Optical signal transmitter and optical communication system using constant modulus formats, and method for generating modulation codes

An optical data coding method for generating optical data codes from a symbol using a processor in communication with a memory, the method comprising steps of;

• selecting a modulation scheme comprising an X-polarization constellation format having first and second amplitude rings with circular grids corresponding to predetermined phase angles and a Y-polarization constellation format having the first and second amplitude rings with the circular grids corresponding to the predetermined phase angles;
• arranging a first part of the symbol on a first circular grid of the first amplitude ring on the X-polarization constellation format;
• arranging a second part of the symbol on a second circular grid of the second amplitude ring on the Y-polarization constellation format;
• encoding the first part of the symbol into a first subset of an optical data code using the first amplitude ring indicating a first amplitude value and the first circular grid indicating a first phase angle;
• and
• encoding the second part of the symbol into a second subset of the optical data code using the second amplitude ring indicating a second amplitude value and the second circular grid indicating a second phase angle.