Intensity modulator fabricated in LiNbO3 by femtosecond laser writing

Abstract

This work presents the design, development and characterization of an integrated optical modulator based on a Mach Zehnder Interferometer (MZI) recorded inside x-cut Lithium Niobate (LNB) wafers. These optical circuits were fabricated by means of femtosecond laser writing on LNB samples under planar configuration. Electro-optics modulation was achieved by adding metal electrodes on the LNB sample surface, configured as a coplanar strip layout. The latter fabrication procedure was conducted by using standard lithography and sputtering techniques from silicon platform. The MZI prototypes developed support single mode propagation at communication wavelengths (1.55 µm) and present a half wave modulation voltage, Vπ close to 45 V measured with a bias unbalance between arms of 15 V. The MZI prototype has unique constructive features because it takes the advantages of the femtosecond laser writing. Additionally, it can be a key element of an opto-electronic device to be implemented in many systems, with high impact among others technological areas such as optical communication, sensing and control.