Clock synchronization and polarization tracking in optical communication systems

An apparatus, comprising:

• a subsystem configured to generate a set of pilot optical frequency lines and a transmitter clock, wherein the transmitter clock is based on a frequency separation between at least two pilot optical frequency lines of the set of pilot optical frequency lines;
• a set of transmitter subsystems configured to generate a set of downstream data signals based on the transmitter clock;
• and
• a multiplexer configured to multiplex the set of pilot optical frequency lines and the set of downstream data signals for transmission via an optical communication channel.

A method, comprising:

• generating a set of pilot optical frequency lines and a transmitter clock, wherein the transmitter clock is based on a frequency separation between at least two pilot optical frequency lines of the set of pilot optical frequency lines;
• generating a set of downstream data signals based on the transmitter clock;
• and
• multiplexing the set of pilot optical frequency lines and the set of downstream data signals for transmission via an optical communication channel.

A method, comprising:

• receiving a multiplexed optical signal including a set of pilot optical frequency lines and a set of downstream data signals;
• generating a receiver clock based on the set of pilot optical frequency lines;
• and
• recovering downstream data from the set of downstream data signals based on the receiver clock.