Wang Wenjie, Sheng Yan, Roppo Vito, Chen Zhihui, Niu Xiaoying, Krolikowski Wieslaw
Key Lab of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China.
Opt Express. 2013 Aug 12;21(16):18671-9. doi: 10.1364/OE.21.018671.
We study second harmonic generation via nonlinear Raman-Nath diffraction in an optical superlattice that maintains a periodic modulation of the second-order nonlinear coefficient χ((2)) in transverse direction but undergoes random modulation in longitudinal direction. We show that the random χ((2)) modulation offers a continuous set of reciprocal lattice vectors to compensate for the phase mismatch of nonlinear Raman-Nath diffraction in the longitudinal direction, leading to more efficient harmonic generation for a wide range of wavelengths. We also characterize the intensity dependence of nonlinear Raman-Nath diffraction on the degree of randomness of the optical supperlattice.
我们研究了在一种光学超晶格中通过非线性拉曼 - 纳特衍射产生二次谐波的现象。该光学超晶格在横向保持二阶非线性系数χ((2))的周期性调制，但在纵向经历随机调制。我们表明，χ((2))的随机调制提供了一组连续的倒易晶格矢量，以补偿纵向非线性拉曼 - 纳特衍射的相位失配，从而在很宽的波长范围内实现更高效的谐波产生。我们还表征了非线性拉曼 - 纳特衍射强度对光学超晶格随机性程度的依赖性。
