Optical intensity modulation device and method

A device for modulating an optical signal, comprising:

• an interferometer comprising:
• an optical signal divider;
• a plurality of arms;
• and an optical signal combiner arranged respectively to divide, convey and interferometrically recombine components of the optical signal into, along and from the arms;
• a DC electrode structure for biasing the interferometer at a working point of the device;
• an AC electrode structure for applying an electrical modulation signal to the interferometer;
• wherein
• the plurality of arms includes first, second and third arms,
• wherein the optical signal divider is structured so that the components of the optical signal coupled into the first and third arms are of approximately equal power, and
• wherein the AC electrode structure is configured so that the electrical modulation signal induces phase shifts of opposite sign and approximately equal magnitude in the first and third arms.