Abstract

We report on the nonlinear optical absorption of InN/In(x)Ga(1-x)N (x=0.8, 0.9) multiple-quantum-well structures characterized at 1.55 mu m by the Z-scan method in order to obtain the effective nonlinear absorption coefficient (alpha(2)) of the samples at high repetition rate. Saturable absorption is observed for the sample with x=0.9, with an effective alpha(2) similar to -9 x 10(3) cm/GW for the studied optical regime. For lower In content in the barrier, reverse saturable absorption is observed, which is attributed to two-photon absorption. (C) 2011 American Institute of Physics. [doi:10.1063/1.3535609]