High-harmonic generation using ultrashort laser pulses with pulse durations 25 to 200 fs is studied theoretically and experimentally. We observe that the harmonic spectrum of argon taken with 25 fs laser pulses contains harmonics up to 20 orders higher than for 100 fs laser pulses with the same intensity. We show that this increase in harmonics is because the atom survives to higher laser inten...

From the pulse length dependence of the absorption of intense ultrashort laser pulses focused inside fused silica, we reveal the role field-assisted collisional ionization plays in the multiphoton ionization process. This constitutes a cold avalanche ionization mechanism that persists at pulse lengths considered too short for a traditional avalanche.

The accurate focusing of ultrashort laser pulses is important in multiphoton microscopy, in order to achieve high resolution imaging in biological specimens. Recent advances have shown the improvements to imaging through the inclusion of an adaptive optic element in the microscope. Using a device such as a liquid crystal spatial light modulator or a deformable mirror to modify the wavefront of ...

A comparative study of the effect of ultrashort (0.5 ps) and short (15 ns) pulses on the laser forward transfer of DNA molecules is presented in this paper. We use femtosecond laser pulses to directly print a wide range of biomaterials, in complicated patterns and structures. The ultrashort laser pulses reduce the thermal effects, thus allowing the effective deposition of sensitive biomaterials...

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a significant role in laser-material interaction, especially in the air environment(1-11). Early plasma evolution has been captured through pump-probe shadowgraphy(1-3) and interferometry(1,4-7). However, the studied time frames and applied laser par...

The paper is devoted to new trends in dispersive control techniques for ultrafast light emission. Acoustooptical dispersive delay lines for controlling the spectral components and phase composition of ultrashort laser pulses are considered. The method of super high frequency modulation of chirped femtosecond laser pulses is proposed. Theoretical approach to dispersive pulse shaping is supported...

We demonstrate the first 1.7 μm bismuth-doped fiber laser generating ultrashort pulses via passive mode-locking. Pulse operation has been achieved for both anomalous and normal dispersion of the laser cavity owing to broadband characteristics of carbon nanotube saturable absorber. The laser delivered 1.65 ps pulses in net anomalous dispersion regime. In normal dispersion regime, the laser deliv...

We review the problem of measuring an ultrashort laser pulse and then describe several experimentally simple, accurate, and very reliable methods for measuring both very simple laser pulses and very complex ultrashort light pulses. Each of these methods comprises only a few easily aligned components, and they allow the measurement of a wide range of pulses, including those with time-bandwidth p...