Abstract
High intensity and high energy laser facilities place increasing demands on optical components, requiring large surface area optics with exacting specifications. Petawatt lasers are high energy, short-pulse laser systems generally based on chirped-pulse amplification, where an initial low energy short pulse is stretched, amplified, and then recompressed to produce fs to ps high-power laser pulses. In such petawatt lasers, the highest demands are placed on the final optics, including gratings which compress the pulses and mirrors which direct and focus the final high-power beams. The limiting factor in these optical components is generally laser-induced damage. Designing and fabricating these optical components to meet reflection, dispersion, and other requirements while meeting laser-induced damage requirements is the primary challenge discussed in this tutorial. We will introduce the reader to the technical challenges and tradeoffs required to produce mirrors for petawatt lasers and discuss current research directions.
Highlights
The damage onset measurements were used to set the operational limits of advanced radiographic capability (ARC) at 30 ps, which has the estimated fluence distribution shown by the red line in Fig. 9 for the final ARC mirror; prior mirrors are exposed to a lower fluence
Defects that lead to damage in e-beam coatings may be more likely to “pop out” and not cause collateral damage to the surrounding material, whereas for denser plasma ion-assisted deposition (PIAD) coatings, damage to the surrounding material leads to faster damage growth with subsequent pulses
Lower fluences (Fig. 16).[35] (During experiments preparing for a previous publication,[61] we did not observe a significant difference for silica coatings.) We show the R/1 damage test results here since the effects of polarization increase with number of shots; such damage test results from larger numbers of shots are relevant to the operating conditions of PW lasers, 1/1 damage results are necessary for improving understanding of physical mechanisms
Summary
Petawatt (PW, 1015 watts) laser facilities are of increasing importance for a range of scientific, engineering, and industrial applications.[1,2] Examples include high energy density science,[3,4,5,6] laser-driven particle accelerators,[7,8,9,10] and laser machining.[11,12] As currently developed, petawatt lasers primarily use chirped-pulse amplification (CPA) to produce high pulse energies with short ps and fs pulse widths.[13,14] Stretching a short pulse from the few-femtosecond regime to the nanosecond regime enables efficient amplification to Joule-scale pulse energy while minimizing deleterious nonlinear light–matter interaction effects and damage to optical components (this work led to a Nobel Prize in physics in 2018 for Strickland and Mourou).[15,16] Of particular interest for a petawatt laser system are nonlinear dispersion effects, especially nonlinear phase accumulation due to the instantaneous intensity dependence of the index of refraction of materials (B-integral). Total energies and fluences for petawatt lasers are lower than for large ns pulsed laser systems such as NIF, but the powers and intensities are significantly higher These limits are shown for single beamline laser systems. 50 fs, the performance of metal mirrors or multi-layer metallic and dielectric mirrors may exceed the performance of multilayer dielectric mirrors in some cases.[31,32] Clearly, high intensity fs–ps pulse widths is a challenging regime, but there is significant practical value in scientifically understanding the behavior of materials at their intensity limits within which they maintain their integrity This tutorial discusses the development of petawatt mirrors, including design, fabrication, and testing (gratings[20,21] will be discussed in a limited fashion primarily as they affect mirror design). The tutorial discusses possible directions for the field to achieve higher performance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
