A non-destructive method for characterizing a surface-illuminated integrated optical coupler associated with an optical waveguide, comprising the steps of measuring the reflection coefficient on a first region of the coupler at a distance from the optical waveguide and constructing a first curve, determining a first model of the reflection coefficient on the first region, performing a first parameter fitting between the first curve and the first model to determine first parameters, measuring the reflection coefficient on a second region of the coupler close to the guide, and constructing a second curve, determining a second model of the reflection coefficient on the second region, performing a second parameter fitting between the second curve and the second model to determine second parameters, and constructing the characteristic of the coupling efficiency of the coupler using the first and second parameters.