Polarization-multiplexed 100 Hz high-energy Nd:YAG multipass slab amplifier

We report on the realization and characterization of a high-efficiency diode-pumped solid-state amplifier integrated into a master oscillator power amplifier (MOPA) architecture. The system is specifically engineered to provide high-energy and throughput for next-generation space and earth observation missions, such as laser atmospheric profiling and altimetry. The PA is based on the optical amplification in a Brewster-cut Nd:YAG slab with an internal optical zigzag path to optimize the overlap efficiency between the pump and the flat-top extraction beam and adopts a multipass scheme based on multiplexing of the polarization state of the laser pulses. Operating at 1064 nm, the power amplifier demonstrates a robust energy extraction of more than 200 mJ per pulse in Q-switching (QS) regime, with a pulse repetition frequency (PRF) of 100 Hz and root mean square (RMS) average power fluctuations lower than 0.25%. Addressing the critical challenge of thermal management, the system exhibits a residual thermal focal length above 1 m. To the best of our knowledge, this is the first side-pumped Nd:YAG slab amplifier with zigzag optical path employing a polarization multiplexed three-pass configuration exceeding 200 mJ of extraction energy and operating with a PRF of 100 Hz at 1064 nm in QS regime.