An optical system (100) is described including: a reconfigurable optical device (103) with multiplexing wavelength division, comprising a plurality of actuators (A1-AN) and having associated a number of optical channels (M) and a number of degrees of freedom (N) lower than the number of optical channels; an optical stimulus source (106) connected to said reconfigurable optical device (103) to provide an optical stimulation signal (Sin) having a wavelength band including a plurality of wavelengths associated with the optical channels; an optical-electric conversion device (200) configured to receive from said reconfigurable optical device (103) an optical monitoring signal (Sout) corresponding to the optical stimulation signal (Sin) and to provide a group of electrical signals of intensity (SEL1-SELK) each representative of an intensity of the optical monitoring signal (Sout) evaluated at a relative wavelength included in said band. The system also includes a control device (110) configured to control the plurality of actuators (A1-AN) according to said group of electrical signals (SEL1-SELK) and according to a control law.