An active/passive mode-locked laser oscillator

A Q-switched/mode-locked Nd:YAG laser oscillator employing simultaneous active (electro-optic) and passive (saturable absorber) loss modulation within the optical cavity is described. This “dual modulation” oscillator can produce transform-limited pulses of duration ranging from <;50 psec to >;5 nsec with greatly improved stability compared to other mode-locked systems. The pulses produced by this system lack intrapulse frequency or amplitude modulation, and hence are ideally suited for amplification to high energies and for other applications where well-defined pulses are required.