Generation of microsecond pulses in a ring laser

A solid-state ring laser is described in which electrooptic negative feedback and a special law for the Q switch were used to obtain rectangular radiation pulses of miscrosecond duration. In order to compensate for the delay in the negative feedback signal, the transit times of the light pulse half way round the ring resonator and of the electrical pulse around the feedback loop were matched, so enabling the spike on the leading edge of the radiation pulse to be eliminated and the fluctuations of its top to be reduced. The use of a traveling-wave lasing regime made it possible to obtain stable rectangular microsecond pulses with a small number of transverse modes, and to reduce the radiation divergence to 3–4'.