Continuous time crystals (CTCs) are nonequilibrium phases that spontaneously break continuous time-translation symmetry to sustain persistent oscillations under time-invariant driving. Here we report the first realization of CTC in a photorefractive carrier-transport system, using iron-doped lithium niobate (${\mathrm{LiNbO}}_3$) crystals under continuous-wave optical excitation. In this platform, carrier-driven nonlinearities give rise to persistent, tunable oscillations of phase-conjugate waves, directly evidencing time-crystalline order at room temperature. By varying excitation conditions, the ordered CTC phase evolves into intermittent chaotic dynamics with quasicrystal-like temporal features, where spikelike fluctuations reveal critical behavior near nonequilibrium phase transitions. Our work demonstrates that photorefractive carrier transport provides a solid-state route to time-crystalline order, offering new opportunities to probe symmetry breaking and criticality in driven many-body systems.

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• Nonlinear optics
• Time crystals