Photonic integration based on a ferroelectric thin-film platform

• Published in: Scientific reports 2019-11, Vol.9 (1), p.16548-8, Article 16548
• Main Authors: Abe, Shunsuke, Joichi, Tomoki, Uekusa, Kouichiro, Hara, Hideo, Masuda, Shin
• Format: Article
• Language: English
• Subjects: 639/624/1075/1079; 639/624/1075/401; Humanities and Social Sciences; Integrated circuits; Lanthanum; multidisciplinary; Optical properties; Optics; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-52895-y

Photonic-integrated circuits (PICs) using ferroelectric materials are expected to be used in many applications because of its unique optical properties such as large electro-optic coefficients. In this study, a novel PIC based on a ferroelectric thin-film platform was designed and fabricated, where high-speed optical modulator, spot-size converters (SSCs), and a variable optical attenuator (VOA) were successfully integrated. A ferroelectric lanthanum-modified lead zirconate titanate (PLZT) thin film was epitaxially-grown by using a modified sol-gel method, and it exhibits large electro-optic coefficients (>120 pm/V) and low propagation loss (1.1 dB/cm). The optical modulator, a Mach-Zehnder type, exhibited a half-wave voltage (V π ) of 6.0 V (V π L = 4.5 Vcm ) and optical modulation up to 56 Gb/s. Also, the VOA (with attenuation range of more than 26 dB) was successfully integrated with the modulator. As a result, it is concluded that the developed ferroelectric platform can pave the way for photonic integration.