Optical communication system using mode-locked frequency comb and all-optical phase encoding for spectral and temporal encrypted and stealthy transmission, and for optical processing-gain applications

An optical system for transmitting data carrying optical information over an optical channel, comprising:

• a) an optical transmitter, that comprises:
• a.1) a light source being a Mode-Locked Optical Frequency Comb (MLFC) for generating a frequency comb of multiple carriers, each of which being modulated by a baseband signal;
• a.2) an optical modulator for modulating each and all of said multiple carriers in a modulation bandwidth extending up to the modes' frequency spacing between said multiple carriers;
• a.3) an optical encoder for all-optical encoding of the modulated carriers by manipulating the optical amplitude and/or phase of all optically modulated carriers, wherein said transmitter is adapted to transmit, by said optical transmitter, said encoded modulated carriers to an optical receiver, over an optical channel;
• and
• b) an optical receiver comprising means for performing coherent addition by:
• b.1) combining the received signal with a mode-locked optical frequency comb which operates as the optical multi-frequency local oscillator;
• b.2) applying opto-electronic coherent detection of the combined optical signal;
• b.3) performing baseband filtering of the “multi-homodyne” mixed signal between the identical frequencies of the two frequency combs at the receiver and the transmitter, by passing the photo-detected signal through a receiver of bandwidth narrower than the frequency spacing between the modes;
• b.4) filtering out all the detected cross-term mixing products between the two frequency combs.

An optical system for transmitting data carrying optical information over an optical channel, comprising:

• a) an optical transmitter, that comprises:
• a.1) a light source being a Mode-Locked Optical Frequency Comb (MLFC) for generating a frequency comb of multiple carriers, each of which being modulated by a baseband signal;
• a.2) an optical modulator for modulating each and all of said multiple carriers in a modulation bandwidth extending up to the modes' frequency spacing between said multiple carriers;
• a.3) an optical encoder for all-optical encoding of the modulated carriers by manipulating the optical amplitude and/or phase of all optically modulated carriers, wherein said transmitter is adapted to transmit, by said optical transmitter, said encoded modulated carriers to an optical receiver, over said optical channel;
• and
• b) an optical receiver comprising a photodiode for performing incoherent detection by:
• b.1) detecting the signal's intensity by applying self-homodyne opto-electronic direct-detection of the modulated optical signal;
• b.2) filtering the baseband of the “multi-direct-detection” signal;
• b.3) filtering out all the cross-term mixing products between the multi-frequencies of the comb by passing the photo-detected signal through said optical receiver, said optical receiver having a bandwidth being narrower than the frequency spacing between modes.