Active photonic devices such as high speed optical modulators are required in various applications such as fiber optic communications, frequency shifting and also in fiber optic gyroscopes for space systems. Bulk lithium niobate have primarily been used due to the lack of method of creating low loss, high index waveguides. Thin film single crystal lithium niobate-on-insulator is a promising platform for advancing optical modulators due to the availability of strong electro-optic effect and high index contrast for wave guiding. We have achieved low-loss waveguides (< 3 dB/cm) in this material system based on our fabrication techniques. With this fabrication technique, we fabricated and characterized optical modulators based on Mach-Zehnder design. We have carried out simulation of the top-bottom electrode configuration and have shown higher electric field compared to side electrode placement which then reduces the required Vπ L hence reducing required length of the active region. Furthermore the arrangement of the electrodes allows a more uniform and directional field to applied across the lithium niobate. Lower drive voltage achieved will enable advances of use of lithium niobate-on-insulator in optical modulators which will be useful in future applications.