of a mid-infrared supercontinuum output with more than 4 W of average power or the generation of tunable ultrashort pulses above 3 μm with peak powers exceeding 400 kW.

Ionization Mechanism of the Generation of Tunable Ultrashort Pulses in the Mid-Infrared Range

The generation of pulses in the mid-infrared range during the ionization of a gas by an intense two-color femtosecond field containing quasimonochromatic components with the frequency ratio close to 2 has been studied. The generation occurs at the detuning frequency equal to the difference between the higher frequency and the doubled lower frequency. It has been shown that the efficiency of the generation is determined both by the magnitude of the detuning frequency and by its sign and is higher at negative detunings. The duration of the generated pulse is determined by the ionization duration, which is much smaller than the duration of the ionizing field, which ensures obtaining few-cycle and subcycle pulses in the mid-infrared range.

Laser-plasma generation of tunable ultrashort pulses in terahertz and mid-infrared ranges

Laser-plasma generation of tunable ultrashort pulses in terahertz and mid-infrared ranges

Tunable Ultrashort Pulse Generation from a Waveguided Laser with Premixed-Dye-Doped Plastic Film

A highly compact ultrashort pulse generator is proposed and demonstrated with a poly-methylmethacrylate (PMMA) waveguide doped with a mixture of laser dye (Rhodamine 6G) and saturable absorber (DODCI). A series of spikes with a pulse duration of 20–30 ps was generated by a distributed feedback dye laser pumped by a ns Nd:YAG laser. First, the spikes were shortened by passive Q-switching effect of the saturable absorber. Then they were compressed to 9 ps FWHM by passing a pulse compressor having an alternative chain of amplifier and saturable absorber integrated on the same waveguide. Performances of both devices were evaluated by calculation and confirmed experimentally.

Generation of tunable ultrashort pulses in the ultraviolet with the aid of distributed feedback dye laser excited by an N2 laser

The aim of the study is to analyze spectral concentration of radiation (SCR) on the basis of the assumption that it arises on account of nonlinear resonant self-action of the radiation generated in the in-resonator cuvette with absorbing gas. SCR in a dye laser with an in-resonator cuvette close to the absorption line of the material filling this cuvette is of considerable interest both for quantum electronics and for in-resonator spectroscopy. The authors show that if the basic mechanism responsible for SCR is assumed to be resonant self-action of the laser radiation in the cuvette with absorbing gas, the spectral picture depends significantly on the magnitude and sign of the repolarization coefficient of the transition close to which SCR is formed.

Generation of tunable ultrashort pulses in a dynamic distributed feedback laser

A study was made of the operation of a dynamic distributed feedback (DFB) laser utilizing dye-activated polyurethane and pumped by a train of ultrashort pulses from a YAG:Nd3+ laser. An interference system with division of the pump pulse duration was used to produce the dynamic DFB. Direct measurements were made of the duration of the generated pulses using an Agat-SF streak camera and it was found that the duration of the output pulses was considerably shorter (up to four times) than that of the pump pulses. Tuning in the 560-600 nm range with an ultrashort pulse duration of ~8 psec, a divergence of ~1 mrad, and a lasing efficiency of ~ 3 % were achieved. The evolution of the ultrashort pump and lasing pulse trains indicated that a thermal phase grating had no influence on the operation of this laser.

Generation of tunable ultrashort pulses by synchronous pumping of dye lasers

An experimental investigation was made of some relationships governing the generation of tunable ultrashort pulses by synchronous pumping of dye lasers. The synchronous pumping was provided by trains of ultrashort pulses of 20–25 psec duration at the second harmonic of a YAG:Nd3+ laser with a repetition frequency of up to 100 Hz. Measurements were made of the power resonances found in the vicinity of equal and multiple resonator lengths, and of the durations, spectral widths, and tuning ranges of the generated pulses.