In a method of manufacturing a photonic integrated circuit having a compound semiconductor structure having a quantum well region, the structure is irradiated using a source of photons to generate defects, the photons having energy (E) at least that of the displacement energy (ED) of at least one element of the compound semiconductor. The structure is subsequently annealed to promote quantum well intermixing. The preferred radiation source is a plasma generated using an electron cyclotron resonance (ECR) system. The structure can be masked in a differential manner to selectively intermix the structure in a spatially controlled manner by controlling the exposure portions of the structure to the source of radiation. |