Nonlinear absorption of InN/lnGaN multiple-quantum-well structures at optical telecommunication wavelengths

摘要

We report on the nonlinear optical absorption of InN/In_xGa_(1_x)N (x=0.8,0.9) multiple-quantum-well structures characterized at 1.55 μm by the Z-scan method in order to obtain the effective nonlinear absorption coefficient (α_2) of the samples at high repetition rate. Saturable absorption is observed for the sample with x=0.9, with an effective α_2~-9×10~3 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.