Enhanced Supercontinuum Spectral Broadening in Thin Film Lithium Niobate Tapered Waveguides

On-chip supercontinuum (SC) generation holds great potential for a wide range of applications, including imaging, optical coherence tomography, spectroscopy, and optical frequency comb technologies [1]. However, achieving broad and coherent SC on-chip is often constrained by the limitations of the material. Recent advances in the nanoscale fabrication of thin-film lithium niobate (TFLN) waveguides have shown great progress for the development of nonlinear devices, offering a wide transparency window, low propagation losses, and both <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\chi^{(2)}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\chi^{(3)}$</tex> nonlinearities [2], which enables <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f-2f$</tex> interferometry and cascaded nonlinear processes. As such, effective SC generation in TFLN have already shown promising performance [3], and chirped periodically poled waveguides have shown to expand the bandwidth significantly in the visible [4].