Optical transmitter that transmits multi-level signal

An optical transmitter comprising:

• a modulator that modulates a first signal to generate a first modulated signal;
• a determinator that determines a modulo amplitude that is larger than an amplitude of the first modulated signal based on a modulation scheme of the first signal;
• an inserter that inserts a second modulated signal into the first modulated signal to generate a transmission signal;
• a signal processor that generates a pre-equalized signal by performing feedback equalization on the transmission signal, the feedback equalization correcting a symbol of the transmission signal by using an amplitude of one or a plurality of previous symbols, and performs subtraction and/or addition of amplitude of the pre-equalized signal and a value related to the modulo amplitude;
• and
• a transmission circuit that generates a modulated optical signal based on an output signal of the signal processor and transmits the modulated optical signal to a reception node, wherein
• an amplitude of the second modulated signal is equal to the modulo amplitude.