1.5 µm Emission Properties of Erbium‐Implanted Thin‐Film Lithium Niobate

Abstract

ABSTRACT Lithium niobate on insulator (LNOI) has emerged as a promising platform for photonic integrated circuits due to its strong electro‐optic, piezoelectric and nonlinear properties. The incorporation of rare‐earth ions, particularly erbium (Er 3+ ), enables potential functionalities such as quantum memory and single‐photon emission in the telecom band. This study presents a method for the Er 3+ doping of X‐cut LNOI using a focused ion beam (FIB) implantation system with sub‐100 nm spatial precision, demonstrating the ability to dope optically emitting rare‐earth ions into this technologically relevant platform. Photoluminescence (PL) studies of doped regions reveal characteristic emission consistent with bulk Er‐doped lithium niobate. The PL temperature dependence is studied from 300 to 5 K. The emission exhibits conventional behavior down to approximately 50 K, followed by a marked decrease in the emission intensity and lifetime at lower temperatures. This anomaly is suggested to relate to a suppression of the pyroelectric response in LiNbO 3 below 50 K, which affects the local electric field and consequently could modify the Er 3 + emission. The results demonstrate a method for targeted Er 3+ doping into the most widely used cut of LNOI for integrated photonic devices and provide further important considerations for their exploitation in cryogenic quantum devices.