This invention provides a solution for operating a regenerative amplifier using a single electro-optical device, such as a Pockels cell. An efficient cavity geometry of a regenerative amplifier is provided for enabling pulse selection, coupling and releasing to an output by operating a single Pockels cell unit placed essentially in the middle of the optical cavity, between two polarizers, whereas a first polarizer is used for release of an amplified pulse and a second polarizer is used for injection of seed pulses and release of at least one of waste amplified pulses and seed pulses. One side of the cavity, with respect to the location of said Pockels cell, includes an empty space, whereas the other side is provided with a gain medium, which is pumped by a pump source. The regenerative amplifier of such optical design is both efficient and cost effective. The single electro-optical unit works both as the control unit for operating the regenerative amplifier and as an output pulse picker unit.