Toward mid-IR FEL pulse stacking for peak power enhancement

We advance the development of underlying technologies for attoseconds next-generation light sources using the femtoseconds mid-IR light pulses from the oscillator free electron laser at Nihon University, through the high-harmonic generations. As a part of our project, currently we attempt an experiment of pulse energy enhancement by an external cavity, enough to process the non-linear phenomena of the high-harmonic generations. In this paper, we report on the result of test enhancement by an IR mode-locked fiber laser, and the current status of the pulse accumulation of free electron laser. (author)