Optical transmitter, optical receiver, and optical transmission method

An optical transmitter, comprising:

• an optical signal generator, N spreaders, N pairs of data modulators, and a combiner, wherein N is a positive integer;
• and
• the optical signal generator is configured to generate N optical carriers with a single wavelength;
• an ith spreader is configured to:
• spread an ith optical carrier generated by the optical signal generator, to obtain a spread optical signal having two subcarriers, wherein frequencies of spread optical signals generated by different spreaders are different;
• and split the spread optical signal into two signals, wherein the two signals are a first optical signal and a second optical signal, and delay the second optical signal to obtain a third optical signal;
• an ith pair of data modulators are configured to:
• modulate the first optical signal and the third optical signal that are obtained by the ith spreader through processing, to obtain a pair of modulated optical signals, and transmit the pair of modulated optical signals to the combiner, wherein the pair of modulated optical signals reaching the combiner differ by 1/(4fsi) in time domain, fsi represents a spreading frequency of the ith spreader, and i is any positive integer not greater than N;
• and
• the combiner is configured to:
• combine, into one optical signal, N pairs of modulated optical signals transmitted by the N pairs of data modulators, and send the optical signal.