ANTICIPATION OF THE SWITCH-OFF AND DELAY OF THE SWITCH-ON OF A LASER WITH A SWEPT PARAMETER

The behavior of a CO2 laser brought from below to above threshold and back by modulating the cavity losses, is studied experimentally and theoretically. It is shown that the usual delay of the switch-on is followed by an anticipation of the switch-off. The competition of the delay and anticipation leads to positive and negative hysteresis cycles. Using numerical simulations we demonstrate that these phenomena always occur for lasers whose decay rate for the population inversion is smaller than the decay rate for the field.