Spiral-like beams from diametric drive acceleration with positive and negative effective mass in a photonic lattice

This paper predicts the spiral-like beams based on the effective mass tensor by extending the diametric drive acceleration mechanism to a two-dimensional local photonic lattice. Such spiral-like beams differ from conventional optical rotation mechanisms that rely on orbital angular momentum, spin-orbit coupling, or exotic materials. Instead, they arise from the combined effects of anisotropic effective mass properties and the optical Kerr effect, without requiring conventional angular momentum or chiral media. Numerical simulations show that the specific beam combinations, such as $\mathrm{\ensuremath{\Gamma}}\text{\ensuremath{-}}X$ and $M\text{\ensuremath{-}}X$, can induce spiral-like motion under both self-focusing or self-defocusing conditions. This study breaks through the physical constraints of existing optical rotation mechanisms, highlighting the crucial role of effective mass in optical field dynamics.