Optical-layer traffic grooming at an OFDM subcarrier level with photodetection conversion of an input optical OFDM to an electrical signal

A reconfigurable add-drop multiplexer (ROADM) node, comprising:

• one or more reconfigurable optical add/drop multiplexer subsystems, each configured to accept an input signal and to pass said input signal to each other ROADM subsystem for retransmission;
• an add/drop aggregator configured to receive the input signals from each of the ROADM subsystems and to control adding and dropping operations on the input signals;
• a grooming subsystem, comprising:
• at least two receivers, each configured to receive an input signal having one or more modulated subcarriers;
• each said optical receiver having a photodetector for converting the respective optical input signal into a respective electrical signal;
• a grooming processor configured to arrange the modulated input subcarriers at the subcarrier level into one or more modulated output subcarriers according to a grooming operation such that the modulated subcarriers are not demodulated or decoded prior to grooming, said grooming processor being a radio frequency RF processor for processing the electrical signals at a subcarrier level to produce an RF orthogonal frequency division multiplexing signal OFDM signal;
• and
• a transmitter FOR modulating the groomed RF OFDM signal by conversion of the groomed RF OFDM into an optical signal.