ELETTRA, Basovizza
INFN/LNF, Frascati (Roma)
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
EOS and coherent radiation based diagnostics of sub-psec electron bunches are longitudinal diagnostics adopted for FERMI and other 4th generation light sources. The performance of both kind of diagnostics depends on the material properties in the THz spectral range. There is a need to characterise the transmission of windows materials and to understand the absolute efficiency of electro-optic detectors. This requirement for absolute EO efficiency is particularly important given observed variations between individual crystals with nominal identical specifications. In this paper we report measurements with THz pulses produced with photoconductive emitters. Our main goal was the characterization of EO crystals such as ZnTe and GaP for EOS and THz windows materials and humidity absorption. Good agreement is found for EO between experimental results and theoretical calculations concerning temporal resolution.
University of Ljubljana, Faculty of Electrical Engineering, Ljubljana
I-Tech, Solkan
ELETTRA, Basovizza
This paper presents a good solution for timing distribution and RF synchronization of multiple events at multiple remote locations in the accelerator facility with femtosecond precision. The proposed electro-optical synchronization system makes use of commercial telecom single-mode optical fibre operating at 1550 nm. Such fibre is subject to change in phase and group velocity correlated to temperature variations and is sensitive to acoustic perturbations. The synchronization system described makes use of stabilization of the fibre link which transports low-jitter microwave signal over a distance of 300 m. It consists of a transmitter, located at the place of low-jitter master oscillator, and receiver, located at the remote location. Both units are connected by a pair of optical single-mode fibres. Using a fibre pair instead of a single fibre allows for compensation of fibre-length changes. The added timing jitter of 20 fs at 100 Hz - 20 MHz is measured on the first experimental synchronization system. Even lower jitter is expected by some planned improvements in the transfer system and the industrialization of it.
