Theory of Z-scan technique using Gaussian-Bessel beams with a phase object

• Published in: Chinese physics B Vol. 19; no. 7; pp. 251 - 255
• Main Author: 金肖 税敏 王玉晓 李常伟 杨俊义 张学如 杨昆 宋瑛林
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.07.2010
• Subjects: Beams (radiation); Gaussian; Gaussian beams (optics); Mathematical models; Nonlinearity; Phase objects; Refractive index; Refractivity; 三阶非线性极化率; 扫描技术; 扫描测量; 测量灵敏度; 相位物体; 非线性系数; 高斯光束
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/19/7/074203

This paper reports the theoretical study of combining Z-scan technique with Gauss-Bessel （GB） beams beside a phase object （PO） to measure the third-order nonlinear susceptibility components. By using this method, the sign of refractive index which depends on the shape of the close aperture Z-scan curve can be easily determined. Meanwhile, the magnitude of nonlinear coefficients can also be deduced by theoretical fit. The proposed method is advantageous for high sensitivity and imposes a lower stress in the cases of fragile materials, since small pulse energy is enough for the measurement of nonlinear coefficients. Predictions of the models are compared with Gaussian Z-scan measurement and GB Z-scan measurement. By using GB beams with a PO, the sensitivity of Z-scan measurements is found to be a factor of over 60 times greater than for Gaussian beams and 2 times greater than for Gaussian-Bessel beams.