State Key Laboratory on Fiber Optic Local Area Communication Networks and Advanced Optical Communication Systems, Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai 200240, China.
Opt Lett. 2013 Jul 1;38(13):2298-300. doi: 10.1364/OL.38.002298.
We propose and experimentally demonstrate a colorful nonlinear Raman-Nath second-harmonic generation by engineering the quadratic nonlinearity χ((2)) in an aperiodically poled lithium tantalite. The engineered nonlinear structure allows multicolored Raman-Nath second-harmonic signal outputs along a uniform direction, which cannot be achieved in a uniform nonlinear grating. The diffraction angles are independent of the beam waist and the position of incidence. This verifies that nonlinear Raman-Nath diffraction does not depend on the local superlattice structure where the fundamental frequency beam locates, but on the whole nonlinear χ((2)) crystal.
我们提出并实验演示了一种通过在非周期极化钽酸锂中工程化二次非线性 χ((2)) 实现的丰富多彩的非线性拉曼-纳特二次谐波产生。该工程化的非线性结构允许沿着均匀方向输出多色拉曼-纳特二次谐波信号，这在均匀非线性光栅中是无法实现的。衍射角与光束腰和入射位置无关。这验证了非线性拉曼-纳特衍射不依赖于基频光束所在的局部超晶格结构，而是依赖于整个非线性 χ((2)) 晶体。
