An analysis of pulse propagation through a saturable absorber having excited-state absorption

The theoretical study of the propagation of a bell-shaped light pulse through a saturable absorber having excited-state absorption is presented . Assuming that the pulse-width is longer than the first excited-state lifetime of the absorber, a general expression for the steady-state transmission of the absorber is obtained . It is shown that when the excited-state absorption cross-section is larger than the ground-state absorption cross-section (reverse saturable absorber) the absorber acts as a power limiter . An explicit expression for the change of temporal pulse-width in a single transit through the absorber is obtained, which shows that the pulsewidth increases due to the presence of excited-state absorption . An analytical expression is presented for the optimum pulse intensity at which the maximum pulse broadening occurs