Control of the duration of ultrashort pulses emitted from a Q-switched solid-state laser

An experimental investigation was made of a new method for controlling the duration of ultrashort pulses in the widest possible range (for pulses shorter than the resonator length) from the axial period to the reciprocal of the width of the gain band of the active medium. The method ensured complete reproducibility of all the parameters of the output radiation. A ruby laser with a saturable absorber in the resonator emitted pulses of ~35 psec duration when pulses of ~1.5 nsec duration were injected from outside into the resonator (the reduction in the pulse duration thus exceeded a factor of 40). The width of the emission spectrum was then close to the limit for a pulse with an exponential envelope.