A system and method for generating an optical return-to-zero signal. The system includes a bit separator configured to receive an electrical non-return-to-zero signal and generate a first signal and a second signal, and a driver configured to receive the first signal and the second signal and generate a driving signal. The driving signal is associated with a difference between the first signal and the second signal. Additionally, the system includes a light source configured to generate a light, and an electro-optical modulator configured to receive the light and the driving signal, modulate the light with the driving signal, and generate an optical signal. The electrical non-return-to-zero signal includes a first plurality of bits and a second plurality of bits. The first signal includes the first plurality of bits, and the second signal includes the second plurality of bits. The optical signal is an optical return-to-zero signal.