Quantum well (QW) inter-mixing based post-growth energy band gap turning of 980 nm InGaAs/InGaAsP QW-structures for high power semi-conductor lasers has been investigated. The QW intermixing was carried out by depositing SiO2 thin film on the samples and followed by high temperature annealing. The band gap energy blue shift of the QWs after the intermixing under various conditions has been studied. The largest band gap energy blue shift of the QWs reaches exceeds 220 nm. (C) 2012 Elsevier Ltd. All rights reserved.