Electro-optical single-sideband modulator

An electro-optical single-sideband modulator (1) comprising: €¢ an electro-optical substrate (2) ; €¢ a bimodal optical waveguide structure (3) formed in the substrate (2) to support different optical modes having associated optical frequencies (É S , É A ) and optical propagation constants (² S , ² A ) and comprising an optical input (IN) to receive an input optical carrier signal having an optical frequency (É S ), and a pair of optical outputs (OUT1, OUT2) to output corresponding SSB modulated optical signals, each having an optical frequency spectrum with a single side lobe; and €¢ an electrode structure (4) formed on the substrate (2) to receive an input electrical modulating signal having an associated electrical frequency (©) and electrical propagation constant (² © ), and to responsively apply an electrical field to the bimodal optical waveguide structure; wherein the bimodal optical waveguide structure (3) and the electrode structure (4) are so formed that the optical propagation constants (² S , ² A ) of the optical modes and the electrical propagation constant (² © ) of the electrical modulating signal meet a Phase Matching condition, according to which the optical propagation constant (² A ) of a first one of the optical modes is equal to the sum of the optical propagation constant (² S ) of a second one of the optical modes and the electrical propagation constant (² © ) of the electrical modulating signal, so resulting in the energy of the first optical mode being transferred at least partially to the second optical mode, and, as a consequence, in the optical frequency (É A ) of the second optical mode being equal to the optical frequency (É S ) of the first optical mode up-shifted of the electrical frequency (©) of the electrical modulating signal.