Lithium Niobate Quadratic Integrated Nonlinear Photonics: Enabling Ultra‐Wide Bandwidth and Ultrafast Photonic Engines

ABSTRACT Integrated photonic coherent light sources capable of generating emission with broad spectral coverage and ultrashort pulse durations are critical for both fundamental science and emerging technologies. In this perspective, we start by discussing emerging quantum and classical photonic applications from the standpoint of operating wavelength and timescale, highlighting the technological gaps that persist in current integrated photonic light sources. Next, we introduce the unique properties of lithium niobate–based integrated quadratic nonlinear photonics and discuss several promising strategies that exploit this platform to realize wavelength‐tunable continuous wave light sources and broadband, ultrashort light pulse generation. We also assess their advantages and limitations while discussing potential solutions. Finally, we outline future prospects and challenges that need to be addressed, aiming at inspiring continued research and innovation in this rapidly evolving field.