Over the past few decades the use of structured light (i.e., light with nontrivial, but programmable, polarization, intensity and phase) has revolutionized our ability to control and enhance light-matter interactions, resulting in a myriad of applications ranging from super-resolution microscopy, telecommunications, optical manipulation, forensic science, and even attosecond physics [1,2]. In particular, light waves with programmable spin and orbital angular momentum (SAM and OAM, respectively) have sparked a revolution in attosecond science, owing to their ability to resolve ultrafast chiral and topological dynamics in emerging material systems with nanoscale spatial and few-to-sub femtosecond temporal resolution [2].
In this talk, I will describe our recent progress in generating extreme ultraviolet (EUV) beams —and attosecond pulses— with designer SAM and OAM properties. By exploiting the nonlinear process of high-harmonic generation, I will describe how we can harness full control of the polarization, divergence, intensity, and topological charge of EUV beams, allowing, for example, the generation of spatially isolated attosecond pulses with opposite circular polarization [3], EUV optical vortices with low, tunable OAM charge and low divergence [3], and coherent EUV light possessing an entirely new optical property associated with a time-varying OAM: the self-torque of light [4]. These unique attosecond waveforms, together with knowledge of how to specifically control their properties, enables new paradigms in extreme light science, ultrafast spectroscopy, and coherent imaging of condensed-matter and chiral dynamics. Finally, I will conclude be describing several ongoing experiments that aim to employ these exotic optical waveforms for enhanced spectroscopy and imaging of ultrafast, nanoscale, and chiral dynamics.
JILA — Department of Physics, University of Colorado Boulder and NIST Boulder