The parametric excitation of pairs of electron surface waves (ESW) in the interaction of an ultrashort, intense laser pulse with an overdense plasma is discussed using an analytical model. The plasma has a simple step-like density profile. The ESWs can be excited either by the electric or by the magnetic part of the Lorentz force exerted by the laser and, correspondingly, have frequencies aroun...

In recent years, femtosecond lasers matured from sensitive research setups to turnkey systems for an increasing number of applications. Now that running an ultra-short pulse laser system needs no longer a specialized scientist, safety issues become more crucial. Ultrashort laser pulses have extremely high peak powers and even scattered radiation may possess severe risks to the unprotected eye. ...

Exploring the dynamics of matter driven to extreme non-equilibrium states by an intense ultrashort X-ray pulse is becoming reality, thanks to the advent of free-electron laser technology that allows development of different schemes for probing the response at variable time delay with a second pulse. Here we report the generation of two-colour extreme ultraviolet pulses of controlled wavelengths...

Acceleration of electrons to relativistic energies by a multidimensional self-modulated laser wakeeeld is discussed. Above a power threshold, a relativis-tically self-guided channel, from an intense ultrashort laser pulse (I 410 18 W/cm 2 , = 1 m, = 400 fs), was found to increase the laser propagation distance, decrease the electron beam divergence, and increase the energy of the electrons. The...

The behavior of a room temperature synchronously mode-locked vertical-external cavity surface-emitting laser (VECSEL) operating at 980 nm is reported. The laser performance was found to be qualitatively the same for different pump pulse duration (3.6 ps and 70 fs). The pulse duration of the laser is limited by strong self-phase modulation to around 10-40 ps. By compressing the strongly chirped ...

Frequency-resolved optical gating (FROG) is a technique that produces a spectrogram of an ultrashort laser pulse. The intensity and phase of the ultrashort laser pulse can be determined through solving for the phase of the spectrogram with an iterative, phase-retrieval algorithm. This work presents a new phase-retrieval algorithm that retrieves both the probe and the gate pulses independently b...

Control over the breakage of a certain chemical bond in a molecule by an ultrashort laser pulse has been considered for decades. With the availability of intense non-resonant laser fields it became possible to pre-determine femtosecond to picosecond molecular bond breakage dynamics by controlled distortions of the electronic molecular system on sub-femtosecond time scales using field-sensitive ...

The cross-correlation single-shot sonogram technique offers exact pulse measurement and real-time pulse monitoring via an intuitive time-frequency trace whose shape and orientation directly indicate the spectral chirp of an ultrashort laser pulse. We demonstrate an algorithm that solves a fundamental limitation of the cross-correlation sonogram method, namely, that the time-gating operation is ...

The ultrashort, ultrahigh intensity pulse laser has been fully developed in past three decades. Chirped amplification (CPA) system plays an important role the generation of laser. Pulse compression gratings (PCGs) are key element CPA and determine performance lifetime whole system. We introduce principle requirements PCGs. Then development status PCGs, including Au-coated grating, multilayer di...

The aim of this study was to evaluate the surface roughness and wettability of dentin following ultrashort pulsed laser ablation with different levels of fluence and pulse overlap (PO). Twenty-five extracted human teeth crowns were cut longitudinally into slices of approximately 1.5-mm thick and randomly divided into nine groups of five. Samples in groups 1 to 8 were ablated with an ultrashort ...