The photonic cavity-mediated precise control of femtosecond optical nonlinearity of several orders of magnitude enhancement is demonstrated in a novel nonlinear one-dimensional (1D) photonic crystal. The demonstrated photonic structure contains a highly nonlinear metal oxide, Bi₂O₃ as a central defect layer within two SiO₂/TiO₂ distributed Bragg reflectors. The nonlinear optical interactions of the electronic states of Bi₂O₃ with the cavity mode and adjacent photonic minibands are closely monitored by femtosecond Gaussian laser beam propagation over a wide-range of spectral wavelengths, 350–1600 nm. Abnormal cross-over from positive (reverse saturation) nonlinear absorption (RSA, β = (+)12 × 10^–10 m W^–1) to negative (saturation) nonlinear absorption (SA, β = (−) 11× 10^–10 m W^–1) is witnessed when the confined optical fields are strongly coupled to the excitation laser and mid-band gap energies of Bi₂O₃, during effective cavity length tuning. The femtosecond laser pulse propagation at different wavelengths effectively probed the multiphoton-induced optical nonlinearities, which are distinctly different from low- and high-energy minibands compared to the cavity resonance and are manifold-enhanced relative to pristine Bi₂O₃. The photonic mode density-dependent pronounced two-/multiphoton absorptions are systematically analyzed with experiments and simulations. The novel photonic architecture can be utilized in optical switches, optical limiters, and ultrafast photonic device applications.

中文翻译：

---

光子腔相互作用对 Bi2O3 基一维光子晶体飞秒多光子光学非线性吸收的影响

在一种新型非线性一维（1D）光子晶体中证明了光子腔介导的对飞秒光学非线性的几个数量级增强的精确控制。展示的光子结构包含高度非线性金属氧化物 Bi ₂ O ₃作为两个 SiO ₂ /TiO ₂分布式布拉格反射器内的中心缺陷层。_{Bi 2} O ₃电子态的非线性光学相互作用通过飞秒高斯激光束在 350-1600 nm 的宽光谱波长范围内的传播密切监测腔模式和相邻的光子微带。^{从正（反向饱和）非线性吸收 (RSA, β = (+)12 × 10 –10} m W ^–1 ) 到负（饱和）非线性吸收 (SA, β = (-) 11×10 ^–10的异常交叉当受限光场与激发激光和 Bi ₂ O ₃的中带隙能量强耦合时，可以看到m W ^{–1 )}，在有效的腔长调谐期间。不同波长的飞秒激光脉冲传播有效地探测了多光子引起的光学非线性，与腔谐振相比，这些非线性与低能和高能微带明显不同，并且相对于原始 Bi ₂ O ₃具有多种增强。通过实验和模拟系统地分析了光子模式密度相关的显着双/多光子吸收。新型光子架构可用于光开关、光限幅器和超快光子器件应用。