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.
Highlights
Direct visualization of ultrafast phenomena with atomic spatial resolution and femtosecond temporal resolution is one of the key challenges pursued in today’s science
In order to design an optimized synchronization phase-locked loop (PLL), we measured the timing jitter power spectral density (PSD) of the Ti:sapphire photocathode laser used in this work (Coherent Vitara-T with 79.33-MHz repetition-rate)
Note that the PSD for 1 0 kHz offset frequency is measured by the balanced optical cross-correlator (BOC)-based method[17] for higher measurement resolution
Summary
Direct visualization of ultrafast phenomena with atomic spatial resolution and femtosecond temporal resolution is one of the key challenges pursued in today’s science To achieve this goal, there have recently been intense research and development efforts for generating femtosecond X-ray pulses and electron pulses from FELs, UED and Thomson-scattering sources. The operation of these ultrafast X-ray/electron sources is based on well-coordinated interplay between ultrafast optical lasers and RF-driven electron accelerators Ultrafast optical lasers, such as femtosecond Ti:sapphire mode-locked lasers, are used to generate electron pulses by photoelectric effect (as a photocathode laser) and to excite ultrafast phenomena in pump-probe experiments (as a pump laser). For small- to mid-scale FELs, UED or Thomson-scattering sources, operating a separate OMO with fibre distribution links for laser-RF synchronization is often costly and unnecessary Since such facilities use a mode-locked solid-state (such as Nd:YAG4, Nd:YLF5, Yb:YAG6 and Ti:sapphire7–15) laser as www.nature.com/scientificreports/. The full time-domain and frequency-domain characterization results show 3.9-fs (rms) short-term residual timing jitter (integrated from 10 Hz to 100 kHz offset frequency) and 12.5-fs (rms) long-term residual timing drift over 24 hours, when synchronizing a commercial 79.33-MHz Ti:sapphire photocathode laser with an S-band (2.856-GHz in this work) RF oscillator
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
