RESUMEN
It is experimentally shown that pulse-to-pulse instabilities in the output of Kerr lens mode-locked Ti:sapphire lasers are usual and that they can affect some of the pulse variables (e.g., the spot size) and not others (e.g., pulse duration and energy). These instabilities are not detectable in the averaged signals (such as the autocorrelation of the pulse) that are customarily used for controlling the laser. But, if they are present but are disregarded, these instabilities have undesirable consequences in almost any application. A simple way to detect and eliminate the instabilities is described.
RESUMEN
We demonstrate that, by changing the altitude and the azimuth incident angles on the gratings of the conventional grating-pair compressor used in chirped-pulse amplification, an extra degree of freedom is added. This results in a continuous adjustment of second-, third-, and fourth-order dispersions, which allows one to compensate for those dispersions that originated in the expansor or in the amplifier medium as a result of material dispersion or self-phase modulation, even with small out-of-plane tilts of the expansor and compressor. Analytical calculations of the high-order dispersions introduced by this compressor and examples for a pulse with a central wavelength at 800 nm are presented.
RESUMEN
A compact pulse stretcher using curved diffraction gratings is presented. It introduces positive group-delay dispersion and can operate in conjunction with a standard grating-pair compressor in chirped-pulse amplification systems. It presents several advantages over other systems proposed: It has no degrees of freedom and so is not highly sensitive to alignment errors, it is easy to align, it has a compact and robust design, and it uses standard optics. The frequency-dependent delay, dispersions up to third order, and the design parameters of the stretcher-compressor system that will yield good matching are analyzed. Examples of design specifications for a 40-fs pulse with a central wavelength of lambda=800 nm are given.