The NTHU High-energy OPtics and Electronics (HOPE) Lab was established in 2008, aimed at goals of high-energy-density and high-energy-efficiency researches in photonics. I will describe how we use quasi-phase-matching nonlinear optics to implement smart laser and photonics devices covering a spectrum range from visible to far infrared. I will also talk about how we employ those smart nonlinear optical lasers to enable high brightness relativistic electron radiation from ultra-compact free-electron laser.