Study Of All-optical OFDM Multiplexing Module And System Performance

For satisfy the increasing requirements of information transmission, optical fibercommunication system is developing toward the trends of a high speed, great capacity andlong span. In recent years, orthogonal frequency division multiplexing (OFDM) technologyin wireless field was introduced into the optical fiber communication field, and was beensutdied widely. Because of the strong resistance of dispersion and high spectral efficiency,optical OFDM has become one of the options for the future high-speed optical fibercommunication systems.In order to enable the optical OFDM system to break through the speed bottleneck ofelectronic device in signal processing, the thesis studys all-optical OFDM system around theoptical domain multiplexing and demultiplexing process of OFDM signal directly. Firstly, ananalysis of the OFDM basic theory is taked through a mathematical model, and themultiplexing and demultiplexing process for OFDM signal is derived by Fourier transformand inverter transform. By the way of processing for optical signal in the unit of phase shiftand delay, an all-optical module is constructed for OFDM demultiplexing based onMach-Zehnder interferometer (MZI) cascade structure and its fundamental. And thedemultiplexing spectrum of8subcarriers spaced with40GHz has been simulated.Then the topology of arrayed waveguide grating (AWG) is analyzed to have the abilityof Fourier transform for optical signal because of its characteristics of phase shift and timedelay, and the signal processing of AWG is derived. Two kinds of transmitter of all-opticalOFDM signal is constructed, and one of them has been simulated to transmit8channelssignal of40Gbps.Combine the transmitter of AWG and the MZI-based demultiplexing module, anall-optical OFDM system with four modulations is built to achieve8×40Gbps signaltransmission with160GHz bandwidth in400km fiber. The BER of the system in differentreceived optical power, optical SNR and dispersion is analyzed, and the high speedtransmission of the system is demonstrated to be effective.