Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
J Am Chem Soc. 2010 Jan 13;132(1):384-9. doi: 10.1021/ja908839s.
We report that the one-dimensional polar selenophosphate compounds APSe(6) (A = K, Rb), which show crystal-glass phase-change behavior, exhibit strong second harmonic generation (SHG) response in both crystal and glassy forms. The crystalline materials are type-I phase-matchable with SHG coefficients chi((2)) of 151.3 and 149.4 pm V(-1) for K(+) and Rb(+) salts, respectively, which is the highest among phase-matchable nonlinear optical (NLO) materials with band gaps over 1.0 eV. The glass of APSe(6) exhibits comparable SHG intensities to the top infrared NLO material AgGaSe(2) without any poling treatments. APSe(6) exhibit excellent mid-IR transparency. We demonstrate that starting from noncentrosymmetric phase-change materials such as APSe(6) (A = K, Rb), we can obtain optical glass fibers with strong, intrinsic, and temporally stable second-order nonlinear optical (NLO) response. The as-prepared glass fibers exhibit SHG and difference frequency generation (DFG) responses over a wide range of wavelengths. Raman spectroscopy and pair distribution function (PDF) analyses provide further understanding of the local structure in amorphous state of KPSe(6) bulk glass and glass fiber. We propose that this approach can be widely applied to prepare permanent NLO glass from materials that undergo a phase-change process.
我们报告了一维极性硒磷酸盐化合物 APSe(6)（A = K、Rb），它们表现出晶体-玻璃相转变行为，在晶体和玻璃态下均表现出强烈的二次谐波产生（SHG）响应。晶态材料是一类相位匹配的材料，其 SHG 系数 chi((2))分别为 151.3 和 149.4 pm V(-1)，适用于带隙大于 1.0 eV 的相位匹配非线性光学（NLO）材料。APSe(6)玻璃的 SHG 强度与无极化处理的顶级红外 NLO 材料 AgGaSe(2)相当。APSe(6)表现出优异的中红外透明度。我们证明，从非中心对称相转变材料（如 APSe(6)（A = K、Rb）），我们可以获得具有强、固有和稳定的二阶非线性光学（NLO）响应的光学玻璃纤维。所制备的玻璃纤维在很宽的波长范围内表现出 SHG 和差频产生（DFG）响应。拉曼光谱和配分函数（PDF）分析进一步提供了对 KPSe(6)块状玻璃和玻璃纤维非晶态局部结构的理解。我们提出，这种方法可以广泛应用于通过相变过程制备永久性 NLO 玻璃。
