Gigantic electric-field-induced second harmonic generation from an organic conjugated polymer enhanced by a band-edge effect

Shumei Chen; King Fai Li; Guixin Li; Kok Wai Cheah; Shuang Zhang

doi:10.1038/s41377-019-0128-z

Gigantic electric-field-induced second harmonic generation from an organic conjugated polymer enhanced by a band-edge effect

Light Sci Appl. 2019 Jan 30:8:17. doi: 10.1038/s41377-019-0128-z. eCollection 2019.

Authors

Shumei Chen¹, King Fai Li², Guixin Li², Kok Wai Cheah³, Shuang Zhang¹

Affiliations

¹ 1School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT UK.
² Department of Materials Science and Engineering, Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055 China.
³ 3Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong China.

Abstract

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^- ¹ 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.