Lithium niobate photonics: Unlocking the electromagnetic spectrum

Lithium niobate (LN), first synthesized 70 years ago, has been widely used in diverse applications ranging from communications to quantum optics. These high-volume commercial applications have provided the economic means to establish a mature manufacturing and processing industry for high-quality LN crystals and wafers. Breakthrough science demonstrations to commercial products have been achieved owing to the ability of LN to generate and manipulate electromagnetic waves across a broad spectrum, from microwave to ultraviolet frequencies. Here, we provide a high-level Review of the history of LN as an optical material, its different photonic platforms, engineering concepts, spectral coverage, and essential applications before providing an outlook for the future of LN. The optoelectronic and nonlinear optical properties of lithium niobate make it a workhorse material for applications in optics and communication technology. Boes et al. reviewed the science and technology of lithium niobate and its role in various aspects of photonic technology. They surveyed the evolution from bulk lithium niobate through weakly confining waveguides to the recent developments with thin-film lithium niobate. The ability to span the entire spectral range from radio to optical wavelengths illustrates the versatility of lithium niobate as a platform material in integrated photonics. —ISO A review discusses the science and technology of lithium niobate and its role in various aspects of photonics.