In this study, a single modelling approach based on fuzzy logic (FL) device is designed for a quantum-well (QW) laser diode to obtain the characteristic quantities and their dependences on wavelength and injection currents. The fuzzy rules are compiled using the input variables which are namely the wavelength and the injection currents, while the output parameters are the modal gain difference, the effective refractive index difference and alpha (alpha) parameter (linewidth enhancement factor). The suggested approach provides fast and reliable predictions which can prevent the engineers from rigorous experiments/calculations. The FL device provides the predictions of modal gain difference, effective refractive index difference and alpha parameter against the wavelength and the injection currents within the accuracy level of 90-99.9%. (C) 2011 Elsevier GmbH. All rights reserved.