An optical transmitter, an optical receiver, and an optical transmission method are disclosed. The optical transmitter includes an optical signal generator, N spreaders, N pairs of data modulators, and a combiner, where the optical signal generator generates N optical carriers; an ith spreader spreads an ith optical carrier, to obtain a spread optical signal having two subcarriers; splits the spread optical signal into a first optical signal and a second optical signal; and delays the second optical signal to obtain a third optical signal; an ith pair of data modulators modulate the first optical signal and the third optical signal to obtain a pair of modulated optical signals, transmit the pair of modulated optical signals to the combiner, where the pair of modulated optical signals reaching the combiner differ by 1/(4 fsi) in time domain; and the combiner combines, into one optical signal, N pairs of modulated optical signals.