Progress in Third-Harmonic Generation of Broadband Low-Coherence Light

Broadband low- coherence light is expected to overcome the laser- plasma instability in inertial confinement fusion. However, achieving an efficient third- harmonic generation of broadband low- coherence light remains a significant technical problem in engineering applications. Currently, limited research has been done on the third- harmonic generation of broadband low- coherence light. In this study, the characteristics of the broadband low- coherence light are introduced, along with the frequency conversion processes involving second- harmonic and sum frequency generation. Subsequently, the fundamental challenges for an efficient third- harmonic generation with broadband low- coherence light are presented and an overview of the developmental history, principles, and limitations of various broadband third- harmonic generation schemes is provided. In experiments on the frequency conversion of low- coherence light, the acceptance bandwidth and nonlinear coefficients of commonly used nonlinear frequency- conversion crystals are compared for reference. Finally, some suggestions for potential breakthrough directions are proposed for an efficient third- harmonic generation of broadband low- coherence light.