Reduced material loss caused by Electron Beam Lithography in thin-film lithium niobate through post-process annealing

Thin-film lithium niobate (TFLN), characterized by its low optical loss, remarkable optical nonlinearity and electro-optic properties, serves as an outstanding platform for integrated photonics. However, the existing processing techniques introduce potential damage, thereby impeding the development of high-performance optical devices. The specific sources of damage caused by the processing steps remain unclear. In this paper, we demonstrate that the high-energy electron beam utilized in the Electron Beam Lithography (EBL) process introduces material damage and thus significantly increase the optical loss in TFLN. We further illustrate that the introduced damage can be effectively repaired through post-process annealing, enabling the realization of microring resonators with intrinsic Q-factor (Qint) as high as 3.93 x 106 on X-cut TFLN.