48 research outputs found
Final EDP Ti: Sapphire amplifiers for ELI project
Recently several ultrahigh intensity Chirped Pulse Amplification (CPA) laser systems have reached petawatt output powers [1, 2] setting the next milestone at tens or even hundreds petawatts for the next three to ten years [3, 4]. These remarkable results were reached when laser amplifiers (opposite to Optical Parametric Amplification (OPA) [5]) were used as final ones and from them Ti:Sapphire crystals supposed to be the working horses as well in the future design of these laser systems. Nevertheless, the main limitation that arises on the path toward ultrahigh output power and intensity is the restriction on the pumping and extraction energy imposed by Transverse Amplified Spontaneous Emission (TASE) [6] and/or transverse parasitic generation (TPG) [7] within the large aperture of the disc-shape amplifier volume. © 2015 SPIE
Drift and noise of the carrier-envelope phase in a Ti:sapphire amplifier
We report on the drift and noise measurement of the carrier-
envelope phase (CEP) of ultrashort pulses in a three-pass
Ti:sapphire-based amplifier. Spectrally and spatially
resolved interferometry makes it possible to investigate the
absolute CEP changes due exclusively to the amplifier, that
is, entirely separated from the incidental phase fluctuations
of the oscillator. We found that propagation through the
amplifier crystal could result in an increase up to 30 mrad
noise depending on the repetition rate, cooling, and pumping
conditions. Most of this noise is related to mechanical
vibrations and thermal instabilities. The absolute CEP drift
of thermal origin can be as large as 11 mrad/degrees C for
each mm of the amplifier crystal, originating from
inefficient heat conduction during the absorption of pump
pulses. The noise of the thermal CEP drift is inversely
proportional to the repetition rate, as was shown
experimentally and proven by simulations
Highly efficient, cascaded extraction optical parametric amplifier
The scheme of cascaded extraction optical parametric amplifier (CE-OPA) has been proposed as a final amplifier for high peak power laser systems. 4D numerical simulations show that conversion efficiency of a CE-OPA system pumped with a temporal Gaussian pump pulse is as close to the theoretical limit of quantum efficiency as a conventional OPA pumped with temporal flat-top pump pulse. The CE-OPA system is also similar to the conventional scheme in output energy stability and alignment sensitivity of the phase-matching angles, too. However, with the use of the CE-OPA scheme, the requirement of pump pulse shaping can be relaxed, leading to an overall higher plug in efficiency as well as compact design. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen
Design of a thin disk amplifier with extraction during pumping for high peak and average power Ti:Sa systems (EDP-TD)
Combination of the scheme of extraction during pumping (EDP)
and the Thin Disk (TD) technology is presented to overcome
the limitations associated with thermal cooling of crystal
and transverse amplified spontaneous emission in high average
power laser systems based on Ti: Sa amplifiers. The optimized
design of high repetition rate 1-10 PW Ti: Sapphire EDP-TD
power amplifiers are discussed, including their thermal
dynamic behavior. (C) 2016 Optical Society of Americ
A unified optical damage criterion based on the probability density distribution of detector signals
Various methods and procedures have been developed so far to test laser induced optical damage. The question naturally arises, that what are the respective sensitivities of these diverse methods. To make a suitable comparison, both the processing of the measured primary signal has to be at least similar to the various methods, and one needs to establish a proper damage criterion, which has to be universally applicable for every method. We defined damage criteria based on the probability density distribution of the obtained detector signals. This was determined by the kernel density estimation procedure. We have tested the entire evaluation procedure in four well-known detection techniques: direct observation of the sample by optical microscopy; monitoring of the change in the light scattering power of the target surface and the detection of the generated photoacoustic waves both in the bulk of the sample and in the surrounding air