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.