On-chip supercontinuum generation: from recent advances to applications [Invited]

Nonlinear frequency conversion is crucial for reaching new optical frequencies and creating light sources that are essential for research and industrial applications. Among the various strategies to generate a multispectral source, supercontinuum generation (SCG), which is the extreme spectral broadening from a pulsed laser source, is suitable for various applications in metrology, imaging, spectroscopy, and optical communications. While initially developed based on optical fibers, tremendous advancements in photonic integrated waveguides have been performed to benefit precise dispersion control, high nonlinearity, and compact size. The fast development of integrated platforms enables new nonlinear processes that go beyond classical SCG, pushing on-chip SCG toward practical applications. This review will begin with the SCG principle in the cubic χ (3) nonlinear process. Then we analyze recent advances in silicon nitride (SiN) for advanced dispersion, high-nonlinearity III–V platform for efficient SCG and lithium niobate (LN), which exploits both χ (2) and χ (3) nonlinearities. Finally, we present a comprehensive discussion of targeted applications, detailing their specific requirements for SCG performance. This analysis provides a forward-looking perspective on the future capabilities of on-chip SCG.