A semiconductor electro-optical phase shifter comprises a central zone (I1, I2) having a minimum doping level; first and second lateral zones (N+, P+) flanking the central zone along a first axis, respectively N and P-doped, so as to form a P-I-N junction between the first and second lateral zones. The central zone comprises first and second optical action zones (I1, I2) separated along the first axis. The second lateral zone is doped discontinuously along a second axis perpendicular to the first axis. Two electrical control terminals (A, C) are provided, one in contact with the first lateral zone, and the other in contact with doped portions of the second lateral zone.