Pulsed frequency-shifted feedback laser for laser guide stars: intracavity preamplifier.

Intensive use of laser guide stars with the new generation of extremely large telescopes and hypertelescopes will require the use of more efficient lasers to surmount novel limitations and aberrations. The pulsed frequency-shifted feedback (FSF) laser we have developed overcomes the saturation of sodium atoms and solves the new problems. This work presents a highly efficient solution for operating pulsed FSF lasers. For the first time, an intracavity preamplifier achieves a gain of 10(4) 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.