Diode-pumped Alexandrite laser instrument for next generation satellite-based Earth observation

In this work the first diode-pumped Alexandrite ring laser in Q-switched single-longitudinal mode (SLM) operation is presented. A carefully designed and complex ring resonator with several functional components is combined with an innovative pumping scheme with high-power red laser diodes. The spectral and energetic suitability of a first laser was demonstrated in hundreds of operating hours and, with a novel mobile lidar system, by the first measurements in the atmosphere by means of a diode-pumped Alexandrite laser, yielding data from the stratosphere to the mesosphere. An improved laser yields a pulse energy of 1.7 mJ at a repetition rate of 500 Hz with an excellent beam quality ofM2 < 1.1. By seeding the resonator with a narrow-band diode laser, SLM operation with a linewidth below 4 MHz is achieved. The electro-optical efficiency of 2 % is the highest archived for all Alexandrite lasers in SLM operation and reasonable for space-operation. The performance analysis as well as benchmarking with the space-qualified mounting technology point out the TRL and the remaining effort of development of the technology.