吸收(声学)
色散(光学)
折射
光子
双光子吸收
非线性光学
光学
材料科学
分子物理学
原子物理学
物理
光电子学
激光器
作者
Xinshou Tian,Hai-Zhou Lu,Tian-Xiang Qian,Wenfa Zhou,Junyi Yang,Xifeng Yang,Sheng Ju,Zhongguo Li,Yinglin Song
摘要
We report the wavelength dependencies of the two-photon absorption coefficients β as well as the nonlinear refractive index n2 of undoped β-Ga2O3 single crystal in the spectral range 350–515 nm (0.51 < Ephoto/Eg < 0.75). Femtosecond Z-scan measurements show that n2 decreases monotonically toward the shortwave side, while the maximum value of n2 is 5.0 × 10−19 m2/W near half of the bandgap, Eg. Interestingly, a second upward trend in β was observed when the incident photon energy is larger than 0.6Eg, indicating the impact of additional inter-band transitions with higher energy. A higher-energy band-to-band transition around 6.0 eV was determined by both femtosecond nondegenerate two-photon absorption spectroscopy and ab initio calculations. Our results could provide guidance for designing nonlinear β-Ga2O3 photonic devices in the UV-visible spectral range.
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