  Lithium Niobate on insulator (LNOI) photonics promises to combine the
excellent nonlinear properties of Lithium Niobate with the high complexity
achievable by high contrast waveguides. However, to date, fabrication
challenges have resulted in high-loss and sidewall-angled waveguides, limiting
its applicability. We report LNOI single mode waveguides with ultra low
propagation loss of 0.4 dB/cm and sidewall angle of 75{\deg}. Our results open
the route to a highly efficient photonic platform with applications ranging
from high-speed telecommunication to quantum technology.
