International audienceIntensive use of Laser Guide Star (LGS) with the new generation of Extremely Large Telescopes and Hypertelescopes will requires the use of more efficient lasers to surmount the novel limitations and aberrations. The Pulsed Frequency Shifted Feedback (FSF) laser we have developed overcomes the saturation of sodium atoms and solves new problems. This work presents a highly efficient solution for operating pulsed FSF lasers. For the first time, an intra-cavity preamplifier achieves a gain of 104 and more than 40 μJ per pulse, with a near diffraction limited beam and without Amplified Spontaneous Emission. Endurance tests have shown that good performance is maintained over several hundred hours
