The Influence Of Integrated SOA On The Characteristics Of Tunable DBR Lasers

Distributed Bragg reflector(DBR)tunable lasers are essential components for future cost-sensitive optical access networks.DBR lasers have a wide tuning range and short tuning time(in nanoseconds),however the output power of single DBR laser is small and unstable.It might be an effective solution to Integrate Semiconductor Optical Amplifier(SOA)with a DBR laser.This article studies the effects of the SOA integrated with the three-section DBR tunable laser on its modulation characteristics,discusses the negative chirp compensation effect of SOA on the positive chirp induced by the directly modulated DBR,and researches the signal extinction ratio degradation problems caused by the SOA.In view of the DBR-SOA applications in the optical access network,the transmission characteristics of DBR-SOA module are analyzed in the simulation.Our works are as follows:(1)The simulation programs are coded through Matlab according to the independent theoretical model of DBR and SOA.Based on these,an integrated device model is established through spectral segmentation technique as well as boundary conditions.The established models would lay a solid foundation for our following researching.(2)The statics characteristics of single DBR lasers and that of SOA are obtained based on the single models.The comparison of small signal modulation characteristics between single three-section DBR lasers and the DBR-SOA module illustrates the influence of the SOA end reflectivity and the saturated gain characteristics of SOA on the small signal modulation bandwidth.(3)Large signal dynamic characteristics of both DBR lasers and DBR-SOA modules are studied through the numerical simulation.We studied the influences of the bias current and the modulation current to the laser chirp characteristic in the above lasers,analyzed the SOA chirp compensation effect on the directly modulated DBR and the modulated signal extinction ratio degradation caused by SOA,proposed to synchronously modulate SOA to improve the extinction ratio(ER)characteristics of DBR-SOA output signal,and studied the effect of synchronously modulate SOA on the chirp characteristics of DBR-SOA output signal.(4)The 10 Gbps optical transmission system is built through Optisystem for the transmission performance comparison of DBR signal and DBR-SOA signal.A better transmission performance can be obtained as the DBR-SOA is synchronously modulated.