The Design And Implementation Of Low Cost Tunable SFP Module Based On DFB Laser Array

With the explosive growth of internet traffic,social requirements for network capacity and flexibility are getting higher and higher.DWDM technology is gradually expanding from backbone network and metropolitan area network to access network,because it can make full use of the huge bandwidth resources of optical fibers.Unlike backbone network,access network is very cost-sensitive,and its cost is borne by a few users.Therefore,the introduction of DWDM technology into access network must reduce the cost of DWDM equipment.However,in traditional DWDM systems,fixed-wavelength lasers are often used in optical transceivers,which results in low utilization of transceivers,high waste of resources and high cost,and increases the difficulty of system updating and maintenance.Even though some DWDM systems use tunable lasers in optical transceivers,the cost of tunable lasers is still very high due to the inherent defects of traditional chip manufacturing technology,and can not be widely promotedIn this thesis,the low cost wavelength-tunable small form-factor pluggable(SFP)module is proposed to help solve this problem.The wavelength-tunable SFP optical module is based on a self-designed 4-channel DFB laser array.The DFB laser array uses a unique chip fabrication technology,that is,reconstructed equivalent chirp(REC)technology.It has the advantages of high wavelength accuracy,low manufacturing cost,high yield and suitable for large-scale production.Semiconductor optical amplifier(SOA)is also integrated in the laser array to realize the modulation and output optical amplification of multi-channel lasers.This thesis starts with the principle and production process of REC technology.Then,according to the internal structure and characteristics of DFB laser array,a wavelength tuning method is designed:channel switching of 4-channel for coarse tuning and temperature tuning combined with current tuning for fine tuning to actualize the tunable output of the DFB laser array.On this basis,the overall design scheme of the tunable SFP module is proposed.The function and design of the hardware circuit are analyzed from three aspects:the transmitting part,the receiving part and the main control part.Then,according to the wavelength tuning mode of the tunable module,the communication protocol and command format for wavelength tuning are designed to realize the software control of the system.Finally,the transmitter and receiver performances of the tunable SFP module are tested.Experimental results show the tunable SFP module can achieve the continuity of wavelength tuning covering 1539.0 nm to 1551.0 nm.It can switch over 16 channels in a 100G-DWDM system or 31 channels in a 50G-DWDM system.The side mode suppression ratios(SMSRs)of most channels are above 40dB over the wavelength tuning range of 12 nm.The optical signal transmission rate is up to 1.25Gbit/s.The low-cost tunable SFP module studied in this thesis is expected to replace multiple fixed-wavelength optical modules in DWDM system,and can greatly reduce application costs,improve resource utilization and system flexibility.Therefore,this module is recommended to be widely used in DWDM systems,especially in cost-sensitive WDM-PON technology.