Patent ID: 7113702

Claim:
A wavelength division multiplexing (WDM) optical transmission system comprising: an optical transmitting section having an optical transmitter that generates N wave (wherein N is an integer of 2 or greater) optical signals with an optical frequency spacing Δf [Hz] and modulated by a modulation bit rate B [bit/s] (wherein B/Δf≦1 [bit/s/Hz]) using a modulation device, and having a coupler that couples the optical signals; an optical receiving section provided with an optical discrete Fourier transform (DFT) circuit that performs a DFT on wavelength division multiplexed signals transmitted from the optical transmitting section at a sampling frequency Δf [Hz] that is equal to the optical frequency spacing and separates the wavelength division multiplexed signals into signal components of each optical frequency; and a bit phase adjustor that makes bit phases of respective wavelength division multiplexed signals synchronous at an input terminal of the optical DFT circuit.