Subchannel security at the optical layer

A method of providing security at the physical layer of an optical network by processing an optical signal received on a fiber optic cable of the optical network, the fiber optic cable carrying a plurality of ITU (International Telecommunications Union) channels, each ITU channel having a corresponding ITU carrier frequency and a plurality of subchannels, each of the subchannels having a corresponding subcarrier frequency within that ITU channel, the method comprising the following steps:

• (a) receiving the optical signal along the fiber optic cable, demultiplexing the received optical signal into a plurality of ITU channels, and demultiplexing each ITU channel into a plurality of subcarrier frequencies of its corresponding ITU carrier frequency, each subcarrier frequency representing a corresponding subchannel within that ITU channel;
• (b) demodulating each subcarrier frequency of the ITU carrier frequencies into its corresponding subchannel of the ITU channels;
• (c) demapping each subchannel of the ITU channels into a buffered and synchronized encoded client signal, wherein each subchannel of the ITU channels corresponds to a subcarrier frequency of its corresponding ITU carrier frequency, and wherein each subcarrier frequency of its corresponding ITU carrier frequency is generated by a separate distinct laser;
• (d) extracting an encoded client signal from each buffered and synchronized encoded client signal;
• (e) decoding each encoded client signal;
• and
• (f) modifying dynamically over time one or more of the processing steps (a)-(e).