Bound modes in the continuum in integrated photonic LiNbO3 waveguides: are they always beneficial?

We discuss several types of integrated photonic LiNbO3 waveguides supporting propagation of modes which can be classified as bound states in the continuum (BICs). The key properties leading to the existence of BICs (or quasi-BICs) considered here are the material anisotropy, the waveguide birefringence, or the combination of both. Typical examples are titanium diffused and proton exchanged waveguides in bulk LiNbO3 crystals and recently proposed dielectric-loaded waveguides on LiNbO3 thin films. Proton exchanged waveguides in thin film LiNbO3 are considered, too. These waveguide structures are discussed from the point of view of their benefit for applications, especially in electro-optic devices. (c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This article discusses several types of integrated photonic LiNbO3 waveguides that support the propagation of modes classified as bound states in the continuum (BICs). The key properties leading to the existence of BICs (or quasi-BICs) are material anisotropy, waveguide birefringence, or a combination of both. Typical examples include titanium diffused and proton exchanged waveguides in bulk LiNbO3 crystals, as well as recently proposed dielectric-loaded waveguides on LiNbO3 thin films.