Ferroelectric BiFeO3 thin-film optical modulators
Tsang, Siu Hon
Teo, Edwin Hang Tong
Date of Issue2016
School of Electrical and Electronic Engineering
Centre for Micro-/Nano-electronics (NOVITAS)
High quality epitaxial BiFeO3 (BFO) thin films have been grown on (001) SrTiO3 substrate by magnetron sputtering. Both a-axis and c-axis BFO orientations were studied. Prism coupler results reveal that the c-axis and a-axis refractive indices of the BFO thin films were 2.721 and 2.653 at 632.8 nm; the corresponding propagation losses were 4.3 and 4.6 dB/cm, respectively. An electro-optic modulator (EO) modulator based on such BFO film has been demonstrated with a fast switching time t=3.8us at 632.8 nm for the a-axis orientation and t=3.4us for c-axis orientation. Moreover, these BFO films gave the Pockels coefficient r eff=19.3pm/V for the c-axis orientation and r eff=15.9 pm/V for the a-axis orientation at 632.8nm. Such an anisotropic refractive index and linear EO behaviors are attributed to the epitaxial strain and stripe domain structure in the BFO thin films with mixed phases. This study illustrates the suitability of the BFO thin films for EO modulators and optical switches beyond their current extensive spintronic and memory applications.
Ferroelectric thin films
Thin film structure
Thin film structure
Applied Physics Letters
© 2016 AIP Publishing LLC. This paper was published in Applied Physics Letters and is made available as an electronic reprint (preprint) with permission of AIP Publishing LLC. The published version is available at: [http://dx.doi.org/10.1063/1.4953201]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.