The development of structured ultrafast laser sources is a key ingredient to advance our knowledge about the fundamental dynamics of electronic and spin processes in matter. In particular, it has been widely recognized the relevance of ultrafast sources structured in their spin angular momentum (SAM, associated to the polarization of light) and orbital angular momentum (OAM, associated with the transverse phase profile, or vorticity of a light beam) to study chiral systems and magnetic materials in their fundamental temporal and spatial scales. In that scenario, structured coherent extreme-ultraviolet (EUV)/soft x-ray pulses are emerging as unique tools to drive strong field physics, particularly thanks to the new opportunities they provide in the highly nonlinear process of high harmonic generation (HHG) [1,2].
Cylindrical vector beams are paradigmatic examples of structured beams, being defined by topological parameters, such as the Poincaré index. It is known that the topology of vector beams is directly transferred to the high-order harmonics when HHG is driven in gas targets [3,4]. In this context, crystalline solids stand as particularly appealing targets in HHG due to their characteristic symmetries which imprint an anisotropic nonlinear response [5].
In this talk we will review several works that have triggered the field of ultrafast structured EUV pulses during the last decade. We will compare the interplay of light and matter topology in HHG in gases and in crystalline targets. In particular, our macroscopic simulations of HHG in graphene [6, 7] allows us to study how the symmetry of the anisotropic response of the target couples with the driver’s topology. This scenario opens the route towards high-order harmonic spectroscopy techniques based on the topology of the harmonic radiation [7].
[1] L. Rego, K. Dorney, N. Brooks, Q. Nguyen, C. Liao, J. San Román, D. Couch, A. Liu, E. Pisanty, M. Lewenstein, L. Plaja, H. Kapteyn, M. Murnane, C. Hernández-García, Science 364, eaaw9486 (2019).
[2] L. Rego, N. J. Brooks, Q. L. D. Nguyen, J. San Román, I. Binnie, L. Plaja, H. C. Kapteyn, M. M. Murnane, C. Hernández-García, Science Advances 8, eabj7380 (2022).
[3] C. Hernández-García et al., Optica, 4, 520 (2017).
[4] A. de las Heras, A. Pandey, J. San Román, J. Serrano, E. Baynard, G. Dovillaire, M. Pittman, C. Durfee, L. Plaja, S. Kazamias, O. Guilbaud, C. Hernández-García, Optica 9, 71-79 (2022).
[5] Ó. Zurrón-Cifuentes, R. Boyero-García, C. Hernández-García, A. Picón, L. Plaja, Opt. Expr., 27, 7776-7786 (2019).
[6] R. Boyero-García, Ó. Zurrón-Cifuentes, L. Plaja, and C. Hernández-García, Optics Express 29, 2488-2500 (2021).
[7] A. García-Cabrera, R. Boyero-García, Ó. Zurrón-Cifuentes, J. Serrano, J. San Román, L. Plaja, C. Hernández-García, https://doi.org/10.21203/rs.3.rs-2161917/v1.