High nonlinear optical performance in Pb(Mg1/3Nb2/3)O₃-PbTiO₃-based crystals

Pb(Mg1/3Nb2/3)O₃-PbTiO₃ (PMN-PT)-based crystals with ultrahigh electro-optic (EO) properties, have become key candidate materials for advanced photonic devices. However, unexplored third-order nonlinear refractive index (n₂) and laser-induced damage threshold (LIDTs) have hindered their breakthrough in ultrafast intense light modulation. In this study, the Z-scan technique was used to evaluate the application potential of PMN-PT-based crystals in nonlinear optical devices. Experimental results show that PMN-0.28PT with rhombohedral phase (R-phase) structure achieves an LIDT of 72.2 mJ/cm² under irradiation with an 800 nm, 100 fs femtosecond laser. Its n₂ was measured to be 5.37 × 10⁻¹⁸ m²/W, with a third-order nonlinear susceptibility of 2.74 × 10⁻¹¹ esu, exceeding those of Z-cut LiNbO₃ by 16 and 20 times, respectively. The ultra-high EO and n₂ performance of PMN-PT-based crystals will form a core basis for next-generation integrated high-performance photonics systems, with substantial significance and promising prospects.