Parameters-dependent nonlinear absorptions in InGaN/GaN MQW and GaN film

The optical nonlinearities of an InGaN/GaN multiple quantum well (MQW) and a GaN film were experimentally investigated by using femtosecond Z-scan method in this paper. It was observed that the InGaN/GaN MQW displays a nonlinear saturable absorption (SA) effect and the nonlinear absorption coefficient β was determined to be -5.5x103cm/GW; and the GaN film shows a reverse saturable absorption (RSA) effect and the β is 7.5x103cm/GW. It is also found that the absorption cross sections and quantum confinement effect (QCE) give an influence on the SA of the InGaN/GaN MQW structure