Thin Films of Lithium Niobate for High Efficiency Electro-Optic Modulators

This Small Business Innovation Research Phase II project exploits the emerging technologies of wafer bonding and ion slicing, referred to as “smart-cut” to substantially improve the performance capability of lithium niobate based electro-optic modulators. The greatest problem has been to achieve high bandwidths while still maintaining low drive switching voltage. Material electro-optic coefficient, optical loss, dielectric loss and permittivity all contribute to these parameters, with lithium niobate currently representing the best balance of materials properties. This Small Business Innovation Research Phase II project develops novel materials processing techniques that extract the maximum possible performance out of the lithium niobate electro-optic material. Specifically, the lithium niobate material is reduced to a thin bulk crystal film on top of a low electrical permittivity and low loss microwave friendly substrate. This geometry vastly reduces dielectric loss and effective microwave index for the traveling wave electrode, making velocity and impedance matched low drive voltage modulators possible. Simulation results indicate that a switching voltage less than 1 Volt and 20 GHz bandwidth would be possible with the new thin film geometry.