A tunable optical wavelength demultiplexer has a plurality of demultiplexer units formed on a planar waveguide. Modulation signals for one or more electrodes are produced as a function of any number of distinct digital codes. The color filters are arranged so that light that has passed through polarization optical elements is transmitted through an associated one of the color filters in a single color. Said array in its deployed condition for large solar elevation angles acquires a characteristic staircase-like form.