Third-order optical nonlinearities of lead-free (Na1−xKx)0.5Bi0.5TiO3 thin films |
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Authors: | Ting Zhang Yonghai Chen |
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Affiliation: | a School of Physics and Electronics, Institute of Microsystem Physics, Henan University, Kaifeng 475004, China b Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China c National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China |
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Abstract: | (Na1−xKx)0.5Bi0.5TiO3 (NKBT) (x = 0.1, 0.2, and 0.3) thin films with good surface morphology and rhombohedral perovskite structure were fabricated on quartz substrates by a sol-gel process. The fundamental optical constants (the band gaps, linear refractive indices and absorption coefficients) of the films were obtained through optical transmittance measurements. The nonlinear optical properties were investigated by Z-scan technique performed at 532 nm with a picosecond laser. A two-photon absorption effect closely related with potassium-doping content was found in thin films, and the nonlinear refractive index n2 increases evidently with potassium-doping. The real part of the third-order nonlinear susceptibility χ(3) is much larger than its imaginary part, indicating that the third-order optical nonlinear response of the NKBT films is dominated by the optical nonlinear refractive behavior. These results show that NKBT thin films have potential applications in nonlinear optics. |
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Keywords: | 77.84.&minus s 42.70.Mp 78.68.+m |
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