COPPER-LASER OSCILLATOR WITH ADJOINT-COUPLED SELF-FILTERING INJECTION

A new injection-controlled laser resonator developed to achieve diffraction-limited beam quality for high-gain short-pulse lasers is reported. The resonator is seeded with a short-pulse laser signal by adjoint-coupled injection. The two-times diffraction-limited injection beam is self-filtered through a prepulse cavity propagation to improve its beam quality. The use of a self-imaging unstable resonator diminishes the edge diffraction-induced beam deterioration. A beam quality of 1.1-1.3 times diffraction limited is achieved throughout the entire 70-ns laser pulse of a 30-W copper-vapor laser.