Two-photon absorption and nonlinear refraction of AlN from ultraviolet to near-infrared
Abstract
We report a detailed characterization of the wavelength dependency of two-photon absorption coefficient β and Kerr nonlinearity n2 in aluminum nitride (AlN) single crystal over a spectral range from 350 to 1030 nm (0.19 < Ephoto/Eg < 0.57). Femtosecond Z-scan results show that the dispersion of β compares favorably with the theoretical prediction at wavelengths shorter than 400 nm (half of bandgap Eg). However, the nonlinear refractive index n2 demonstrated a substantial deviation from theoretical calculations in the 350–450 nm regime, which is correlated with the sub-bandgap absorption band observed in AlN single crystal. The effects of trapped carrier-induced absorption and refraction were determined by femtosecond pump–probe measurements, which could be attributed to the transition from valence band maximum to mid-gap defect states in AlN. Our results provide guidance for developing AlN-based nonlinear integrated photonic devices in the UV–visible spectral range.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (7)
Zhong-guo Li
School of Electronic and Information Engineering, Changshu Institute of Technology 1 , Changshu 215500,
Wenfa Zhou
Department of Physics, Harbin Institute of Technology 2 , Harbin 150001,
Zenghua Wang
The 46th Research Institute, CETC 3 , Tianjin 300220,
Datang Xu
School of Electronic and Information Engineering, Changshu Institute of Technology 1 , Changshu 215500,
Xifeng Yang
School of Electronic and Information Engineering, Changshu Institute of Technology 1 , Changshu 215500,
Xuekun Hong
School of Electronic Information Engineering, Suzhou University of Technology 3 , Changshu, Jiangsu 215500,
Yinglin Song