Research On The Modulation Ethods Used In The High Capacity Optical Communication Systems Of The Data Centers

The high-speed optical interconnection of data center has shorter transmission distance and less complexity than traditional high-speed optical communication network,but the energy consumption is higher.Therefore,it is very important to study the direct detection modulation technology for high-speed optical interconnection.The main work of this thesis is to study three main modulation formats which are suitable for high-speed optical interconnection in data center,and two of them are studied in depth.The main content of this thesis is as follows:(1)Three main modulation methods of short-range high-speed optical fiber communication are analyzed and studied in detail,which are PAM,DD-OFDM and CAP.The advantages and disadvantages of the three methods are compared,and the applicable scenarios of the three modulation methods are illustrated.PAM-4 is suitable for high-speed interconnection within the data center while DD-OFDM is suitable for high-speed interconnection between data centers within a city.(2)For the high-speed optical interconnection in the data center,the simulation model of optical fiber communication system based on PAM modulation format is established,and the encoding and decoding principle of PAM-4 modulation format is analyzed in detail.The high-order PAM modulation scheme is also studied.(3)For the high-speed optical interconnection between data centers,the simulation model based on DD-OFDM modulation format is established,and the principle of DD-OFDM is described in detail according to the transmission process in the simulation model.The dispersion of optical fiber decreases the signal quality and sensitivity of receiver in high speed and long distance transmission.Dispersion may be compensated by optical components or digital signal processing units.Improve OSNR can improve the signal quality of at the receiver.