Attosecond delay lines: design, characterization and applications Ankur Mandal, Mehra S. Sidhu, Jan M. Rost, Thomas Pfeifer and Kamal P. Singh Eur. Phys. J. Spec. Top., 230 23 (2021) 4195-4213 Published online: 11 August 2021 DOI: 10.1140/epjs/s11734-021-00261-3