The ability to create multiple-wavelength chip with high spatial bandgap selectively across a III-V semiconductor wafer for monolithic photonic integration using a simple postgrowth bandgap engineering process such as quantum well intermixing (QWI) is highly advantageous and desired. Preferably, this process should not result in drastic change in both optical and electrical properties of the processed material. In addition, the process should also give high reproducibility to both lattice-matched and strained quantum well (QW) structures. In this paper, we report a new method that meets most of these requirements. This process is performed by first implanting the InGaAs/InGaAsP laser structures using phosphorous ion at 300 keV prior to QWI, the samples were pre-annealed at 600°C for 20 min. Subsequently the annealing temperature was ramped to 700°C and stayed constant for 120s for QWI. Blue bandgap shift of over 140 nm, relative to the as grown and control samples, has been obtained from the strained InGaAs-InGaAsP laser structure. Using this process, devices such as bandgap tuned lasers, multiple-section device such as integrated optically amplified photodetector have been demonstrated.