Record-high near-band-edge optical nonlinearities and two-level model correction of poled polymers by spectroscopic electromodulation and ellipsometry

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Detail(s)

Original languageEnglish
Pages (from-to)584-593
Number of pages10
Journal / PublicationScience China Chemistry
Volume65
Issue number3
Online published21 Dec 2021
Publication statusPublished - Mar 2022

Abstract

The determination of nonlinearities near the band edge of organic and polymeric electro-optic (EO) materials is important from the viewpoint of molecular nonlinear optics (NLO) and photonic device applications. Based on transmission-mode Stark effect electromodulation (EM) spectroscopy, we study the electric-field-induced changes in optical absorption and refraction of newly developed EO polymers from the visible to near-infrared (NIR) wavelengths and report record-high near-band-edge complex EO effects from poled thin films. Values of Δn and Δk up to 10−3 and 10−2 are found at an applied electric field of 2.0×105−3.0×105 V/cm. The study of linear optical properties of poled films by spectroscopic ellipsometry shows large poling-induced birefringence and a nearly two-fold increase in the extinction coefficients at the extraordinary polarization. Through the Kramers-Kronig analysis, we obtained the real and imaginary second-order nonlinear coefficients up to ∼3,500 and ∼5,600 pm/V, respectively, which are believed to be the highest NLO coefficients of poled polymers through the resonance enhancement. Our approach goes beyond the previous works, applicable only to several discrete wavelengths, to a full-spectral analysis with independent verification of slab waveguide measurements. By considering both the electroabsorption and electrorefraction effects, our study overcomes the limitation of the classic qualitative two-level model and provides a quantitative understanding of near-resonance optical nonlinearities of organic EO materials. It can inspire the exploration of high-speed, absorptive, or phase-shifting light-modulators using EO polymers for on-chip applications.

Research Area(s)

  • electro-optic effect, electroabsorption, poled polymers, second-order nonlinear susceptibilities

Citation Format(s)

Record-high near-band-edge optical nonlinearities and two-level model correction of poled polymers by spectroscopic electromodulation and ellipsometry. / Liu, Taili; Zhang, Di; Huqe, Md Rashedul et al.
In: Science China Chemistry, Vol. 65, No. 3, 03.2022, p. 584-593.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review