The Vulcan laser can amplify a laser pulse to hundreds of Joules of energy. The laser amplifier chain is formed by a set of rod amplifiers and disc amplifiers.
The amplifiers have been manufactured using Nd:glass as the gain medium. The combination of amplifiers used to increase the energy of a pulse will depend on the type of pulse (short or long), the beam line used and the target area where the pulse is delivered.
The purpose of amplification is to get as much energy into the laser pulse as possible without exceeding the damage threshold of the laser glass. To achieve this we increase the beam diameter between each amplifier. The beam at the input of the chain is just a few millimetres in diameter and will be gradually expanded up to one- or two-hundred millimetres by the time it reaches the output of the disc chains.
There are two types of pulses to be amplified: short pulses and long pulses. These two pulses will be amplified to the mJ level of energy, in what we call the pre-amplification stage, prior to their injection in the rod chain and disc chain.
The short pulses are generated with energy of the order of nanojoules. The amplification of these pulses to a few mJ is either conducted in an OPCPA pre-amplifier or using the conventional pre-amplification stage where the pulse undergoes amplification in a couple of small diameter rod amplifiers. The long pulses are generated in a different type of oscillator that delivers a higher energy pulse, so they only require amplification by a single small rod amplifier.
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