

Laser chain is a heart for electron accelerator; without it would be just a heap of metal.
Principle of operation
The laser chain produces two independent pulses on two different channels: the low rate channel (0.1 - 50 Hz), called "Radiolysis" and the high rate channel (1 kHz), called "Photolysis". The pulses from the low rate channel are synchronized with the accelerator.
The femtosecond laser chain fulfills several functions:
- It forms the electrons for the accelerator by excitation of the photocathode (low rate channel),
- It serves the Radiolysis pump-probe spectroscopy experiments linked to the accelerator (low rate channel),
- It is the source of femtosecond pulse photons for transient absorption experiments (high rate channel),
- It serves the start-up TERATONICS (high rate channel).
The laser chain includes:
- a femtosecond fiber oscillator ( C-Fiber 780 Femtosecond Erbium Laser) synchronized by the clock at about 79.8MHz. This source is common to both channels;
- a broadband stretcher common to both channels;
- a low rate diode-pumped amplification module, operating between 0.1 and 50 Hz, composed of a regenerative amplifier and a multi-pass amplifier, followed by a compressor (TRIDENT);
- a high rate diode-pumped amplification module, operating at 1 kHz, consisting of a regenerative amplifier and a multi-pass amplifier, followed by a compressor.
The output characteristics
Low rate channel “Radiolysis”:
- Pulse duration: 100 fs;
- Wavelength: 780 nm;
- Energy = 2 mJ;
- Frequency: 0.1 – 50 Hz. The frequencies used with the accelerator and for the Radiolysis experiments are between 0.1 and 10 Hz.
High rate channel “Photolysis”:
- Pulse duration: 130fs;
- Wavelength: 780 nm;
- Energy: 2.3 mJ;
- Frequency: 1 kHz.