Chen Shumei, Li King Fai, Li Guixin, Cheah Kok Wai, Zhang Shuang
1School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT UK.
Department of Materials Science and Engineering, Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055 China.
Light Sci Appl. 2019 Jan 30;8:17. doi: 10.1038/s41377-019-0128-z. eCollection 2019.
Electric-field-induced second harmonic generation (EFISH), a third-order nonlinear process, arises from the interaction between the electric field of an external bias and that of two incident photons. EFISH can be used to dynamically control the nonlinear optical response of materials and is therefore promising for active nonlinear devices. However, it has been challenging to achieve a strong modulation with EFISH in conventional nonlinear materials. Here, we report a large tunability of an EFISH signal from a subwavelength-thick polymer film sandwiched between a transparent electrode and a metallic mirror. By exploiting the band-edge-enhanced third-order nonlinear susceptibility of the organic conjugated polymer, we successfully demonstrate a gigantic EFISH effect with a modulation ratio up to 422% V at a pumping wavelength of 840 nm. The band-edge-enhanced EFISH opens new avenues for modulating the intensity of SHG signals and for controlling nonlinear electro-optic interactions in nanophotonic devices.
电场诱导二次谐波产生（EFISH）是一种三阶非线性过程，源于外部偏置电场与两个入射光子电场之间的相互作用。EFISH可用于动态控制材料的非线性光学响应，因此在有源非线性器件方面具有广阔前景。然而，在传统非线性材料中利用EFISH实现强调制一直具有挑战性。在此，我们报道了夹在透明电极和金属镜之间的亚波长厚聚合物薄膜的EFISH信号具有很大的可调性。通过利用有机共轭聚合物的带边增强三阶非线性极化率，我们成功地展示了在840nm泵浦波长下调制率高达422% V的巨大EFISH效应。带边增强的EFISH为调制二次谐波信号强度以及控制纳米光子器件中的非线性电光相互作用开辟了新途径。
