Fabrication of PPLNOI Waveguides via In-situ Poling Monitoring and Optimized Dry Etching Conditions for Efficient Frequency Conversion

Lithium niobate on insulator (LNOI) is an important high <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-\chi^{(2)}$</tex> material platform for applications in nonlinear and quantum photonic integrated circuits [1]. Submicron-waveguide structures of periodically poled LNOI (PPLNOI) are particularly attractive, since they enable enhanced functionality through strong mode confinement and quasi-phase matching between different wavelengths, as well as improved scaling. To fully capitalize on these advantages, it is essential to fabricate waveguides with well-defined periodically poled domains and low optical losses, both of which remain technological challenges.