System and method for pilot tone modulation by data bias

Abstract

Embodiments are provided for applying pilot tone modulations to optical signals by introducing bias bits to data frames carried on the optical signals. Since the modulation is done by modifying data, the modulation depth is accurate, and there is no need for calibration or feedback control, which can improve power monitoring accuracy and simplify implementation. In an embodiment, a transmitter determines a period of a pilot tone modulation for tracking or identifying an optical channel. The transmitter inserts a sequence of bias bits, periodically according to the determined period, in a plurality of frames comprising original data bits. The amplitudes of the optical signals carrying the frames are modulated at a higher frequency than the pilot tone modulation. The optical signals are then transmitted including the bias bits within the frames.