Femtosecond dissipative quadratic soliton mode-locking of cavity-enhanced second-harmonic generation

Abstract Nonlinear frequency conversion underpins numerous classical and quantum photonics applications but conventionally relies on synchronized femtosecond mode-locked lasers and dispersion-engineered enhancement cavities—an approach that imposes substantial system complexity. To address the challenges, here we report a fundamentally different paradigm: mode-locking of nonlinear frequency conversion enabled by the physics of dissipative quadratic soliton (DQS). We present the operating princip