Mg_xZn_(1-x)O薄膜的折射率及三阶非线性研究

Refractive Indeces and Third-order Susceptibilities of Mg_xZn_(1-x)O Thin Films

利用电子束蒸发反应沉积技术，在蓝宝石和硅化玻璃衬底上生长得到MgxZn1-xO薄膜。立方相MgxZn1-xO（0．55≤x≤1．00）薄膜的折射率通过透射光谱技术和Manifacier方法计算得到。与六方相MgxZn1-xO薄膜相似，在400～800nm波长范围内，立方相MgxZn1-xO薄膜的折射率色散关系遵循最小平方根的一阶Sellmeier色散方程。不同组分的MgxZn1-xO薄膜的三阶非线性极化率采用光克尔效应（OKE）技术测试获得。六方-立方双晶相结构的Mg0.37Zn0.63O薄膜具有最大的三阶非线性极化率，其原因可归功于薄膜微结构中六方和立方晶相分离所导致的晶粒散射。

The MgxZn1-xO thin films were deposited on the sapphire and silica glass substrates by reactive electron beam evaporation deposition. Refraction indices of the cubicphase MgxZn1-xO （0.55≤x≤1.00） thin film alloys were obtained by the transmission spectra and Manifacier method. The Mg-concentration dependent dispersion at the wavelength from 400 to 800 nm follows the first-order Sellmeier dispersion equation that is similar to those of hexagonal MgxZn1-xO reported previously. Using optical Kerr effect（OKE）, the third-order susceptibilities of the ternary films over a wide range of Mg concentrations were determined. The sample with phase mixture of both hexagonal and cubic structures shows the largest third-order susceptibility. The difference observed in the magnitude of X^（3） of MgxZn1-xO films is attributed to the different microstructure of the ternary films, such as crystalline phase separation and crystal grains that enhance the stimulated scattering.