Segment‐Chirped Periodically Poled Lithium Niobate Waveguides for Broadband Supercontinuum Generation

ABSTRACT Supercontinuum generation is a key technology in nonlinear optics, supporting a wide range of applications in frequency metrology and spectroscopy. Integrated photonics offers a promising route toward compact and efficient supercontinuum sources, yet extending the bandwidth while maintaining high spectral flatness remains a central challenge. Here we demonstrate an integrated broadband supercontinuum source based on segment‐chirped periodically poled lithium niobate (SC‐PPLN) waveguides. By discretizing the chirped poling profile into independently optimized segments, this approach enables high‐fidelity ferroelectric domain inversion with near‐ideal duty cycles and establishes broadband quasi‐phase matching, overcoming the domain inhomogeneity and efficiency limitations commonly encountered in conventional chirped poling. The engineered phase‐matching landscape supports efficient wavelength conversion and simultaneous activation of multiple second‐ and third‐order nonlinear processes. Experimentally, we achieve a supercontinuum spanning three optical octaves, from 320 nm in the ultraviolet to 2600 nm in the mid‐infrared. These results establish segment‐chirped poling as a practical strategy for broadband wavelength conversion and supercontinuum generation in integrated photonics.