Enhanced Electro‐Optic Coefficients in Single‐Crystalline BaTiO3 Thin Films Enabled by Domain Alignment

• Published in: Advanced optical materials 2024-05, Vol.12 (15), p.n/a
• Main Authors: Wen, Yiyang, Cao, Yilin, Chen, Haisheng, Du, Xiaona, Guo, Jiaxing, Shen, Jiaying, Zhang, Fan, Bian, Taiyu, An, Yu, Ren, Hongda, Wu, Zhenping, Liu, Weiwei, Zhang, Yang
• Format: Article
• Language: English
• Subjects: Alignment; Barium titanates; Buffer layers; electro‐optic coefficients; ferroelectric domain; Linear polarization; optical modulators; Pockels effect; Pulsed laser deposition; Pulsed lasers; Second harmonic generation; Silicon; Substrates; Thin films
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202303058

In silicon photonics, BaTiO3 (BTO) emerges as a promising electro‐optic (EO) integrated material due to its excellent EO modulation capabilities. Nevertheless, the EO response of multi‐domain BTO thin films tends to be lower than that of bulk materials. BTO thin films are fabricated with strong EO responses utilizing the pulsed laser deposition technique. Considering the importance of the SrTiO3 (STO) buffer layer, a series of epitaxial BTO thin films are deposited on STO substrates with engineered domain alignment. Given the contribution of domain variants in BTO thin films to their EO response, specific electrode patterns are designed to enhance their performance. An effective Pockels coefficient of 286 pm V−1 is determined for the BTO thin film via the transmission geometry method, which surpasses recent reports. Through domain engineering in the BTO thin film, the remarkable enhancement in the EO response arising from in‐plane polarization (a‐axis) characteristics is confirmed. Simultaneously, utilizing the Second Harmonic Generation (SHG) optical probe, deep exploration into the domain dynamics within BTO thin films is conducted. These findings provide insights into the contribution of domain variants to the EO response and shed light on further developing silicon‐based heterogeneously integrated devices. This work presents a notable electro‐optic (EO) coefficient of up to 286 pm V−1 stemming from domain engineering in epitaxial BaTiO3 (BTO) thin films. In situ domain dynamics in BTO films are analyzed by the Second Harmonic Generation optical probe. These findings provide insights into the contribution of domain variants to the EO response and promote the development of silicon‐based heterogeneously integrated devices.