The insensitivity of photons to magnetic fields calls for symmetry-based approaches in the design of photonic topological insulators. We experimentally demonstrate the realization of pseudomagnetic fields in deformed photonic crystals, and investigate the resulting photonic Landau-levels and guided topological states. Akin to strained graphene sheets, deformations (i.e., designed strain) in photonic crystals generate synthetic gauge fields for photons, leading to localization at flat bands and new types of topologically protected edge states at the boundaries of strained photonic crystals. We reveal that tailoring these gauge fields via strain-engineering yields new control over light dispersion, localization, and allows broadband minimization of radiation losses.
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