@article{4184, author = {Pei-Chi Huang and Carlos Hernández-García and Jen-Ting Huang and Po-Yao Huang and Chih-Hsuan Lu and Laura Rego and Daniel Hickstein and Jennifer Ellis and Agnieszka Jaron-Becker and Andreas Becker and Shang- Da Yang and Charles Durfee and Luis Plaja and Henry Kapteyn and Margaret Murnane and A. Kung and Ming-Chang Chen}, title = {Polarization control of isolated high-harmonic pulses}, abstract = {High-harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, thus far, the shortest isolated attosecond pulses have only been produced with linear polarization, which limits the range of physics that can be explored. Here, we demonstrate robust polarization control of isolated extreme-ultraviolet pulses by exploiting non-collinear high-harmonic generation driven by two counter-rotating few-cycle laser beams. The circularly polarized supercontinuum is produced at a central photon energy of 33 eV with a transform limit of 190 as and a predicted linear chirp of 330 as. By adjusting the ellipticity of the two counter-rotating driving pulses simultaneously, we control the polarization state of isolated extreme-ultraviolet pulses--from circular through elliptical to linear polarization--without sacrificing conversion efficiency. Access to the purely circularly polarized supercontinuum, combined with full helicity and ellipticity control, paves the way towards attosecond metrology of circular dichroism.}, year = {2018}, journal = {Nature Photonics}, volume = {12}, pages = {349-354}, month = {2018-04}, issn = {1749-4885}, url = {https://www.nature.com/articles/s41566-018-0145-0}, doi = {10.1038/s41566-018-0145-0}, }