Large Quadratic Electro-Optic Effect of the PLZT Thin Films for Optical Communication Integrated Devices

Developing large electro-optic (EO) effect material is crucial technology for developing current levels of optical communication, and the lanthanum-modified lead zirconate titanate (PLZT) transparent thin films with an excellent theoretical quadratic EO coefficient has been paid great attention. High-quality PLZT thin films have been fabricated by improved sol–gel, including multiple spin coating and plasma annealing. The XRD patterns show the PLZT thin films with preferred (110) orientations and highly crystallized on the ITO/SiO2 substrate. The PLZT thin films are smooth and crack-free and can achieve a maximum transmittance of 93.8%. The piezo-response force microscopy images of the thin film reveal that non-180° domain determines the magnitude of the EO coefficient and plays vital role in the piezoelectric response. Furthermore, the effective quadratic EO coefficients of PLZT thin films are obtained by the designed test system. The quadratic EO measurements indicate excellent quadratic Kerr coefficient of 3.54 × 10–15 m2/V2, and the optical modulation effect of the EO modulator based on PLZT thin films is almost consistent with the theory and has low insertion losses. The PLZT thin films made in this study are a competitive candidate material as an optical modulator for modern optical communication.