Patent ID: 8842997

Claim:
A method comprising: conversion, by a first two digital-to-analog convertors (DACs), of a first pair of drive patterns at a rate of 2/Ts to output a first two analog drive signals, each of the first two analog drive signals having a non-zero value in a first half of the symbol period and value of about zero in a second half of the symbol period; performing Return To Zero (RZ) shaping of a first optical carrier by a first modulator whose output corresponds to a first polarization component using the first two analog drive signals; conversion, by a second two DACs, of a second pair of drive patterns at the rate of 2/Ts to output a second two analog drive signals, each of the second two analog drive signals having a value of about zero in the first half of the symbol period and a non-zero value in the second half of the symbol period; performing RZ shaping of a second optical carrier by a second modulator whose output corresponds to a second polarization component using the second two analog drive signals.