Optimization Design Of Chirp-managed Lasers By Integral Layer-peeling Method

The increasing demands for larger communication bandwidth has driven the transmission networks towards larger capacity and higher speed.Low cost as well as high performance of the optical devices is very important with the commercialization of the high-speed short-reach/long-reach passive optical network and metropolitan switching network.The DML is compact and low cost.However,limited by modulation bandwidth and the parasitic frequency chirp,it is often used for short-reach access networks.The Chirp Management Laser(CML)is a transmitter technology that advances the direct modulation lasers(DML),which can adapt the original direct modulation lasers to higher speed and longer reach applications in optical communication networks.Compared with external modulation lasers,such as the electro-absorption modulated laser,the CML has the advantages of relatively simple structure,low power consumption and low cost.The CML mainly includes a DML and a optical spectral reshaper(OSR).In existing work,the multi FP cavity or multi ring filters are often adopted for the OSR implementation,which normally has a periodic comb-like spectral responses.If one of the narrow passing bands is selected as OSR,it will increase the extinction ratio of the output signal with suppressed noises,according to the working principle of the CML.However,this type of filter based on FP interferences inherently suffers the drawback that the slop of the pass-band edge and the bandwidth of the filter cannot be designed separately.As a result,targeting at optimizing the spectral response of the OSR filter in a more effective fashion,this thesis has proposed and studied the application of the integral layer-peeling(ILP)algorithm in synthesizing the grating-based OSR unit.A complete simulation platform is then developed to model the signal generation of the CML,transmission by the fiber link and reception by an optical receiver.By using this platform,we have investigated several important factors that impact the transmission performances in a standard fiber link,including the adiabatic chirp of the DML,the bandwidth and edge slope of the OSR filter.Optimization designs of the CML have been respectively given under the modulation speed of 10 Gbps and 25 Gbps.Finally,a prescribed dispersion property is encoded into the OSR by IPL algorithm to achieve a CML with dispersion pre-compensation,which successfully leads to a further increase of the transmission distance.The main contents of this thesis:1)By using the ILP algorithm,a grating-based OSR unit has been synthesized,i.e.the grating structure is obtained according to the prescribed spectral responses,to work as the OSR filter in the CML.2)Implemented a simulation platform of the optical transmitter,fiber link and the receiver.3)Optimization designs of the 10 Gbps and 25 Gbps CML in a typical setting of the system link have been carried by the implemented numerical model.4)A prescribed dispersion property is embeded into the OSR by IPL algorithm to achieve a CML with dispersion pre-compensation,which is in favor of a longer transmission distances.