title: 10-fs-level synchronization of photocathode laser with RF-oscillator for ultrafast electron and X-ray sources.
abstract: Ultrafast electron-based coherent radiation sources, such as free-electron lasers (FELs), ultrafast electron diffraction (UED) and Thomson-scattering sources, are becoming more important sources in today's ultrafast science. Photocathode laser is an indispensable common subsystem in these sources that generates ultrafast electron pulses. To fully exploit the potentials of these sources, especially for pump-probe experiments, it is important to achieve high-precision synchronization between the photocathode laser and radio-frequency (RF) sources that manipulate electron pulses. So far, most of precision laser-RF synchronization has been achieved by using specially designed low-noise Er-fibre lasers at telecommunication wavelength. Here we show a modular method that achieves long-term (>1 day) stable 10-fs-level synchronization between a commercial 79.33-MHz Ti:sapphire laser oscillator and an S-band (2.856-GHz) RF oscillator. This is an important first step toward a photocathode laser-based femtosecond RF timing and synchronization system that is suitable for various small- to mid-scale ultrafast X-ray and electron sources.
authors.affiliation: School of Mechanical and Aerospace Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea.
authors.forename: Heewon
authors.initials: H
authors.lastname: Yang
authors.affiliation: Center for Quantum-Beam-based Radiation Research, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057, South Korea.|Department of Physics, Hannam University, Daejeon 34430, South Korea.
authors.forename: Byungheon
authors.initials: B
authors.lastname: Han
authors.affiliation: School of Mechanical and Aerospace Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea.
authors.forename: Junho
authors.initials: J
authors.lastname: Shin
authors.affiliation: School of Mechanical and Aerospace Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea.|University of Electronic Science and Technology of China, Chengdu 610054, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Hou
authors.affiliation: Department of Electronics and Information Engineering, Korea University, Sejong 30019, South Korea.
authors.forename: Hayun
authors.initials: H
authors.lastname: Chung
authors.affiliation: Center for Quantum-Beam-based Radiation Research, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057, South Korea.
authors.forename: In Hyung
authors.initials: IH
authors.lastname: Baek
authors.affiliation: Center for Quantum-Beam-based Radiation Research, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057, South Korea.
authors.forename: Young Uk
authors.initials: YU
authors.lastname: Jeong
authors.affiliation: School of Mechanical and Aerospace Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea.
authors.forename: Jungwon
authors.initials: J
authors.lastname: Kim