Ferroelectric nematic liquid crystals (FNLCs) represent a frontier in soft matter physics, offering unprecedented coupling between fluid order and electric polarization. However, achieving precise 3D control over their polar director fields remains a formidable challenge due to strong electrostatic interactions that typically favor uniform or twisted orientations. Here, we demonstrate the realization of a spontaneously stabilized "lying" polar helix—a configuration historically elusive in polar fluids—enabled by a bespoke chiral dopant. We uncover a distinct topological evolution driven by the competitive interplay between chirality and polar ordering: the system undergoes a symmetry-breaking transition from an apolar helix to a "lying" polar helix (FP1*), and ultimately to a "standing" polar helix (FP2*) mediated by topological soliton defects. Crucially, unlike conventional cholesteric fingerprints that require antagonistic confinement, this polar lying helix emerges as a thermodynamic ground state without external fields, offering a robust platform for self-assembled second-order nonlinear optical diffraction with microscale periodicity. We further demonstrate the arbitrary programmability of these superstructures via photopatterning and low-field switching. Our findings bridge the gap between soft-matter self-assembly and giant nonlinearity, establishing a paradigm for reconfigurable active topological photonics.
Zhu et al. (2026) studied this question.