Cover Feature: Experimental Demonstration of Unified Kerr Nonlinear Effective Lengths for Gallium Phosphide‐On‐Insulator Photonic Devices (Adv. Photonics Res. 3/2026)

Four-Wave Mixing Four-wave mixing is an enabling technique for optical frequency generation and translation. Boosting four-wave mixing conversion efficiency is of central importance to a variety of applications that require rich spectral information. In their Research Article (10.1002/adpr.70166), Yi Li, Xingchen Ji, Qiancheng Zhao, and co-workers propose a new perspective that field enhancement can be interpreted as an elongation of effective length. A unified framework is established to bridge nonresonant waveguides and resonant cavities and is experimentally verified in the gallium phosphide-on-insulator platform.