Multidimensional manipulation of nanoscale photothermal distributions using vortex beams.

Controlling and manipulating temperature at the nanoscale hold substantial promise for advancing applications such as photothermal therapy, nanoscale chemical reactions, and micro/nanodevices. However, current temperature regulation methods predominantly rely on continuously tunable optical parameters (e.g., wavelength and polarization), which limit discrete and digitally addressable control states and result in insufficient degrees of freedom for tailoring local temperature distributions. The orbital angular momentum (OAM) of light offers a novel perspective for light-near-field thermal interactions, yet its potential to regulate nanoscale spatial temperature distributions remains unexplored. Herein, we demonstrate the unique regulatory role of the OAM of vortex beams for nanoscale thermal fields. By tuning the phase distribution of vortex beams characterized by the helical phase factor eilϕ, pronounced spatially asymmetric temperature distributions and multiple local temperature inversions are induced in plasmonic structures. Through the synergistic modulation of key vortex beam parameters-including topological charge l, wavelength, and polarization direction-we achieve multi-degree-of-freedom reconstruction of thermal near-field distributions with subwavelength spatial resolution, where the temperature increase ratio is tunable over the range of 0.6-1.7. This work not only provides discrete and digitally addressable control states for thermal regulation but also broadens the understanding of light-thermal field interactions. It offers guidance for realizing multidimensional far-field optical control over local thermal distributions, opening a new route toward frontier applications such as micro-electro-mechanical systems (MEMS), spatially selective photothermal catalysis, nanoscale phase transition manipulation, and super-resolution photothermal therapy.