The Design And Implementation Of 40G QSFP+LR4 Optical Module

In the past few years,in response to the rapid development of high-definition video,cloud storage and cloud computing business,the world's leading IT giants and telecom operators are actively planning to build large-scale data centers.Traditional 10 G Ethernet is obviously unable to meet the high-bandwidth requirements of data center;it's inevitable that the next generation high-speed Ethernet is being applied.In June 2010,IEEE(Institute of Electrical and Electronics Engineers)has officially published the 40G/100 G Ethernet standards: IEEE 802.3ba,which paved the way for commercializing 40 G and 100 G.Considering the cost and product maturity,40 G Ethernet has been widely used in data centers.The corresponding 40 G optical modules have also achieved good results in the booming field of data center,and will have a huge prospect in the foreseeable future.In this context,this paper presents a design scheme of 40 G QSFP+ LR4 module based on the IEEE 802.3ba 40GBASE-LR4 and QSFP+ MSA,and verifies the feasibility.The scheme uses 4 MAXIM's MAX3949 11.3Gbps laser drive chips as the transmit driving unit,a Silicon Labs C8051F390 microcontroller is used to provide controlling and registers storage functions,and a 40 G CWDM laser is used as TOSA.This paper consists of 6 parts: the first part introduces the development status and trends of 40 G optical modules;the second part introduces the 40 G Ethernet standards: IEEE 802.3ba and QSFP+ Multi-Source Agreement;the third part analyzes QSFP+ LR4's working principle and introduces the scheme of main hardware design;the fourth part introduces the module's registers design and configuration;the fifth part introduces the test scheme of the optical module based on the existing hardware equipment,and analyzes the test results;the last part makes the summary and outlook of the paper.The test results indicate that the optical transceiver module's output optical power is stable;the extinction ratio can be kept in the vicinity of 5dB,output eye diagram is good;4 channels maximum sensitivity is-12 dB.All the indicators meet the IEEE 802.3ba agreement on 40 G BASE-LR4 and QSFP+ MSA specification,satisfy the commercial application in 40 G Ethernet.