Topological solitons hold great promise for revolutionizing information and energy technologies, yet their controlled creation remains a major challenge. Here, we demonstrate room-temperature nucleation of fractional, skyrmion loops—three-dimensional, half-integer topological defects—within a nematic liquid crystal microfluidic cell. A single beam of linearly polarized light rotates the surface alignment, accumulating elastic twist until a topologically trivial texture collapses into a robust skyrmion loop. The loop’s cross section continuously morphs between half Néel skyrmions, antiskyrmions, and bimerons. Real-time polarized microscopy and Landau–de Gennes free energy based simulations reveal that the transition occurs via a $2\pi$ twist discontinuity and a sharp energy drop. The same protocol can be triggered by electric fields or local heating, and spawns a pair of $\pm 1$ topological monopoles that migrate along the loop to minimize the free energy. Our findings establish nematic liquid crystals as an optically rewritable, low-energy platform for generating arbitrary three-dimensional topological textures, offering immediate avenues for reconfigurable photonics and topological metamaterials.

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• Skyrmions
• Topological defects
• Nematic liquid crystals