Electro- and Thermo-Optics Response of X-Cut Thin Film LiNbO<sub>3</sub> Waveguides
Alessandro Prencipe, Katia Gallo
Abstract
Lithium niobate has been for decades the material of election for integrated nonlinear and electro-optics. Its recent availability in thin films affording subwavelength confinement of light and nanostructuring capabilities has led to ground-breaking results in numerous applications, ranging from ultrafast signal processing to efficient nonlinear optics, where electro-optic (EO) and thermo-optic (TO) functionalities can be further leveraged for enhanced tunability and reconfigurability. This work provides a consistent comparison between these two approaches in the most widely used configuration in LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanophotonics at telecom wavelengths. Using state of the art Bragg grating technology for high precision index measurements, we evaluate the guided-wave EO and TO tunability to be 3×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and 3.6×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , respectively, and study further operation and design tradeoffs, cross-talk effects and long-term stability. The results provide useful insights to identify the most appropriate strategies for implementing reconfigurable integrated photonic circuits effectively leveraging the unique features of LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> .