Development of timing synchronization system and femtosecond laser seeding in NewSUBARU

We are developing a coherent light source combining an accelerator-based light source and a femtosecond pulsed laser at a synchrotron radiation facility of NewSUBARU. The aim is to demonstrate the principle that enables single-cycle free electron laser oscillation using the laser-seeding method. In the method, a femtosecond pulsed laser and electron bunch should interact in an undulator in a coaxial direction. Timing synchronization of the electron bunches and the femtosecond pulsed laser is then essential to realize the laser seeding. A Ti:sapphire laser system with a pulse duration of about 13 fs was installed at the experimental hall, and the laser pulses have been synchronized to the specific electron bunch in the storage ring. The synchronization precision was evaluated using a streak camera, and is sufficiently higher than the bunch width of the storage ring. The result has led to the successful observation of coherent pulsed light by laser seeding. The characteristics of the obtained coherent pulsed light is also reported. (author)