  In this article, we studied intensity dependent third order nonlinear optical
response in ternary As40Sb7Se53 and As40Sb10Se50 chalcogenide glasses by
employing nanosecond Z-scan technique. At low intensity, we observed saturable
absorption in As40Sb7Se53 which makes a remarkable transition to reverse
saturable absorption at higher intensities. On the other hand, when the Sb
concentration increased in As40Sb10Se50, saturable absorption disappears and
the sample exhibits only two-photon absorption. Experimental results further
indicate that the strong two-photon absorption in our samples can be exploited
to fabricate high performance solid state optical limiting devices for next
generation all-optical network.
