Thin-Disk Regenerative Amplifier for Low-Loss Multi-Pass Gain

The patent implements multiple round trips of the seed laser through the thin-disk crystal by configuring the optical cavity with mirrors and beam splitters. The laser beam circulates through the amplification medium multiple times, accumulating gain with each pass. This periodic circulation allows the system to achieve high overall gain while maintaining a relatively simple single-stage amplifier structure, resolving the contradiction between device complexity and amplification effectiveness.

The regenerative amplifier design enables continuous amplification action by maintaining the laser beam in circulation through the thin-disk crystal for multiple round trips. Rather than a single discrete amplification event, the useful amplification action continues across multiple passes, accumulating energy transfer from the pump to the signal beam. This continuous action approach achieves high gain while avoiding the need for complex multi-stage cascading systems.

The patent employs dynamic control of the optical cavity using a Pockels cell as an electro-optic modulator. By applying voltage to the Pockles cell, the system can dynamically switch between storing amplified energy and releasing it as the final output. This dynamic control mechanism allows the system to achieve high gain through multiple round trips while using a single thin-disk crystal, avoiding the need for multiple crystals or complex cascaded amplifier structures.

The system changes the refractive index parameter of the optical cavity by applying voltage to the Pockels cell, which alters the polarization state of the circulating laser beam. This parameter change enables selective coupling of the amplified beam out of the cavity at the desired moment. By controlling this parameter dynamically, the system achieves high amplification effectiveness with a relatively simple single-stage structure rather than requiring complex multi-stage systems.